CONTINUOUS PROCESS FOR THE PREPARATION OF PROPYLENE OXIDE

专利摘要:
a continuous process for the preparation of propylene oxide, comprising (a) reacting propene with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining an s0 stream containing at least propylene oxide, acetonitrile, water an additional component b, wherein the normal boiling point of the at least one component b is greater than the normal boiling point of acetonitrile; (b) separating propylene oxide from s0 to obtain a stream s1 containing acetonitrile, water and the at least one additional component b; (c) split s1 into two streams, s2 and s3; (d) subject s3 to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction s4a being depleted, in relation to s3, of at least one of the at least one component b, obtaining a liquid bottoms stream s4b, and subjecting at least part of the vapor fraction stream s4a to a vapor-liquid fractionation in a second fractionating unit, obtaining a vapor fraction stream s4c and a liquid bottoms stream s4 being impoverished, relative to s4a, of at least one of the at least one component b; (e) recycle at least a portion of s4, optionally after work-up, to (a).
公开号:BR112017008648B1
申请号:R112017008648-4
申请日:2015-10-27
公开日:2021-08-10
发明作者:Joaquim Henrique Teles；Dominic RIEDEL；Bianca Seelig；Philip Kampe；Markus Weber；Alexander Schroeder；Andrei-Nicolae PARVULESCU；Ulrich Mueller；Daniel Urbanczyk；Meinolf Weidenbach；Werner WITZL；Holger Baer
申请人:Dow Global Technologies Llc；Basf Se；
IPC主号:

专利说明:

[0001] The present invention relates to a continuous process for the preparation of propylene oxide, in which, in a downstream acetonitrile solvent recovery stage, a stream S1 containing the acetonitrile solvent and at least one component that has a normal boiling point, which is higher than the normal boiling point of acetonitrile, where the decadic logarithm of the octanol-water partition coefficient (log KOW) of at least one component B, measured at 25 °C, is greater than zero, it is divided into two streams S2 and S3, where the total weight of S3 in relation to the total weight of S1 is in the range of 0.01 to 25%. Stream S3 is subjected to a vapor-liquid fractionation comprising fractionation units coupled in series, and a stream S4 obtained from the depleted vapor-liquid fractionation of the at least one component B, optionally after further processing (workup), is recycled as a solvent stream to the epoxidation reaction.
[0002] Especially in industrial scale continuous processes for the epoxidation of propene to acetonitrile as solvent, one of the key aspects of the general process is the recycling of the solvent back to the epoxidation step. An advantageous process which allows to effectively recycle acetonitrile is described in WO 2011/006990 A1. That document discloses a method for separating acetonitrile from water, which method can be advantageously included in a continuous process for preparing propylene oxide in acetonitrile as a solvent. In carrying out this epoxidation process, it was found that, although the process allows to achieve excellent results, in particular with regard to the recycling of acetonitrile, certain impurities contained in at least one of the starting materials in the acetonitrile or hydrogen peroxide, used for the epoxidation reaction or obtained during the epoxidation reaction as by-products or by-products or formed during at least one of the work-up stages, which are preferably carried out downstream of the epoxidation reaction, may tend to accumulate in the current of acetonitrile recycling. These impurities may additionally tend to have a negative influence on the performance of the heterogeneous catalyst that is preferably employed in the epoxidation process, in particular a zeolite-based catalyst with MWW frame structure and containing Ti. Such a decrease in performance can be observed both in a decrease in selectivity and/or catalyst activity.
[0003] Therefore, it is an objective of the present invention to provide an economically advantageous continuous process for the preparation of propylene oxide in acetonitrile as a solvent, which allows to essentially avoid the accumulation of such impurities in the acetonitrile solvent recycling stream.
[0004] In general, if such impurities accumulate in a given stream, the stream is subjected to one or more suitable separation stages, such as distillation stages which, if carried out under suitable distillation conditions, can result in a stream depleted of impurities. However, in particular, in industrial scale processes, subjecting a solvent recycling stream to such separation stages necessarily involves considerable investment and energy consumption, due to the generally high flow rates and thus the resulting large apparatus.
[0005] However, it has been found that, for the separation of impurities from an acetonitrile, the recycling stream in a continuous process for the preparation of propylene oxide, this disadvantage can be avoided by submitting only a fraction of a stream of specific recycle for impurity separation using a specifically designated fractionation unit, and leaving the main portion of that specific recycle stream untreated. For those impurities that are found to be critical, it has been found that catalyst performance can be assured over a very long period of time although only such a smaller portion of a recycle stream is subjected to impurity separation.
[0006] Therefore, the present invention relates to a continuous process for the preparation of propylene oxide, comprising: a) reacting propene, optionally mixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as a solvent, obtaining a current S0 leaving the reaction apparatus, S0 containing propylene oxide, acetonitrile, water, at least one additional component B, optionally propene and optionally propane, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and where the decadic logarithm of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero; b) separating propylene oxide from S0, optionally after separating propene and optionally propane, obtaining a stream S1 containing acetonitrile, water and the at least one additional component B; c) divide S1 into two streams S2 and S3, where the total weight of S3 in relation to the total weight of S1 is in the range of 0.01 to 25%; d) subjecting S3 to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction S4a being depleted in relation to S3 of at least one of the at least one component B, and obtaining a liquid bottoms stream S4b, and subjecting at least part of the vapor fraction stream S4a to a vapor-liquid fractionation in a second fractionating unit, obtaining a vapor fraction stream S4c and a bottoms stream liquid S4 being depleted, relative to S4a, of at least one of the at least one component B; e) recycling at least a portion of S4, optionally after work-up, to (a), and recycling at least a portion of S2, optionally after processing (work-up), to (a).
[0007] Step (a)
[0008] According to step (a) of the present invention, propene, optionally mixed with propane, is reacted with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent.
[0009] In general, there are no specific restrictions on how propene optionally mixed with propane is reacted with hydrogen peroxide, whereas the S0 stream is obtained by leaving the reaction apparatus, such S0 stream contains propylene oxide, acetonitrile, water, the at least one additional component B is optionally propene and optionally propane.
[0010] In general, it is conceivable to use a pure or essentially pure propene as a starting material and as a stream subjected to epoxidation in (a). Preferably, a mixture of propene and propene is used. If a mixture of propene and propane is used as the stream subjected to epoxidation in (a), the weight ratio of propene:propane is preferably at least 7:3. For example, commercially available propylene can be employed which can be either a polymer grade propene or a chemical grade propene. Typically, polymer grade propene has a propene content in the range of 99 to 99.8% by weight and a propane content in the range of 0.2 to 1% by weight. Chemical grade propylene typically has a propene content in the range of 92 to 98% by weight and a propane content in the range of 2 to 8% by weight. According to a preferred embodiment of the present invention, a mixture of propene and propane is subjected to epoxidation, which has a propene content in the range of 99 to 99.8% by weight and a propane content in the range of 0.2 to 1% by weight. Therefore, the process of the present invention preferably comprises: a) reacting propene, mixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining an S0 current leaving the reaction apparatus, S0 containing propylene oxide , acetonitrile, water, at least one additional component B, propane and optionally propene, wherein the normal boiling point of the at least one component B is greater than the normal boiling point of acetonitrile and wherein the decadic logarithm of the coefficient of octanol-water (log KOW) partition of at least one component B is greater than zero.
[0011] Preferably, the epoxidation reaction in (a) is carried out in the presence of at least one suitable catalyst, preferably in the presence of at least one suitable heterogeneous catalyst. Even more preferably, the at least one suitable catalyst comprises at least one zeolite which, in particular, contains Ti. Preferably, the at least one Ti-containing zeolite has MWW framework structure. Even more preferably, such Ti-containing zeolite having MWW framework structure, referred to below as TiMWW, contains at least one additional heteroatom in addition to Ti. Among such additional heteroatoms, Zn is most preferred. Such a zeolite containing Zn and Ti and having MWW frame structure is referred to below as ZnTiMWW.
[0012] Catalysts, especially preferably titanium zeolite catalysts, and even more preferably TiMWW or ZnTiMWW, in particular ZnTiMWW, can be used as powder, as granules, as microspheres, as shaped bodies having, for example, the shape of pellets, cylinders, wheels, stars, spheres and so on, or as extruded, such as extrudates having, for example, a length from 1 to 10, more preferably from 1 to 7 and even more preferably from from 1 to 5 mm, and a diameter from 0.1 to 5, more preferably from 0.2 to 4 and especially preferably from 0.5 to 2 mm.
[0013] The preparation of such preferred TiMWW catalysts is described, for example, in US 2007043226 A1, in particular in Examples 3 and 5 of US 2007043226 A1.
[0014] With regard to the preferred ZnTiMWW catalyst, it is additionally more preferred to employ such catalyst in the form of a micropowder or in the form of a molding, wherein the molding preferably contains said micropowder.
[0015] Said ZnTiMWW catalyst in the form of a micropowder is preferably characterized by the following aspects and modalities, including combinations of modalities according to certain dependencies: 1. A micropowder, whose particles having a Dv10 value of at least 2 micrometers , said micropowder comprising mesopores having an average pore diameter (4V/A) in the range of 2 to 50 nm as determined by Hg porosimetry according to DIN 66133, and comprising, based on the weight of the micropowder, at least 95% in weight of a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc (ZnTiMWW). The value of Dv10 is understood to be determined in accordance with Reference Example 2 of the present invention; 2. The modality 1 micropowder, having a Dv10 value in the range of 2 to 5.5 micrometers, preferably from 3 to 5.5 micrometers; 3. Mode 1 or 2 micropowder, having a Dv50 value in the range of 7 to 25 micrometers and a Dv90 value in the range of 26 to 85 micrometers. Dv50 and Dv90 values are understood to be determined in accordance with Reference Example 2 of the present invention; 4. The micropowder of any one of modalities 1 to 3, mesopores have an average pore diameter (4V/A) in the range of 10 to 50 nm, preferably from 15 to 40 nm, more preferably from 20 at 30 nm, as determined by Hg porosimetry according to DIN 66133; 5. The micropowder, according to any one of embodiments 1 to 4, further comprising macropores having an average pore diameter (4V/A) in the range of more than 50 nm, said macropores preferably having an average pore diameter in the range from 0.05 to 3 micrometers as determined by Hg porosimetry in accordance with DIN 66133; 6. The micropowder, according to any one of modalities 1 to 5, characterized by the fact that the micropores of ZnTiMWW have an average pore diameter in the range of 1.10 to 1.16 nanometers, as determined by nitrogen adsorption , according to DIN 66135; 7. The micropowder according to any one of embodiments 1 to 6, comprising, based on the weight of the micropowder, at least 99% by weight, preferably at least 99.7% by weight of the ZnTiMWW; 8. The micropowder, according to any one of modalities 1 to 7, wherein the ZnTiMWW contains zinc in an amount from 1.0 to 2.0% by weight, preferably from 1.2 to 1, 9% by weight, more preferably from 1.4 to 1.8% by weight, calculated as Zn and based on the weight of the ZnTiMWW; 9. The micropowder, according to any one of modalities 1 to 8, wherein the ZnTiMWW contains titanium in an amount from 1.0 to 2.0% by weight, preferably from 1.2 to 1, 8% by weight, more preferably from 1.4 to 1.6% by weight, calculated as Ti and based on the weight of ZnTiMWW; 10. The micropowder, according to any one of embodiments 1 to 9, having a crystallinity, as determined by X-ray diffraction (XRD) analysis, of at least 80%, preferably at least 85%; 11. The micropowder, of any one of the modalities 1 to 10, comprising, based on the total weight of the micropowder and calculated as an element, less than 0.001% by weight, preferably less than 0.0001% by weight of a metal noble, preferably selected from the group consisting of gold, silver, platinum, palladium, iridium, ruthenium, osmium and a mixture of two or more thereof, most preferably selected from the group consisting of gold, platinum, gold and a mixture of two or more of them; 12. The micropowder of any of embodiments 1 to 11, comprising, based on the total weight of the micropowder and calculated as element, less than 0.1% by weight, preferably less than 0.01% by weight of boron; 13. The micropowder, according to any modality from 1 to 12, having a bulk density in the range of 80 to 100 g/ml; 14. The micropowder, of any of the embodiments 1 to 13, being a spray powder, preferably obtainable or obtained by spray drying.
[0016] Additionally, said ZnTiMWW catalyst in the form of a molding is preferably characterized by the following aspects and modalities, including modality combinations according to certain dependencies: 1. A molding, comprising a microporous aluminum-free zeolitic material of the MWW structure type containing titanium and zinc (ZnTiMWW), said molding preferably comprising a micropowder comprising, based on the weight of the micropowder, at least 95% by weight of a microporous aluminum-free zeolitic material of structure type MWW containing titanium and zinc (ZnTiMWW), said molding more preferably comprising the micropowder according to any one of micropowder embodiments 1 to 14 as described above, the molding preferably further comprising at least one binder, preferably a silica binder; 2. The molding of modality 1, comprising mesopores having an average pore diameter in the range from 4 to 40 nm, preferably from 20 to 30 nm as determined by Hg porosimetry in accordance with DIN 66133; 3. The molding of modality 1 or 2, having a crystallinity, as determined by XRD analysis, of at least 55%, preferably in the range of 55 to 75%; 4. The molding, of any of the modalities 1 to 3, comprising the micropowder in an amount ranging from 70 to 80% by weight and the silica binder in an amount from 30 to 20% by weight, the micropowder together with the silica binder comprising at least 99% by weight of the molding, wherein the molding has a concentration of silanol groups with respect to the total number of Si atoms of at most 6%, preferably at most 3%, as determined according to NMR of 29Si MAS. The concentration of the silanol groups is understood to be determined in accordance with Reference Example 3 of the present invention; 5. The molding, of any of the modalities 1 to 4, being a filament having a circular cross section and a diameter in the range of 1.5 to 1.7 mm and having a crush strength of at least 5 N, preferably in the range of 5 to 20 N, more preferably in the range of 12 to 20 N, the crush strength being determined by Z2.5/TS1S crush strength testing machine according to the method as described in Reference Example 4 of the present invention ; 6. Casting, of any of modalities 1 to 5, the 29Si NMR spectrum of said casting comprising six peaks at the following position: peak 1 at -98 +/- x ppm, peak 2 at -104 +/- x ppm, peak 3 at -110 +/- x ppm, peak 4 at -113 +/- x ppm, peak 5 at -115 +/- x ppm, peak 6 at -118 +/- x ppm, with x at any of the peaks being 1.5, preferably 1.0, more preferably 0.5, where Q which is defined as: Q = 100 * { [a1+a2] / [a4+a5+a6] } / a3 is at most 1.6, preferably at most 1.4 and most preferably at most 1.3, with [a1+a2] being the sum of the peak areas of peaks 1 and 2, and [a4 + a5 + a6] being the sum of the peak areas of peaks 4, 5 and 6, and a3 being the peak area of peak 3. Such 29Si-NMR characteristics are understood to be determined in accordance with Reference Example 5 of the present invention; 7. The molding, according to any embodiments from 1 to 6, having a water intake in the range of 3 to 8% by weight, preferably from 4 to 7% by weight, more preferably from 4.5 to 6.5% by weight. Water intake is understood to be determined in accordance with Reference Example 6 of the present invention; 8. The casting, of any of the modalities 1 to 7, the infrared spectrum of said casting comprising in a band in the region of 3746 cm-1 +/- 20 cm-1 and a band in the region of 3678 cm-1 + /- 20 cm-1, where the intensity ratio of the band in the region of 3746 cm-1 +/- 20 cm-1 in relation to the band in the region of 3678 cm-1 +/- 20 cm-1 is maximum 1.5, preferably at most 1.4, more preferably at most 1.3, most preferably less than at most 1.2. These IR characteristics are understood to be determined in accordance with Reference Example 7 of the present invention.
[0017] A preferred process for the preparation of a preferred ZnTiMWW catalyst and the respective characterization of that ZnTiMWW catalyst is described in Reference Example 1 of the present invention.
[0018] Therefore, the present invention also relates to the process described above, in which in (a), propene is reacted with hydrogen peroxide in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite , more preferably a titanium zeolite of the MWW structure type (TiMWW), more preferably a titanium zeolite containing zinc of the MWW structure type (ZnTiMWW).
[0019] Therefore, the process of the present invention preferably comprises: (a) reacting propene, mixed with propane, with hydrogen peroxide in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite, more preferably a titanium zeolite of the MWW structure type (TiMWW), more preferably a titanium zeolite containing zinc of the MWW structure type (ZnTiMWW), in a reaction apparatus in the presence of acetonitrile as solvent, obtaining an S0 current leaving the apparatus to reaction, S0 containing propylene oxide, acetonitrile, water, at least one additional component B, propane and optionally propene, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and in that the decadic logarithm of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero.
[0020] In general, the reaction in (a) can be carried out in any suitable manner. Thus, for example, it can be carried out in a batch reactor or in at least one reactor operated semi-continuously or in at least one reactor operated continuously. The continuous mode of operation is preferred, wherein the reaction is preferably carried out at a temperature in the range of -10 to 120 °C, more preferably 30 to 90 °C, most preferably 30 to 65 °C. Preferably, the temperature at which the reaction is carried out is not kept constant during the reaction, but is adjusted continuously or stepwise to adjust a constant hydrogen peroxide conversion, as determined in the S0 current leaving the reactor in which the reaction takes place. epoxidation in (a) is performed. Preferably, the reaction in (a) is carried out in at least one continuously operated reactor, such as a tube reactor or a tube-bundle reactor which preferably contains at least one cooling jacket surrounding the at least one tube. If the reaction in (a) is carried out in such a reactor containing at least one cooling jacket, the term "reaction temperature" as used herein refers to the temperature of the cooling medium when entering the cooling jacket. In general, due to catalyst deactivation, the reaction temperature is increased continuously or in stages. Preferably, the reaction temperature is increased continuously or stepwise by at most 1°C/d, more preferably by less than 1°C/d. Preferably, the hydrogen peroxide conversion, which is preferably kept constant is at least 80%, more preferably at least 85%, more preferably at least 90%, most preferably in the range of 90 to 95%. The principle of a preferential hydrogen peroxide conversion determination is described in Example 1, section 1.1 a) below. Expressions in the at least one reactor are generally in the range from 3 to 100 bar, preferably from 15 to 45 bar. In particularly preferred embodiments of the process of the present invention, the reaction is carried out at temperatures and pressures where the reaction mixture is liquid and no gas phase is present in the at least one reactor in which two or more liquid phases may exist. The molar ratio of propene to hydrogen peroxide with respect to starting materials passed in the at least one reactor in which epoxidation is carried out in (a) is preferably in the range of 0.9:1 to 3.0:1, plus preferably from 0.98:1 to 1.6:1, more preferably from 1.0:1 to 1.5:1. The amount of acetonitrile passed to the at least one reactor is adjusted so that the hydrogen peroxide concentration of the general current passed to the at least one reactor, in which the epoxidation is carried out in (a) is preferably in the range of 2 to 20% by weight, more preferably from 5 to 12% by weight, based on the total weight of the general stream.
[0021] Preferably, the general stream passed to at least one epoxidation reactor, i.e. the reactor feed contains from 50 to 80% by weight, more preferably from 60 to 70% by weight of acetonitrile, from 7 to 14% by weight, more preferably from 8 to 11% by weight of propene, from 5 to 12% by weight, more preferably from 6 to 10% by weight of hydrogen peroxide, and from 10 to 25 % by weight, preferably from 12 to 20% by weight of water.
[0022] Preferably, the reaction in (a) is carried out in two or more stages, preferably in two or three stages, more preferably in two stages. Preferably, a two-stage reaction comprises: (a1) reacting propene optionally mixed with propane, with hydrogen peroxide, preferably in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite, more preferably a zeolite titanium of the MWW structure type (TiMWW), more preferably a titanium zeolite containing zinc of the MWW structure type (ZnTiMWW), in a reaction apparatus in the presence of acetonitrile as solvent, obtaining an S0-a1 current leaving the apparatus to reaction, S0-a1 containing propylene oxide, acetonitrile, water, optionally at least one additional component B, optionally propane, optionally propene and unreacted hydrogen peroxide; (a2) separating propylene oxide from S0-a1, obtaining an S0-a2-1 stream being enriched in propylene oxide and depleted in hydrogen peroxide, and an S0-a2-2 stream being depleted in propylene oxide and comprising unreacted hydrogen peroxide, acetonitrile and water; (a3) subject the current S0-a2-2, preferably after mixing with propene optionally mixed with propane, to epoxidation reaction conditions, preferably in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite , more preferably a titanium zeolite of the MWW structure type (TiMWW), more preferably a titanium zeolite containing zinc of the MWW structure type (ZnTiMWW), in a reaction apparatus to obtain an S0-a3 current leaving the reaction apparatus , S0-a3 containing propylene oxide, acetonitrile, water, optionally at least one additional component B, optionally propane and optionally propene; wherein either S0-a1 and/or S0-a3 contain at least one additional component B and wherein the normal boiling point of the at least one component B is greater than the normal boiling point of acetonitrile and wherein the log decadic of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero.
[0023] In a preferred configuration of the process of the present invention, as shown in Figure 1 below, current (5) is a preferred current S0-a1, current (6) is a preferred current S0-a2-1, the current (7) is a preferred current S0-a2-2, and current (9) is a preferred current S0-a3. Stream (8) in Figure 1 is a preferred stream of propene optionally mixed with propane which is preferably mixed in (a3).
[0024] Preferably, the currents S0-a2-1 and S0-a3 together constitute the current S0 according to the present invention.
[0025] With regard to the epoxidation reaction conditions of stage (a1), reference is made to the preferred epoxidation reaction as discussed above. Hydrogen peroxide can be separated according to (a2) by any suitable method. The hydrogen peroxide is preferably distilled off using one or more distillation towers, preferably a distillation tower. Such a distillation tower is preferably operated under conditions allowing to obtain an overhead stream containing hydrogen peroxide in an amount of at most 100 ppm by weight, based on the total weight of the overhead stream, preferably containing essentially hydrogen peroxide. Additionally, such distillation tower is preferably operated under conditions allowing to obtain an overhead stream which contains at least 80%, more preferably at least 90% more preferably at least 95% of the propylene oxide contained in the feed stream S0-a1. Preferably, this distillation tower has from 15 to 45, preferably from 20 to 40 theoretical plates and is operated at a pressure at the top of the tower in a range from 0.5 to 1.2 bar, preferably from 0. 7 to 1.1 bar. The reflux ratio of such a distillation tower is preferably in the range 0.05:1 to 0.5:1, more preferably 0.1:1 to 0.2:1. The bottom streams obtained from the distillation tower in (a2), containing essentially all of the unreacted hydrogen peroxide from (a1) and additionally containing acetonitrile, water, is preferably passed to stage (a3). With regard to stage (a3), it is preferable to use an adiabatic reactor, preferably an adiabatic shaft reactor. The epoxidation conditions in (a3) are preferably chosen to allow a hydrogen peroxide conversion at the output of (a3) of at least 99%, preferably at least 99.5%, more preferably at least 99.9% based on hydrogen peroxide fed to (a1). In (a3), it is preferable to use the same catalyst as in (a1). As regards the propene which is preferably introduced into the reactor used in (a3), reference is made to the propene already discussed above in the context of (a). Thus, for example, chemical grade propene or polymeric grade propene can be used, with polymeric grade propene being preferred. If stages (a1) and (a3) are performed, the reactors are preferably operated so that the overall propylene conversion, taking into account the conversion to (a1) and conversion to (a3), is at least 65%, more preferably at least 70%, more preferably at least 75%.
Depending on the specific epoxidation conditions in (a), S0 may contain any conceivable amounts of propylene oxide, acetonitrile, water, the at least one additional component B, optionally propene and optionally propane. Preferably from 90 to 97% by weight, more preferably from 92 to 97% by weight, more preferably from 95 to 97% by weight of SO consists of acetonitrile, water and propylene oxide, and from 0.01 to 3% by weight, more preferably from 0.015 to 2% by weight, most preferably from 0.02 to 0.1 ppm by weight of SO consists of the at least one component B. The term "...% by weight of SO consists of at least one B component” refers to the overall quantity of all B components contained in S0. More preferably, from 90 to 97% by weight, more preferably from 92 to 97% by weight, more preferably from 95 to 97% by weight of SO consists of acetonitrile, water and propylene oxide, from 0.05 to 7% by weight, more preferably from 0.1 to 6% by weight, more preferably from 0.15 to 4% by weight consists of propene and optionally propane, and wherein from 0.01 to 3% by weight , preferably from 0.015 to 2% by weight, more preferably from 0.02 to 1 ppm by weight of SO consists of the at least one component B.
[0027] According to the present invention, the decadic logarithm of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero. The octanol-water partition coefficient (log KOW) is a parameter well known to the person skilled in the art. For the sake of completeness, its definition and determination are described in Reference Example 8 below.
[0028] Typically, the at least one component B contained in S0 is a by-product and/or a by-product obtained during the epoxidation reaction in (a), and/or is a compound that is formed during at least one of the stages work-up, preferably being carried out downstream of (a), and which accumulates if certain process streams of the preferential integrated process are recycled in (a), and/or is contained as an impurity in at least one of the starting materials employed in (a), such as an impurity in acetonitrile or an impurity in hydrogen peroxide.
[0029] Preferably, the at least one component B is propionitrile, 1-nitropropane, 2-nitropropane, 3-methylbutanenitrile, n-pentanenitrile, 1-pentanol, 2-pentanol, 2-butanone, 2-pentanone, 2-hexanone, 4-methyl-2-heptanone, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol, 2,6-dimethyl-4-heptanone, 4,6-dimethyl-2-heptanone, 2, 6-dimethyl-4,6-heptandiol, 2,4-dimethyl-oxazoline, 2,5-dimethyloxazoline, cis-2,4-dimethyl-1,3-dioxolane, trans-2,4-dimethyl-1,3- dioxolane, acetaldehyde, propionaldehyde, 2-butanone at least one impurity contained in the hydrogen peroxide employed in (a), or a combination of two or more of these compounds.
Preferably, the at least one component B includes propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol, 2,6-dimethyl-4- heptanone, acetaldehyde, propionaldehyde, 2-butanone, or a combination of two or more of these compounds. More preferably, the at least one component B includes a combination of three or more such compounds, more preferably a combination of four or more such compounds, most preferably a combination of five or more such compounds. More preferably, the at least one component B includes a combination of propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol and 2,6-dimethyl-4- -heptanone. Also, preferably, the at least one component B includes a combination of seven or more such compounds, more preferably a combination of eight or more such compounds. More preferably, the at least one component B includes a combination of propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol, 2,6-dimethyl-4 - heptanone, acetaldehyde and propionaldehyde. Furthermore, preferably, the at least one component B includes a combination of nine or more such compounds. More preferably, the at least one component B includes a combination of propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol, 2,6-dimethyl-4 -heptanone, acetaldehyde, propionaldehyde and 2-butanone.
[0031] With respect to the at least one impurity contained in the hydrogen peroxide employed in (a), this at least one impurity is preferably an alkyl phosphate, such as tris-(2-ethylhexyl) phosphate, a nonyl alcohol , such as diisobutylcarbinol, an alkylcyclohexanol ester such as 2-methyl-cyclohexylacetate, an N,N-dialkyl carbonamide such as N,N-dibutylpropionamide, an N-alkyl-N-aryl carbonamide such as N- ethyl-N-phenylbenzamide, an N,N-dialkyl carbamate such as 2-ethylhexyl-N-butylcarbamate, a tetraalkyl urea such as tetra-n-butyl urea, a cycloalkyl urea such as di-propaneurea hexyl, a phenylalkyl urea such as N,N-dibutyl-N'-methyl-N'-phenylurea, an N-alkyl-2-pyrrolidone such as octyl pyrrolidone, an N-alkyl caprolactam such as n-octyl caprolactam, compound of C8-C12 aromatic alkyl, dibutyl amine, dibutyl formamide, 1-butanol, butyl aldehyde, 2-ethylhexanol, 2-ethylanthraquinone, 2-ethyl-5,6,7,8-tetrahydroanthraquinone or a combination of two or more of these compounds.
[0032] It is conceivable that the reaction of propene, mixed with propane, with hydrogen peroxide in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite, more preferably a structure-type titanium zeolite MWW (TiMWW), more preferably a zinc-containing titanium zeolite of the MWW structure type (ZnTiMWW), in a reaction apparatus in the presence of acetonitrile as solvent, such as propene reaction in (a1) and/or (a3), is carried out in the presence of at least one potassium salt, which is dissolved in the respective mixtures which are subjected to the epoxidation conditions in (a), such as in (a1) and/or (a3). Preferably, the at least one potassium salt is selected from the group consisting of at least one inorganic potassium salt, at least one organic potassium salt and combinations of at least one inorganic potassium salt and at least one organic potassium salt , wherein preferably at least one of the at least one potassium salt is an organic potassium salt. More preferably, the at least one potassium salt is selected from the group consisting of at least one inorganic potassium salt selected from the group consisting of potassium hydroxide, potassium halides, potassium nitrate, potassium sulfate, hydrogen sulfate of potassium, potassium perchlorate, di-potassium hydrogen phosphate, potassium dihydrogen phosphate, at least one organic potassium salt selected from the group consisting of the potassium salt of aliphatic saturated monocarboxylic acids preferably having 1, 2, 3 , 4, 5 or 6 carbon atoms, potassium carbonate and potassium hydrogen carbonate and a combination of at least one of the at least one inorganic potassium salt and at least one of the at least one organic potassium salt. More preferably, the at least one potassium salt is selected from the group consisting of at least one inorganic potassium salt selected from the group consisting of potassium hydroxide, potassium chloride, potassium nitrate, at least one potassium salt organic selected from the group consisting of potassium formate, potassium acetate, potassium carbonate and potassium hydrogen carbonate and a combination of at least one of the at least one inorganic potassium salt and at least one of the at least one salt of organic potassium.
[0033] Therefore, the present invention also relates to a process wherein (a) comprises reacting propene, optionally mixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent and in the presence of at least one dissolved potassium salt, obtain a current S0 leaving the reaction apparatus, S0 containing propylene oxide, acetonitrile, water, at least one additional component B, optionally propene and optionally propane, where the normal boiling point of the at least one component B is greater than the normal boiling point of acetonitrile and where the decadic logarithm of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero. STEP (B)
[0034] According to step (b) of the process of the present invention, propylene oxide is separated from S0, and an S1 current is obtained which, compared to S0, is depleted of propylene oxide and which contains acetonitrile , water and the at least one additional component B. If S0 additionally contains propene and/or propane, it is preferred that propene and/or propane are also separated from S0 to obtain a stream, S1 is obtained wherein, in compared to S0, it is depleted of propylene oxide, propene and/or propane, and which contains acetonitrile, water and the at least one additional component B. Additionally, if S0 additionally contains oxygen, it is preferred that the oxygen is also prepared from of S0, current S1 is obtained which, compared to S0, is depleted of propylene oxide and oxygen and which contains acetonitrile, water and the at least one additional component B. Preferably, S0 is obtained according to the process of the present invention contains propene, propane and opc ionally oxygen, and away from propylene oxide, propene, propane and optionally oxygen are separated from S0 to obtain S1 which, compared to S0, is depleted of propylene oxide, propene and propane and optionally oxygen, and which contains acetonitrile , water and the at least one additional component B.
[0035] Regarding the separation of propene and/or propane, and/or oxygen from S0, there are no specific restrictions. In particular, all conceivable consequences of separating the individual components and all conceivable separation techniques such as distillation are possible. Therefore, it is conceivable to separate propene and/or propane and optionally oxygen together with propylene oxide from S0 to obtain S1. The stream enriched in propene and/or propane and optionally separated oxygen is then preferably subjected to suitable separation stages and/or work-up stages from which a stream is obtained which consists essentially of propylene oxide as a valuable product. Preferably, the S0 stream is subjected to a first separation stage in which the propene and optionally propane are separated. If S0 additionally contains oxygen, it is preferable that the oxygen is separated together with the propene and/or the propane.
[0036] Therefore, the present invention relates to the process as described above, comprising (b) separating propylene oxide from S0, after having separated propene and optionally propane, obtaining a stream S1 containing acetonitrile, water and the at least one additional component B. Also, the present invention relates to the process as described above, comprising (b) separating propylene oxide from S0, after having separated propene and propane, obtaining a stream S1 containing acetonitrile, water and the at least one additional component B. Also, the present invention relates to the process as described above, comprising (b) separating propylene oxide from S0, after having separated propene, propane and optionally oxygen, obtaining a stream S1 containing acetonitrile, water and the at least one additional component B. Also, the present invention relates to the process as described above, comprising (b) separating propylene oxide from SO, after having propene, propane and oxygen. o separated, obtain a stream S1 containing acetonitrile, water and the at least one additional component B.
[0037] Therefore, it is preferred that step (b) of the process of the present invention comprises a step (I) in which propene, optionally together with propane and oxygen which is optionally additionally contained in S0, are separated from S0 to obtain an S01 stream enriched in propylene oxide, acetonitrile, water and the at least one component B which S01 stream is depleted of propene, optionally propane and oxygen; and further comprises a step (II) in which propylene oxide is separated from SO1 obtaining an SO2 stream enriched in acetonitrile, water and the at least one component B whose SO2 stream is depleted of propylene oxide.
[0038] Regarding the separation in (I), there is no specific restriction. Preferably, the separation is carried out with at least 90% by weight, more preferably at least 95% by weight, more preferably at least 98% by weight, most preferably at least 99% by weight of SO1 consisting of acetonitrile, water, or at least one component B and propylene oxide. Preferably, a fractionation unit is employed for the separation in (I). Additionally preferably, the separation in (I) is carried out in at least one distillation tower, more preferably in a distillation tower. From this distillation tower, S01 is preferably obtained as a bottom stream. Preferably, this distillation tower has from 10 to 30, more preferably from 15 to 25 theoretical plates. The distillation tower is preferably operated at a top pressure from 0.5 to 1.2 bar, more preferably from 0.7 to 1.1 bar. In order to facilitate said separation task, it has been found that it is advantageous to add both liquid acetonitrile and a liquid mixture of acetonitrile with water to the top of the column. This external reflux is believed to serve as an embedding agent which, among others, prevents propylene oxide from being separated through the top of the distillation tower. According to a preferred embodiment of the present invention, a portion of the lower parts stream from the distillation tower preferably employed in stage (II) is used. It is also conceivable that the TL2 stream described below or a portion thereof is used as an embedding agent. The amount of TL2 will not be enough, and another stream will be added. Preferably, the weight ratio of the amount of acetonitrile fed as external reflux to the top of the distillation tower, relative to the weight of the S0 stream fed into the distillation tower and to be separated in the distillation tower is in the range of 1:1 to 4:1 preferably from 1.5:1 to 3:1. The temperature of the external reflux is generally in the range of 2 to 20 °C, preferably in the range of 5 to 15 °C. According to the present invention, preferably at least 85% by volume, more preferably at least 90% by volume, most preferably at least 93% by volume of the head stream of the distillation column according to (I) consists of propene, oxygen and optionally propane. Depending on its oxygen content, this top stream can be passed to a suitable new processing stage (work-up) where the oxygen content is adequately decreased in order to allow, for example, to recycle the depleted oxygen stream to be recycled to one or more stages of the present invention, such as a starting material for stage (a) of the inventive process as stage (a1) or stage (a3), or as a portion of stream P described below. If the oxygen content of said overhead stream is reduced, it is preferable to reduce the oxygen by reaction with hydrogen in the presence of a suitable catalyst. Such catalysts are, for example, catalysts comprising tin and at least one noble metal, as described in WO 2007/000396 A1, in particular in Example 1 of WO 2007/000396 A1. It is also conceivable to use catalysts comprising copper in oxidic and/or elemental form on a support, where copper is present on the support in an amount of 30 to 80% by weight based on the entire catalyst and calculated as CuO. Such catalysts can be prepared, for example, according to the example of EP 0 427 062 A2, catalyst 2, page 4, lines 41 to 50 (corresponding to US 5,194,675). In order to reduce the oxygen content, also other suitable methods are conceivable. Optionally, said overhead stream, before being subjected to hydrogenation, can be compressed and partially condensed whereby a liquid stream is obtained which consists essentially of propene and optionally propane and acetonitrile and which contains minor amounts of water. The non-condensed portion consists essentially of propene and optionally propane and oxygen and contains a smaller amount of water in which, compared to the basic stream, the oxygen content is increased while still being in a range such that the mixture is not flammable. . This oxygen-enriched stream is then subjected to hydrogenation.
[0039] As mentioned above, before using S01 stream as S1 stream according to the present invention, it is especially preferable to separate propylene oxide from S01 in (II) to obtain an S02 stream which is essentially oxide free of propylene. Regarding the separation in (II), there is no specific restriction. Preferably, the separation is carried out so that preferably at least 90% by weight, more preferably at least 95% by weight, more preferably at least 99% by weight of SO2 consists of acetonitrile, water and the at least one component B. More preferably, the weight ratio of acetonitrile to water in SO2 is greater than 1:1, preferably in the range from 2:1 to 10:1, more preferably from 2.5:1 to 5:1. Preferably, a fractionation unit is employed for the separation in (II). Additionally preferably, the separation in (II) is carried out in at least one distillation tower, more preferably in a distillation tower. Preferably, this tower has from 50 to 80, more preferably from 60 to 70 theoretical plates. The distillation tower is preferably operated at a top pressure from 0.2 to 2 bar, more preferably from 0.4 to 1 bar. Optionally, at least one suitable polar solvent or a mixture of two or more polar solvents, preferably water, can be added at the top of the column as an extracting agent. According to an embodiment of the process of the present invention, the separation according to stage (III) can be carried out by: - introducing SO1 into an extracting distillation column; - additionally introducing a polar extraction solvent or a mixture of two or more thereof, preferably water, into said extraction distillation column; - distilling propylene oxide overhead from said extraction distillation column as an overhead, wherein the overhead comprises only small amounts of acetonitrile, such as 500 ppm or less; - compressing said overhead stream obtained overhead in the previous step by means of at least one compressor to yield a compressed steam; - condense the compressed steam obtained in the previous step and return at least part of the condensing head to at least one reboiler used in the extraction distillation column.
[0040] From that distillation tower, according to (II), an overhead stream is obtained which contains at least 90% by weight, preferably at least 95% by weight, more preferably at least 99% by weight of oxide of propylene. Additionally, from that distillation tower, SO2 is preferably obtained as a bottoms stream which preferably contains 500 ppm by weight at most, preferably 100 ppm by weight at most and more preferably 60 ppm by weight at most propylene oxide, with based on the weight of S02.
[0041] Depending on the requirements of the quality of propylene oxide, it is conceivable to use this propylene oxide fraction without any further purification. Therefore, it is also conceivable to further purify said propylene oxide fraction, for example, in at least one further distillation stage.
[0042] From the distillation tower, according to (II), or optionally from the further distillation stage, a stream of propylene oxide is obtained in which at least 99.5% by weight, more preferably at least 99.9% by weight, more preferably at least 99.999% by weight of said stream consists of propylene oxide. Therefore, the present invention also relates to a composition comprising at least 99.999% by weight of propylene oxide, obtainable or obtained by a process as described above and comprising the separation stage (II).
[0043] Thus, the present invention preferably relates to the process as described above, wherein (b) comprises: (I) separating propene, optionally together with propane, and oxygen which is optionally additionally contained in S0, from S0 obtaining an SO1 stream enriched in propylene oxide, acetonitrile, water and the at least one component B, wherein preferably at least 99% by weight of SO1 consists of acetonitrile, water, the at least one component B and propylene oxide; wherein, for separation, preferably a fractionating unit is used, wherein preferably, on top of the fractionating unit, liquid acetonitrile, optionally mixed with liquid water, is added as an embedding agent; (II) separating propylene oxide from SO1, obtaining an SO2 stream enriched in acetonitrile, water and the at least one component B, wherein preferably at least 95% by weight of SO2 consists of acetonitrile, water and the at least one component B, and in which the weight ratio of acetonitrile to water is greater than 1:1.
[0044] Preferably, S02 obtained from step (b), preferably from step (II) comprised in (a), is submitted to step (c) as current S1.
[0045] Preferably, from 90 to 99.9% by weight, more preferably from 95 to 99.8% by weight, most preferably from 99 to 99.7% by weight of S1 consists of acetonitrile and water, and preferably from 0.01 to 5% by weight, more preferably from 0.015 to 3% by weight, more preferably from 0.02 to 2% by weight of S1 consists of the at least one component B.
[0046] Optionally, at least a portion of SO2 is diverted and used as the incorporation agent in the fractionation unit, according to (I), as described above. Preferably, if used as an embedding agent, from 15 to 35%, more preferably from 20 to 35% of SO 2 is bypassed and preferably added on top of the fractionating unit used in (I). OPTIONAL ADDITIONAL STEPS INCLUDED IN (B)
[0047] Depending on the specific conditions during the upstream stages of the process of the present invention, respectively stages (a), (I) and (II), the stream of lower parts obtained from the distillation tower, according to (II ), may also run certain amounts of hydroperoxides, such as certain amounts of hydrogen peroxide and/or certain amounts of organic hydroperoxides, for example, 1-hydroperoxypropanol-2 and/or 2-hydroperoxypropanol-1. Preferably, the bottoms stream obtained from the distillation tower according to (III) may contain at most 2% by weight, more preferably at most 1% by weight of such hydroperoxides in total, based on the weight of the stream. of lower parts. In order to reduce the hydroperoxide content and thus prevent the formation of hydroperoxides which are likely to have a detrimental influence with respect to the formation of undesirable by-products and safety aspects based on the decomposition of the hydroperoxides, it is conceivable to subject said stream of lower parts obtained from the distillation tower, according to (II), for at least one additional process stage. Such formation takes place especially if the highly inventive integrated process is carried out. While any method suitable for at least partially removing such hydroperoxides is conceivable, it is especially preferred to catalytically reduce, preferably to catalytically hydrogenate, the hydroperoxides. As a suitable catalyst, a catalyst can be mentioned which is described in US 2004068128 A1, in particular in paragraphs [0053] to [0076]. Preferred catalysts are selected from the group consisting of heterogeneous catalysts comprising Ru, Ni, Pd, Pt either individually or as a mixture of two or more thereof as active metal on a suitable support material. An especially suitable catalyst, respectively a supported catalyst comprising 5% by weight of Pd on activated carbon is described in Example E2 of US 2004068128 A1. The pressure during hydrogenation is typically in the range from 1 to 100 bar (abs), preferably from 1 to 10 bar (abs), and the temperature during hydrogenation is typically in the range from 0 to 180 °C, preferably from 25 to 120 °C , more preferably from 65 to 85°C. The hydrogen partial pressure during hydrogenation is preferably in the range from more than 1 to 20 bar, more preferably from 2 to 15 bar, most preferably from 3 to 13 bar. If the hydrogenation is carried out in a fixed bed, which is preferred, the residence time of the liquid passed through the hydrogenation reactor is generally in the range of 1 second (s) to 1 hour (h), preferably 10 s 20 minutes (min), in particular from 30 s to 5 min. Depending on the reaction conditions employed to reduce, preferably hydrogenate the bottoms stream obtained from the distillation tower, according to (II), it may be necessary to separate the resulting stream from the catalyst, preferably hydrogenation catalyst and/or unreacted reducing agent, preferably hydrogen and/or by-products from hydrogenation, preferably CO and/or methane. In particular, the stream resulting from reduction, preferably hydrogenation, contains at least 95% by weight of acetonitrile and water, based on the total weight of the bottoms stream, wherein the weight ratio of acetonitrile to water is preferably greater than 1:1. In general, it is conceivable to use this stream obtained from the hydrogenation and preferably separation of the catalyst as stream S1 of the present invention.
[0048] Depending on the specific conditions during the upstream stages of the present invention, i.e., stages (a), (I) and (II), and the reduction, preferably the hydrogenation stage, the current obtained from the reduction, preferably hydrogenation may contain certain amounts of acetaldehyde and optionally additional low boils, such as, for example, propionaldehyde and acetone. Typically, such a stream may contain up to 2000 ppm by weight, preferably up to 1000 ppm by weight, more preferably up to 300 ppm by weight of acetaldehyde and other low boils in total, based on the total weight of that stream. In order to reduce the acetaldehyde content and optionally the content relative to other low boilers and thus avoid the formation of these compounds which especially occurs if the highly inventive integrated process is carried out, it is preferable to subject this current to at least one stage of additional process. While all suitable methods for removing at least partially acetaldehyde are conceivable, it is especially preferred to separate acetaldehyde at least partially from the stream by distillation. The separation, according to this stage, is preferably carried out in at least one distillation tower, more preferably in a distillation tower. Preferably, this tower has from 15 to 40, more preferably from 20 to 35 theoretical plates. The distillation tower is preferably operated at a top pressure in the range of 0.7 to 2 bar, more preferably 1.1 to 2 bar.
[0049] From this distillation tower, a stream of bottoms is obtained that preferably contains 200 ppm by weight at most, preferably 100 ppm by weight at most, more preferably 50 ppm by weight at most acetaldehyde and other low-in boilers total, based on the weight of the bottom chain. Preferably at least 98% by weight, more preferably at least 98.5% by weight, more preferably at least 98.7% by weight of the bottoms stream consists of acetonitrile, water and the at least one component B. Preferably, at least 98% by weight, more preferably at least 98.5% by weight, more preferably at least 98.7% by weight of the bottoms stream consists of acetonitrile, water and the at least one component B, and wherein the acetonitrile to water weight ratio is greater than 1:1. In general, it is conceivable to use this bottom stream as current S1 in the process of the present invention. According to a conceivable embodiment of the present invention, no stage of distillation is performed.
Therefore, the present invention also relates to the process as described above, wherein (b) further comprises: (IIIa) subjecting SO2 obtained from (II) to hydrogenation; and/or (IIIb) subjecting the stream obtained from (II) or (IIIa) to distillation to obtain a bottoms stream, wherein the hydrogenated stream obtained from (IIIa) or the bottoms stream obtained to from (IIIb) is subjected to (c) as S1.
[0051] Thus, the present invention also relates to the process as described above, wherein (b) further comprises: (IIIa) subjecting a stream obtained from (II) to hydrogenation, obtaining current S1 and subjecting S1 to the step (ç).
[0052] Thus, the present invention also relates to the process as described above, in which (b) further comprises: (IIIb) subjecting the stream obtained from (II) to a distillation stage, preferably carried out in a column of Distillation operated at a top pressure from 0.7 to 2 bar, more preferably from 1.1 to 2 bar, to obtain current S1 and subject S1 to step (c).
[0053] Also, the present invention relates to the process as described above, wherein (b) further comprises: (IIIa) subjecting the S02 stream obtained from (II) to a hydrogenation stage, preferably to a hydrogenation stage catalytic, the catalyst preferably being a heterogeneous catalyst comprising Ru, Ni, Pd, Pt, either individually or as a mixture of two or more thereof, as active metal on a suitable support material, in particular Pd on activated carbon; said hydrogenation preferably being carried out at a pressure during hydrogenation in the range from 1 to 100 bar (abs), preferably from 1 to 10 bar (abs), and a temperature during hydrogenation in the range from 0 to 180 °C, preferably from 25 to 120 °C, more preferably from 65 to 85 °C; (IIIb) submit the stream obtained from (IIIa) to a distillation stage, preferably carried out in a distillation column operated at a top pressure from 0.7 to 2 bar, more preferably from 1.1 at 2 bar, for current S1 obtained and submit S1 to step (c).
[0054] As mentioned above, it is preferred that stage (b) of the process of the present invention does not comprise (IIIa) nor (IIIb). STEP (C)
[0055] According to step (c) of the process of the present invention, the current S1 is divided into two streams S2 and S3 in which the current S3 is subjected, as the partial current of the present invention, to step (d), as discussed below. The term "is divided into two streams", as used in this context of the present invention, broadly encompasses the modalities according to which current S1 is divided into more than two streams whereas currents S2 and S3 as defined in that document, are obtained. There are no specific restrictions, where the portion of S1 is separated as S3. Preferably, the total weight of S3 relative to the total weight of S1 is less than 50%, more preferably less than 40%, most preferably less than 30%. More preferably, the total weight of S3 relative to the total weight of S1 is at least 0.01%. More preferably, the total weight of S3 relative to the total weight of S1 is in the range of 0.01 to 25%. More preferably, the total weight of S3 with respect to the total weight of S1 is in the range from 0.05 to 20%, preferably from 0.1 to 15%, more preferably from 0.2 to 10%, most preferably from 0. 5 to 7.5%. Preferred conceivable ranges are from 0.5 to 1.5% or from 1.0 to 2.0% or from 1.5 to 2.5% or from 2.0 to 3.0 % or from 2.5 to 3.5%, or from 3.0 to 4.0%, or from 3.5 to 4.5%, or from 4.0 to 5.0%, or from 4 .5 to 5.5%, or from 5.0 to 6.0%, or from 5.5 to 6.5%, or from 6.0 to 7.0%, or from 6.5 to 7.5 %. STEP (D)
[0056] According to step (d) of the process of the present invention, the stream S3 is subjected to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction S4a being impoverished, in relation to S3 , of at least one of the at least one component B and obtaining a net bottom stream S4b, wherein at least part of the vapor fraction stream S4a is subjected to a vapor-liquid fractionation in a second fractionation unit, obtaining a vapor fraction stream S4c and a net bottoms stream S4 being depleted, relative to S4a, of at least one of the at least one component B.
[0057] In general, it was found that using, for the separation of impurities, according to the present invention, a fractionation unit comprising a single distillation column, already leads to optimal results with respect to the maximum of impurities. However, it was found that, in view of the complexity of the spectrum of impurities comprised in current S1, although comprised only in traces, even smaller results are obtained when two fractionation units coupled in series are used. In particular, it has been found that while the first fractionating unit is especially useful for separating impurities having a comparatively high boiling point, including, for example, propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4- heptanol, 4,6-dimethyl-2-heptanol and/or 2,6-dimethyl-4-heptanone, the second fractionating unit is especially useful for separating impurities having a comparatively high boiling point, including, for example, acetaldehyde, propionaldehyde or 2-butanone. Thus, by using the two fractionation units coupled in series, it was possible to essentially separate all the impurities which, when accumulating in the course of a continuous process to prepare propylene oxide, tend to have a negative influence on the performance of the heterogeneous catalyst that is preferably employed in the epoxidation process, in particular a catalyst based on zeolite with a MWW frame structure and containing Ti.
[0058] Therefore, the present invention relates to the process as described above, in which in (d), the stream S3 is subjected to a vapor-liquid fractionation in a first fractionation unit, obtaining a vapor fraction stream S4a being depleted, relative to S3, of at least one of the at least one component B, the at least one of the at least one component B comprising propionitrile or 1-nitropropane or 2-nitropropane or 2,6-dimethyl-4-heptanol or 4 ,6-dimethyl-2-heptanol or 2,6-dimethyl-4-heptanone or a combination of two, three, four, five or six of them, and obtaining a liquid bottom stream S4b, in which at least part of the vapor fraction stream S4a is subjected to a vapor-liquid fractionation in a second fractionation unit, obtaining a vapor fraction stream S4c and a net lower parts stream S4 being depleted, in relation to S4a, of at least one of the hair. minus one component B, the at least one of the at least one component B comprising acetaldehyde or propionaldehyde or 2-butanone or a combination of two or three thereof.
[0059] The term "S4a being depleted, relative to S3, of at least one of the at least one component B" as used in this context of the present invention refers to a current S4a in which the amount of the at least one of at least a B component is less than the respective amount of the at least one of the at least one B component in stream S3. The term "S4 being depleted, relative to S4a, of at least one of at least one component B" as used in this context of the present invention refers to a current S4 wherein the amount of the at least one of at least one component B is less than the respective amount of the at least one of at least one B component in current S4a.
[0060] Additionally, the present invention relates to the process as described above, wherein in (d), stream S3, comprising propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4, 6-dimethyl-2-heptanol, 2,6-dimethyl-4-heptanone or a combination of two, three, four, five or six thereof, and further comprising acetaldehyde or propionaldehyde or 2-butanone or a combination of two or three of these, is subjected to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction S4a being impoverished, in relation to S3, of propionitrile or 1-nitropropane or 2-nitropropane or 2,6-dimethyl -4-heptanol or 4,6-dimethyl-2-heptanol or 2,6-dimethyl-4-heptanone or a combination of two, three, four, five or six of them, and obtaining a liquid bottom stream S4b, wherein at least part of the vapor fraction stream S4a is subjected to a vapor-liquid fractionation in a second fractionation unit. then obtaining a vapor fraction stream S4c and a liquid bottoms stream S4 being depleted, relative to S4a, of acetaldehyde or propionaldehyde or 2-butanone or a combination of two or three of them.
[0061] In particular, it has been found that if the configuration of two fractionation units coupled in series is used, that in addition to impurities having a comparatively high boiling point, including, for example, propionitrile, 1-nitropropane, 2- nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol and/or 2,6-dimethyl-4-heptanone, another compound having a comparatively low boiling point including, for example, acetaldehyde, propionaldehyde or 2-butanone, can be suitably separated from S3, whereby, with respect to S3, the respective amount of such compound in S4 is in the range of 10 to 70%, preferably of 15 to 60%.
[0062] In general, there are no specific restrictions with respect to step (d) considering that a net bottoms stream S4 is obtained that is depleted of at least one component B and that can be fed back into the process of the present invention. However, it has been found to be especially preferable if the acetonitrile concentration of the liquid bottom stream S4b is in a specific range. This specific range has been found to allow to keep the acetonitrile concentration in the bottom liquid S4b stream as low as possible, thus avoiding a very high loss of acetonitrile, while simultaneously separating a very high amount of the at least one B component by means of the net bottom chain S4b. This specific range of acetonitrile concentration in the liquid bottom stream S4b obtained in (d) may be from 1 to 50% by weight, from 2 to 45% by weight, or from 5 to 40% by weight. Weight. Preferably, in (d), vapor-liquid fractionation is carried out in the first fractionation unit so that from 10 to 30% by weight, preferably from 10 to 25% by weight of the liquid bottom stream S4b consists of acetonitrile. More preferably, in (d), vapor-liquid fractionation is carried out in the first fractionation unit so that from 10 to 30% by weight, preferably from 10 to 25% by weight of the liquid bottom stream S4b consists of acetonitrile and from 0.1 to 10% by weight, preferably from 0.25 to 5% by weight of the liquid bottom stream S4b consisting of the at least one additional component B.
[0063] Therefore, the present invention preferably refers to the process as described above, wherein in (c), the total weight of S3 in relation to the total weight of S1 is in the range of 0.5 to 7.5% and in whereas in (d), vapor-liquid fractionation is carried out in the first fractionation unit so that from 10 to 25% by weight of the liquid bottom stream S4b consists of acetonitrile. More preferably, the present invention relates to the process as described above, wherein in (c), the total weight of S3 with respect to the total weight of S1 is in the range of 0.5 to 7.5% and wherein in ( d) the vapor-liquid fractionation is carried out in the first fractionation unit so that from 10 to 25% by weight of the liquid bottom stream S4b consists of acetonitrile and from 0.25 to 5% by weight of the stream of liquid bottom part S4b consists of at least one additional component B.
[0064] In general, there are no specific restrictions on how the vapor-liquid fractionation is performed in the first fractionation unit considering that the aforementioned acetonitrile concentrations in the liquid bottom stream S4b are reached. In particular, the pressure and/or temperature and/or the number of theoretical plates of the fractionating unit and/or the reflux ratio will be suitably adjusted by the person skilled in the art.
[0065] Preferably in (d), vapor-liquid fractionation is carried out in the first fractionation unit at an absolute pressure at the top of the first fractionation unit in the range from 0.5 to 5 bar, more preferably from 0.75 to 2 bar , more preferably from 1 to 1.5.
[0066] Preferably, in (d), the number of theoretical plates of the first fractionation unit is in the range from 1 to 100, more preferably from 2 to 25, more preferably from 3 to 10.
[0067] According to a conceivable embodiment of the present invention, the first fractionation unit in (d) is operated with reflux. While it is generally possible to use any suitable stream as reflux, it may be preferable to use a portion of S4a, preferably after condensation, as reflux. The reflux ratio can range from 0.01:1 to 10:1, such as from 0.1:1 to 5:1, or from 0.5:1 to 2:1. The term "reflow ratio" as used in this document is defined as the ratio of the reflux flow to S4a and is a measure of how much of the material going to the top of the first fractionation unit is returned back to the first fractionation unit like reflux.
[0068] According to a preferred embodiment of the present invention, the first fractionation unit in (d) is operated without reflux. According to this modality, it is preferable to supply current S3 to the top of the first fractionation unit. In that case, it is generally possible to operate the first fractionation unit as a sterilization unit by boiling steam or as a sterilization unit by unreferred steam. If the first fractionating unit is designed as a referential steam sterilization unit, it is preferred that at least one heat exchanger is suitably arranged in the lower parts of the first fractionating unit in order to allow evaporation of the lower parts stream of the first fractionation unit in which steam sterilization steam is generated internally. If the first fractionation unit is designed as a non-referred steam sterilization unit, it is preferred that at least one external steam feed stream is employed as steam sterilization steam and to omit the at least one heat exchanger arranged in the lower parts of the first fractionation unit. Generally speaking, it is possible to combine at least one heat exchanger arranged in the lower parts in the first fractionating unit and at least one external steam feed stream. Preferably, in case the first fractionating unit is operated without reflux, the first fractionating unit is operated as a boiling steam sterilization unit.
[0069] In general, from 1 to 10%, preferably from 2 to 5% of the stream S3 subjected to the first fractionation unit is removed by means of the liquid bottom stream S4b. The liquid bottom stream S4b obtained from the first fractionation unit according to (d) can, in general, be subjected to further processing stages (work-up). For example, it is possible to properly separate acetonitrile from S4b. Additionally, it may be possible for the liquid bottoms stream to comprise or consist of two liquid phases wherein the bottom phase, which consists essentially of acetonitrile and water, can be further tested to minimize loss of acetonitrile in the course of step (d). If present, the upper organic phase is generally made up of less than 10% by weight of the total amount of the lower parts stream. Preferably, the liquid bottom stream S4b, optionally after separation of additional acetonitrile, is discarded, and since S3 splits from S2 it preferably only constitutes a smaller portion of S2 whose smaller portion effectively prevents the formation of the concentration of the at least a component B in the highly integrated process of the present invention, and since only a minor portion of S3 is removed via S4b, simply discarding S4b even without any further work-up is economically advantageous.
[0070] Preferably in (d), at least 75% by weight, more preferably at least 80% by weight, more preferably at least 85% by weight, most preferably at least 90% by weight of the vapor fraction stream S4a are submitted to vapor-liquid fractionation in the second fractionation unit. More preferably in (d), 95 to 100% by weight, more preferably 99 to 100% by weight, most preferably 99.9 to 100% by weight of the vapor fraction stream S4a is subjected to vapor-liquid fractionation in the second fractionation unit. More preferably, the vapor fraction stream S4a obtained from the first fractionation unit is completely subjected to vapor-liquid fractionation in the second fractionation unit.
[0071] While it is generally possible to condense at least part of the steam fraction stream S4a before it is subjected to the second fractionating unit, it is preferable not to condense the steam fraction stream S4a before it is subjected to the second unit of fractionation.
[0072] In general, there are no specific restrictions in which at least part of the current S4a is fed to the second fractionation unit. Preferably, the at least part of the stream S4a is fed to the lower part of the second fractionating unit, preferably to the lower parts of the second fractionating unit.
[0073] Preferably, the second fractionating unit is operated at an absolute pressure at the bottom of the second fractionating unit in the range from 65 to 95%, more preferably from 70 to 90, most preferably from 75 to 85% of the pressure at the top of the first fractionation unit.
[0074] Therefore, the present invention relates to the process as defined above, in which S3 is fed to the top of the first fractionating unit and at least a part of the steam fraction stream S4a a is fed to the bottom of the second fractionating unit. fractionation, wherein in (d), the first fractionation unit is operated at an absolute pressure at the top of the first fractionation unit in the range of 0.5 to 5 bar, preferably from 0.75 to 2 bar, more preferably 1 at 1.5 bar, and wherein the second fractionating unit is operated at an absolute pressure at the bottom of the second fractionating unit in the range from 65 to 95%, preferably from 70 to 90, more preferably from 75 to 85% of the pressure at the top of the first fractionation unit.
[0075] Preferably, in (d), the number of theoretical plates of the second fractionating unit is in the range from 1 to 100, preferably from 3 to 50 more preferably from 5 to 30.
[0076] According to a preferred embodiment of the present invention, the second fractionation unit in (d) is operated with reflux. While it is generally possible to use any suitable stream as reflux, it is preferable to use a portion of S4c, preferably after condensation, as reflux. Preferably, the reflux ratio is in the range of from 0.5:1 to 1:1, more preferably from 0.7:1 to 1:1, more preferably from 0.9:1 to 1:1. The term "backflow ratio" as used in this context is defined as the ratio of the backflow to S4c and is a measure of how much material to the top of the second fractionation unit is returned back to the second fractionation unit as reflux.
[0077] According to a conceivable embodiment of the present invention, the second fractionating unit in (d) is operated without reflux. According to this embodiment, it is preferable to feed at least part of the stream S4a to the top of the second fractionating unit. In that case, it is generally possible to operate the second fractionation unit as a boiled steam sterilization unit or as a non-referred steam sterilization unit. If the second fractionating unit is designed as a referential steam sterilization unit, it is preferred that at least one heat exchanger is suitably arranged in the lower parts of the second fractionating unit in order to allow evaporation of the lower parts stream of the second fractionation unit in which steam sterilization steam is generated internally. If the second fractionating unit is designed as a non-referred steam sterilization unit, it is preferred that at least one external steam feed stream be employed as steam sterilization steam and omit the at least one heat exchanger arranged in the parts lower than the second fractionation unit. Generally speaking, it is possible to combine at least one heat exchanger arranged in the lower parts of the second fractionating unit and at least one external steam feed stream. Preferably, in case the second fractionating unit is operated with reflux, the second fractionating unit is operated as a non-referred steam sterilization unit.
[0078] Therefore, the present invention relates to the process as described above, wherein in (d), the first fractionation unit is operated without reflux, at least a part of the vapor fraction stream S4a subjected to vapor-liquid fractionation in the second fractionating unit preferably not being condensed prior to subjecting to vapor-liquid fractionation in the second fractionating unit, and the second fractionating unit is operated with reflux, wherein the fraction of vapor fraction stream S4c is used, after condensation , as reflux and wherein the reflux ratio is preferably in the range of from 0.5:1 to 1:1, more preferably from 0.7:1 to 1:1, most preferably from 0.9:1 to 1:1 .
[0079] According to the present invention, it is preferred that from 90 to 99.99% by weight, more preferably from 95 to 99.9% by weight, most preferably from 98 to 99.9% by weight of S4 consists of acetonitrile and water, and from 0.0001 to 0.2% by weight, preferably from 0.001 to 0.15% by weight, more preferably from 0.005 to 0.1% by weight of S4 consists of at least a component B. STEP (E)
[0080] According to step (e) of the process of the present invention, at least a portion of S4 and at least a portion of S2 are recycled to step (a) of the process of the present invention. Generally speaking, it is possible to recycle S4 or a portion thereof without any further processing stages (work-up) to step (a). Preferably, S4 or a portion thereof undergoes a downstream processing stage (work-up) before recycling to (a). Additionally, according to step (e) of the process of the present invention, at least a portion of S2 is recycled to step (a) of the process of the present invention. Generally speaking, it is possible to recycle S2 or the portion thereof without any further processing stages (workup) to step (a). Preferably, S2 or a portion thereof undergoes a downstream processing stage (work-up) before recycling to (a). In the case of S2 or the portion thereof is subjected to a processing stage (work-up) downstream before recycling to (a), and in the case of, during this processing stage (work-up), the ratio of weight of acetonitrile with respect to the at least one component B is increased compared to the respective weight ratio of S2, said weight ratio after the work-up stage is less than the respective weight ratio of S4.
[0081] Therefore, the present invention relates to the process as described above, wherein (e) comprises recycling at least a portion of S4, optionally after processing (work-up), to (a), and recycling at least a portion from S2, optionally after processing (work-up), to (a).
[0082] Preferably, in the processing stage (work-up) with respect to S4, S4 or the portion thereof is combined with at least a portion of S2. Preferably, in the work-up stage with respect to S2, S2 or portion thereof is combined with at least a portion of S4. The combined stream respectively obtained is recycled, optionally after processing (work-up), to (a). More preferably, the complete S4 stream, optionally after having separated a portion of it used as reflux to the fractionating unit employed in (d), and the complete S2 stream are suitably combined and the combined stream is recycled, optionally after processing (work- up), to (a). More preferably, S4 or a portion thereof is condensed and combined with stream S2 to obtain a liquid stream. Preferably, the complete stream S4, optionally after separating a portion of it used as reflux to the fractionating unit employed in (d), is condensed and combined with S2 obtaining a liquid stream. Preferably, this liquid stream is subjected to a processing stage (work-up) downstream before recycling to (a).
[0083] Therefore, the present invention relates to the process as described above, wherein (e) comprises combining at least a portion of S4 and at least a portion of S2, and recycling the combined stream, optionally after processing (work-up ), to the).
[0084] According to the present invention, said processing stage (work-up) downstream with respect to the combined stream preferably comprises an acetonitrile-water separation from such separation a stream enriched in acetonitrile is obtained which, optionally after processing (work-up) is preferably recycled to (a).
[0085] Therefore, the present invention relates to the process as described above, wherein (e) comprises combining at least a portion of S4 and at least a portion of S2, subjecting the combined stream to an acetonitrile-water separation obtaining a stream enriched in acetonitrile, and recycling the enriched stream in acetonitrile, optionally after further work-up, to (a).
[0086] Therefore, the present invention also relates to the process as described above, wherein (e) comprises formation of S4, said formation comprising combining at least a portion of S4, preferably after condensation, with S2 obtaining a preferably liquid stream, subjecting said preferably liquid stream to acetonitrile-water separation obtaining a stream enriched in acetonitrile, and recycling said stream enriched in acetonitrile, optionally after further work-up, to (a).
[0087] With respect to said acetonitrile-water separation, there is no specific restriction. Preferably, the acetonitrile-water separation comprises adding a stream P preferably comprising at least 95% by weight, based on the total weight of P, of C3 wherein C3 is propene optionally mixed with propane, preferably a liquid stream P, - both for S2, wherein the resulting stream is combined with at least the portion of S4 to obtain a preferably liquid stream S5; - as for at least the portion of S4, wherein the resulting stream is combined with S2 to obtain a preferably liquid stream S5; - or, preferably, for a liquid stream obtained from the combination of at least the portion of S2 and at least the portion of S4.
[0088] It is also possible to add a first portion of stream P to at least the portion of S4 and add a second portion of stream P to S2 and combine the two resulting streams to obtain a preferably liquid stream S5. The preferably liquid stream P preferably comprises at least 95% by weight, based on the total weight of P, of C3 wherein C3 is propene optionally mixed with propane. With respect to C3, it is preferred that the minimum weight ratio of propene to propane of 7:3. In the context of the present invention, all modalities with respect to the addition of the stream P described above are encompassed by the term "subjecting the combined stream to an acetonitrile-water separation obtaining a stream enriched in acetonitrile" as used in the context of step (e) above .
Preferably, at least 95% by weight of P consists of propene or a mixture of propene with propane. If P contains a mixture of propene and propane, the weight ratio of propene to propane will be at least 7:3. Therefore, propene streams can be employed as P or C3 which have propane variant contents. For example, commercially available propene can be employed as P or C3 which can also be polymer grade propene or a chemical grade propene. Typically, polymer grade propene will have a propene content from 99 to 99.8% by weight and a propane content from 0.2 to 1% by weight. Chemical grade propylene will typically have a propene content from 92 to 98% by weight and a propane content from 2 to 8% by weight. According to a preferred embodiment of the present invention, a P-stream is employed, at least 95% by weight thereof consisting of C3, where C3 is a mixture of propene and propane and the content of C3 with respect to propene is in the range from 92 to 98% by weight, preferably from 94 to 97% by weight, and the content of C3 with respect to propane is in the range from 2 to 8% by weight, preferably from 3 to 6% by weight.
[0090] With regard to the amount of P, it is preferred that P is added so that in S5, the weight ratio of C3 to acetonitrile is in the range of 0.2:1 to 5:1, preferably of 0.5 to 1 to 2:1. Therefore, preferably from 90 to 99.9% by weight, more preferably from 95 to 99.8% by weight, most preferably from 98 to 99.5% by weight of the S5 stream consists of acetonitrile, water and C3, and preferably of 0.01 to 3% by weight, preferably from 0.015 to 2.5% by weight, more preferably from 0.02 to 1.5% by weight of stream S5 consists of the at least one component B, wherein the weight ratio of acetonitrile to water is preferably greater than 1:1 and wherein the weight ratio of C3 to acetonitrile is preferably in the range from 0.2:1 to 5:1, more preferably from 0.5 to 1 to 2:1, where with respect to C3, the weight ratio of propene to propane is at least 7:3.
[0091] Preferably, the stream S5 is subjected to a suitable temperature and a suitable pressure by the said treatment of temperature and pressure two liquid phases L1 and L2 are formed. It has been found that it is beneficial for the division into these phases L1 and L2 to subject current S5 to as low a temperature as possible with the consideration that the temperature is still adequate; for example, the temperature should not be so low that a solid phase such as ice is formed. Preferably, the liquid phase L1 enriched in acetonitrile is suitably separated from L2 and recycled to (a), optionally after further work-up. Regarding the temperature and pressure treatment, there is no specific restriction, considering that the two phases L1 and L2 are formed where L1 is enriched in acetonitrile. Preferably, S5 is placed at a temperature of maximum 92 °C. According to the present invention, it is preferable to place S5 at a temperature in the range from 5 to 90 °C, preferably from 7 to 80 °C, more preferably from 8 to 60 °C, most preferably from 9 to 40 °C, and more preferably from 10 to 30°C. Preferably, S5 is subjected to a pressure of at least 10 bar so that S5 will be essentially or completely in liquid form. The term "essentially in its liquid form", as used in this context of the present invention, refers to an embodiment according to which at least 95% by weight, more preferably at least 99% by weight and most preferably at least 99, 9% by weight of S5 are present in liquid form after being subjected to the temperature and pressure mentioned above. According to the present invention, it is preferable to subject S5 to a pressure of at least 15 bar, more preferably a pressure in the range of 15 to 50 bar, more preferably 15 to 40 bar, more preferably 15 to 30 bar, and more preferably from 15 to 25 bar.
[0092] Placing S5 at the temperature mentioned above can be achieved by any suitable method. In accordance with the present invention, it is preferred to use one or more suitable heat transfer media, eg water, in a suitable apparatus, eg a shell and tube heat exchanger. Subjecting S5 to the pressure mentioned above can be achieved by any suitable method. According to the present invention, it is preferable to use a suitable pump, such as a centrifugal pump or a radial pump.
[0093] Preferably, at least 95% by weight, preferably at least 98% by weight of L1 consists of C3, acetonitrile, water and the at least one component B, wherein the water content of L1 is less than 10% by weight, preferably in the range of 1 to 5% by weight, based on the total weight of L1.
[0094] Preferably, at least 98% by weight of L2 consists of C3, acetonitrile, water and the at least one component B, wherein the C3 content of L2 is 5% by weight at most, based on the total weight of L2, and the acetonitrile content of L2 is less than 45% by weight, preferably in the range of 10 to 35% by weight, based on the total weight of L2.
[0095] According to the present invention, temperatures and pressures as described above allow the existence of two distinct liquid phases L1 and L2. Preferably, the two distinct liquid phases L1 and L2 are properly separated from each other. Generally speaking, for this separation of the two liquid phases, every conceivable method can be applied. Suitable apparatus used for separating L1 from L2 are, for example, gravity settlers, settlers with coalescence aids such as dam, inclined plate separator, coalescers such as, for example, mats, beds, layers of porous or fibrous solids, or membranes, decanter-phase mixer equipment, hydrocyclones, centrifuges, suitable columns with or without energy input. Generally speaking, batch mode or continuous mode is conceivable. Preferably, a gravity settler such as a vertical or horizontal gravity settler is employed. Even more preferably, a horizontal gravity decanter is employed. It was found that due to the considerable density difference and low viscosities reached for the liquid phases L1 and L2 according to the inventive method, the gravity decanter, one of the simplest devices, can be used. According to the present invention, it is conceivable that at least one liquid phase separation enhancing agent, such as at least one suitable anti-emulsifier, emulsion breaking agent or demulsifier is added. Generally speaking, it is possible to add such liquid phase separation enhancing agent to S4 or S5 or to S4 and S5. The amount of liquid phase separation enhancing agent added is preferably at most 1% by weight based on the total weight of S4 and/or S5. Typically, the amount will be less than 1% by weight such as below 0.5% by weight or below 0.1% by weight. Suitable agents are known to the person skilled in the art. Reference is made, for example, to KJ Lissant, Making and Breaking Emulsions, Res. Lab., Petrolite Corp., St. Louis, Missouri, USA, in: KJ Lissant (ed.), Emulsion Technology (1974), chapter 2, page 111-124, Dekker, New York; and S.E. Taylor, Chem. Ind. (1992), pages 770-773.
[0096] Therefore, step (e) of the process of the present invention preferably comprises: (i) preparing a preferably liquid stream S5 by adding a preferably liquid stream P to S2, or to at least a portion of S4, or to the liquid stream obtained from the combination of S2 and at least the portion of S4, wherein P comprises at least 95% by weight of C3, based on the total weight of P, wherein C3 is propene optionally mixed with propane at a weight ratio minimum propene to propane of 7:3, and where P is preferably added in an amount such that in S5, the weight ratio of C3 to acetonitrile is in the range of 0.2:1 to 5: 1, preferably from 0.5:1 to 2:1; (ii) subject S5 to a temperature of at most 92 °C and a pressure of at least 10 bar, preferably to a temperature in the range of 5 to 90 °C and a pressure in the range of 15 to 50 bar, more preferably to a temperature in the range of 25 to 45 °C and a pressure in the range of 15 to 25 bar, obtaining a first liquid phase L1 and a second liquid phase L2, wherein at least 95% by weight, preferably at least 98% by weight of L1 consists of C3, acetonitrile, water and the at least one component B, the water content of L1 being less than 10% by weight, preferably in the range of 1 to 5% by weight, based on the total weight of L1. and wherein at least 95% by weight, preferably at least 98% by weight of L2 consists of C3, acetonitrile, water and the at least one component B, the C3 content of L2 being 5% by weight maximum, based in the total weight of L2, and the acetonitrile content of L2 being less than 45% by weight, preferably in the range of 10 to 35% by weight, based on the total weight of L2; (iii) separate L1 from L2, preferably in a gravity decanter; (iv) recycle L1 as the stream enriched in acetonitrile, optionally after further work-up, to (a). THE L2 CURRENT
[0097] Preferably, from the process of the present invention, a liquid phase L2 is obtained that consists essentially of water and acetonitrile wherein the weight ratio of acetonitrile:water in L2 is less than 1. The term "consists essentially of acetonitrile and water" as used in this context of the present invention refers to a liquid phase L2 in which at least 90% by weight of L2 consists of acetonitrile and water. Preferably at least 95% by weight, more preferably at least 97% by weight and even more preferably at least 98% by weight of L2 consists of C3, acetonitrile and water, wherein the C3 content of L2 is 5% in weight at most, preferably 3% by weight at most, and more preferably 2% by weight at most based on the total weight of L2. With regard to acetonitrile, its L2 content is preferably less than 45% by weight, more preferably in the range of 10 to 40% by weight, more preferably 10 to 35% by weight, based on the total weight of L2.
[0098] In general, the liquid phase L2 can be used in any suitable process. For example, it is conceivable that the liquid phase L2 is employed as a stream which is passed to an oxidation reaction or a processing stage (work-up) downstream of said oxidation reaction in which acetonitrile is used as solvent and in which propene is oxidized, such as an epoxidation reaction where acetonitrile is used as a solvent and where propene is oxidized by hydrogen peroxide to obtain propylene oxide.
[0099] Preferably, the liquid phase L2, before being employed in a suitable process, is subjected to at least one additional separation stage. A preferred method for said separation comprises subjecting the liquid phase L2 to a distillation stage. Preferably, the distillation is carried out in a suitable manner so that a stream TL2 is obtained which contains from 75 to 95% by weight, preferably from 80 to 85% by weight of acetonitrile, based on the total weight of TL2. In general, L2 distillation can be carried out in one, two or more distillation towers. If such distillation is carried out in a distillation tower, the dew point of water at the top of said distillation tower is typically at least 40 °C, preferably in the range 40 to 80 °C, more preferably in the range 40 to 65 °C. Typically, the number of theoretical plates is in the range of 10 to 25. Typical reflux ratios are in the range of 0.5 to 3. By such a process, current TL2 is obtained as an overhead stream from the distillation tower. The respective bottoms stream, BL2, is preferably essentially free of acetonitrile. In this context, the term "essentially acetonitrile free" refers to a modality, according to which the acetonitrile content of BL2 is 500 ppm by weight at most, preferably 300 ppm by weight at most, more preferably 100 ppm by weight maximum, based on the total weight of BL2.
[00100] It has been found that it is possible to subject liquid phase L2 to a specially designed distillation stage that allows for a highly integrated distillation process by heat. Thus, it has been found that the separation of L2 is advantageously carried out using a two pressure distillation process, where in a first distillation tower, the distillation is carried out at a top pressure that is greater than the top pressure of a second distillation tower coupled with said first distillation tower, wherein the condenser used to condense the overflow from the first distillation tower is used simultaneously as the vaporizer of the second distillation tower. According to this preferred embodiment, the liquid stream L2 is preferably introduced into said first distillation tower from which a first bottom stream and a first top stream are obtained. Preferably, said first distillation tower is operated under conditions whereby to obtain a VTL2 vapor overhead stream containing from 50 to 70% by weight, preferably from 55 to 65% by weight of acetonitrile, based on the total weight of VTL2. Typically, said first distillation tower is operated at pressures at the top of the tower in the range from 10 to 20 bar, preferably from 10 to 15 bar. In general, the first distillation tower has from 10 to 25, preferably from 15 to 20 theoretical plates. Generally speaking, the reflux ratio of said first distillation tower is in the range from 0.25:1 to 2:1, preferably from 0.25:1 to 1:1. The respective bottoms stream obtained from the first distillation tower is preferably essentially free of acetonitrile. In this context, the term "essentially acetonitrile free" refers to a modality according to which the acetonitrile content of the lower parts stream of the first distillation tower is 500 ppm by weight at most, preferably 300 ppm by weight in the maximum, more preferably 100 ppm by weight at most, based on the total weight of the bottom stream from the first distillation tower. Hereinafter, said bottoms stream obtained from said first distillation tower, optionally mixed with the bottoms stream obtained from the second distillation tower as described below, is referred to as stream BL2. In the two-pressure distillation process, at least a portion of, preferably all of the VTL2 is suitably condensed, and that condensed stream is introduced into the second distillation tower from which a second bottom stream and a second top stream are obtained. Preferably, said second distillation tower is operated under conditions which allow to obtain an overhead TL2 which contains from 75 to 95% by weight, preferably from 80 to 85% by weight of acetonitrile, based on the total weight of TL2. Typically, said second distillation tower is operated at pressures at the top of the tower in the range from 1 to 5 bar, preferably from 1 to 2 bar. In general, the second distillation tower has from 8 to 20, preferably from 10 to 15 theoretical plates. Generally speaking, the reflux ratio of said second distillation tower is in the range from 0.5 to 5, preferably from 1 to 3. The respective bottom stream obtained from the second distillation tower is preferably essentially free. of acetonitrile. In this context, the term "essentially acetonitrile free" refers to a modality according to which the acetonitrile content of the second distillation tower bottoms stream is 500 ppm by weight at most, preferably 300 ppm by weight at most , more preferably 100 ppm by weight at most, based on the total weight of the bottom stream from the second distillation tower.
[00101] Preferably, TL2 obtained from the respective distillation tower is at least partially, preferably completely recycled into the inventive process. More preferably, TL2 is both combined with S4 and/or with S5 and/or with P, and optionally also combined with TL1 as described below.
[00102] If stream S5 contains at least one propylene glycol, stream BL2 obtained from said distillation preferably contains the at least one propylene glycol in an amount from 1 to 5% by weight, more preferably in an amount to from 2 to 5% by weight, based on the total weight of BL2, while stream TL2 is essentially free of at least one propylene glycol. In this context of the present invention, the term "TL2 is essentially free of the at least one propylene glycol" refers to an embodiment according to which the content of TL2 with respect to the at least one propylene glycol is 500 ppm by weight at the most TL2 it is essentially free of at least one propylene glycol, preferably 200 ppm by weight at most. If BL2 does not or essentially does not contain propylene glycol, it is preferable to pass BL2 directly to a suitable wastewater treatment plant, such as a biological wastewater treatment plant. It was found that no proper treatment for the wastewater produced by the inventive process is required, making the process even more cost-effective and environmentally friendly. If BL2 contains at least one propylene glycol in significant amounts, such as in an amount from 1 to 5% by weight, more preferably in an amount from 2 to 5% by weight, based on the total weight of BL2, it may be preferable to pass BL2 to a suitable propylene glycol separation stage in which the at least one propylene glycol is suitably separated from the water and/or in which two or more different propylene glycols are separated from each other. This process for separating the at least one propylene glycol from BL2 can be carried out, for example, by evaporating the mixture in at least two, preferably three evaporation and/or distillation stages, preferably three evaporation stages, when decreasing operating pressures, preferably in the ranges of 1.5 to 5.5 bar at a temperature of 111 to 155 °C, followed by 1.3 to 5.0 bar at a temperature of 107 to 152 °C, followed by its time, for 0.7 to 4.0 bar at a temperature of 90 to 144 °C, thus obtaining BL2-a mixture and BL2'-b mixture; and separating a BL2-a mixture in at least one further distillation step, obtaining a BL2-I mixture comprising at least 70% by weight of water and a BL2-II mixture comprising less than 30% by weight of water. It is especially preferred to further separate the BL2-b mixture into a BL2-Ia mixture comprising at least 90% by weight of water and a BL2-Ib mixture comprising less than 95% by weight of water by means of reverse osmosis. Preferably, the at least one propylene glycol is separated from the BL2-II mixture, preferably mixed with the BL2-Ib mixture, in at least one additional distillation step. More preferably, BL2'-b and BL2-I mixtures are combined and further separated into BL2-Ia mixture comprising at least 90% by weight of water and BL2-Ib mixture comprising less than 95% by weight of water by means of reverse osmosis.
[00103] Therefore, the present invention also relates to a method as described above in which: (aa) L2 is introduced into the first distillation tower from which a VTL2 vapor top stream is obtained containing from 50 at 70% by weight of acetonitrile, based on the total weight of VTL2 overhead stream, the distillation preferably being carried out at an overhead pressure from 10 to 20 bar; and (bb) condensing at least partially TL2 obtained in (aa) and introducing the condensed stream into the second distillation tower from which TL2 is obtained as an overhead, the distillation preferably being carried out at an overhead pressure from 1 at 5 bar, where preferably the condenser used to condense VTL2 is simultaneously used as the vaporizer of the second distillation tower. THE L1 CURRENT
[00104] According to the present invention, it is preferred that the stream L1 separated according to (iii) is recycled to (a) after further work-up.
[00105] Preferably, this further work-up serves to separate C3, preferably a portion of C3, from the acetonitrile. A conceivable method is, for example, evaporation of the liquid phase L1 by decompression at a suitable pressure. Preferably, the temperature of the liquid phase is kept essentially constant during decompression. By this decompression, C3 is obtained in gaseous form. Therefore, it is possible to recycle at least a portion of that gaseous stream C3, after adequate compression to obtain a liquid stream, for example, as at least a portion of stream P.
[00106] Preferably, L1 is subjected to fractionation, more preferably to distillation, from which a stream is obtained which is enriched in acetonitrile and which is preferably recycled to (a), optionally after a work-up. Preferably, said stream enriched in acetonitrile is recycled to (a) without further formation. More preferably, such distillation is carried out in a suitable manner so that a stream TL1 is obtained which contains at least 90% by weight, preferably at least 95% by weight of C3, based on the total weight of TL1. Preferably, according to such distillation, a BL1 stream is obtained which preferably at least 95% by weight, more preferably at least 98% by weight consists of C3, acetonitrile, water and the at least one component B. More preferably, the content of C3 of BL1 is in the range of from 7 to 18% by weight, preferably from 10 to 15% by weight, in each case based on the total weight of BL1.
[00107] In general, this L1 distillation can be performed according to any suitable method. For example, one, two or more distillation towers can be employed considering that the TL1 and BL1 currents mentioned above are obtained. Preferably, in said distillation stage, a distillation tower is employed. More preferably, said distillation is carried out at a dew point of water at the top of said distillation tower of at least 40°C, preferably in the range of 40 to 80°C, more preferably in the range of 40 to 70°C. Preferably, the number of theoretical plates is in the range of 10 to 20. Preferred reflux ratios are in the range of 0.01:1 to 0.2:1 such as 0.05:1 to 0.15:1.
[00108] Therefore, the present invention also relates to the process as described above, further comprising L1 work-up, said work-up comprising subjecting L1 to a distillation stage from which a stream of parts lower BL1 is obtained wherein at least 95% by weight, preferably at least 98% by weight of BL1 consists of C3, acetonitrile, water and the at least one component B, wherein the C3 content of BL1 is in the range of 7 to 18% by weight, preferably from 10 to 15% by weight, and recycling BL1 as the stream enriched in acetonitrile, optionally after no further work-up, to (a). Preferably, from 0.01 to 5% by weight, more preferably from 0.015 to 3% by weight, more preferably from 0.02 to 2% by weight of BL1 consists of the at least one component B. In particular, the tower distillation is operated in a suitable manner, for example, by adjusting the energy input to the reservoir, which leads to a BL1 stream with a content of propene which, when fed back to the epoxidation reaction as a recycling stream, results in a molar ratio of propene to hydrogen peroxide in stream (1) in the range of from 0.9:1 to 3.0:1, more preferably from 0.98:1 to 1.6:1, most preferably from 1.0:1 to 1.5:1, such as from 1.2:1 to 1.4:1.
[00109] Thus, the present invention relates to the process as described above, which process comprises processing (work-up) of L1 comprising subjecting L1 to a distillation stage from which a stream of lower parts BL1 is obtained, wherein at least 95% by weight, preferably at least 98% by weight of BL1 consists of C3, acetonitrile, water and the at least one component B, wherein the C3 content of BL1 is in the range of 7 to 18% by weight, preferably from 10 to 15% by weight, and recycle BL1 as the stream enriched in acetonitrile, preferably without any further work-up, to (a).
[00110] Preferably, from 0.01 to 5% by weight, more preferably from 0.015 to 3% by weight, more preferably from 0.02 to 2% by weight of BL1 consists of the at least one component B.
[00111] Additionally, it has been found that combining the inventive separation of L1 from L2 and the downstream separation of TL1 from BL1 allows for a highly integrated design of the process of the present invention. On the one hand, stream TL1 is especially suitable to be recycled within the inventive process as at least a portion of P. If, in addition to at least a portion of TL1, C3 is additionally added to S1, that additional source of C3 can be chosen properly. For example, additional C3 can be added as fresh propene, for example, as chemical grade propene containing about 95% by weight propene and about 5% by weight propane. All other suitable sources of additional C3 are conceivable, such as a C3 stream obtained from a supplier at a Verbund site or the like. Additionally, it has been found that the more C3 is recycled through TL1, the more efficient is the separation step according to (i) to (iii) of the inventive process works in terms of a more complete separation of S1 as possible. Therefore, it is preferred that at least a portion of TL1, preferably all TL1 is recycled in (ii).
[00112] In general, it is conceivable that partial steam distillation can be arranged elsewhere in the process downstream of epoxidation, preferably in a location with current access to acetonitrile solvent.
[00113] Preferably, such a conceivable location would be a location where the acetonitrile solvent stream is free of or essentially free of propene and optionally propane, and/or where the acetonitrile solvent stream is free of or essentially free of peroxide of hydrogen. More preferably, such a conceivable site would be a site downstream of the epoxidation reaction step (a) and downstream of the site where the P stream is mixed, downstream of the liquid-liquid separation in (ii). More preferably, such a conceivable location would be a location downstream of the location where propylene oxide is removed from the acetonitrile solvent stream in step (b) and upstream of the location where the P stream is mixed, upstream of the separation liquid-liquid in (ii). More preferably, the location of the partial stream distillation is the location as described above where S3 as a portion of the stream S1 is subjected to distillation. Additionally, it is generally conceivable that at more than one location in the process downstream of epoxidation, partial stream distillation whereby a portion, preferably a smaller portion of the acetonitrile solvent stream is subjected to distillation, is arranged.
[00114] The present invention is illustrated by the following examples and comparative examples. EXAMPLES EXAMPLE 1: A PREFERRED PROCESS ACCORDING TO THE INVENTION - GENERAL CONFIGURATION
[00115] As for the abbreviations, reference is made to the scheme according to Figures 1 and 3, described in general in the section "Description of Figures" below. All pressures determined are absolute pressures. 1.1 PREPARATION OF THE s0 CHAIN (STEP (A)) A) EpoxiDATION IN A MAIN EpoxiDATION REACTOR (EpoxiDATION UNIT A)
[00116] The main reactor A was a vertically mounted tube bundle reactor with 5 tubes (tube length: 12 m, inner tube diameter: 38 mm), each tube being equipped with an axially placed multi-point thermocouple with 10 evenly spaced measuring points enclosed in a suitable thermowell with a diameter of 18 mm. Each tube was loaded with 17.5 kg of the ZnTiMWW catalyst moldings as prepared in accordance with Reference Example 1, section 1.8 (post-treated moldings). The eventually remaining free space was filled with steatite spheres (diameter 3 mm). The heat of reaction was removed by circulating a thermostated heat transfer medium (water/glycol mixture) on the jacket side in co-current with the feed. The flow rate of the heat transfer medium was adjusted so that the temperature difference between inlet and outlet did not exceed 1 °C. The reaction temperature referred to below was defined as the temperature of the heat transfer medium entering the reactor shell. At the reactor outlet, the pressure was controlled by a pressure regulator and kept constant at 20 bar.
[00117] The reactor was fed from below with a liquid single-phase current (1). Stream 1 was prepared by mixing four streams (2), (3), (3a) and (4). Stream temperature (1) was not actively controlled, but was generally in the range of 20 to 40 °C: - Stream (2) having a flow rate of 85 kg/h. At least 99.5% by weight of stream (2) consisted of acetonitrile, propene and water. This stream (2) came from the bottoms of the acetonitrile recycling distillation unit (J). - Stream (3) having a flow rate of 15 kg/h was an aqueous hydrogen peroxide solution having a hydrogen peroxide concentration of 40% by weight ("crude/washed" Solvay grade with TOC in the range of 100 at 400 mg/kg). The aqueous hydrogen peroxide solution was supplied from the storage tank, allowing for continuous feed, and fed using a suitable metering pump. - Stream (3a) was an aqueous stream comprising dissolved potassium formate. Additional current was supplied from a storage tank, allowing for continuous feed, and was fed using a suitable metering pump. The potassium formate concentration was 2.5% by weight, the current feed rate (S3a) was 370 g/h. Stream (3a) was thoroughly mixed with stream (3) before the combined stream was mixed with the resulting stream from mixing stream (2) and (4). - Stream (4) was a work-up stream of pure acetonitrile (chemical grade, from Ineos, purity about 99.9%, containing between 70-180 ppm by weight of propionitrile, 5-20 ppm in weight of acetamide and less than 100 ppm by weight of water as impurities). Sufficient fresh acetonitrile was added to make up for losses in the process. Under regular conditions, a measure from 100 to 150 g/h of work-up acetonitrile was added.
[00118] The output current leaving epoxidation unit A was sampled every 20 minutes in order to determine the hydrogen peroxide concentration using the titanyl sulfate method and to calculate the hydrogen peroxide conversion. The hydrogen peroxide conversion was defined as 100 x (1-mout/min) where min is the molar flow rate of H2O2 in the reactor feed and mout is the molar flow rate of H2O2 in the reactor outlet. Based on the hydrogen peroxide conversion values respectively obtained, the inlet temperature of the heat transfer medium was adjusted in order to keep the hydrogen peroxide conversion essentially constant in the range of 90 to 92%. The heat transfer medium inlet temperature was set at 30°C at the beginning of a given run with a fresh batch of epoxidation catalyst and was increased, if necessary, to keep the hydrogen peroxide conversion in the mentioned range. The required temperature rise was generally less than 1 K/d. B) INTERMEDIATE PROPYLENE OXIDE REMOVAL (DISTILLATION UNITB)
[00119] After releasing pressure, the effluent from the epoxidation unit A (stream (5)) was sent to an intermediate propylene oxide removal column (distillation unit B) operated at about 1.1 bar. The column was 6 m high, had a diameter of 200 mm and was equipped with 30 bubble trays, an evaporator and a condenser. Feed to the column that entered above the bubble tray 25 (contained from the top). The air stream leaving the column at about 50°C contained mainly propylene oxide, unconverted propene, and small amounts of oxygen formed as a by-product. This stream was partially condensed (T = 15-25 °C) and the condensed liquid served as an internal reflux stream whereas the gaseous part (stream (6)) was sent to the light separation column (distillation unit D) .
[00120] The temperature of the lower parts of the intermediate propylene oxide removal column was about 80 °C. The bottoms stream (stream (7)) was almost free of propylene oxide (< 300 wt%) and was a mixture of acetonitrile (about 78-80% by weight), water (about 18-20% by weight), unconverted hydrogen epoxide and heavy kettles having a normal boiling point of about 100°C, the main heavy kettle being propene glycol. This bottoms stream (7) was subsequently cooled to 35 °C and pumped into the finishing reactor (epoxidation unit C; see section c) below) using a suitable metering pump. C) EPOXIDATION IN A FINISHING REACTOR (EPOXIDATION UNITC)
[00121] The total feed stream to the C completion reactor was obtained by mixing stream (7), obtained in accordance with section b) above, with a stream (8) of liquid propene of polymeric grade containing propane (purity > about 99.5%, feeding rate: 0.9kg/h, at room temperature). Both streams (7) and (8) were mixed using a static mixer and fed to the bottom of completion reactor C.
[00122] The C-finishing reactor was a fixed bed reactor operated adiabatically. In this context, the term “adiabatically” refers to a mode of operation according to which no active cooling is performed and, according to which, the completion reactor is adequately insulated in order to minimize heat loss. Finishing reactor C had a length of 4 m and a diameter of 100 mm. The reactor was filled with 9 kg of the same epoxidation catalyst that was used in the main epoxidation reactor A. Spare space was filled with steatite spheres (3 mm diameter). The operating pressure of the C-finishing reactor was 10 bar which was kept constant by a suitable pressure regulator at the reactor outlet. The exit from the C-finishing reactor was sampled every 20 min in order to determine the hydrogen peroxide concentration using the titanyl sulfate method.
[00123] The effluent from the C finishing reactor, stream (9), was depressurized in a firing drum, and both the liquid and the gas from this drum were fed to a light boiler separation column (unit of distillation D).
[00124] Stream (6) obtained from the top of the intermediate propylene oxide removal column (distillation unit B) and stream (9) obtained as effluent from completion reactor C (epoxidation unit C) , together, constitute the current S0, according to the present invention.
[00125] This S0 stream had, on average, an acetonitrile content of 69 to 70% by weight, a propylene oxide content of 9.8% by weight, a water content of 17% by weight, a content of propene of about 3% by weight, a propane content of about 0.05% by weight, a hydrogen peroxide content of about 250 ppm by weight, a propene glycol content of about 0.1% by weight weight and an oxygen content of about 150 ppm by weight. 1.2 SEPARATION OF PROPYLENE OXIDE FROM S0 CURRENT TO OBTAIN S1 CURRENT (STEP (B)) A) SEPARATION OF LIGHT BOILERS FROM CURRENTS (6) AND (9) (S0 CURRENT) TO OBTAIN A CURRENT (11) ( CURRENT S01 ACCORDING TO STAGE (I) OF THE PRESENT INVENTION)
[00126] The overhead stream, from the intermediate propylene oxide removal column (distillation unit B) (stream (6), see section 1.1 b) above), and the depressurized output current of the C-finishing reactor (stream (9), see section 1.1 c) above) were sent to a light boiler separation column (distillation unit D) operated at 1.1 bar. The distillation column had a length of 8.5 m, a diameter of 170 mm and was equipped with 40 bubble trays, an evaporator at the bottom and a condenser at the top. The column was operated as a mixed distillation/wash tower. As a washing agent, the part of the bottoms stream from distillation unit E (stream 14, ca. 20-30 kg/h) was taken out, cooled to 10°C and introduced to the top of the column. Gaseous and liquid inlet streams were introduced into the column at different points. The liquid stream feed point (stream (6) plus the liquid stream portion (9)) was above the blister tray 37; the gas stream was introduced into the column above bubble tray 28 (counted from the top).
[00127] The gas stream (10) leaving the cooling means at the top of the column mainly contained propene, propane (which was contained as an impurity in the used polymer grade propene), oxygen formed as a small amount and by-products from other light boilers (acetonitrile (about 4.7% by volume), propionaldehyde (about 200ppm by volume), acetone (about 100ppm by volume, H2 (about 400ppm by volume), CO2 (about 400ppm by volume) ) and acetaldehyde (about 100ppm by volume)) and was essentially free of propylene oxide (less than 300ppm by volume).This overflow was sent to incineration for disposal.
The bottoms stream of the light kettle separation column (stream (11), which is stream S01 of the present invention) having a temperature of 70°C, had a propene content of 100 to 200 ppm by weight. B) SEPARATION OF PROPYLENE OXIDE FROM CHAIN (11) (CHAIN S01) TO OBTAIN A CURRENT S02 ACCORDING TO STEP (II) OF THE PRESENT INVENTION.
[00129] The stream S01, obtained according to section 1.2 a) above, was introduced into a distillation column (distillation unit E) in order to separate propylene oxide from the stream S01. The column had a height of 50 m and a diameter of 220 mm and was equipped with a package (Sulzer BX64) with a total package length of 27.5 m divided into 8 beds with a length of 3060 mm each, and two beds with a length of 1530 mm each. Between each bed, intermediate flow distributors were installed. The column was operated at a top pressure of 750 mbar. The current supply point S01 was located below the fourth packing bed, counted from the top.
[00130] The air stream from the column was condensed and partially returned to the column as reflux (reflux ratio approx. 5:1). The remainder (stream (12)), having a flow rate of 10.1 kg/h, was considered as an aerial product and essentially consisted of propylene oxide having a purity of more than 99.9% by weight.
[00131] The bottoms evaporator was operated in such a way that the concentration of propylene oxide in the bottoms stream was below 100 ppm by weight. The resulting temperature of the bottoms stream was about 69°C. Current S02 was then split in two. The main portion of this (stream (13), with a flow rate of ca. 85 kg/h) was sent to the next distillation column (distillation unit F). The remainder (stream (14), 20-30 kg/h) was cooled and recirculated to the top of the light kettle separation column (distillation unit D) as a washing agent, as described above in section 1.2 a).
[00132] This S02 stream had an acetonitrile content of about 80% by weight, a propylene oxide content of less than 100 ppm by weight, a water content of about 20% by weight, a propene content glycol of about 0.1% by weight and a hydroxypropanol content of about 0.1% by weight. C) SEPARATION OF LIGHT BOILING COMPOUNDS FROM CURRENT (13) (CURRENT S02) TO OBTAIN A CURRENT (16) (CURRENT S1 ACCORDING TO STEP (IIIB) OF THE PRESENT INVENTION).
[00133] The current S02, obtained according to section 1.2 b) above, was introduced into a light separation column (distillation unit F). This light separation column had a height of 8 m and a nominal diameter of 150 mm and was equipped with 35 blister trays. The column was operated at a top pressure of 2 bar, and S02 current was introduced above bubble tray number 7 (counted from the bottom).
[00134] The obtained air stream (stream (15), flow rate of about 1 kg/h) left the column with a temperature of 40 to 45 °C and was not condensed, as the column was operated without any current of internal reflux. Despite the acetonitrile (6500 ppm by volume), this air stream contained mainly nitrogen, which was used to keep the column operating pressure at a value of 2 bar) and small amounts of light boilers (acetaldehyde (900 ppm by volume), oxygen ( 300 ppm by volume) and propionaldehyde (320 ppm by volume) This overhead stream was sent to incineration for disposal.
[00135] The reservoir evaporator was operated by feeding it a constant amount (5 kg/h) of saturated current at a pressure of 16 bar. The column bottom temperature was 100°C. The bottoms stream, S1 stream of the present invention, consisted primarily of acetonitrile and water, the remainder being in high kettles. This S1 stream had an acetonitrile content of about 80% by weight and a water content of about 20% by weight. 1.3 DIVIDING S1 CURRENT INTO S2 AND S3 CURRENTS (STEP (C))
[00136] According to the present invention, step (c), the current S1, flow rate 86 kg/h, obtained in accordance with section 1.2 c) above, was divided into two currents, current S2 (current 16a of according to figure 1) and S3 (current 17 according to figure 1). Stream S2 had a flow rate of 84 kg/h and stream S3 had a flow rate of 2 kg/h. Stream S3, 2.3% of stream S1, was subjected to partial stream distillation unit G (partial stream distillation column). 1.4 PARTIAL CURRENT DISTILLATION OF S1 CURRENT (STEP (D))
[00137] The first fractionation unit, ie the first distillation column, G1, had a height of 9.5 m and a diameter of 85 mm and was equipped with 6.5 meters of Rombopak 9M package structured with metal installed in three identical beds. Above the first bed of the structured package counted from the top, stream S3 ((stream 17)) was introduced into the first distillation column. The temperature of current S3 current was 60 ± 3 °C. The first distillation column was operated at a top pressure of about 1.4 bar and a bottom temperature of 92 ± 5 °C. No reflux was applied. The amount of steam fed to the bottom evaporator of the first fractionation unit was controlled in such a way that the concentration of acetonitrile in the bottom part was in the range of 10 to 25% by weight. Bottom stream S4b (stream (18b), about 3% of stream S3) has been removed. This stream consisted mainly of water (72-85% by weight) and acetonitrile (10-24% by weight). The sum of all high boiling components (27 components) varied in the range of 2-10% by weight.
[00138] The top stream, steam fraction stream S4a (18a stream), having a temperature from 85 ± 3 °C, was not condensed and passed to the bottom of the second fractionation unit, i.e., second column of distillation, G2. S4a entered G2 below the last bed of the structured package counted from the top. G2 had a height of 9.5 m and a diameter of 85 mm and was equipped with 6.5 m of metal-structured Rombopak 9M package installed in 3 identical beds. The second distillation column was operated at a top pressure of about 1.25 bar and a bottom temperature of 85 ± 5 °C. The top stream, vapor fraction stream S4c (stream (18c), at most 1% of stream S4a), was completely condensed by an external air condenser (not shown in Figure 2) and applied essentially completely to use the liquid stream. condensed as reflux into the second distillation column. The net bottoms stream S4(stream 18) was removed and passed to the next step (recycle stream S4). Stream S4 had an acetonitrile content of about 80% by weight and a water content of about 20% by weight. 1.5 RECYCLING OF THE S4 CHAIN (STEP (4)) A) PREPARE A LIQUID CHAIN5 ACCORDING TO STEP (I)
[00139] The current S4, (current 18, according to figure 1 and figure 2) was mixed with the current S2 (current (16a), according to figure 1 and figure 2). Thus, stream S4 was pumped back into the batch process acetonitrile solvent stream. Mixing took place at a point downstream from where the S3 stream was bypassed from the S1 stream.
[00140] This combined stream having a flow rate of 86 kg/h was mixed with a liquid stream P (referred to as stream (23) in figure 1 and figure 2) to obtain a stream S5. Stream P was propene stream containing fresh propane (polymer grade, purity > 96% by weight, liquefied under pressure, feed rate: 10 kg/h).
[00141] According to this specific modality of the present invention, in order to obtain the current S5, the combined current of S2 and S4 was additionally mixed with two other streams: the first of these streams is the stream (19) according to figure 1, said stream being obtained from the top of the distillation unit I. The second of these streams is the stream (22), according to figure 1, said stream being obtained from the J. Both streams of the distillation unit recovery of acetonitrile (19) and (22) are described in detail below. B) ADJUST THE CURRENT TEMPERATURE S5 AND SEPARATE LIQUID PHASES L1 AND L2 (STEPS (II) AND (III))
[00142] The S5 stream having a flow rate of 150 kg/h ± 10 kg/h was then fed to a decanter-mixer unit operated at 18 bar and a temperature in the range of 15 ± 5 °C. The settling tank had a volume of 5.3 liters. Two liquid phases L1 and L2 were obtained, an aqueous phase L2 and an organic phase L1. The upper organic phase L1 was removed from the settling tank as stream (20), the lower aqueous phase L2 was removed from the settling tank as stream (21). The stream (20) had a flow rate in the range of 130 kg/h ± 13 kg/h.
[00143] The stream (20) then passed to the acetonitrile recycling unit J, the stream (21) was passed to the acetonitrile recovery unit I from which the stream (19), mentioned above, was obtained.
The stream (20) thus obtained had an acetonitrile content of about 46% by weight, a propene content of about 51% by weight and a water content of about 3 to 4% by weight.
[00145] The stream (21) thus obtained had an acetonitrile content of about 21% by weight, a water content of about 79% by weight and a propene content of less than 0.5% by weight . C) ACETONITRILE RECOVERY (ACETONITRILE RECOVERY UNIT I)
[00146] In order to recycle as much solvent as possible, and in order to minimize loss of acetonitrile, stream (21) was introduced into a distillation column from which stream (19), also referred to as stream TL2, was obtained as an overhead stream which, in turn, was recycled into the solvent stream as described above.
[00147] For this purpose, a distillation column with a height of 9.5 m and a diameter of 100 mm, equipped with 50 bubble trays, was used. The column was operated at a top pressure of 1.5 bar with a reflux ratio of 1:4. Stream (21) was fed into the column above blister tray 26 (counted from the bottom).
[00148] The bottom temperature was about 113 °C, and the bottom product consists mainly of water containing high boiling by-products. A typical composition of the underparts stream was as follows (% by weight given in parentheses): water (> 99.0), propene glycol (0.5), acetonitrile (maximum 0.001), dipropylene glycol (0.06 ), acetamide (0.01), acetic acid (0.03), TOC (2.4)). After optional measurement and analysis, this current was discarded.
[00149] The aerial product (current (19) = current TL2) had the following typical composition ranges (% by weight given in parentheses): acetonitrile (75-80), water (15-20), low kettles (for example , propene, 1). As described above, the stream (19) is recycled to the feed stream which is passed to the decanter-mixer unit. D) ACETONITRILE RECYCLING (ACETONITRILE RECYCLING UNIT J), STEP (IV)
[00150] To recycle acetonitrile, the stream (20) obtained from the decanter-mixer unit H was introduced into a distillation column with a height of 10 m and a nominal diameter of 200 mm, equipped with 40 bubble trays. The column was operated at a top pressure of 18 bar with a reflux ratio of 1:4. Stream (20) was fed to the column above blister tray 26 (counted from the top). The top product (stream (22)), also referred to as stream TL1, containing mainly propene (ca. 97% by volume) with small amounts of propane (ca. 1-3% by volume) was returned to the unit feed. decanter-mixer H, as described above. Thus, excess propene was removed from steam (20) and recycled.
[00151] The bottom parts current (current (2), also referred to as BL1 current), had a temperature in the range of 106 to 110 °C. The precise operating parameters of the column, such as energy input to the reservoir, are adjusted in such a way that the amount of propene returned to the reactor with current (2) is in a range such that the molar ratio of propene to hydrogen peroxide in the stream (1) was about 1:1.3. For the above mentioned feed rate of 15 kg/h of aqueous hydrogen peroxide, this means that the conditions needed to be adjusted, such as the flow rate of propene in stream (2) was about 9.7 kg/ H.
[00152] Before feeding stream (2) to the main A epoxidation reactor, acetonitrile (stream (4), chemical grade, from Ineos, purity of about 99.9%, containing between 70-180 ppm by weight of propionitrile, 5-20 ppm by weight of acetamide and <100 ppm by weight of water as impurity) was optionally added to compensate for possible solvent losses. The exact amount of additionally added acetonitrile required depended on the loss in output currents and in by-products and also on the number of samples considered for analysis. A typical amount of acetonitrile added in addition to the process design described above might be in the range of 100 to 150 g/h. EXAMPLE 2A: COMPARATIVE (NO PARTIAL CURRENT DISTILLATION, NO HYDROGENATION)
[00153] The process as described above in Example 1 was first considered in operation using a fresh charge of epoxidation catalyst and fresh acetonitrile (same quality as for the work-up stream (4), see section 1.5 (d) ) above), but without using inventive partial current distillation. Thus, from stream (16) (stream S1), no stream (17) (stream S3) was separated and subjected to distillation in unit G. Stream 1 was mixed as with streams (19), (22) and ( 23).
[00154] The start temperature for the epoxidation main reactor cooling medium loop was set at 30 °C. In the beginning, the conversion of hydrogen peroxide in the main epoxidation reactor A was almost complete. Within 24 hours, the hydrogen peroxide conversion started to decrease, and when it reached the target value of approximately 90% (after about 100 - 200 hours), the temperature of the cooling medium was slowly raised to maintain the peroxide conversion. of hydrogen in the main constant A epoxidation reactor. The rate of temperature rise of the cooling medium was always less than 1 °C/day).
[00155] The plant was then operated as described above in Example 1 for 441 h. At the end of this period, the temperature of the cooling medium of the main epoxidation reactor was 35 °C. At this point, various components (by-products of the epoxidation reaction and/or impurities in the feed streams that were not present at the beginning of the run) have accumulated in the solvent loop. Accumulation increased linearly with no signs of reaching a steady state. The concentration of the components that accumulated in stream (2), the acetonitrile recycle stream obtained from unit J, after 441 hours in stream is given in Table A. Additionally, stream (2) was found to contain additional traces of acetaldehyde, propionaldehyde and 2-butanone, which also accumulated in the solvent loop, without reaching a steady state. TABLE - RESULTS OF EXAMPLE 2


[00156] This experiment shows that, in the absence of inventive partial stream distillation, the general process including solvent recycling suffers from an accumulation of various compounds in the solvent loop. No steady state was reached regarding the concentration of these compounds. EXAMPLE 2B: ACCORDING TO THE INVENTION (WITH PARTIAL CURRENT DISTILLATION, NO HYDROGENATION)
[00157] The execution, as described in Example 2a, was continued, and at t = 441 hours in stream, the partial stream distillation (unit G, with the first distillation column G1 and the second distillation column G2) was considered on the operation. Execution was then continued until a running time of 1800 hours had been reached. During this period, a current S3 with a constant flow rate of 2 kg/h (± 0.1 kg/h) was diverted from the current S1 and fed to unit G, corresponding to about 2.3% of the quantity. total current S1. A bottoms stream S4b (stream 18b)) with a constant flow rate of 40 g/h (± 10 g/h) was removed at the bottom of distillation column G1 and discarded. The composition of this bottom stream after 1800 hours in stream was as follows (wt% in parentheses): water (77.5), propene glycol (6.1), acetonitrile (14.1), dipropylene glycol (0 .20), tripropylene glycol (0.12), acetamide (0.16), 2,6-dimethyl-4-heptanol (0.16), 4,6-dimethyl-2-heptanol (0.08), 1 -nitropropane (0.004), 2-nitropropane (0.004), hydroxyacetone (0.4), acetic acid (0.6), ammonia (0.02), TOC (0.02), acid value = 1.4 mg /g (determined in accordance with DIN EN ISO 2114). The concentration of the impurities in the solvent loop (in stream (2)) just before starting the partial stream distillation (in 441 hours in stream) and at the end of the run with partial stream distillation (after 1329 hours in stream) is determined in Table B. TABLE B - RESULTS OF EXAMPLE 2B
A) CONCENTRATION OF THIS COMPONENT WAS STILL FALLING WHEN THE EXPERIMENT WAS FINISHED.
[00158] At the end of the run, all respective current concentrations (2), including acetone, acetaldehyde, propionaldehyde, and 2-butanone concentrations, not listed in Table B, reached steady state, and no accumulation was observed again. This inventive example clearly shows that by making use of inventive partial stream distillation, according to which only a minor fraction of stream S1 is separated and subjected to distillation, the accumulation of by-products and impurities during solvent recycling can be stopped and a steady state at very low concentration levels can be achieved. Still further, the example shows that the inventive partial stream distillation method still allows to significantly reduce the concentration of by-products and impurities accumulated in the acetonitrile solvent loop. This also shows that it is enough to perform processing (workup) on a small side stream to get the desired result, thus offering big energy and investment savings. EXAMPLE 3A: COMPARATIVE (WITHOUT PARTIAL CURRENT DISTILLATION, WITH HYDROGENATION)
[00159] In a new run, the process as described above in Example 1 was first considered in operation using a fresh charge of epoxidation catalyst and fresh acetonitrile (same quality as for the work-up stream) (4 ), see section 1.5 (d) above), but without using the inventive partial stream distillation. Thus, from stream (16) (stream S1), no stream (17) (stream S3) was diverted and subjected to distillation in unit G. Stream 1 was mixed as such with streams (19), (22) and ( 23).
[00160] In this example, the current (13) (current S02) was passed through the hydrogenation reactor (not shown in Figure 1) located downstream of unit E and upstream of unit F. The hydrogenation reactor was a tubular reactor with a diameter of 53 mm and a height of 3.25 m, filled with a fixed bed catalyst (0.3% by weight Pd in Al2O3, 4 mm diameter wires, H0-13 S4 from BASF SE, operated adiabatically). The reactor was operated as a bubble column packed with gas and liquid flowing cocurrently from the bottom to the top of the reactor at a pressure of about 15 bar. Provided hydrogen was fed at a constant rate of 100 g/h. The temperature of the liquid feed stream (13) to the hydrogenation reactor was adjusted to 70°C and kept constant throughout the run. At the hydrogenation reactor outlet, the pressure was reduced to 1 bar, and the liquid phase and gas phase leaving the hydrogenation reactor were separated. Gas phase two was discarded and the liquid phase was fed to unit F as described above.
[00161] The start temperature for the cooling medium loop of the main epoxidation reactor A was set at 30 °C. At first, the conversion of hydrogen peroxide in the main epoxidation reactor was almost complete. Within 24 hours, the hydrogen peroxide conversion started to decrease, and when it reached the target value of approximately 90% (after about 100 - 200 hours) the temperature of the cooling medium was slowly raised to maintain the peroxide conversion of hydrogen in the main constant A epoxidation reactor. The rate of temperature rise of the cooling medium was always less than 1 °C/day).
[00162] The plant was then operated as described above in Example 1 for 864 h. At the end of this period, the temperature of the cooling medium of the main epoxidation reactor was 39.2 °C. At this point, various components (either by-products from the epoxidation reaction and/or impurities in the feed streams that would not have been present at the start of the run) have accumulated in the solvent loop. Accumulation increased linearly with no signs of reaching a steady state. The concentration of the components that accumulated in stream (2), the acetonitrile recycling stream, obtained from unit J, after 864 hours in stream, is given in Table C. Additionally, it was found that stream (2) additionally it contained traces of acetone, acetaldehyde, propionaldehyde and 2-butanone which also accumulated in the solvent loop, without reaching a steady state. TABLE C - RESULTS OF EXAMPLE 3

[00163] This experiment shows that in the absence of inventive partial stream distillation, the general process including solvent recycling suffers from an accumulation of various compounds in the solvent loop. No steady state was reached regarding the concentration of these compounds. EXAMPLE 3B: ACCORDING TO THE INVENTION (WITH PARTIAL CURRENT DISTILLATION, WITH HYDROGENATION)
[00164] The execution, as described in Example 3a, was continued, and at t= 864 hours in the stream, the partial stream distillation (unit G) was considered in operation. The execution was then continued until a current point of 1600 hours had been reached.
[00165] During this period, a stream S3 with a constant flow rate of 2 kg/h (± 0.1 kg/h) was diverted from stream S1 and fed to distillation unit G, corresponding to about 2, 3% of the total amount of current S1. A bottoms stream with a constant flow rate of 50 g/h was removed at the bottom of the G1 distillation column and, after being analyzed, was discarded.
[00166] The composition of the S2 stream after reaching steady state was as follows: water (76.1), propene glycol (0.43), propionitrile (0.11), acetonitrile (14.1), dipropylene glycol (0 .20), tripropylene glycol (0.13), acetamide (0.17), 2,6-dimethyl-4-heptanol (0.14), 4,6-dimethyl-2-heptanol (0.12), 1 -nitropropane (0.10), 2-nitropropane (0.11), hydroxyacetone (0.34), acetic acid (0.46), ammonia (0.03), TOC (0.02), acid value = 1 .4 mg/g.
[00167] The concentration of impurities in the solvent loop (in stream (2)) just before starting the partial stream distillation (in 864 hours in stream) and at the end of the experiment (after 1600 hours in stream) is given in the Table D. TABLE D - RESULTS OF EXAMPLE 3B


[00168] Between 1370-1580 hours on stream, all stream concentrations (2), including acetone, acetaldehyde, propionaldehyde and 2-butanone concentrations, not listed in Table D, reached steady state and no further accumulation was observed. . Until the end of the run, no more rollups were run.
[00169] This inventive example clearly shows that it makes use of the inventive partial stream distillation, according to which only a smaller fraction of the S1 stream is separated and subjected to distillation, the accumulation of by-products and impurities during solvent recycling can be interrupted and a steady state at very low concentration levels can be reached. Still further, the example shows that the inventive partial stream distillation method also allows to significantly reduce the concentration of by-products and impurities accumulated in the acetonitrile solvent loop. It also shows that it is enough to perform processing (work-up) on a small side stream to get the desired result, thus offering big savings in energy and investment. REFERENCE EXAMPLE 1: PREPARATION OF THE EPOXIDATION CATALYST (ZNTIMWW) 1.1 PREPARATION OF MWW CONTAINING BORON
[00170] 470.4 kg of deionized water were provided in a container. Under stirring at 70 rpm (revolutions per minute), 162.5 kg of boric acid were suspended in the water. The suspension was stirred for another 3 h. Subsequently, 272.5 kg of piperidine was added, and the mixture was stirred for another hour. To the resulting solution, 392.0 kg of Ludox® AS-40 was added and the resulting mixture was stirred at 70 rpm for an additional hour. The mixture finally obtained was transferred to a crystallization vessel and heated to 170 °C within 5 h under autogenous pressure and under stirring (50 rpm). The temperature of 170 °C was kept essentially constant for 120 h; during those 120 h, the mixture was stirred at 50 rpm. Subsequently, the mixture was cooled to a temperature from 50-60 °C within 5 h. The aqueous suspension containing B-MWW had a pH of 11.3 as determined by measuring with a pH electrode. From said suspension, B-MWW was separated by filtration. The filter cake was then washed with deionized water until the wash water had a conductivity of less than 700 microSiemens/cm. The filter cake thus obtained was subjected to spray drying in a spray tower with the following spray drying conditions: drying gas, nozzle gas: technique nitrogen drying gas temperature: - spray tower temperature ( inside): 288-291 °C - spray tower temperature (outside): 157-167 °C - filter temperature (inside): 150-160 °C - scrubber temperature (inside): 40-48 °C - scrubber temperature (outside): 34-36 °C pressure difference filter: 8.3-10.3 mbar nozzle: - top component nozzle from Gerig supplier; size 0 - nozzle gas temperature: ambient temperature - nozzle gas pressure: 2.5 bar operating mode: direct nitrogen Apparatus used: spray tower with one nozzle configuration: spray tower -filter - scrubber gas flow: 1,900 kg/h filter material: 20 m2 Nomex® needle felt dosing via flexible tube pump: SP VF 15 (supplier: Verder)
[00171] The spray tower was comprised of a vertically arranged cylinder having a length of 2650 mm, a diameter of 1200 mm, which cylinder was conically tapered at the bottom. The length of the cone was 600 mm. In the cylinder head, the atomizing means (a two-component nozzle) has been arranged. The spray dried material was separated from the drying gas in a filter downstream of the spray tower, and the drying gas was then passed through a scrubber. The suspension was passed through an internal opening of the nozzle, and the nozzle gas was passed through the ring-shaped slit surrounding the opening. The spray dried material was then subjected to calcination at 650 °C for 2 h. The calcined material had a boron (B) content of 1.9% by weight, a silicon (Si) content of 41% by weight, and a total organic carbon (TOC) content of 0.18% by weight. 1.2 PREPARATION OF DEBORATED MWW
[00172] Based on the spray dried material obtained according to section 1.1 above, 4 batches of deborated MWW zeolite were prepared. In each of the first 3 batches, 35 kg of the spray dried material obtained according to section 1.1 and 525 kg of water was employed. In the fourth batch, 32 kg of spray dried material obtained according to section 1.1 and 480 kg of water were used. In total, 137 kg of spray dried material obtained according to section 1.1 and 2025 kg of water were used. For each batch, the respective amount of water was passed into a vessel equipped with a reflux condenser. Under stirring at 40 r.p.m., a certain amount of the spray-dried material was suspended in the water. Subsequently, the vessel was closed and the reflux condenser was put into operation. The agitation rate was increased to 70 r.p.m. Under agitation at 70 r.p.m., the container contents were heated to 100 °C within 10 h and held at that temperature for 10 h. Then, the contents of the container were cooled to a temperature of less than 50 °C. The resulting deborated zeolitic material of the MWW structure type was separated from the suspension by filtration under a nitrogen pressure of 2.5 bar and washed four times with deionized water. After filtration, the filter cake was dried in a stream of nitrogen for 6 h. The debored zeolitic material obtained in 4 batches (625.1 kg of filter cake dried by nitrogen in total) had a residual moisture content of 79%, as determined using an IR (infrared) scale at 160 °C. From the nitrogen-dried filter cake having a residual moisture content of 79% obtained according to section a) above, an aqueous suspension was prepared with deionized water, the suspension having a solid content of 15% by weight. This suspension was subjected to spray drying in a spray tower with the following spray drying conditions: drying gas, nozzle gas: nitrogen technique drying gas temperature: - spray tower temperature (inside): 304 °C - spray tower temperature (outside): 147-150 °C - filter temperature (inside): 133-141 °C - scrubber temperature (inside): 106-114 °C - scrubber temperature (outside): 13-20 °C filter pressure difference: 1.3-2.3 mbar nozzle: used device: spray tower with one nozzle configuration: spray tower - filter- scrubber gas flow: 550 kg/h filter material : Nomex® needle felt 10 m2 dosing via flexible tube pump: VF 10 (supplier: Verder)
[00173] The spray tower was comprised of a vertically arranged cylinder having a length of 2650 mm, a diameter of 1200 mm, which cylinder was conically tapered at the bottom. The length of the cone was 600 mm. In the cylinder head, the atomizing means (a two-component nozzle) has been arranged. The spray dried material was separated from the drying gas in a filter downstream of the spray tower, and the drying gas was then passed through a scrubber. The suspension was passed through the internal opening of the nozzle, and the nozzle gas was passed through the ring-shaped slit surrounding the opening. The spray dried MWW material obtained had a B content of 0.08% by weight, an Si content of 42% by weight and a TOC of 0.23% by weight. 1.3 PREPARATION OF TIMWW
[00174] Based on the deborated MWW material, as obtained according to section 1.2 above, a zeolitic material of the MWW structure type containing titanium (Ti) was prepared, referred to below as TiMWW. The synthesis was performed in two experiments described below as a) and b): A) FIRST EXPERIMENT Starting materials: deionized water: 244.00 kg piperidine: 118.00 kg tetrabutylorthotitanate: 10.90 kg deborated zeolitic material: 54.16 kg
[00175] 54.16 kg of the deborated zeolitic material of the MWW structure type were transferred into a first container A. In a second container B, 200.00 kg of deionized water were transferred and stirred at 80 rpm 118.00 kg of piperidine were added under stirring and, during addition, the temperature of the mixture increased to about 15°C. Subsequently, 10.90 kg of tetrabutylorthotitanate and 20.00 kg of deionized water were added. Stirring was then continued for 60 min. The mixture from vessel B was then transferred into vessel A and stirring in vessel A was started (70 r.p.m.). 24.00 kg of deionized water was filled into container A and transferred to container B. The mixture in container B was then stirred for 60 min. at 70 r.p.m. At the beginning of the stirring, the pH of the mixture in vessel B was 12.6, as determined with a pH electrode. After said stirring at 70 r.p.m., the frequency was decreased to 50 r.p.m., and the mixture in vessel B was heated to a temperature of 170°C within 5 h. At a constant stirring rate of 50 r.p.m., the temperature of the mixture in vessel B was maintained at an essentially constant temperature of 170 °C for 120 h under autogenous pressure. During this crystallization of TiMWW, a pressure increase up to 10.6 bar was observed. Subsequently, the obtained suspension containing TiMWW having a pH of 12.6 was cooled within 5 h. The cooled suspension was subjected to filtration and the separated mother liquor was transferred to a waste water discharge. The filter cake was washed four times with deionized water under a nitrogen pressure of 2.5 bar. After the last washing step, the filter cake was dried in a stream of nitrogen for 6 h. From 246 kg of said filter cake, an aqueous suspension was prepared with deionized water, the suspension having a solid content of 15% by weight. This suspension was subjected to spray drying in a spray tower with the following spray drying conditions: drying gas, nozzle gas: nitrogen technician spray tower with one nozzle spray tower - filter-cleaner gas flow: 10 m Nomex® needle felt dosing via flexible tube pump: VF 10 (supplier: Verder)
[00176] The spray tower was comprised of a vertically arranged cylinder having a length of 2650 mm, a diameter of 1200 mm, which cylinder was conically tapered at the bottom. The length of the cone was 600 mm. In the cylinder head, the atomizing means (a two-component nozzle) has been arranged. The spray dried material was separated from the drying gas in a filter downstream of the spray tower, and the drying gas was then passed through a scrubber. The suspension was passed through the internal opening of the nozzle, and the nozzle gas was passed through the ring-shaped slit surrounding the opening. The spray-dried TiMWW material obtained from the first experiment had an Si content of 37% by weight, a Ti content of 2.4% by weight, and a TOC of 7.5% by weight. B) SECOND EXPERIMENT
[00177] The second experiment was carried out in the same way as the first experiment described in section a) above. The spray-dried TiMWW material obtained from the second experiment had an Si content of 36% by weight, a Ti content of 2.4% by weight, a TOC of 8.0% by weight. 1.4 TIMWW ACID TREATMENT
[00178] Each of the two spray-dried TiMWW materials, as obtained in the first and second experiment described in sections 1.3 a) and 1.3 b) above, was subjected to an acid treatment as described in the following sections a) and b ). In section c) below, it is described how a mixture of the materials obtained from a) and b) is spray dried. In section d) below, it is described how the spray dried material is calcined. A) ACID TREATMENT OF SPRAY DRIED MATERIAL OBTAINED IN ACCORDANCE WITH SECTION 1.3.A) Starting material: deionized water: 690.0 kg nitric acid: (53%): 900.0 kg spray dried Ti-MWW 1.3 . a): 53.0 kg
[00179] 670.0 kg of deionized water was filled into a container. 900 kg of nitric acid was added and 53.0 kg of the spray dried TiMWW was added under stirring at 50 r.p.m. The resulting mixture was stirred for another 15 min. Subsequently, the stirring rate was increased to 70 r.p.m. Within 1 h, the mixture in the vessel was heated to 100 °C and maintained at that temperature and under autogenous pressure for 20 h under stirring. The mixture thus obtained was then cooled within 2 h to a temperature of less than 50 °C. The cooled mixture was subjected to filtration, and the filter cake was washed six times with deionized water under a nitrogen pressure of 2.5 bar. After the last washing step, the filter cake was dried in a stream of nitrogen for 10 h. The wash water after the sixth wash step had a pH of about 2.7. 225.8 kg of dry filter cake was obtained. B) ACID TREATMENT OF SPRAY DRIED MATERIAL OBTAINED IN ACCORDANCE WITH SECTION 1.3.B) Starting materials: deionized water: 690.0 kg nitric acid: (53%): 900.0 kg spray dried Ti-MWW1. 3. b): 55.0 kg
[00180] The acid treatment of the spray dried material obtained according to section 1.3.b) was carried out in the same manner as the acid treatment of the spray dried material obtained according to section 1.3.a), as described in section 1.4 a). The wash water, after the sixth wash step, had a pH of about 2.7. 206.3 kg of dry filter cake was obtained. C) DRYING BY SPRAYING THE MIXTURE OF MATERIALS OBTAINED FROM 1.4.A) AND 1.4 B)
[00181] From 462.1 kg of the filter cake mixture obtained from 1.4.a) and 1.4b), an aqueous suspension was prepared with deionized water, the suspension having a solid content of 15% by weight . This suspension was subjected to spray drying in a spray tower with the following spray drying conditions: drying gas, nozzle gas: nitrogen technician drying gas temperature: - spray tower temperature (inside): 304 -305 °C - spray tower temperature (outside): 151 °C - filter temperature (inside): 141-143 °C - scrubber temperature (inside): 109-118 °C
[00182] The spray tower was comprised of a vertically arranged cylinder having a length of 2,650 mm, a diameter of 1,200 mm, whose cylinder was tapered conically at the bottom. The length of the cone was 600 mm. In the cylinder head, the atomizing means (a two-component nozzle) has been arranged. The spray dried material was separated from the drying gas in a filter downstream of the spray tower, and the drying gas was then passed through a scrubber. The suspension was passed through the internal opening of the nozzle, and the nozzle gas was passed through the ring-shaped slit surrounding the opening. The spray-dried acid-treated TiMWW material had an Si content of 42% by weight, a Ti content of 1.6% by weight, and a TOC content of 1.7% by weight. D) CALCINATION OF SPRAY-DRIED MATERIAL OBTAINED IN ACCORDANCE WITH 1.4. ç)
[00183] The spray dried material was then subjected to calcination at 650 °C in a rotary kiln for 2 h. The calcined material had an Si content of 42.5% by weight, a Ti content of 1.6% by weight and a TOC content of 0.15% by weight. 1.5 IMPREGNATION OF TlMWW WITH ZN
The spray-dried and acid-treated calcined material as obtained according to 1.4 d) was then subjected to an impregnation stage. Starting materials: deionized water: 2610.0 kg zinc acetate dihydrate: 15.93 kg calcined Ti-MWW 1.4.d): 87.0 kg
[00185] The impregnation was carried out in 3 batches a) ac) as follows: a) In a vessel equipped with a reflux condenser, a solution of 840 kg of deionized water and 5.13 kg of acetate dihydrate zinc was prepared within 30 min. Under agitation (40 r.p.m.), 28 kg of the calcined Ti-MWW material obtained according to 1.4.d) was suspended. Subsequently, the vessel was closed and the reflux condenser put into operation. The agitation rate was increased to 70 r.p.m. b) In a vessel equipped with a reflux condenser, a solution of 840 kg of deionized water and 5.13 kg of zinc acetate dihydrate was prepared within 30 min. Under agitation (40 r.p.m.), 28 kg of the calcined Ti-MWW material obtained according to 1.4.d) was suspended. Subsequently, the vessel was closed and the reflux condenser put into operation. The stirring rate was increased to 70 r.p.m. c) In a vessel equipped with a reflux condenser, a solution of 930 kg of deionized water and 5.67 kg of zinc acetate dihydrate was prepared within 30 min. Under agitation (40 r.p.m.), 31 kg of the calcined Ti-MWW material obtained according to 1.4.d) was suspended. Subsequently, the vessel was closed and the reflux condenser put into operation. The agitation rate was increased to 70 r.p.m.
[00186] In all batches a) ac), the mixture in the vessel was heated to 100 °C within 1 h and maintained under reflux for 4 h at a stirring rate of 70 rpm. Then the mixture was cooled within 2 h a temperature of less than 50 °C. For each batch a) to c), the cooled suspension was subjected to filtration, and the mother liquor was transferred to a waste water discharge. The filter cake was washed five times with deionized water under a nitrogen pressure of 2.5 bar. After the last washing step, the filter cake was dried in a stream of nitrogen for 10 h. For batch a), 106.5 kg of filter cake dried by nitrogen was obtained at the end. For batch b), 107.0 kg of filter cake dried by nitrogen was obtained at the end. For batch c), 133.6 kg of filter cake dried by nitrogen was obtained at the end. The thus dried Zn-impregnated TiMWW material (ZnTiMWW), for each batch, had an Si content of 42% by weight, a Ti content of 1.6% by weight, a Zn content of 1.4% by weight. weight and a TOC of 1.4% by weight. 1.6 PREPARATION OF A MICROPOW
[00187] From 347.1 kg of the filter cake mixture obtained according to 1.5 above, an aqueous suspension was prepared with deionized water, the suspension having a solid content of 15% by weight. This suspension was subjected to spray drying in a spray tower with the following spray drying conditions: - ) room temperature - apparatus used: spray tower with one nozzle - mode of operation: direct nitrogen - configuration: dehumidifier - filter - scrubber - dosing: flexible tube pump VF 10 (supplier: Verder) nozzle with a diameter of 4 mm (supplier: Niro) - filter material: 10 m2 Nomex® needle felt

[00188] The spray tower was comprised of a vertically arranged cylinder having a length of 2650 mm, a diameter of 1200 mm, which cylinder was conically tapered at the bottom. The length of the cone was 600 mm. In the cylinder head, the atomizing means (a two-component nozzle) has been arranged. The spray dried material was separated from the drying gas in a filter downstream of the spray tower and the drying gas was then passed through a scrubber. The suspension was passed through the internal opening of the nozzle and the nozzle gas was passed through the ring-shaped slit surrounding the opening. The spray dried material thus obtained had a Zn content of 1.4% by weight, a Ti content of 1.7% by weight, an Si content of 40% by weight, and a TOC content of 0. 27% by weight. The spray dried product was then subjected to calcination for 2 h at 650 °C under air in a rotary kiln, yielding 76.3kg of calcined spray dried ZiTiMWW. The spray-dried calcined material thus obtained had a Zn content of 1.4% by weight, a Ti content of 1.7% by weight, a Si content of 42% by weight, and a C content of 0 .14% by weight. The bulk density of the calcined spray-dried ZiTiMWW was 90 g/l (gram/liter). 1.7 PREPARING AN MOLDING
[00189] Starting from the calcined spray-dried ZiTiMWW material obtained according to section 1.6 above, an impression was prepared, dried and calcined. Therefore, 22 batches were prepared, each starting from 3.4 kg of the calcined spray-dried ZiTiMWW material obtained in Example 1, 0.220 kg of Walocel™ (Walocel MW 15000 GB, Wolff Cellulosics GmbH & Co. KG, Germany), 2.125 kg of Ludox® AS-40 and 6.6 liths of deionized water, as follows: 3.4 kg of ZnTiMWW and 0.220 kg of Walocel were subjected to kneading in a corner mill for 5 min. Then, during further kneading, 2.125 kg of Ludox was added continuously. After another 10 min, the addition of 6 liters of deionized water was started. After another 30 min, an additional 0.6 liters of deionized water was added. After a total time of 50 min, the kneaded mass became extractable. Afterwards, the kneaded mass was subjected to extrusion under 65-80 bar where the extruder was cooled with water during the extrusion process. Per batch, the extrusion time was in the range of 15 to 20 min. Power consumption per batch during extrusion was 2.4 A. A die head was employed allowing to produce cylindrical filaments having a diameter of 1.7 mm. In die head output, the filaments were not cut to length. The filaments thus obtained were dried for 16 h at 120 °C in an air-drying chamber. In total (sum of 22 batches), 97.1 kg of white filaments with a diameter of 1.7 mm were obtained. 65.5 kg of the dried filaments were calcined in a rotary kiln at 550 °C for 1 h under air, yielding 62.2 kg of calcined filaments. Afterwards, the filaments were sieved (mesh size of 1.5 mm) and the yield after sieving was 57.7 kg. The moldings thus obtained exhibited a bulk density of 322 g/l (gram per liter) and had a Zn content of 1.2% by weight, a Ti content of 1.4% by weight, an Si content of 43 % by weight, and a C content of 0.13% by weight. The sodium (Na) content was 0.07% by weight. 1.8 FURTHER MOLDING TREATMENT
[00190] Starting from the calcined filaments obtained according to 1.7 above, a further treatment stage was performed as follows: 590 kg of deionized water was filled in a container. Then, 29.5 kg of the calcined castings obtained according to section 1.7 above were added. The vessel was closed (pressurized), and the obtained mixture was heated to a temperature of 145 °C within 1.5 h and maintained at that temperature under autogenous pressure (about 3 bar) for 8 h. Then the mixture was cooled for 2 h. The water-treated filaments were subjected to filtration and washed with deionized water. The filaments obtained were heated in a drying chamber under air within 1 h to a temperature of 120 °C and kept at this temperature for 16 h. Subsequently, the dried material was heated under air to a temperature of 450 °C within 5.5 h and held at this temperature for 2 h. Afterwards, the filaments were sieved (mesh size of 1.5 mm), and the yield, after sieving, was 27.5 kg. The obtained water-treated moldings exhibited a bulk density of 340 g/l (gram per liter) and had a Zn content of 1.3% by weight, a Ti content of 1.4% by weight, a Si content of 43% by weight and a C content of 0.10% by weight. REFERENCE EXAMPLE 2: DETERMINATION OF DV10, DV50 AND DV90S VALUE 1. Sample preparation: 1.0 g of the micropowder is suspended in 100 g of deionized water and stirred for 1 min. 2. Apparatus and related parameters used: Mastersizer S version 2.15 long bed, Serial No. 33544-325; supplier: Malvern Instruments GmbH, Herrenberg, Germany - focal width: 300RF mm - beam length: 10.00 mm - module: MS17 - shading: 16.9% - dispersion model: 3$$D - analysis model: polydisperse - correction: none REFERENCE EXAMPLE 3: DETERMINATION OF SILANOL CONCENTRATION
[00191] For the determination of the silanol concentration, 29Si MAS NMR experiments were carried out at room temperature in a VARIAN Infinityplus-400 spectrometer using 5.0 mm ZrO2 rotors. The 29Si MAS NMR spectra were collected at 79.5 MHz using 1.9 microsecond pi/4 pulses with 10 second recycle delay and 4000 scans. All 29Si spectra were recorded on samples rotated at 6 kHz, and chemical permutations were referred to as sodium 4,4-dimethyl-4-silapentane sulfonate (DSS). For the determination of the silanol group concentration, a given 29Si MAS NMR spectrum is deconvolved by the appropriate Gaussian-Lorentzian line formats. The concentration of the silanol groups with respect to the total number of Si atoms is obtained by integrating the deconvolved 29Si MAS NMR spectra. REFERENCE EXAMPLE 4: DETERMINATION OF RESISTANCE TO CRUSHING OF MOLDINGS
The crush strength as referred to in the context of the present invention is to be understood as determined by means of a Z2.5/TS1S crush strength testing machine, supplier Zwick GmbH & Co., D-89079 Ulm, Germany . As for the rationale of this machine and its operation, reference is made to the respective instruction manual "Register 1: Betriebsanleitung / Sicherheitshandbuch für die Material-Prüfmaschine Z2.5/TS1S", version 1.5, December 2001 by Zwick GmbH & Co. Technische Dokumentation, August-Nagel-Strasse 11, D-89079 Ulm, Germany. With said machine, a certain filament, as described in Reference Example 1, is subjected to an increasing force by means of a plunger having a diameter of 3 mm until the filament is crushed. The force at which the filament is crushed is referred to as the crush strength of the filament. The machine is equipped with a fixed horizontal table on which the filament is placed. A piston that is freely movable in the vertical direction activates the filament against the fixed table. The apparatus was operated with a preliminary force of 0.5 N, a shear rate under preliminary force of 10 mm/min and a subsequent test rate of 1.6 mm/min. The vertically movable piston was connected to a load cell for a force sensor and, during measurement, moved towards the fixed turntable on which the molding (filament) to be investigated is positioned, thus activating the filament against the table. The plunger was applied to the filaments perpendicular to its longitudinal axis. The control of the experiment was carried out by means of a computer that recorded and evaluated the measurement results. The values obtained are the mean values of the measurements per 10 filaments in each case. REFERENCE EXAMPLE 5: 29SI SOLID STATE NMR SPECTRA WITH RESPECT TO Q3 AND Q4 STRUCTURES
[00193] All 29Si solid state NMR experiments were performed using a Bruker Avance spectrometer with a frequency of 300 MHz 1H Larmor (Bruker Biospin, Germany). Samples were packed in 7 mm ZrO2 rotors, and measured under 5 kHz Magic Angle Spinning at room temperature. The 29Si forward polarization spectra were obtained using pulse excitation of (pi/2) with a pulse width of 5 microseconds, a carrier frequency of 29Si corresponding to -65 ppm in the spectrum, and a scan recycle delay of 120 s. The signal was acquired for 25 ms under 45 kHz of high power proton decoupling and accumulated for 10 to 17 hours. Spectra were processed using Bruker Topspin with 30 Hz exponential line amplitude, manual phasing and manual baseline correction over the entire spectral range. Spectra were reported with polymer Q8M8 as an external secondary standard, adjusting the resonance of the trimethylsilyl M group to 12.5 ppm. The spectra were then fitted with a set of Gaussian line shapes, according to the number of discernible resonances. With respect to the spectra evaluated at present, 6 lines in total were used, counting the five distinct maximum peaks (at approximately 118, 115, 113, 110 and 104 ppm) plus a clearly visible bounce at 98 ppm. The adjustment was performed using DMFit (Massiot et al., Magnetic Resonance in Chemistry, 40 (2002) pp 70-76). Peaks were manually set to the maximum visible peak or bounce. Both the linewidth and the peak position were then left unstoppable, that is, fit peaks were not fixed at a certain position. The result of the fit was numerically stable, that is, distortions in the initial fit setting, as described above, led to similar results. The fitted peak areas were used further normalized as done by DMFit. For the quantification of spectrum changes, a ratio was calculated that reflects changes in the “left side” and “right side” peak areas as follows. The six peaks, as described, were labeled with 1, 2, 3, 4, 5 and 6, and the Q ratio was calculated with the formula 100 * { [a1+a2] / [a4+a5+a6] } / a3 . In this formula, ai, i=1..6 represents the adjusted peak area to which this number was assigned. REFERENCE EXAMPLE 6: WATER ADSORPTION / DESORPTION
[00194]Isothermal water adsorption/desorption measurements were performed on a VTI AS instrument, from TA Instruments, following an isothermal step program. The experiment consisted of one run or a series of runs performed on a sample material that was placed on the microbalance tray inside the instrument. Before measurements were started, residual moisture from the sample was removed by heating the sample to 100 °C (heat ramp to 5 °C/min) and holding for 6 h under a flow of N2. After the drying program, the temperature in the cell was lowered to 25 °C and kept isothermal during the measurements. The microbalance was calibrated, and the weight of the dry sample was weighed (maximum mass deviation 0.01% by weight). The water intake of the sample was measured as the increase in weight over that of the dry sample. First, an adsorption curve was measured by increasing the relative humidity (RH) (expressed as % by weight of water in the atmosphere within the cell) to which the samples were exposed and measuring the water uptake by the sample at equilibrium. The RH was increased in one step from 10% by weight from 5 to 85% and, at each step, the System controlled the RH and monitored the sample weight until it reached equilibrium conditions and recorded the intake and weight. The amount of total water adsorbed by the sample was considered after the sample had been exposed to 85% by weight of RH. During the desorption measurement the RH was decreased from 85% by weight to 5% by weight with a 10% step and the change in sample weight (water intake) was monitored and recorded. REFERENCE EXAMPLE 7: FT-IR MEASUREMENTS
[00195] The FT-IR (Fourier Transform Infrared) measurements were performed on a Nicolet 6700 spectrometer. The impression was fed and then pressed into a self-supporting pellet without the use of any additives. The pellet was introduced into a high vacuum (HV) cell placed on the FT-IR instrument. Before measurement the sample was pretreated in high vacuum (10-5 mbar) for 3 h at 300 °C. Spectra were collected after cooling the cell to 50 °C. Spectra were recorded in the range of 4000 to 800 cm-1 at a resolution of 2 cm-1. The spectra obtained are plotted on the x-axis, the wave number (cm-1) and, on the y-axis, the absorbance (arbitrary units, a.u.). For the quantitative determination of peak heights and the ratio between these peaks a baseline correction was performed. Changes in the region from 3000 to 3900 cm-1 were analyzed and to compare multiple samples, a reference band at 1880 ± 5 cm-1 was considered. REFERENCE EXAMPLE 8: DEFINITION AND DETERMINATION OF THE OCTANOL-WATER PARTITION COEFFICIENT KOW
[00196] The octanol-water partition coefficient KOW of a given compound is defined as the ratio of chemical concentration of said compounds in the octanol phase to the chemical concentration of said compounds in the aqueous phase in a two-phase system of 1 - octanol and water at a temperature of 25 °C.
[00197] The octanol-water KOW partition coefficient of a certain compound is determined using the shake flask method which consists of dissolving the compound in a volume of high purity 1 -octanol and deionized water (pre-mixed and calibrated by at least 24 h) and measure the concentration of the compound in each 1-octanol phase and the water phase by a sufficiently accurate method, preferably by means of UV/VIS spectroscopy. This method is described in the OECD Guide to the Testing of Chemicals, number 107, adopted 27 July 1995. DESCRIPTION OF THE FIGURES
[00198] Fig. 1 shows a block diagram of a preferred process of the present invention. In Fig. 1, the letters and numbers have the following meanings: The epoxidation unit; B distillation unit; C epoxidation unit; D distillation unit; And distillation unit; F distillation unit; G partial current distillation unit; H decanter-mixer unit; I acetonitrile recovery unit; J acetonitrile recycling unit; (1)-(23) standard, according to a specifically preferred process as described in the examples; S0, S01, S02, S1, S2, S3, S4, S4b, S5, L1, L2, TL1, TL2, TL2, BL2 current, according to a preferred process as described in the general description and in the examples;
[00199] Fig. 2 shows in a block diagram the partial current distillation G of the unit of Fig. 1 in detail. In Fig. 1, the letters and numbers have the following meanings: G1 first fractionation unit of the partial current distillation unit G; G2 second fractionation unit of the partial stream distillation unit G; (16), (16a), (17), (18), (18a), (18b), (18c), (19), (22), (23) current, according to a specifically preferred process as described in the examples; S1, S2, S3, S4, S4a, S4b, S4c, S5, TL2 current, according to a preferred process as described in the general description and the examples; STATE OF THE ART CITED - WO 2011/006990 A1; - US 2007043226 A1; - WO 2007/000396 A1; - EP 0 427 062 A2; - US 5,194,675; - US 2004068128 A1; - KJ Lissant, Making and Breaking Emulsions, Res. Lab., Petrolite Corp., St. Louis, Missouri, USA, in: KJ Lissant (ed.), Emulsion Technology (1974), chapter 2, pages 111-124, Dekker , New York; - S.E. Taylor, Chem. Ind. (1992), pages 770-773.

权利要求:
Claims (22)
[0001]
1. CONTINUOUS PROCESS FOR THE PREPARATION OF PROPYLENE OXIDE, characterized in that it comprises: (a) reacting propene, optionally mixed with propane, with hydrogen peroxide in a reaction apparatus in the presence of acetonitrile as solvent, obtaining an S0 current leaving the reaction apparatus, S0 containing propylene oxide, acetonitrile, water, at least one additional component B, optionally propene and optionally propane, wherein the normal boiling point of the at least one component B is higher than the normal boiling point of acetonitrile and in which the decadic logarithm of the octanol-water partition coefficient (log KOW) of the at least one B component is greater than zero; (b) separating propylene oxide from S0, optionally after separating propene and optionally propane, obtaining a stream S1 containing acetonitrile, water and the at least one additional component B; (c) divide S1 into two streams, S2 and S3, where the total weight of S3 in relation to the total weight of S1 is in the range of 0.01 to 25%; (d) subjecting S3 to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction S4a being depleted, in relation to S3, of at least one of the at least one component B and obtaining a liquid bottoms stream S4b, and subjecting at least part of the vapor fraction stream S4a to a vapor-liquid fractionation in a second fractionating unit, obtaining a vapor fraction stream S4c and a liquid bottoms stream S4 being depleted, relative to S4a, of at least one of the at least one component B; (e) recycling at least a portion of S4, optionally after work-up, to (a), and recycling at least a portion of S2, optionally after processing (work-up), to (a).
[0002]
Process according to claim 1, characterized in that in (c), the total weight of S3 in relation to the total weight of S1 is in the range from 0.05 to 20%, preferably from 0.1 to 15%, more preferably from 0.2 to 10%, more preferably from 0.5 to 7.5%.
[0003]
Process according to any one of claims 1 to 2, characterized in that from 90 to 99.9% by weight, preferably from 92.5 to 99.8% by weight, more preferably from 95 to 99.7 % by weight of S1 consists of acetonitrile and water and wherein from 0.01 to 5% by weight, preferably from 0.015 to 4% by weight, more preferably from 0.02 to 3% by weight of S1 consists of at least one component B.
[0004]
Process according to any one of claims 1 to 3, characterized in that in (d), 90 to 100% by weight, preferably from 95 to 100% by weight, more preferably from 98 to 100% by weight, most preferably from 99.9 to 100% by weight of the steam fraction stream S4a are subjected to vapor-liquid fractionation in the second fractionation unit.
[0005]
Process according to any one of claims 1 to 4, characterized in that S3 is fed to the top of the first fractionating unit and at least part of the steam fraction stream S4a is fed to the bottom of the second fractionating unit, wherein in (d), the first fractionating unit is preferably operated at an absolute pressure at the top of the first fractionating unit in the range 0.5 to 5 bar, more preferably 0.75 to 2 bar, most preferably 1 at 1.5 bar, and wherein the second fractionating unit is preferably operated at an absolute pressure at the bottom of the second fractionating unit in the range from 65 to 95%, more preferably from 70 to 90%, most preferably from 75 to 85% of the pressure at the top of the first fractionation unit.
[0006]
Process according to any one of claims 1 to 5, characterized in that in (d) the number of theoretical plates of the first fractionating unit is in the range from 1 to 100, preferably from 2 to 50, more preferably from 5 to 30, and the number of theoretical plates of the second fractionating unit is in the range from 1 to 100, preferably from 2 to 50, more preferably from 5 to 30.
[0007]
Process according to any one of claims 1 to 6, characterized in that in (d) the first fractionation unit is operated without reflux, the at least part of the steam fraction stream S4a is subjected to vapor-liquid fractionation in the second fractionating unit preferably not being condensed before being subjected to vapor-liquid fractionation in the second fractionating unit, and the second fractionating unit is operated with reflux, wherein the fraction of the steam fraction stream S4c is used, after condensation , as reflux and wherein the reflux ratio is preferably in the range of from 0.5:1 to 1:1, more preferably from 0.7:1 to 1:1, most preferably from 0.9:1 to 1:1 .
[0008]
Process according to any one of claims 1 to 7, characterized in that from 10 to 30% by weight, preferably from 10 to 25% by weight of the liquid bottoms stream S4b consists of acetonitrile and from 0.1 to 10 % by weight, preferably from 0.25 to 5% by weight of the liquid bottoms stream S4b consists of the at least one additional component B.
[0009]
Process according to any one of claims 1 to 8, characterized in that from 90 to 99.99% by weight, preferably from 95 to 99.9% by weight, more preferably from 98 to 99.9% by weight of S4 consists of acetonitrile and water, and wherein from 0.0001 to 0.2% by weight, preferably from 0.001 to 0.15% by weight, more preferably from 0.005 to 0.1% by weight of S4 consists of the hair. minus one component B.
[0010]
Process according to any one of claims 1 to 9, characterized in that (e) comprises performing work-up S4, said work-up comprising combining at least a portion of S4 with S2 obtaining a stream preferably liquid.
[0011]
Process according to claim 10, characterized in that (e) it comprises subjecting the preferably liquid stream to acetonitrile-water separation, obtaining a stream enriched in acetonitrile and recycling said stream enriched in acetonitrile, optionally after processing ( additional work-up, for (a).
[0012]
Process according to claim 11, characterized in that (e) comprises: (i) preparing a preferably liquid stream S5 by adding a preferably liquid stream P to S2, or to at least a portion of S4, or to the liquid stream obtained from the combination of S2 and at least the portion of S4, wherein P comprises at least 95% by weight of C3, based on the total weight of P, wherein C3 is propene optionally mixed with propane at a weight ratio minimum propene to propane of 7:3, and where P is preferably added in an amount such that, at S5, the weight ratio of C3 to acetonitrile is in the range of 0.2:1 to 5:1, preferably from 0.5:1 to 2:1; (ii) subject S5 to a temperature of at most 92 °C and a pressure of at least 10 bar, preferably to a temperature in the range of 5 to 90 °C and a pressure in the range of 15 to 50 bar, more preferably to a temperature in the range of 10 to 30 °C and a pressure in the range of 15 to 25 bar, obtaining a first liquid phase L1 and a second liquid phase L2, wherein at least 95% by weight, preferably at least 98% by weight of L1 consists of C3, acetonitrile, water and in the at least one component B, the water content of L1 being less than 10% by weight, preferably in the range of 1 to 5% by weight, based on the total weight of L1. and wherein at least 95% by weight, preferably at least 98% by weight of L2 consists of C3, acetonitrile, water and the at least one component B, the C3 content of L2 being 5% by weight at most, based in the total weight of L2, and the acetonitrile content of L2 being less than 45% by weight, preferably in the range of 10 to 35% by weight, based on the weight to such as L2; (iii) separate L1 from L2, preferably in a gravity decanter; (iv) recycle L1 as the stream enriched in acetonitrile, optionally after further work-up, to (a).
[0013]
Process according to claim 12, characterized in that it further comprises carrying out processing (work-up) L1, said processing (work-up) comprising subjecting L1 to a distillation stage from which a stream of lower parts BL1 is obtained, wherein at least 95% by weight, preferably at least 98% by weight of BL1 consists of C3, acetonitrile, water and the at least one component B, wherein the C3 content of BL1 is in the range of 7 to 18 % by weight, preferably from 10 to 15% by weight, and recycle BL1 as the stream enriched in acetonitrile, optionally without any further workup, to (a).
[0014]
Process according to claim 13, characterized in that from 0.01 to 5% by weight, preferably from 0.015 to 3% by weight, more preferably from 0.02 to 2% by weight of BL1 consists of the at least a component B.
[0015]
A process according to any one of claims 1 to 14, characterized in that (b) comprises: (I) separating propene, optionally together with propane, and oxygen which is optionally additionally contained in S0, from S0 , obtaining a stream SO1 enriched in propylene oxide, acetonitrile, water and in at least one component B, wherein preferably at least 99% by weight of SO1 consists of acetonitrile, water, in the at least one component B and in propylene oxide ; wherein for separation preferably a fractionating unit is used, wherein, preferably on top of the fractionating unit, liquid acetonitrile, optionally mixed with liquid water, is added as an embedding agent; (II) separating propylene oxide from SO1, obtaining an SO2 stream enriched in acetonitrile, water and in the at least one component B, wherein preferably at least 95% by weight of SO2 consists of acetonitrile, water and in the at least one component B, and wherein the weight ratio of acetonitrile to water is greater than 1:1, wherein S02 is preferably subjected to (c) as S1.
[0016]
Process according to claim 15, characterized in that (b) further comprises: (IIIa) subjecting SO2 obtained from (II) to hydrogenation; and/or (IIIb) subjecting the stream obtained from (II) or (IIIa) to distillation to obtain a bottoms stream, wherein the hydrogenated stream obtained from (IIIa) or the bottoms stream obtained from from (IIIb) is subjected to (c) as S1.
[0017]
17. Process according to any one of claims 1 to 16, characterized in that in (a) propene is reacted with hydrogen peroxide in the presence of a heterogeneous catalyst, said heterogeneous catalyst preferably comprising a zeolite, preferably a titanium zeolite, plus preferably an MWW structure type titanium zeolite (TiMWW), more preferably a MWW structure type zinc containing titanium zeolite (ZnTiMWW).
[0018]
Process according to any one of claims 1 to 17, characterized in that from 90 to 97% by weight, preferably from 92 to 97% by weight, more preferably from 95 to 97% by weight of SO consists of acetonitrile, water and propylene oxide, and wherein from 0.01 to 3% by weight, preferably from 0.015 to 2% by weight, more preferably from 0.02 to 1% by weight of SO consists of the at least one component B .
[0019]
Process according to any one of claims 1 to 18, characterized in that at least one component B is propionitrile, 1-nitropropane, 2-nitropropane, 3-methylbutanenitrile, n-pentanenitrile, 1-pentanol, 2-pentanol, 2 -butanone, 2-pentanone, 2-hexanone, 4-methyl-2-heptanone, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2-heptanol, 2,6-dimethyl-4-heptanone, 4 ,6-dimethyl-2-heptanone, 2,6-dimethyl-4,6-heptanediol, 2,4-dimethyloxazoline, 2,5-dimethyloxazoline, cis-2,4-dimethyl-1,3-dioxolane, trans-2 ,4-dimethyl-1,3-dioxolane, acetaldehyde, propionaldehyde, at least one impurity contained in the hydrogen peroxide employed in (a) or a combination of two or more of these compounds.
[0020]
Process according to claim 19, characterized in that at least one component B includes a combination of propionitrile, 1-nitropropane, 2-nitropropane, 2,6-dimethyl-4-heptanol, 4,6-dimethyl-2- heptanol, 2,6-dimethyl-4-heptanone, acetaldehyde and propionaldehyde.
[0021]
21. Process according to any one of claims 19 to 20, characterized in that in (d) the stream S3 is subjected to a vapor-liquid fractionation in a first fractionation unit, obtaining a stream of vapor fraction S4a being depleted, relative to S3, of at least one of the at least one component B, the at least one of the at least one component B comprising propionitrile, or 1-nitropropane or 2-nitropropane or 2,6-dimethyl-4-heptanol or 4,6-dimethyl-2-heptanol or 2,6-dimethyl-4-heptanone or a combination of two or more thereof, and obtaining a liquid bottoms stream S4b, wherein at least part of the fraction stream of steam S4a is subjected to a vapor-liquid fractionation in a second fractionation unit, obtaining a stream of vapor fraction S4c and a stream of liquid lower parts S4 being depleted, in relation to S4a, of at least one of the hair. minus one component B, the at least one of the at least one component B comp resending acetaldehyde, or propionaldehyde, or 2-butanone or a combination of two or more thereof.
[0022]
22. Process according to any one of claims 19 to 21, characterized in that at least one impurity contained in the hydrogen peroxide employed in (a) is an alkyl phosphate, such as tris-(2-ethylhexyl) phosphate, a nonyl alcohol such as diisobutylcarbinol, an alkylcyclohexanol ester such as 2-methyl-cyclohexylacetate, an N,N-dialkyl carbonamide such as N,N-dibutylpropionamide, an N-alkyl-N-aryl carbonamide, such as such as N-ethyl-N-phenylbenzamide, an N,N-dialkyl carbamate such as 2-ethylhexyl-N-butylcarbamate, a tetraalkyl urea such as tetra-n-butyl urea, a cycloalkyl urea such as di-propaneurea. -hexyl, a phenylalkyl urea such as N,N-dibutyl-N'-methyl-N'-phenylurea, an N-alkyl-2-pyrrolidone such as octyl-pyrrolidone, an N-alkyl caprolactam such as n- octyl caprolactam or a combination of two or more of these compounds.

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法律状态:
2019-10-29| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|

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2021-06-08| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|

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2021-08-10| B16A| Patent or certificate of addition of invention granted [chapter 16.1 patent gazette]|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 27/10/2015, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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EP14190535|2014-10-27|

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EM14190535.6|2014-10-27|

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PCT/EP2015/074839|WO2016066629A1|2014-10-27|2015-10-27|Part-stream distillation|

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