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    • 专利摘要:
    Dehydration of sorbitol to isosorbide in the absence of solvent by heterogeneous catalysis using sulfonic resins as catalysts. The present invention, which comes to solve problems associated with homogeneous catalysis as well as requirements of other sulfonic resins and other catalysts, refers to the use of different styrene-divinylbenzene resins, whose polymer structure consists of macroporous polystyrene crosslinked with divinylbenzene, as acid catalysts solids in a heterogeneous catalytic process for the dehydration of sorbitol to isosorbide. Likewise, the invention relates heterogeneous catalytic processes for the dehydration of sorbitol to isosorbide in the absence of solvent, either at atmospheric pressure or under vacuum conditions, comprising the addition of said resins used as catalysts in a sorbitol: catalyst ratio comprised in the range 10: 1 - 10: 2, the reaction at 140-180ºC for 1.5-12 hours, the subsequent dilution of the melt volume, and the separation of catalyst and sugars by microfiltration. (Machine-translation by Google Translate, not legally binding)
    公开号:ES2548483A1
    申请号:ES201500549
    申请日:2015-07-20
    公开日:2015-10-16
    发明作者:Pedro Jesús MAIRELES TORRES；María José GINÉS MOLINA；José SANTAMARÍA GONZÁLEZ；Ramón MORENO TOST；Josefa María MÉRIDA ROBLES
    申请人:Universidad de Malaga；
    IPC主号:
    专利说明:

    Dehydration of sorbitol to isosorbide in the absence of solvent by heterogeneous catalysis using sulfonic resins as catalysts
    TECHNICAL SECTION
    The present invention relates to catalytic processes aimed at the transformation of biomass, in particular lignocellulose, into high value-added chemicals and biofuels. More particularly, it refers to the dehydration of sorbitol to isosorbide by heterogeneous catalysis, using as a catalyst a sulfonic resin.
    STATE OF THE TECHNIQUE
    In recent years, the use of biomass as a renewable and sustainable raw material for the production of biofuels, energy and chemicals has been receiving increasing interest. In this sense, an alternative to the traditional refinery where raw materials of fossil origin I (oil, natural gas) are processed is the biorTefinería, where through different mechanical-physical, biochemical, chemical and thermochemical processes the biomass processing is carried out, in a sustainable and integrated way, for its conversion into a broad spectrum of chemical products and energy.
    Two categories of biomass-derived resources are distinguished: those of first generation from high-starch edible plant crops such as sugar cane, beets, sweet sorghum, and vegetable oils, animal fats, etc., and the second generation that use lignocellulosic biomass, Jatropha oil. microalgae, etc.
    A very important aspect is the use of lignocellulose present in residues
    forestry, agricultural, agri-food, urban and industrial, as it is the main
    biomass component.
    Lignocellulosic biomass is a molecular complex consisting primarily of cellulose, hemicellulose, and lignin. The latter prevents access to
    sugars Being around the cellulose and hemicellulose present in the biomass. necessary
    a pretreatment of this one so that carbohydrates are affordable.
    The transfer of matter of biomass origin to simple monomers is viable and
    S feasible although the difficulties presented by the different components of linocellulose
    to make them accessible they are subject to investigation, and the development of
    appropriate technologies to obtain high yields in gluta from biomass
    lignocellulosic Recent studies have demonstrated the feasibility of performing a pretrimentation
    of cellulose, increasing the surface area of the biomass, breaking the lignin seal and
    10 eliminating the hemicellulose present, in order to modify the structure and facilitate
    subsequent processes [N. Mosier, C. Wyman. B. Dale, R. Elander, Y. Lee, M. Holtzapple,
    M. Ladisch, Bioresour Technol 96 (2005) 673-686]. As expected, this stage
    Preliminary treatment makes the biomass sugar production system more expensive,
    which represents a new challenge for the scientific community.
    1S
    Lignocellulosic biomass can be triturated by two procedures: ténn ico e
    Hydro lysis
    o The tennochemical route implies a treatment at high temperatures and pressures. The
    Strategies to highlight in this way are gasification, pyrolysis and liquefaction. Is the
    twenty process commonly used for lithic tasting conversion or production of
    fuels, as is the case with the Fischer · Tropsch or hydro-oxygenation process.
    o In the case of hydrolysis or fractionation of lignocellulosic biomass,
    manages to isolate lignin and sugars to be treated through processes
    2S biological (catalytic isis) or chemical (acid catalysis).
    Through acid hydrolysis only yields of 70% can be achieved, but doing
    Using enzymatic hydrolysis, values of up to 95% are obtained [T. Lloyd, C. Wyman,
    Bioresour Technol 96 (2005) 1967-1 977J. It is done you justify attending that in the
    30 Acid hydrolysis has a heterogeneous system based on a bi-phase solid and the reagent
    liquid acid, pudding: no mass transfer limitations appear.
    On the other hand, to solve this disadvantage: niente and directly obtain polyols, such as sorbitol, from cellulose, systems where cellulose is hydrolyzed by protons from water molecules and acidic surface sites are being investigated. catalytic, being the determining stage of the process, and subsequently hydrogenation is performed on a metallic catalyst [G. Liang, C. Wu, L. He. J. Ming, H. Cheng, L. Zhuo, F. Zhao, Oreen Chem 13 (2011) 839-842]. In addition, hydrolysis can be favored by increasing the system temperature above 225 ° C, combining it with the use of acidic metal catalysts.
    One of the most attractive routes of cellulose transformation is its conversion to glucose. Glucose is an important precursor to a broad spectrum of chemicals with high added value.
    Of all the possible derivatives of glucos: a, sorbitol stands out, one of the polyols obtained by reduction, being a very important product from an industrial point of view.
    Sorbitol is one of the most important platafonna products, which is obtained by reducing the glucose present in the lignocellulose composition, in particular in hemicellulose and cellulose.
    Sorbitol is the hydrogenated form of glucose. It can be easily obtained from cellulose with very low production costs, being an ideal compound for the synthesis of derivatives of particular interest in the industry, cellulose hydrolysis and subsequent c.t.litic hydrogenation. of the resuscient glucose can also lead to degradation products of the resulting sorbitol.
    It is a continuous or series process that requires high temperature and pressure for hydrogenation, subsequent filtration and refining by ion exchange, where
    Finally, sorbitol is concentrated.
    It is a product of interest, since it can be transformed into biofuels, through an aqueous phase refraining (APR), or high value-added products such as glycols, after an aqueous phase hydrodeoxygenation.
    Among the compounds obtained derived from sorbitol, isosorbide and 1,4sorbitan, compounds widely used in the pharmaceutical industry, such as surfactants, food additives and in the synthesis of polyethylene terephthate. In addition, ascorbic acid (vitamin C) and isosorbide dinitrate are also of special interest because of their applications in medicine.
    Dehydration of sorbitol to isosorbide is carried out by homogeneous catalysis, in the presence of strong mineral acids as catalysts, among which sulfuric (H2S04), hydrochloric (Hel) and fostoric (H3P04) acids stand out. These systems have high conversions at low temperatures, ¡x: ro entail a series of drawbacks, such as high separation costs and corrosion problems in the equipment. Consequently. To solve these problems, today, research is aimed at the development of heterogeneous catalysis processes, where solid acid catalysts such as zeolites, phosphate metals, ion exchange resins, among others are used. When replacing liquid catalysts with acid solids, separation and corrosion problems are avoided, although it should be noted that the selectivities to the product of interest must be improved, in addition to solving the possible problems of catalyst deactivation and leaching. On the other hand, the separation of the different mixing products is an important challenge, due to the different compounds that can be obtained with similar chemical properties. Therefore, optimization of the dehydration process is required to achieve maximum isosorbide yield.
    In recent years, interest in the production of sorbitol and its dehydration to isosorbide has increased significantly in the presence of heterogeneous catalysts, and the challenge is to obtain it directly from cellulose. instead of using glucose as raw material.
    Isosorbide is a versatile platform chemical, due to its high stability and the two functional hydroxyl groups that penniten various chemical modifications, since
    which can be converted into other functional groups, being able to generate different monomers used for the production of polymeric materials.
    Isosorbide has excellent physico-chemical properties applicable to different fields of industry, being an extraordinary pharmaceutical intent (diuretic, and mainly to treat hydrocephalus and glaucoma), it is used as an additive to improve the resistance and stiffness of polymers such as polyethene terephthalate (PET), and as a monomer for the production of biodegradabh polymers: s.
    Among the compounds derived from isosorbide are isosorbide di nitrate and mononitralo, the latter being widely used as a vasodilator for angina pectoris and congestive heart failure.
    Isosorbide derivatives also find applications as fuels or fuel additives, due to the high energy content that aliphatic substituents can provide, (dimethyl i, osorbide (DMI).
    Dehydration of sorbitol to isosorbide takes place through two consecutive stages. It begins with a first celation with loss of a water molecule where chemical intermediates can be formed: 2,5-sorbitan and 1,5-sorbitan, which do not evolve to isosorbide, so they can be considered reaction byproducts, and the 1,4-sorbitan and 3,6-sorbitan, which progress to isosorbide. Subsequently, the second dehydration occurs, with a new delation generated by the isosorbide molecule.
    Currently, this reaction is carried out using homogeneous acid catalysis, in the presence of liquid mineral acids, which leads to problems of corrosion of the reactors, stages of neutralization and separation of the catalyst that cannot be reused. In this context, the development of catalysts solids represents a more sustainable alternative from an economic and environmental point of view, in addition to allowing in some cases a modulation of
    the selectivity.
    On the other hand, one of the objectives of Green Chemistry is the substitution of liquid mineral acids used in homogeneous catalytic processes by solid acid catalysts.
    Thus, several reaction systems (aqueous solutions in gas and liquid phase, use of molten sorbitol) have been studied in the presence of a broad spectrum of solid acid catalysts.
    In the bibliography (scientific works and patt: ntes) the use of catalysts has been published
    solid acids such as zeolites (Andrews et al. W02001092266 A2, 2001; Liu et al., EP2146998 Al, 2010), tetravalent metal phosphates (Gu et al., Catal. Let !, 133 (2009) 214-220), heteropolyacids sopotted on silica (Sun et al., Korean J. Chem. Eng. 28 (2011) 99-105), sulfated copper oxide (Xia et al., Catal. Cornmun. 12 (2011) 544-547), acid silicotungstic (Oltmanns et al., Appl. Catal. A 456 (2013) 168-173), trivalent metal phosphates (Igert et al., W02014023789 Al, 2014), sulfated titania (Ahmed et al., Chem. Eng. Se .93 (2013) 91-959), sulfated tin oxide (Dabbawala et al, Catal. Cornmun. 42 (2013) 1-5), sulfated zireonia (Kban et al., Appl. Catal. A 452 (2013) 34 -48), niobyl phosphate (Xi et al., Appl. Catal. A 469 (2014) 108-115), phosphate tantalum oxide (Zhang et al., Catal. Cornmun. 43 (2014) 29-33) Y Bronsted and Lewis acids of very diverse nature (Dabbawala et al., Appl. Catal. A 492 (2015) 252-261). The catalytic data
    collected in these works reflect maximum isosorbide yields close to 70%. but using aqueous solutions of high temperature sorbitol in gas phase, or by using microwaves.
    At present, active and selective catalytic systems for the transfonation of sorbitol in isosorbide are still being sought: and among the acid catalysts studied are sultonic resins, also used as ionic exchangers. These ionic exchange resins may have acidic or basic groups, depending on whether cationic or anionic exchange is pursued, respectively. In relation to the dehydration reaction of sorbitol, cationic exchange resins become important because they have strong acidic sulfonic groups (-S03H). They can also be used in a wide range
    depH.
    One of the systems proposed so far with this type of materials is to use Amberlyst ™ 35 (Hu el al., US 2007/0173653, 2007; Holladay el al., US 7649099 B2, 2010; Moore and Sanbom, US 6849748 B2, 2005; Polaert el al., Chem. Eng. J. 222 (2013) 228239). For example, in I. Polaert, M. Felix, M. Fomasero, S. Marcotte, 1. Buvat, L. Estel, Chem Eng J 222 (2013) 228-239 refers to the use of dry Amberlyst ™ 35 (8.16% w / w), heating with microwave at atmospheric pressure, obtaining an isosorbide selectivity of 70010.
    US 6849748 82 shows the results obtained with Amberlyst 35 and other sulfonic resins (Amberlysl 15, Dowex 50WX4 and RCP 2lH), where molten sorbitol is also used, but under vacuum conditions (1-10 torr), and the mixture is distilled under vacuum. US2007 / 0173653 Al (Hu et al., 2007) refers to the use of Amberlyst-35, but works with aqueous solutions of sorbitol in the gas phase.
    More recently, Zhang et al. Have compared an Amberlyst-15 and superhydrotobic mesoporous polymer based on P-S03-H as acid catalysts [J. Zhang, L. Wang, F. Liu, X. Meng, J. Mao, F. Xiao, Catal Today 242 (2015) 249-254]. At 140 ° C, for 10 hours, the resin showed a high conversion (94.3%) and isosorbide selectivity of 71.8%, but increased to 87.9% and the conversion of sorbitol was practically complete (99%) with the polymer pink mesopo In addition, subsequent reuse studies corroborated the excellent performance of the P-S03-H polymer for 5 cycles, maintaining a selectivity of 77.7%, higher than the value of the first cycle of the Amberlyst-15 and well above the 3 reuse cycles of the same. where it loses its activity and only reaches 15.4% isosorbide selectivity.
    DESCRIPTION OF THE INVENTION
    The present invention relates to the development of a heterogeneous catalytic process for the dehydration of sorbitol9 obtained from glucose from lignocellulosic biomass, to isosorbide, in a sustainable and efficient way. proposing the replacement of liquid acid catalysts with solid acid catalysts that remedy the environmental, corrosion and separation problems associated with homogeneous catalysis.
    Thus, the use of styrenedivinylbenzene resins with acidic sulfonic groups whose polymeric structure consists of macroporous polystyrene crosslinked with divinylbenzene, with an acidity of 5.2 eq / kg, with a residual moisture percentage of 3% is a first object of the invention. , (: on a particle size in the range 425-1200 micrometers, a specific area in the range 20-50 m'g, a pore volume in the range 0.2-0.6 mUg, an average pore diameter in the range 23-70 run, and one, technical stability that extends to a maximum temperature of 180 oC, as a solid acid catalyst in a heterogeneous catalytic process for the dehydration of sorbitol to isosorbide In a particular embodiment of said first object , the invention relates to the use of styrene-divinylbenzene resins with acid sulfonic groups whose polymeric structure consists of macroporous polystyrene cross-links. Do with divinylbenzene, with an acidity of 5.2 eq / Kg, with a percentage of residual humidity of 3%, with a particle size in the range 425-1200 micrometers, a specific area in the range 35-50 m2¡g , a pore volume in the range 0.2-0.5 mVg, an average pore diameter in the range 23.1-42.5 nm, and a technical stability that extends to a maximum temperature of 180 oC, as a solid acid catalyst in a process Heterogeneous catalytic for the dehydration of sorbitol to isosorbide. In another particular embodiment of said first object, the invention relates to the use of styrene-divinylbenzene resins with acidic sulfonic groups whose polymeric structure consists of macroporous polystyrene crosslinked with divinylbenzene, with an acidity of 5.2 eq / Kg, with a percentage of residual moisture of 3%, with a particle size in the range 600-850 micrometers, a specific area comprised
    t: n the range 20-40 m2¡g, a pore volume in the range 0.2-0.6 mUg, an average pore diameter in the range 40-70 run, and a thermal stability that extends to a maximum temperature of 180 oC, as a solid acid catalyst in a heterogeneous catalytic process for the dehydration of sorbitol to isosorbide.
    A second object of the invention relates to a heterogeneous catalytic process for the dehydration of sorbitol to isosorbide which comprises the use of a styrene divinylbenzene resin with acid sulfonic groups as a solid acid catalyst according to the first object of the invention. In a preferred embodiment of said second object, the process comprises (i) the addition to a reactor of the catalyst and sorbitol in a sorbitol: catalyst mass ratio in the range 10: 1 -20: 1, preferably 20: 1; (H) the reaction of the sorbitol mixture: catalyst under stirring, in the absence of solvent, and at a temperature in the range 140-180 ° C, preferably in the range 140-160 ° C, more preferably at 140 ° C, for one ti € : reaction time in the range 90 minutes -12 hours, preferably in the range 10-12 hours, more preferably for 10 hours; (iii) dilution of the volume of melt resulting from the reaction with distilled water; Y
    (iv) the separation of the catalyst from sugars by micro filtration of the volume of molten diluted in water. In a particular embodiment of the invention, the reaction is carried out at atmospheric pressure without an inert atmosphere. In another particular embodiment of the invention, the reaction is carried out at atmospheric pressure but in an inert atmosphere by introducing a stream of an inert gas, for example Nz. In another particular embodiment of the invention, the reaction is carried out under vacuum conditions. Alternatively, and in another particular embodiment of the invention, the catalytic process comprises, after the catalyst separation stage from the fused sugars by dehydration of sorbitol, a catalyst recovery stage for subsequent reuse, said step comprising washing the catalyst and its drying.
    In this context, the present invention relates to the use of sulfonic resins. different (among others) from Amberlyst-type resins (which have differences in porosity level, particularly having a smaller average pore diameter than resins whose use is referred to in the present invention), as solid acid catalysts for sorbitol dehydration to isosorbide, yields in isosorbide reaching close to 70%, with a total conversion of sorbitol. when molten sorbitol at 140OC is used, in the absence of solvent, after 10 hours of reaction, when a sorbitol: catalyst mass ratio of 20: 1 is used. The reaction is carried out by melting the sorbitol (mp 95'C) at 140 ° C, and conversions close to 100% are achieved after 3 hours of reaction, with yields of 43% isosorbide increasing to 74.8% at 12 o'clock This evolution is justified by the formation of sorbitan, products of monoleshydration of sorbitol, of which 1,4-Y 3,6-sorbitan are the only ones that evolve towards isosorbide.
    These catalysts can be reused, being stable in the reaction medium without loss.
    significant of its catalytic activity. On the other hand, the remaining sorbitol and the products ofThe reaction is dissolved in water to separate them from the catalyst. The present invention pennitePerform the process either at atmospheric pressure or under vacuum conditions.
    The proposed catalysts require lower reaction temperatures to reachperformance values comparable to the data described in the prior art ondehydration of sorbitol to isosorbide.
    Throughout the description and claims the word Itcomprendelt and its variants do notthey intend to exclude other technical characteristics: components or steps. For experts in theMatter, other objects, advantages and features of the invention will be partly detached from thedescription and in part of the practice of the invention. The following examples and figures areprovided by way of illustration, and are not intended to be limiting of the presentinvention.
    DESCRIPTION OF THE FIGURES
    Figure 1: N2 adsorption-desorption thermometers,Figure 2: Sorbitol FTIR spectrum.Figure 3: FTIR spectrum of isosorbide.Figure 4: FTIR spectra of the Purolite CT269DR and CT269DR * (after reaction).Figure 5: Comparison of conversion, selectivity, performance of catalytic resinsfor 10 hours at 1400C.Figure 6: Catalytic activity of Purolite CT269DR as a function of the temperature ofreaction.
    Figure 7: Kinetic study of sorbitol dehydration at 140 ° C, up to 12 hours ofreaction.Figure 8: Kinetic study of sorbitol dehydration at 1400C, up to 44 hours ofreactionFigure 9: Influence of the CT269DR resin mass at 140 ° C, for 90 min with 2 g ofsorbitol.Figure 10: Study of the influence of the size of Purolite CT269DR at 140 ° C, during 90
    min with 2 g sorbitol.Figure 11: Reuse study of Purolite CT269DR at 140 "C, for 90 min with 2gsorbitol.
    MODES OF REALIZATION OF THE INVl: NTION
    The constitution and characteristics of the invention will be better understood with the aid of the following description of embodiments, it being understood that the invention is not limited to these embodiments, but that the protection encompasses all those alternative embodiments that may be included within the content and content. scope of the claims. Likewise, the present document refers to various documents as prior art, being understood by reference the content of all these documents, as well as the complete content of the documents referred to in said documents, in order to offer a description as possible complete state of the art in which the present invention fits. The tenninology used below is intended to describe the examples of embodiments that follow and should not be construed as limiting or restrictive.
    Next, illustrating the invention, the results obtained using different commercial sulphonic resins of the Puro lita type are described, the polymeric structure of which consists either of macroporous polystyrene cross-linked with divinylbenzene (CT275DR and CT269DR) or polystyrene gel intercrossed with divinylbenzene (PD206) , as catalysts for the dehydration of sorbitol to isosorbidu.
    Destrip <ion of the Catalysts
    Within the wide range of existing ionic exchange resins are styrene-divinylbenzene resins with acidic sulfonic groups.
    Three commercial Purolite resins have been used: CT275DR, CT269DR and PD206. This type of resin has pores of large diameters, which facilitate access to acid sites and avoid diffusional limitations that could appear with microporous materials. These are resins with a high concentration of acid centers. Its macroporous skeleton is formed by polyvinylbenzenesulfonic groups.
    lfIIm <dod
    T ..... ao <k
    An.
    DüJDl.tto
    Acidity
    ., .. oo.¡.
    E.sp «ífin
    Vol. POIOf
    Mt'diodd
    T
    (oC)
    [~.
    ¡'' .J
    p. <o (A)
    [mV.J
    baal '' '': r
    ,
    <25-00)
    '-2
    cr269DR
    ~
    03-0 '
    ~
    ,
    , ..
    725:!: 1 ~
    > .1
    0.4-0.6
    40-10
    20-10
    crl7SDR
    ...
    300-120)
    -
    PO 2 "
    -
    -
    -
    5 Table 1. Physico-chemical characteristics of Purolite resins used
    The main chemical physical characteristics of the resins are shown in Table 1.
    Textural properties
    10 The determination of the textural purposes of solid catalysts is very important in heterogeneous catalysis, since this process is a superficial phenomenon. The textural parameters have been deduced from the adsorption-desorption isotherms of N2 at -196 ° C. 8ET specific surface data, pore volume and average pore diameter,
    15 determined according to the methods of Brunauer-Emmett-Teller (BET) and Barrett-JoynerHalenda (BJH), are presented in Table 2.
    Sen Im'jg] V. [cm'jg)d. 10m)
    CT 269 DR 39.530.20123.1
    CT275DR 22.150.16046.4
    PD206 2.540.0025.6
    Table 2. Textural properties of sulfonic resins
    The values obtained reflect that the dry Purol itas, CT269DR and CT275DR, are the ones with the greatest surface areas. In addition, although the Pure lita CT269DR shows approximately twice the BET surface area than the CT275DR, its average pore diameter is considerably lower (Table 2). On the other hand, the Purolite PD206 has lower values of the textural parameters evaluated.
    5 These textural parameter values coincide with the specifications provided by the company that supplies the resins (Purolite), although the pore volume values are slightly lower. Figure 1 shows the adsorption-desoreion nitrogen isotherms at -196 ° C.
    10 For CT269DR and CT275DR resins, isotennes conform to type IV in the IUPAC classification, corresponding to multilayer adsorption on mesoporous materials. On the other hand, Purolite PD206 has a characteristic isotenna of non-porous solids. without hysteresis cycle or appreciable amount di; adsorbed nitrogen.
    15 Elementary analysis (EA)
    This technique pennite the determination of the percentage composition of e, N, H and S of the resins studied. It is based on the complete oxidation of the sample by combustion with pure oxygen, in a controlled atmosphere. at a temperature of up to 11 OOOc. 20 The different resulting combustion products, C02, H20, S02 and N2, are subsequently quantified by IR and thermal conductivity sensor. The percentages of carbon range between 35 and 45% with respect to the weight of the sample, while the mass ratios indicate that the degree of sulfonation of these resins is different (Table 3). Thus, the lowest values are found for resins that have
    25 larger specific surfaces, that is, the CT269DR and CT275DR purolites. It is to be expected that this suitable combination of high acidity and high surface area results in optimal catalytic behavior.
    %C % H% N% SI / O ratio
    CT269DR 35.325.250.0413.007.25
    CT275DR 40.565.210.0115.457.00
    PD206 44.405.620.0013.636.56
    Table 3. Mass chemical composition of Purolite CT269DR at different reaction times
    Differential and thermogravimetric thermal analysis (ATD-TG)
    Through differential and tennogravimetric technical analysis, structural information is obtained on the mass variations that a solid undergoes as a function of temperature, associated with phase transitions and endothenic or exothenic processes that the sample undergoes when subjected to a temperature incident.
    In the TD-TG curve of Purolite CT269DR, a first weight loss of 15% is observed, associated with an endothenic effect centered at 10O "C, attributable to the loss of hydration water.
    At a higher temperature, two very intense exothermic effects are observed in the ATO curve, associated with the decomposition of the sulphonic groups (weight loss around 275 ° C) and the combustion of the organic skeleton between 300-550 ° C. From these technical data it can be deduced that at working temperatures above 2001 {: degradation of this material occurs, which limits the working temperature.
    Similar curves are obtained for Purolite CT2750R, with percentages of weight loss and thermal effects similar to those of CT2690R resin. However, P0206 purolite requires a temperature close to 7500C for total combustion.
    Fourier transform infrared spectroscopy (FTIR)
    This technique consists in the study of the interaction of infrared radiation with matter. This pennite spectroscopy identifies chemical species through the determination of the frequency at which the different functional groups have characteristic absorption bands in the IR spectrum. The concentration of the species is determined from the intensities and areas of the sample bands.
    In the infrared spectra of the solid samples of sorbitol and isosorbide (Figures 2 and 3), between 3,000 and 3,500 cm-], characteristic bands of the voltage vibrations of the OH groups are observed, highlighting the wide width in the case of sorbitol due to the higher content of hydroxyl groups in the molecule, which favor the formation of hydrogen bonds. On the other hand, the tension vibrations of the C-H bonds appear between 2800 and 3000 cm-1, and the tension vibrations of the e-o bonds of these alcohols between 1050 and 1150 cm-l. In the region of the FTIR spectrum between 700 and 1400 cm-l, numerous bands associated with the different deformation vibration modes of sorbitol and isosorbide molecules are detected.
    Figure 4 shows, as an example, the FTIR spectrum of the CT269DR resin, before and after the reaction. Both spectra are identical: indicating that the resin is thermally resistant. maintaining its structural integrity after the catalytic process. The vibration modes associated with the sulphonic groups, with symmetric and asymmetric voltages of the links i> = 0 to 620 and 1220 cm-l and the voltage vibration is at 1050 cm-l _ are masked by the intense bands of the organic skeleton of the Puro lita resin, formed by divinylbenzene groups.
    Measures of catalytic activity
    Different reaction systems have been used for the study of sorbitol dehydration by heterogeneous acid catalysis: with O without N2 current and under vacuum conditions to eliminate the water in the dehydration process.
    Melt reaction system without inert atmosphere
    This reaction system consists of a batch batch reactor immersed in a silicone bath.
    The reaction is carried out by introducing 2 g of sorbital and 100 mg of catalyst into the reactor, which in turn is immersed in a silicone bath placed on a heating plate, with magnetic stirring at 600 rpm, at 1400C for 10 hours, as standard reaction conditions. The reaction time measurement is started once the bath tennometer reaches that temperature, and the reaction is interrupted by cooling the reactor in a cold water bath.
    After the reaction time has elapsed, the melt volume is diluted to 100 ml with distilled water. A fraction is taken from this solution, which is microfiltered and analyzed.
    In all cases, sorbitol conversions close to 100% are achieved. but with yields in isosorbide between 70 and 75% (Figure 5).
    The study of the influence of the reaction temperature has been carried out with a reaction time of 90 minutes (Figure 6). A moderate increase in isosorbide yield is observed in the range of 140-160OC, with an increase in conversion of 24%, to achieve a conversion greater than 90% at 160 ° C. Assuming 180 ° C as the maximum working temperature that ensures the technical stability of the catalyst, 140 ° C has been chosen as the reaction temperature for subsequent catalytic tests.
    A kinetic study was then carried out at 140OC using 2 g of sorbitol and 100 mg of Puro lita CT269DR, until reaching 22 hours of reaction (Figures 7 and 8).
    From Figure 7 it follows that at low reaction times, about 180 minutes, almost complete conversion of sorbitol is achieved, but with an isosorbide yield of only 43.2%. To obtain maximum performance, 10-12 hours must be reached, and from this reaction time (Figure 8) there is a drop in the yield to isosorbide, which can be attributed to possible side reactions of the isosorbide or simply to pyrolytic processes as a consequence. of the high reaction times and temperature.
    The stability evaluation of the Purolite CT269DR has been carried out by CHNS chemical analysis of the catalysts used, after different reaction times. In this sense, it is important to maintain the concentration of sulfonic groups in the resin to preserve their catalytic activity. In general, it is appreciated that there is no loss of sulfonic groups in the CT269DR resin, since the sulfur content of the catalysts
    used remains virtually constant in all samples (Table 4).
    CT269DR
    Time [mine)
    %C
    % H
    C / S ratio
    % N
    % S
    .
    0.04
    13.00
    7.25
    35.32
    5.25
    39.91
    0.08
    13.99
    7.61
    S.H
    H, 14
    5.33
    0.06
    13.91
    7.89
    41.27
    5.26
    13.66
    8.06
    0.06
    40.91
    5.18
    0.04
    13.58
    8.03
    40.77
    13.30
    8.17
    5.09
    0.03
    43.48
    13.90
    8.34
    5.15
    0.03
    Table 4. Mass chemical composition of the Purolite CT269DR at different reaction times 5 To complete this study on the stability of the catalysts, the analyzes by inductively coupled plasma emission spectrometry (ICP-OES) of the reaction liquids have been performed obtained during the kinetic study. The ICP-OES procedure is based on the detection of the photons emitted by the atoms / ions present in the sample studied. It uses a plasma system with inductive coupling as a source of atomization and excitation to generate these ions, and measures the UV-VIS radiation of the atomic emission lines characteristic of each element.
    Time [min 30 Concentration S ["SIL) 2 64SD 0.09
    180 300 '' ', 79 4.84Or, 0.02
    4 20 5.640.08
    600 6.400.06
    720 1.000.10
    15 Table 5. S concentration data in the reaction liquid determined by ICP-OES
    Data regarding sulfur concentrations indicate a maximum amount in solution of 7 ppm after 12 hours of reaction, corresponding to 5.38% of the maximum leachable amount (130 ppm). So. It can be considered that the leaching of the active phase of the catalyst is practically insignificant (Table 5).
    To optimize the catalyst load, a study was carried out varying its mass between 25 and 200 mg (Figure 9). The maximum conversion of sorbitol is achieved with 150 mg of catalyst, but the yield in isosorbide increases very little when the amount of catalyst is increased between 100 and 200 mg. Therefore, it has been estimated that 100 mg is the optimal loading in the reaction, since it is necessary to double the catalyst mass up to 200 mg to only increase the yield by 7%.
    Due to the diversity of particle sizes that this Purolite CT269DR resin could present, it has been considered of interest to conduct a study on its influence on catalytic behavior. For this, this resin has been screened to obtain particle sizes in the ranges: [0.40-0.50], [0.50-, 71], [0.71-1.00] AND [1.00- 1.18] mm. The catalytic data demonstrate an improvement in performance with the use of the catalyst with the smallest particle size. between 0.4-0.5 mm, for which the highest sorbitol conversion is obtained. The study was carried out at 140 ° C with the same sorbitol / catalyst mass ratio, but at 90 minutes of reaction in all cases (Figure 10).
    Finally, the reuse of the catalyst has been evaluated to verify its viability in a heterogeneous industrial process. For this, 5 reactors were prepared, which were reacted at 140 ° C for 90 minutes, with 2 g of sorbitol and 100 mg of CT269DR catalyst. At the end of the reaction time, the melting of each reactor was brought to the relevant dilution with distilled water, and the different solids recovered were collected in a single batch, which was washed with distilled water and dried in an oven at 100 ° C during the hour. Sufficient quantities of this sample were converted from this solid to perform a second cycle in four identical reactors, and so the experience was repeated until repeating the
    experiment for 4 cycles.
    The catalytic activity data obtained in each cycle is shown in the bar chart of Figure 11. A slight decrease in conversion is observed after the first cycle. However, it is possible to maintain an average 27-29% growth in isosorbide in the first 3 cycles.
    In order to check if there is leaching of the active phase of the catalyst in the reaction medium, measurements of the chemical composition CHNS of the catalysts used have been made, after the 2nd and 4th cycles of re: action. The data obtained are shown in Table 6 where no loss of sulfonic groups is observed. The content in e and H increases slightly over the 4 cycles, corresponding to the possible carbonaceous residues. This increase in the amount of carbon leads to a continuous awning of the mass C / S ratio, after each catalytic cycle.
    Table 6. Percent composition of Purolite CT269DR after 4 reuse cycles
    System of melt reaction by means of a run !: nte of atmosphere in ~ rte
    In the second reaction system a stream of N2 is introduced into a flask with three mouths and an outlet, with the intention of removing the water vapor generated during the dehydration reaction. The temperature is controlled by an external tennometer submerged in the bath if it liquefies at 140 ° C, but in turn a tennometer is introduced through one of the mouths to know the thermal gradient when an inert entrainment gas is used.
    20 Both the temperature and the reaction time are kept constant, 140 ° C for 10 hours; however, it is necessary to keep the initial sorbitol mass in the system at 4 g to provide a sufficient mass in the reactor, although the sorbitol / catalyst mass ratio of 20: 1 is maintained.
    In order to maximize the reaction efficiency a system has been used in which nitrogen flow is passed through the reaction atmosphere to remove the water formed during the dehydration process, and thus move the reaction towards the
    isosorbide phonation.
    In a previous test it was observed how the reaction yield was doubled from 23.7 to 41.5% at low reaction times (90 min) (Table 7). However, the experiment was performed during the optimized time (10h) with the sieved and unselected Purolite,
    5 and it was found in both cases that the nitrogen flow did not improve the yield of the reaction. The nitrogen injection removes the water formed, but also causes a decrease in the reaction temperature, by removing heat from the medium, observing a difference of up to 300C between the heating bath and the reaction atmosphere, with a negative effect on the evolution of the catalytic dehydration process.
    Table 7. Influence of the type of atmosphere of 'reaction on the catalytic behavior.
    Vacuum Melt Reaction System
    15 In order to increase the yield of the reaction, a system similar to the previous one has also been used, but replacing the nitrogen current with a vacuum system. The rest of the parameters remained unchanged.
    20 Finally, another method has been proposed to remove the water from the reaction, such as coupling a vacuum pump to the reaction system. In this case a slight improvement is obtained at low reaction times. Despite this, the yields achieved with the use of nitrogen current in the reaction atmosphere (Table 8) were not improved.
    Table 8. Comparison of catalytic behavior f: using different reaction systems, based on molten sorbitol
    Conclusions
    Among the sulphonic resins studied, the best yields in isosorbide were achieved with Pure litas CT269DR and CT275DR, COI1 values close to 70% when molten sorbitol was used at 140 ° C. with sorbitol mass ratios: 20: 1 catalyst. These are two mesoporous resins with values of average pore diameter sufficiently high to ensure the access of sorbitol molecules to the active sites and the subsequent exit of reaction products. In the case of PD206 resin, its low thermal stability (20'C) limits its use in these reaction conditions.
    On the other hand, the CT269DR resin exhibits greater mechanical stability, which ensures its structural integrity in the reaction conditions.
    The influence of the reaction temperature was evaluated in the range between 100 and 160 ° C, with 1400C being the optimum value, sufficiently far from the degradation temperature of the resin TC269DR (180'C).
    The kinetic study showed that a complete conversion of sorbitol is achieved after 3 hours of reaction, but with an isosorbide yield of 43.2%, requiring 10 hours to obtain maximum yield (68.9%). The catalyst is stable under the reaction conditions, as can be inferred from the dt! sulfur from the catalyst used and in the reaction medium.
    The optimum catalyst loading and particle size have been 100 mg of catalyst particles with sizes between 0.4 and 0.5 mm.
    On the other hand, it has been possible to reuse the catalyst for 4 reaction cycles, after an intermediate stage of washing and oven drying at 10 lfe for one hour between each cycle. maintaining an average isosorbide yield of 27-29%. The chemical analysis of the catalysts used confirmed the stability of the catalyst.
    权利要求:
    Claims (11)
    [1]
    one. Use of styrene-divinylbenzene resins with acidic sulfonic groups whose polymeric structure consists of macroporous polystyrene cross-linked with divinylbenzene, with an acidity of 5.2 eq / Kg, with a percentage of residual humidity of 3%, with a particle size in the range 425-1200 micrometers, a specific area in the range 20-50 m2 / g, a pore volume in the range 0.2-0.6 mllg, an average pore diameter in the range 23-70 run, and a technical stability which extends to a maximum temperature of 180 oC, as a solid acid catalyst in a heterogeneous catalytic process for the dehydration of sorbitol to isosorhyde.
    [2]
    2. Use according to the preceding claim of styrene-divinylhencene resins with acidic sulfonic groups whose polymeric structure consists of macroporous polystyrene cross-linked with divinylbenzene, with an acidity of 5.2 eq / Kg, with a residual moisture percentage of 3%, with a particle size in the range 425-1200 micrometers, a specific area in the range 35-50 m2 / g, a pore volume in the range 0.2-0.5 ml / g, an average diameter d. the pore in the range 23.1 -42.5 run, and a technical stability that extends to a maximum temperature of 180 oC, as a solid acid catalyst in a heterogeneous catilitic process for the dehydration of sorbitol to isosorbide.
    [3]
    3. Use according to claim 1 of d ~: styrene-divinylbenzene resins with acidic sulphonic groups whose polymorphic eslructuC'd consists of: n macroporous polystyrene cross-linked with divinylbenzene, with an acidity of 5.2 eq / Kg, with a percentage of residual moisture 3%, with a particle size in the range 600-850 micrometers, a specific area in the range 20-40 m2 / g, a pore volume in the range 0.2-0.6 mUg, an average pore diameter in the range 40-70 nm, and a technical stability that extends to a maximum temperature of 180 oC, as a solid acid catalyst in a heterogeneous catalytic process for dehydration of
    sorbitol to isosorbide.
    [4]
    Four. Heterogeneous catalytic process for the dehydration of sorbitol to isosorbide characterized in that it comprises the use of a styrene divinylbenzene resin with acid sulfonic groups as a solid acid catalyst confonm: to any of claims 1 to 3.
    [5]
    5. Process according to the preceding claim characterized in that it comprises: the addition to a reactor of the catalyst and sorbitol in a sorbitol: catalyst mass ratio in the range 10: 1-20: 1; -the reaction of the sorbitol mixture: catalyst (; n stirring, in the absence of solvent, and at a temperature in the range 140-180 oC for a reaction time in the range 90 minutes -12 hours; -the volume dilution of melt resulting from the reaction with distilled water, and - the separation of the catalyst from the sugars by micro filtration of the volume of molten diluted in water.
    [6]
    6. Process according to the preceding claim characterized in that the reaction mixture is reacted at a temperature in the range 140-160 ° C for a reaction time in the range 10-12 hours.
    [7]
    7. Process according to the preceding claim characterized in that the reaction mixture is reacted at a temperature of 140 'C for a reaction time of 10 hours.
    [8]
    8. Process according to any one of claims 5 to 7 characterized in that the sorbitol: catalyst mixture is reacted at atmospheric pressure without an inert atmosphere.
    [9]
    9. Process according to any one of claims 5 to 7 characterized in that the sorbitol: catalyst mixture is reacted in an inert atmosphere while a stream of inert gas (Nz) is passed through it.
    [10]
    10. Process according to any of the claims 5 to 7 characterized in that the sorbitol: catalyst mixture is reacted under vacuum conditions.
    [11 ]
    eleven . Process according to any of claims 5 to 10, characterized in that it comprises, after the step of separating the catalyst from the fused sugars by dehydrating the sorbitol. a catalyst recovery stage for subsequent reuse, said step comprising washing the catalyst and drying it.
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    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2002036598A1|2000-11-01|2002-05-10|Archer-Daniels-Midland Company|Process for the production of anhydrosugar alcohols|
    WO2009155020A2|2008-05-28|2009-12-23|Archer Daniels Midland Company|Production of 5-membered and 6-membered cyclic esters of polyols|
    WO2014070371A1|2012-10-31|2014-05-08|Archer Daniels Midland Company|Improved method of making internal dehydration products of sugar alcohols|
    CN109261202A|2018-09-30|2019-01-25|中国科学院山西煤炭化学研究所|A kind of catalyst and its preparation method and application preparing isobide for sorb dehydration of alcohols|
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