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    • 专利摘要:
    "process for the preparation of an alkylene glycol from an alkene, and, absorber apparatus". the invention provides a process for preparing an alkylene glycol from an alkene comprising the steps of: (a) providing a gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor to the bottom of an alkylene oxide absorber, said absorber comprising a column of vertically stacked trays, each of the vertically stacked trays comprising a perforated gas-liquid contact member or members, a liquid inlet area, an outlet dam which extends vertically above the surface of the tray at the opposite end of the tray from the liquid inlet area and a down-pipe element which, in cooperation with the inner surface of the column wall, forms a down-pipe for the passage of liquid from descending form to the liquid inlet region of the vertically adjacent tray directly below, where the output dam in each tray has lint. minus 200 mm and maximum 1,500 mm in height and allows the gas composition to pass upwards through the column; (b) providing a lean absorbent to the top of the alkylene oxide absorber and allowing the lean absorbent to pass down through the column; and (c) intimately contacting the gas composition with poor absorbent on the trays in the alkylene oxide absorber in the presence of one or more catalysts that promote carboxylation and hydrolysis; and (d) removing grease absorber from the alkylene oxide absorber.
    公开号:BR112017005709B1
    申请号:R112017005709-3
    申请日:2015-09-21
    公开日:2021-08-03
    发明作者:Peter Mervyn Wilkinson；Jesse Raymond Black；Roel Guillaume Hubertus Leonardus Bastings
    申请人:Shell Internationale Research Maatschappij B.V.；
    IPC主号:
    专利说明:

    field of invention
    [001] The present invention relates to a process and an apparatus for the preparation of an alkylene glycol from the corresponding alkene. Fundamentals of Invention
    [002] Monoethylene glycol is used as raw material in the manufacture of polyester fibers, plastics and poly(ethylene terephthalate) (PET) resins. It is also incorporated into car antifreeze liquids.
    [003] Monoethylene glycol is typically prepared from ethylene oxide, which is in turn prepared from ethylene. Ethylene and oxygen are passed over a silver oxide catalyst, typically at pressures of 10-30 bar (1-3 mPa) and temperatures of 200-300oC, producing a product stream comprising ethylene oxide, carbon dioxide, ethylene , oxygen and water. The amount of ethylene oxide in the product stream is usually between about 0.5 and 10 percent by weight. The product stream is supplied to an ethylene oxide absorber and the ethylene oxide is absorbed by a recirculating solvent stream containing mostly water. The depleted ethylene oxide stream is supplied partially or completely to a carbon dioxide absorption column in which the carbon dioxide is at least partially absorbed by a recirculating absorber stream. Gases that are not absorbed by the recirculating absorbent stream are recombined with any gases that bypass the carbon dioxide absorption column and are recycled to the ethylene oxide reactor.
    [004] The solvent stream leaving the ethylene oxide absorber is referred to as the grease absorber. The grease absorber is supplied to an ethylene oxide extractor, in which ethylene oxide is removed from the grease absorber as a stream of vapor. The ethylene oxide depleted solvent stream is said to be a lean absorbent and is recirculated to the ethylene oxide absorber to absorb additional ethylene oxide.
    [005] The ethylene oxide obtained from the ethylene oxide extractor can be purified for storage or sale or can be further reacted to provide ethylene glycol. In a well-known process, ethylene oxide is reacted with a large excess of water in a non-catalytic process. This reaction typically produces a glycol product stream consisting of nearly 90 percent by weight monoethylene glycol, the remainder being predominantly diethylene glycol, some triethylene glycol, and a small amount of higher homologs. In another well known process, ethylene oxide is catalytically reacted with carbon dioxide to produce ethylene carbonate. Ethylene carbonate is subsequently hydrolyzed to provide ethylene glycol. The reaction through ethylene carbonate significantly improves the selectivity of converting ethylene oxide to monoethylene glycol.
    [006] Efforts have been made to simplify the process to obtain ethylene glycol from ethylene, reducing the equipment that is required and reducing energy consumption. GB 2107712 describes a process for the preparation of monoethylene glycol in which ethylene oxide reactor gases are supplied directly to a reactor in which ethylene oxide is converted to ethylene carbonate or a mixture of ethylene glycol and ethylene carbonate.
    [007] EP 776890 describes a process in which gases from the ethylene oxide reactor are supplied to an absorber in which the absorbent solution mainly contains ethylene carbonate and ethylene glycol. Ethylene oxide in the absorbent solution is fed to a carboxylation reactor and allowed to react with carbon dioxide in the presence of a carboxylation catalyst. The ethylene carbonate in the absorbent solution is subsequently supplied, with the addition of water, to a hydrolysis reactor and subjected to hydrolysis in the presence of a hydrolysis catalyst.
    [008] EP 2178815 describes a reactive absorption process for the preparation of monoethylene glycol in which ethylene oxide reactor gases are supplied to an absorber and the ethylene oxide is contacted with lean absorbent comprising at least 20% by weight of water in the presence of one or more catalysts that promote carboxylation and hydrolysis and most of the ethylene oxide is converted to ethylene carbonate or ethylene glycol in the absorber.
    [009] Towers or columns that allow the intimate gas-liquid contact required for such absorption are well known in the art and are said to be, for example, fractionation, distillation or absorption towers. Such towers or columns contain trays stacked vertically through the column and are designed to conduct liquids in a zigzag-type course downwardly through the column while admitting gases upwardly into horizontal flowing portions of the liquid for intimate contact with the liquid. .
    [0010] Trays for providing the horizontal course of liquid are well known in the art and have been widely used. A tray generally comprises a perforated gas-liquid contact member or members to effect intimate contact between a gas rising through the tray and a liquid flowing across the surface of the tray through the perforated member. The perforated gas-liquid contact member is in some instances provided with bubble covers or valves. On one edge of the tray contact member is a liquid inlet area for receiving liquid over the tray. This area will generally not contain perforations. At the opposite edge of the contact member is the liquid discharge end or region of the tray, which is provided with an outlet dam that extends vertically above the surface of the tray. The flowing liquid floods the exit dam for tray discharge. Consequently, this outlet dam maintains a given depth of liquid in the tray.
    [0011] Extending below the trays is one or more down-pipe element which, in cooperation with the inner surface of the column or tower wall, forms a down-pipe for the passage of liquid downwardly from the end or discharge region of tray liquid to the vertically adjacent tray liquid inlet region directly below. The downwardly flowing liquid received in the liquid inlet area or region then flows across the surface of this tray in a path through the perforated gas-liquid contact member, to the discharge region or end of the tray and is discharged from the tray. , over the exit dam into the next downpipe.
    [0012] A gas flows upwards in the column through the perforations of the gas-liquid contact members of the trays, allowing intimate contact with the liquid flowing horizontally across the surface of the tray. Gas is not allowed to pass above the downpipes, as the downpipe element also functions as a baffle which extends below the surface level of the flowing liquid to seal the downpipes from the gas bypass. However, gas bypass through the downpipes can occur during process start-up when the column is not yet sufficiently filled with liquid.
    [0013] The structure of an individual column and the trays therein shall be determined based on the process for which they are intended to be used. For example, outlet dams in the technique vary in height depending on the nature of the column or tower operation. US 4435595 describes a reactive distillation process for the production of high purity methyl acetate in which high dams are used. The exit dams in this case are 5 inches (12.7 cm) high.
    [0014] US 2013/0245318 provides a grinding column for the production of a methionine salt in which the dams have a height of 100 mm or more.
    [0015] EP 1964829 describes a multistage distillation column comprising vertically stacked trays having a dam height in the range of about 3 to 20 cm.
    [0016] The present inventors have managed to provide an improved process for the manufacture of alkylene glycol from an alkene. In particular, the present inventors have managed to provide a process and an absorption system that allows reactive absorption of the gas composition of an alkylene oxide reactor with high selectivity. Invention Summary
    [0017] Accordingly, the present invention provides a process for preparing an alkylene glycol from an alkene comprising the steps of: (a) providing a gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and steam of water to the bottom of an alkylene oxide absorber, said absorber comprising a column of vertically stacked trays, each of the vertically stacked trays comprising a perforated gas-liquid contact member or members, a liquid inlet area , an outlet dam extending vertically above the surface of the tray at the opposite end of the tray from the liquid inlet area and a downpipe member which, in cooperation with the inner surface of the column wall, forms a downpipe for passing liquid downwardly to the liquid inlet region of the vertically adjacent tray directly below, where the tube descends. outlet inlet on each tray is at least 200 mm and maximum 1500 mm high and allows the gas composition to pass upwards through the column; (b) providing a lean absorbent to the top of the alkylene oxide absorber and allowing the lean absorbent to pass down through the column; and (c) intimately contacting the gas composition with poor absorbent on the trays in the alkylene oxide absorber in the presence of one or more catalysts that promote carboxylation and hydrolysis; and (d) removing grease absorber from the alkylene oxide absorber.
    [0018] The present invention also provides an absorber apparatus for the reactive absorption of a gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor comprising a column containing vertically stacked trays, with an inlet for lean liquid absorbent at the top of the column, an inlet for gas composition at the bottom of the column above a sump, a fat absorbent outlet at the bottom of the column and an outlet for unabsorbed gas at the top of the column, where each of the vertically stacked trays comprises a perforated gas-liquid contact member or members, a liquid inlet area, an outlet dam at the opposite end of the tray from the liquid inlet area extending vertically above the surface. of the tray and a down-pipe element which, in cooperation with the inner surface of the column wall, forms a down-pipe for the passage of liquid. descending to the liquid inlet region of the vertically adjacent tray directly below and wherein the output downpipe in each tray is at least 250 mm, preferably at least 350 mm and at most 1500 mm in height. Brief description of the drawings
    [0019] Figure 1 is a schematic diagram showing an exemplary but non-limiting embodiment of the invention. Detailed description of the invention
    [0020] The present invention provides a process and an apparatus for preparing alkylene glycol. Alkylene glycols are generally produced from the corresponding alkylene as specified below:
    R 1 , R 2 , R 3 and R 4 are preferably chosen from hydrogen or an optionally substituted alkyl group having 1 to 6 carbon atoms, more preferably 1 to 3 carbon atoms. As substituents, moieties such as hydroxy groups may be present. Preferably, R 1 , R 2 and R 3 represent hydrogen atoms and R 4 represents hydrogen or an unsubstituted C 1 -C 3 alkyl group and more preferably R 1 , R 2 , R 3 and R 4 all represent hydrogen atoms.
    [0021] Examples of suitable alkylene glycols therefore include ethylene glycol and propylene glycol. In the present invention the most preferred alkylene glycol is ethylene glycol.
    [0022] In the present invention, the gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor is preferably derived from the reactor product of an alkylene oxide reactor, in which an alkene is reacted with oxygen in the presence of a catalyst in a reactor to form alkylene oxide. In such a reaction, oxygen can be supplied as oxygen or as air, but is preferably supplied as oxygen. Ballast gas, eg methane or nitrogen, is typically supplied to allow operation at high levels of oxygen without producing a flammable mixture. Moderator, eg monochloroethane or dichloroethane, can be provided for controlling the performance of the ethylene oxide catalyst. The alkene, oxygen, ballast gas and moderator are preferably supplied to the recycle gas which is supplied to the alkylene oxide reactor of the alkylene oxide absorber (optionally via a carbon dioxide absorption column).
    [0023] The alkylene oxide reactor is typically a fixed bed, multi-tube reactor. The catalyst is preferably finely dispersed silver and optionally promoter metals on a support material, for example alumina. The reaction is preferably carried out at pressures greater than 1 MPa and less than 3 MPa and temperatures greater than 200oC and less than 300oC. The alkylene oxide reactor gas composition is preferably cooled in one or more coolers, preferably with steam generation at one or more temperature levels.
    [0024] A gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor is supplied to an alkylene oxide absorber comprising a column of vertically stacked trays. The trays provide a surface area for the absorbent and gas composition to come into contact, facilitating mass transfer between the two phases. Additionally, trays provide considerable liquid volume in which the liquid phase reaction can take place.
    [0025] Each of the trays vertically stacked in the column comprises a perforated gas-liquid contact member or members, a liquid inlet area, an outlet dam that extends vertically above the surface of the tray at the opposite end of the tray to from the liquid inlet area and a downpipe element. The downpipe element, in cooperation with the inner surface of the column wall, forms a downpipe for the passage of liquid downwardly to the liquid inlet region of the vertically adjacent tray directly below. In embodiments of the invention where the column is of a large size, there may be more than one liquid inlet area, more than one outlet dam and more than one downpipe element per tray. The singular term "a" or "an" has been used throughout this text for clarity. However, in this case, the expression 'a liquid inlet area' refers to one or more liquid inlet areas, the expression 'an outflow dam' refers to one or more outflow dams and the expression 'a downtube element' refers to one or more downtube elements.
    [0026] The reaction rate of the reactive absorption process for the conversion of alkylene oxide to alkylene glycol is relatively low and therefore requires a large liquid retention in the absorption column. The present inventors have found that this can be achieved using exceptionally large exit dams in the process and apparatus of the invention. A feature like this provides a reduced column size and an efficient process and reduces both CAPEX and OPEX while still maintaining high selectivity (>95%) for MEG production.
    [0027] In the present invention, the exit dam in each tray is preferably at least 250 mm, more preferably at least 350 mm, even more preferably at least 400, also even more preferably at least 500, more preferably at least 600 mm of height. The exit dams are at most 1500mm in height, preferably at most 1000mm, more preferably at most 800mm in height.
    [0028] The distance between two consecutive trays in a column is called the plate spacing. The space between the top of the dam and the tray directly above it, termed 'vapor space' here, can be calculated as the plate spacing minus the height of the dam and is preferably at least 150 mm, more preferably at least 200 mm. The vapor space is preferably not more than 1000mm, more preferably not more than 500mm.
    [0029] In all embodiments of the invention, the gas composition is supplied at the base of the column and passes upwards through the trays. The gas composition is preferably supplied below the base tray in the column. Lean absorbent liquid is provided at or near the top of the absorber and the liquid flows down from tray to tray. The lean absorbent is preferably supplied to the upper tray in the absorption column. In another embodiment, the lean absorber is provided such that there are trays above the point at which the lean absorber is provided to the alkylene oxide absorber. In this embodiment, additional cold water or lean absorbent that has been cooled may be provided on top of the alkylene oxide absorber to absorb alkylene oxide or contaminants on top of the alkylene oxide absorber.
    [0030] The number of trays present in the column will depend on the height of the dam and the amount of liquid retention required in the column. Preferably, the column comprises at least 20 trays, more preferably at least 30 trays. Preferably the column comprises less than 100 trays, more preferably less than 70 trays, more preferably less than 50 trays. More trays increase the column's absorption capacity and reaction volume for any given height of the dam, but the addition of additional trays increases the column's size and therefore increases the expense involved in its construction and operation.
    [0031] In a particularly preferred embodiment of the invention, each of the downtubes is provided with one or more openings positioned below the top edge of the downtube and in a position or positions that would be completely below the surface of the poor absorbent in the tray during operation normal. Preferably, openings are present in the base half of each exit dam.
    [0032] Normal operation is defined here as operation in which the trays are filled and at least 90% of the liquid flowing down through the column is drained over the dam rather than through the openings.
    [0033] In the modality in which openings are present in the outlet dams, they are designed in such a way that, during normal operation, less than 10% of the total liquid flow is passing through the openings. Preferably not more than 20%, more preferably not more than 10%, even more preferably not more than 5%, more preferably not more than 2%, of the surface area of each exit dam is taken with one or more openings. In a preferred embodiment of the invention the height of the dam is in the range of about 250 mm, more preferably of 350 mm to 1000 mm and the opening area (in mm2/tray) is in the range of about 10 to 20 times the rate of process flow (in m3/hr).
    [0034] This mode provides the advantage of a smoother starting process. In the start-up process, as liquid (lean absorbent) is fed into the column, it will begin to fill trays starting from the point at which it is fed and flowing downwards. Until each tray is filled past the point where the downpipe element from the tray above reaches below the liquid level in the tray, gas supplied to the column will be able to pass upwards through the column through the empty downpipes, bypassing the liquid. A problem like this will be exacerbated by high dams. The use of openings in the outlet dams allows the column to fill smoothly at startup and reduces the time required to achieve effective column operation.
    [0035] The gas composition is intimately contacted with poor absorbent in the trays in the alkylene oxide absorber in the presence of one or more catalysts that promote carboxylation and hydrolysis. If this occurs in the presence of only one catalyst, then the catalyst must promote carboxylation and hydrolysis. If this occurs in the presence of two or more catalysts, then each catalyst can promote carboxylation or hydrolysis or can promote both reactions (provided that at least one catalyst promotes carboxylation and at least one catalyst promotes hydrolysis). In the preferred embodiment, the gas composition is contacted with poor absorbent in the presence of at least two catalysts including a first catalyst that promotes carboxylation and a second catalyst that promotes hydrolysis.
    [0036] In an embodiment of the invention, one or more catalysts that promote carboxylation and hydrolysis is/are homogeneous, and the poor absorbent comprises one or more catalysts. Homogeneous catalysts that are known to promote carboxylation include alkali metal halides such as potassium iodide and potassium bromide, and halogenated organic phosphonium or ammonium salts such as tributylmethylphosphonium iodide, tetrabutylphosphonium iodide, triphenylmethylphosphonium iodide, triphenylpropylphosphonium bromide, triphenylbenzylphosphonium chloride, tetraethylammonium bromide, tetramethylammonium bromide, benzyltriethylammonium bromide, tetrabutylammonium bromide and tributylmethylammonium iodide. Homogeneous catalysts that are known to promote hydrolysis include basic alkali metal salts such as potassium carbonate, potassium hydroxide and potassium bicarbonate, or alkali metal metalates such as potassium molybdate. Preferred homogeneous catalyst systems include the combination of potassium iodide and potassium carbonate, and the combination of potassium iodide and potassium molybdate.
    [0037] In another embodiment of the invention, one or more catalysts that promote carboxylation and hydrolysis is/are heterogeneous and the heterogeneous catalyst(s) are contained in the vertically stacked trays. Heterogeneous catalysts that promote carboxylation include quaternary ammonium and quaternary phosphonium halides immobilized on silica, quaternary ammonium and quaternary phosphonium halides bound to insoluble polystyrene beads, and metal salts such as zinc salts immobilized on solid supports containing quaternary ammonium or phosphonium groups quaternary, such as ion exchange resins containing quaternary ammonium or quaternary phosphonium groups. Heterogeneous catalysts that promote hydrolysis include metalates immobilized on solid supports, for example, molybdates, vanadates or tungstates mobilized on ion exchange resins containing quaternary ammonium or quaternary phosphonium groups, or basic anions such as bicarbonate ions immobilized on solid supports, for example, bicarbonate immobilized on ion exchange resins containing quaternary ammonium or quaternary phosphonium groups.
    [0038] In the modality in which the gas composition is contacted with poor absorbent in the presence of at least two catalysts including a first catalyst that promotes carboxylation and a second catalyst that promotes hydrolysis, the ratio of the first catalyst to the second catalyst can be adjusted in order to vary the amount of carbon dioxide that is consumed or released into the alkylene oxide absorber. Preferably, the alkylene oxide absorber gases are partially or fully supplied to a carbon dioxide absorption column in which the carbon dioxide is at least partially absorbed by a recirculating absorbent stream. By controlling the amount of carbon dioxide that is consumed or released into the alkylene oxide absorber, the capacity and cost of a carbon dioxide absorber column can be reduced.
    [0039] The lean absorbent comprises at least 5% by weight of water. The water that is present in the lean absorbent is used in the hydrolysis of alkylene oxide and alkylene carbonate which takes place in the alkylene oxide absorber. Preferably, the lean absorbent comprises at least 10% by weight of water, more preferably at least 15% by weight of water, more preferably at least 20% by weight of water. Preferably the lean absorbent comprises less than 80% by weight of water, more preferably not more than 50% by weight of water, even more preferably not more than 30% by weight of water. Higher water levels in the lean absorbent can still provide good catalyst selectivity and performance, but larger amounts of water require additional water removal, with associated energy and equipment costs. The lean absorbent may also comprise alkylene glycol.
    [0040] The temperature in the alkylene oxide absorber is preferably from 50°C to 160°C, preferably from 80°C to 150°C, more preferably from 80 to 120°C. This is higher than the temperature in an absorbent in the conventional process and is required to promote carboxylation and hydrolysis reactions. Temperature greater than 160°C is not preferred as this may reduce the selectivity of the conversion of alkylene oxide to alkylene glycol. Both the gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor and the lean absorbent are preferably supplied to the alkylene oxide absorber at temperatures in the range of 50°C to 160°C.
    [0041] The pressure in the alkylene oxide absorber is 1 to 4 MPa, preferably 2 to 3 MPa. The preferred pressure is a balance between lower pressures that require less expensive equipment (eg, equipment having thinner walls) and higher pressures that increase absorption and reduce the volumetric flow of the gas, thus reducing the size of equipment and piping.
    [0042] At least 50% of the alkylene oxide entering the alkylene oxide absorber is converted to the alkylene oxide absorber. Preferably at least 60%, more preferably at least 70%, even more preferably at least 80%, more preferably at least 90% of the alkylene oxide entering the alkylene oxide absorber is converted to the alkylene oxide absorber. Alkylene oxide can undergo carboxylation, providing alkylene carbonate. Alkylene oxide can undergo hydrolysis to provide alkylene glycol. Additionally, the alkylene carbonate that is produced from the alkylene oxide can undergo hydrolysis, providing the alkylene glycol.
    [0043] Preferably, in the present invention, the alkylene absorbent forms part of a reaction system and process for the production, isolation and purification of alkylene glycol from alkylene by means of the corresponding alkylene oxide such as those described in EP 2178815 and the like. It will be easily understood that the absorbent will be integrated into such a system which will contain a number of reactor vessels, columns and recycle streams.
    [0044] The gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor that is supplied to the alkylene oxide absorber comprises carbon dioxide. It is possible that the gas composition may contain insufficient carbon dioxide to obtain desired levels of carboxylation. An additional source of carbon dioxide is preferably provided to the alkylene oxide absorber, e.g. carbon dioxide from a finishing reactor recycle, carbon dioxide from a carbon dioxide recovery unit or, at startup, dioxide of carbon from an external source. The ratio of the total amount of carbon dioxide supplied to the alkylene oxide absorber to the amount of alkylene oxide supplied to the alkylene oxide absorber is preferably between 5:1 and 1:3, more preferably between 3:1 and 4:5. A greater amount of carbon dioxide improves the selectivity of the process because most of the alkylene oxide reacts with carbon dioxide with alkylene carbonate, which is subsequently hydrolyzed to alkylene glycol, and there is less opportunity for reaction between alkylene oxide and alkylene glycol to produce higher glycols. However, the increased amount of carbon dioxide may also require additional removal capacity for carbon dioxide in the process and may also lead to a higher level of by-product formation. Alternatively, operation of an alkylene oxide reactor connected with a stream of recycled gas containing excess carbon dioxide can adversely affect catalyst performance.
    [0045] Gases which are not absorbed in the alkylene oxide absorber are preferably partially or totally supplied to a carbon dioxide absorption column in which the carbon dioxide is at least partially absorbed by a recirculating absorbent stream. Gases that are not absorbed by the recirculating absorbent stream are preferably recombined with any gases that bypass the carbon dioxide absorption column and are recycled to the alkylene oxide reactor. Preferably, the gases are cooled prior to recycling to the alkylene oxide reactor in order to reduce the water content. Water removed from the gas stream can optionally be recirculated to the alkylene oxide absorber.
    [0046] The performance of the catalyst in the alkylene oxide reactor can be detrimentally affected by an excess of water.
    [0047] If one or more catalysts that promote carboxylation and hydrolysis include a halogen-containing catalyst (for example, an alkali metal halide, an organic halogenated phosphonium or ammonium salt or a quaternary ammonium or quaternary phosphonium halide immobilized on a solid support ), then gases that are recycled from the alkylene oxide absorber to the alkylene oxide reactor can comprise halide-containing impurities such as iodide-containing impurities or bromide-containing impurities. It is possible that the catalyst in the alkylene oxide reactor could be detrimentally affected by these impurities. Therefore, in this embodiment, it is preferred that gases that are recycled by the alkylene oxide absorber in the alkylene oxide reactor are contacted with one or more purification adsorbents capable of reducing the amount of halide-containing impurities (especially impurities containing iodide or bromide-containing impurities) before contacting the catalyst in the alkylene oxide reactor. One or more purification adsorbents may be located within the reactor tubes of the alkylene oxide reactor, within the alkylene oxide reactor upstream of the reactor tubes, or separately upstream of the alkylene oxide reactor.
    [0048] Fat absorber is withdrawn from the alkylene oxide absorber, preferably drawing liquid from the base of the alkylene oxide absorber, i.e. below the vertically stacked trays.
    [0049] In one embodiment of the invention, a portion or all of the fat absorbent from step (d) is subsequently supplied to one or more finishing reactors. Such finishing reactors may include reactors suitable for carboxylation and/or reactors suitable for hydrolysis and/or reactors suitable for hydrolysis and carboxylation. Supply to one or more finishing reactors is preferred if a significant amount (eg, at least 1%) of alkylene oxide or alkylene carbonate is not converted to alkylene glycol in the alkylene oxide absorber. Conversely, if the majority (eg greater than 90%) of alkylene oxide and alkylene carbonate is converted to alkylene glycol in the alkylene oxide absorber, then one or more finishing reactors may not be required and the equipment used in the process it is thereby reduced. To maximize the conversion of alkylene oxide into the alkylene oxide absorber, spray nozzles can be employed in the sump (bottom section) of the alkylene oxide absorber to disperse carbon dioxide and promote carboxylation. Optionally, steam can be injected into a finishing reactor suitable for hydrolysis.
    [0050] Carbon dioxide can be produced in one or more finishing reactors and is preferably separated from the product stream as it leaves one or more finishing reactors and is optionally recycled to the reactive absorbent.
    [0051] The temperature in one or more finishing reactors is typically 100 to 200°C, preferably 100 to 180°C. The pressure in one or more finishing reactors is typically 0.1 to 3MPa.
    [0052] The grease absorbent of step (d) or the product stream from at least one of one or more finishing reactors is optionally supplied to a cleaning vessel or in a light remover. Lights are removed in the cleaning vessel or light remover. (Light are gases such as alkene, and also ballast gases such as methane, which are present in the gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor and are absorbed into the absorbent in step (c )).
    [0053] A cleaning vessel may be located directly after the alkylene oxide absorber so that the grease absorber passes directly from step (d) to the cleaning vessel. When there is at least one finishing reactor, the cleaning vessel can be located after all of one or more finishing reactors so that the product stream passes from said finishing reactors to the cleaning vessel. When there is more than one finishing reactor, a cleaning vessel may be located between the finishing reactors in such a way that the grease absorber passes from step (d) to at least one finishing reactor, then the product stream passes to the cleaning vessel and then the stream from the cleaning vessel passes to at least one other finishing reactor.
    [0054] Cleaning can be at pressure from 0.01 to 2 MPa, preferably from 0.1 to 1 MPa, more preferably from 0.1 to 0.5 MPa.
    [0055] Fat absorber from step (d) or the product stream from finishing reactors or other product stream comprising alkylene glycol is supplied in a dehydrator. The stream that is supplied to the dehydrator preferably comprises very little alkylene oxide or alkylene carbonate, i.e. most of the alkylene oxide or alkylene carbonate has been converted to alkylene glycol prior to supply to the dehydrator column, either in the oxide absorber of alkylene or in a finishing reactor. Preferably, the molar ratio of alkylene glycol to alkylene oxide and alkylene carbonate (combined) in the stream supplied to the dehydrator column is greater than 90:10, more preferably greater than 95:5, more preferably greater than 99: 1.
    The dehydrator preferably has one or more columns, including at least one vacuum column, preferably operating at a pressure of less than 0.05MPa, more preferably less than 0.025MPa and most preferably about 0.0125MPa.
    The dehydrated product stream is purified to remove impurities and provide a purified alkylene glycol product stream. If one or more catalysts are homogeneous catalysts, it will be necessary to separate one or more catalysts from the dehydrated product stream, preferably in a cleaning vessel. One or more homogeneous catalysts are preferably recombined with the lean absorbent and supplied to the alkylene oxide absorber. Detailed description of drawings
    [0058] Figure 1 illustrates an embodiment of the present invention. It shows section 1 of an absorption column. It should be noted that a small number of trays are illustrated in this figure and that the top of the upper tray and the base of the lower tray are not shown.
    [0059] The column consists of a number of vertically stacked trays 2. Each tray 2 comprises a perforated gas-liquid contact member 3, a liquid inlet area 4 and an outlet dam 5 which extends vertically above the surface of the tray 2 at the opposite end of the liquid inlet area.
    [0060] A down tube element 6 extends below each tray and, in cooperation with the inner surface of the column wall, forms a down tube 7 for the passage of liquid downwardly to the liquid inlet region directly below .
    [0061] In operation, the gas composition (illustrated by arrows 8) moves upwards through the pierced gas-liquid contact members. Liquid 9 fills the trays and passes over the outlet dams 5 as illustrated by arrows 10.
    [0062] Apertures (11) may be provided in each outlet dam below the upper edge of said downpipe.
    权利要求:
    Claims (9)
    [0001]
    1. Process for preparing an alkylene glycol from an alkene, characterized in that it comprises the steps of: (a) providing a gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor for the bottom of an alkylene oxide absorber, the absorber comprising a column of vertically stacked trays, each of the vertically stacked trays comprising a perforated gas-liquid contact member or members, a liquid inlet area, a dam of outlet extending vertically above the surface of the tray at the opposite end of the tray from the liquid inlet area and a down-tube element which, in cooperation with the inner surface of the column wall, forms a down-tube for the passage of liquid descending to the liquid inlet region of the vertically adjacent tray directly below, where each of the outlet dams is provided. with one or more openings positioned below the top edge of the downpipe, and wherein the outlet dam in each tray is at least 200 mm and at most 1500 mm high and allows the gas composition to pass upwardly through the column; (b) supplying lean absorbent to the top of the alkylene oxide absorber and allowing the lean absorbent to pass down through the column; (c) intimately contacting the gas composition with poor absorbent on the trays in the alkylene oxide absorber in the presence of one or more catalysts that promote carboxylation and hydrolysis; and, (d) removing grease absorber from the alkylene oxide absorber.
    [0002]
    2. Process according to claim 1, characterized in that the exit dam in each tray is at least 250 mm, preferably at least 350 mm and at most 1000 mm high.
    [0003]
    3. Process according to any one of claims 1 or 2, characterized in that the one or more catalysts that promote carboxylation and hydrolysis are selected from alkali metal halides, alkali metal salts and combinations thereof.
    [0004]
    4. Process according to any one of claims 1 to 3, characterized in that the poor absorbent comprises at least 5% by weight and less than 80% by weight of water.
    [0005]
    5. Absorber apparatus for the reactive absorption of a gas composition comprising alkylene oxide, alkene, oxygen, carbon dioxide and water vapor, characterized in that it comprises a column containing vertically stacked trays, with an inlet for lean absorbent of liquid at the top of the column, an inlet for the gas composition at the bottom of the column above a sump, an outlet for fat absorbent at the bottom of the column and an outlet for unabsorbed gas at the top of the column, each of the vertically stacked trays comprises a perforated gas-liquid contact member or members, a liquid inlet area, an outlet dam at the opposite end of the tray from the liquid inlet area which extends vertically above the surface of the tray and a down-pipe element which, in cooperation with the inner surface of the column wall, forms a down-pipe for the downward passage of liquid. and to the liquid inlet region of the vertically adjacent tray directly below, wherein each of the output dams is provided with one or more openings positioned below the upper edge of the output dam, and wherein the output dam in each tray it is at least 250 mm and at most 1500 mm high.
    [0006]
    6. Absorber according to claim 5, characterized in that the output dam in each tray is at least 350 mm and at most 1000 mm high.
    [0007]
    7. Absorber according to any one of claims 5 or 6, characterized in that the openings are designed so that during normal operation less than 10% of the total liquid flow is passing through the openings.
    [0008]
    8. Absorber according to any one of claims 5 to 7, characterized in that not more than 5% of the surface area of each outgoing downpipe is fitted with one or more openings.
    [0009]
    9. Absorber according to any one of claims 5 to 8, characterized by the fact that one or more openings are present in the bottom half of each outlet downpipe.
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    法律状态:
    2019-09-10| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2021-05-18| B09A| Decision: intention to grant [chapter 9.1 patent gazette]|
    2021-08-03| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 21/09/2015, OBSERVADAS AS CONDICOES LEGAIS. |
    2021-08-03| B350| Update of information on the portal [chapter 15.35 patent gazette]|
    优先权:
    申请号 | 申请日 | 专利标题
    EP14186273|2014-09-24|
    EP14186273.0|2014-09-24|
    PCT/EP2015/071534|WO2016046100A1|2014-09-24|2015-09-21|Process and apparatus for the preparation of alkylene glycol|
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