Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/14—Fractional distillation or use of a fractionation or rectification column
  • B01D3/141—Fractional distillation or use of a fractionation or rectification column where at least one distillation column contains at least one dividing wall
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/34—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping with one or more auxiliary substances
  • B01D3/36—Azeotropic distillation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
  • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
  • C07C29/80—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by distillation
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
  • C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
  • C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
  • C07C29/86—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment by liquid-liquid treatment
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C68/00—Preparation of esters of carbonic or haloformic acids
  • C07C68/06—Preparation of esters of carbonic or haloformic acids from organic carbonates
  • C07C68/065—Preparation of esters of carbonic or haloformic acids from organic carbonates from alkylene carbonates
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C68/00—Preparation of esters of carbonic or haloformic acids
  • C07C68/08—Purification; Separation; Stabilisation
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/10—Process efficiency
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• the invention relates to a process for obtaining a dialkyl carbonate and an alkylene glycol from a dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream.
• the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing stream is usually formed in the production of dialkyl carbonate as the main product and alkylene glycol as a by-product by transesterification of a cyclic alkylene carbonate with alcohols in the presence of a catalyst.
• the preparation of dialkyl carbonate from cyclic alkylene carbonate and alcohol, which simultaneously produces alkylene glycol as a by-product, is known and has been described many times.
• the synthesis is a reversible equilibrium reaction in which the product mixture of dialkyl carbonate and alkylene glycol also always contains portions of unreacted alkylene carbonate and alcohol.
• the transesterification reaction in a reactor followed by purification of the products in several distillation columns is e.g. in WO-A 201 1/058168. In the transesterification reaction described here, it is only possible to achieve the equilibrium possible conversion. Unreacted starting materials must be separated as pure as possible from the products, since recycled product in the transesterification reaction adversely affects the balance and reduces productivity.
• a favorable influence on the residence time in the reactive distillation column can be, for example, by suitable length / diameter ratios as described in US-A 2009/030223 or by certain distance ratios between feed point of the alcohol and the alcohol and dialkyl carbonate-containing mixture as recycled power from the workup, as described in DE-A 10 2009 030 680 achieve.
• the disadvantage is that in the over Head withdrawn dialkyl carbonate containing low boiler mixture is also included unreacted alcohol and that the alkylene glycol taken from the sump additionally contains unreacted alkylene carbonate. The purification of the dialkyl carbonate takes place in these cases in at least one further distillation column.
• the high-boiling mixture containing alkylene carbonate and a water stream are passed together continuously into a hydrolysis reactor and the resulting alkylene glycol is taken off continuously.
• the alkylene carbonate is decomposed to alkylene glycol and carbon dioxide.
• JP-A 2006/023065 To carry out a multi-stage purification in which the bottom stream containing alkylene glycol and alkylene carbonate is distilled in a further column and the alkylene glycol is obtained from a side draw.
• the object of the present invention is therefore to provide a continuous process for the preparation of dialkyl carbonates which does not have the disadvantages known from the prior art and in which the products and unreacted starting materials can be separated in an energetically favorable manner and with less expenditure on equipment.
• the object is achieved by a process for obtaining a dialkyl carbonate and an alkylene glycol from a dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream, which comprises the following steps:
• essentially the first crude product stream containing dialkyl carbonate means that the proportion of dialkyl carbonate in this stream is at least 70% by weight, preferably at least 90% by weight and in particular at least 95% by weight.
• the first crude product stream generally still contains residues of alkylene glycol.
• Essentially containing alkylene glycol second crude product stream means that this crude product stream contains at least 70 wt .-% alkylene glycol, more preferably at least 90 wt .-% alkylene glycol and in particular at least 95 wt .-% alkylene glycol.
• the second crude product stream generally still contains residues of dialkyl carbonate.
• the preparation of the dialkyl carbonate it is necessary for the preparation of the dialkyl carbonate to use an alcohol which forms a dialkyl carbonate by the transesterification of the alkylene carbonate which together with the resulting alkylene glycol forms a heteroazeotrope.
• the formation of the hetero-azeotrope makes possible a separation in a device for phase separation without expenditure of energy.
• the alcohol used does not form an azeotrope with the dialkyl carbonate formed in the reaction.
• the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material Ström from which the dialkyl carbonate and alkylene glycol containing heteroazeotrope stream is removed by distillation, comes from a transesterification reaction in which the alkylene carbonate is transesterified with the alcohol to dialkyl carbonate.
• the alkylene glycol is obtained as a by-product.
• the transesterification is generally carried out homogeneously or heterogeneously catalyzed. In a homogeneous catalysis, the catalyst is also contained in the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream.
• Suitable catalysts are known to the person skilled in the art and are described, for example, in DE-A 10 2009 053 370, EP-A 1 961 721 and WO-A 201 1/058168.
• the homogeneous catalyst is, for example, an alkali metal, an alkali metal salt of an organic acid such as acetic acid, propionic acid, butyric acid, benzoic acid, stearic acid, a hydride, oxide, hydroxide, alcoholate, amide, carbonate or dicarbonate of an alkali metal or an alkali metal salt, which consists of an inorganic Acid, for example, hydrochloric acid, bromine-hydrogen or iodine-hydrogen acid, nitric acid, sulfuric acid, fluorine-hydrogen acid, phosphoric acid, hydrocyanic acid, hydrocyanic acid or rodane-derived hydrofluoric acid.
• an organic acid such as acetic acid, propionic acid, butyric acid, benzoic acid,
• the amount of homogeneous catalyst is usually less than 10 wt .-%, generally in the range of 0.0001 to 5 wt .-% and in particular in the range of 0.001 to 2 wt .-%, each based on the amount of reaction mixture , In principle, it is also possible to carry out the transesterification catalyzed heterogeneously.
• the catalysis can be carried out both in an upstream reactor and in the first distillation stage.
• Suitable heterogeneous catalysts are, for example, ion exchange resins having functional groups of tertiary amines, quaternary ammonium groups, chloride, hydrogen sulfate or hydroxide being mentioned, for example, as counterions, ammonium-exchanged zeolites or alkali metal or alkaline earth metal silicates impregnated on silica supports.
• the reaction can be carried out either in a separate reactor, wherein the reactor alkylene carbonate and alcohol and catalyst are fed and the transesterification is carried out in the reactor.
• the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream are then taken from the reactor and fed to the first distillation stage in step (a).
• the first distillation stage in step (a) comprises a reactive distillation to which alkylene carbonate and alcohol are added as starting materials, which are reacted in an equilibrium reaction to dialkyl carbonate and alkylene glycol, wherein the dialkyl carbonate, alkylene carbonate, alkylene glycol and monoalcohol containing stream is generated.
• the reactive distillation column the alkylene glycol and dialkyl carbonate are then separated off directly from this material stream as a heteroazeotrope-containing material stream.
• the first distillation stage comprises a dividing wall column in which the material stream containing dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol is passed into an alcohol-containing overhead stream, a homoazeotrope-forming alkyl carbonate and alkylene glycol-containing material stream as bottom stream and the dialkyl carbonate and alkylene glycol as heteroazeotrope-containing material stream, which is withdrawn as a side stream, is separated.
• the alcohol-containing top stream can be recycled directly to the reactor or into the reactive distillation column as starting material.
• the bottom stream generally additionally contains the catalyst used for the transesterification.
• the dialkyl carbonate and alkylene glycol as a heteroazeotrope-containing stream, which is removed via a side draw from the dividing wall column, is free of catalyst.
• the first distillation stage comprises two distillation columns, wherein in a first distillation column of the di-Ikylcarbonat, alkylene carbonate, alkylene glycol and alcohol-containing stream contained in a dialkyl carbonate, alkylene glycol and alcohol-containing overhead stream and a homoazeotrope-forming alkylene carbonate and alkylene glycol Sumpfstrom is separated.
• a second distillation column the dialkyl carbonate, alkylene glycol and alcohol-containing top stream of the first distillation column is separated into a top stream containing the alcohol and the dialkyl carbonate and alkylene glycol as the heteroazeotrope-containing stream as the bottom stream.
• the dialkyl carbonate and alkylene glycol as heteroazeotrope-containing material stream obtained as side draw of the dividing wall column or as bottom stream of the second distillation column are then fed to the separation in a device for phase separation in step (b).
• the homoazeotrophic alkylene carbonate and alkylene glycol-containing material stream obtained in the first distillation stage and obtained either as the bottom stream of the dividing wall column or as the bottom stream of the first distillation column is fed to a second distillation stage.
• a portion of the dialkyl carbonate-containing first crude product stream from step (b) is fed as entraining agent.
• the second distillation stage is then taken from a bottom stream containing alkylene carbonate and an overhead stream containing dialkyl carbonate and alkylene glycol.
• the bottom stream containing the alkylene carbonate can then also be recycled as starting material into the transesterification. If the transesterification is carried out homogeneously catalysed, the homoazeotrope-forming alkylene carbonate and alkylene glycol-containing stream fed to the second distillation stage additionally contains the catalyst. This also falls to the bottom of the second distillation stage and can be recycled together with the alkylene carbonate in the transesterification.
• the dialkyl carbonate and alkylene glycol-containing overhead stream is fed to the phase separation apparatus in step (b) to recover dialkyl carbonate and the alkylene glycol as products. By doing so, the unreacted alkylene carbonate is recycled to the transesterification without loss.
• the dividing wall column is preferably at a pressure in the range of 0.01 to 0.5 bar, preferably in the range of 0.02 to 0.2 bar and in particular in the range of 0.03 operated to 0.1 bar.
• the temperature at the bottom of the dividing wall column is preferably in the range from 120 to 200 ° C., more preferably in the range from 130 to 190 ° C. and in particular in the range from 140 to 180 ° C. and the temperature at the top of the dividing wall column in the range from 10 to 100 ° C, more preferably in the range of 20 to 80 ° C and in particular in the range of 25 to 60 ° C.
• the preceding and following listed pressure data are absolute pressure specifications.
• the first distillation column is preferably at a pressure in the range of 0.01 to 0.5 bar, more preferably in the range of 0.01 to 0.1 bar and in particular in the range of 0 , 01 to 0.05 bar operated, wherein the sump temperature preferably in the range of 120 to 200 ° C, more preferably in the range of 130 to 190 ° C and in particular in the range of 150 to 185 ° C and the head temperature in the range of 20 to 100 ° C, more preferably in the range of 30 to 80 ° C and in particular in the range of 40 to 70 ° C.
• the pressure of the second distillation column is preferably at a pressure in the range of 0.05 to 0.5 bar, more preferably in the range of 0.1 to 0.3 bar and in particular in the range of 0.1 to 0.2 bar.
• the temperature at the bottom of the second distillation column is preferably in the range of 80 to 200 ° C, more preferably in the range of 100 to 150 ° C and in particular in the range of 1 10 to 130 ° C and the temperature at the top of the second distillation column in the range of 10 to 100 ° C, more preferably in the range of 20 to 80 ° C and especially in the range of 25 to 70 ° C.
• the second distillation stage in which the homoazeotrope of alkylene carbonate and alkylene glycol is separated in the presence of the dialkyl carbonate as entraining agent, is preferably at a pressure in the range from 0.01 to 0.5 bar, more preferably in the range from 0.02 to 0 , 2 bar and in particular operated in the range of 0.05 to 0.1 bar, wherein the bottom temperature preferably in the range of 100 to 200 ° C, more preferably in the range of 130 to 190 ° C and in particular in the range of 140 to 180 ° C and the head temperature in the range of 50 to 150 ° C, more preferably in the range of 80 to 120 ° C and in particular in the range of 90 to 1 10 ° C.
• the first distillation stage comprises a dividing wall column in which the material stream containing dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol is separated into a bottom stream containing alkylene carbonate, an overhead stream containing alcohol and the stream of dialkyl carbonate and alkylene glycol withdrawn as a side stream.
• the first distillation stage in this case comprises a first distillation column in which the stream comprising dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol is separated into a bottom stream containing alkylene carbonate and a top stream containing dialkyl carbonate, alcohol and alkylene glycol, and a second distillation column in which the dialkyl carbonate , Alcohol and alkylene glycol-containing top stream of the first distillation column into an alcohol-containing overhead stream and the dialkyl carbonate and alkylene glycol as a heteroazeotrope-containing material stream is separated as the bottom stream.
• the first distillation stage is additionally admixed with a portion of the dialkyl carbonate-containing first crude product stream from step (b) as entrainer.
• the homoazeotrope is broken up from alkylene carbonate and alkylene glycol, so that the alkylene carbonate can be separated off without alkylene glycol and can be recycled to the reaction. This avoids that in the reaction recycled alkylene glycol adversely affects the equilibrium.
• the alkylene oxide-containing overhead stream is free of alkylene carbonate and no alkylene carbonate passes into the downstream process stages.
• step (b) When a portion of the dialkyl carbonate-containing first crude product stream from step (b) is added as an entraining agent to the first distillation stage, it is possible to mix the portion of the dialkyl carbonate-containing first crude product stream with the feed to the first distillation stage.
• the first crude product stream containing essentially dialkyl carbonate which is removed from the apparatus for phase separation in step (b), is subjected to a distillative treatment in the first crude product stream comprising essentially dialkyl carbonate the still contained alkylene glycol is separated.
• the alkylene glycol separated from the first crude product stream containing essentially the dialkyl carbonate generally still contains dialkyl carbonate and is therefore preferably recycled to the apparatus for phase separation in step (b). This makes it possible to still win the separated in the distillation dialkyl carbonate as a product.
• the distillation step for separating the alkylene glycol from the first crude product stream containing essentially dialkyl carbonate is preferably carried out at a pressure in the range from 0.05 to 1 bar, more preferably at a pressure in the range from 0.09 to 0.5 bar and in particular at one pressure carried out in the range of 0.1 to 0.2 bar.
• the head temperature is preferably in the range of 10 to 150 ° C, more preferably in the range of 50 to 145 ° C and especially in the range of 90 to 140 ° C and the bottom temperature in the range of 80 to 200 ° C, more preferably in the range of 90 to 160 ° C and in particular in the range of 95 to 140 ° C.
• the second crude product stream comprising essentially alkylene glycol is preferably also fed to a distillative treatment in which the dialkyl carbonate still present is separated from the crude product stream comprising essentially alkylene glycol becomes.
• the dialkyl carbonate is generally separated in the form of an azeotrope with alkylene glycol contained therein, it is preferred to recycle the separated dialkyl carbonate into the phase separation apparatus in step (b). This makes it possible to also recover the separated in the distillation alkylene glycol as a product.
• the distillation for the treatment of the second crude product stream containing essentially alkylene glycol is preferably carried out at a pressure in the range from 0.05 to 1 bar, more preferably at a pressure in the range from 0.09 to 0.3 bar and in particular at a pressure in the Range operated from 0.1 to 0.2 bar.
• the bottom temperature is preferably in the range of 80 to 200 ° C, more preferably in the range of 90 to 180 ° C and in particular in the range of 1 10 to 150 ° C.
• the top temperature is preferably in the range from 20 to 180.degree. C., more preferably in the range from 50 to 170.degree. C. and in particular in the range from 80 to 160.degree.
• phase separation apparatus in step (b) may be any suitable liquid phase separator known to those skilled in the art, for example, as mentioned in Perry's Chemical Engineers' Handbook, seventh edition, 1998, pp. 15-26 to 15-27, Gravity Settiers, Decanters, and Liquid Extraction, second edition, McGraw-Hill Book Company 1963, pp. 440-450.
• the device for phase separation is preferably at a pressure in the range of 1 to 5 bar, more preferably in the range of 1 to 3 bar and in particular in the range of 1 to 2 bar and at a temperature in the range of 1 to 90 ° C, more - operated in the range of 1 to 50 ° C and in particular in the range of 5 to 40 ° C.
• the process according to the invention can be carried out continuously or batchwise. It is preferred to operate the process continuously. For this purpose, it is particularly necessary to use a device for phase separation, which can be operated continuously.
• Suitable alcohols for the process according to the invention are those of the general formula (I)
• R is linear or branched C 2 -C 8 alkyl.
• R is linear or branched C 3 -C 8 -alkyl which is unsubstituted or substituted by 1 methoxy substituent, in particular C 3 -C 6 -alkyl which is unsubstituted or substituted by 1 methoxy substituent.
• R is branched C 2 -C 8 -alkyl
• the branching is preferably in the ⁇ - and / or ⁇ -position, in particular in the ⁇ -position.
• RC is C 3 -C 8 alkynyl, it is preferably propargyl.
• R is C 3 -C 8 cycloalkyl, it is preferably cyclopentyl, cyclohexyl or cycloheptyl, in particular cyclopentyl or cyclohexyl.
• R is linear C 3 -C 6 -alkyl containing one oxygen atom in the ⁇ -position.
• R is substituted, preferably the ⁇ - and / or ⁇ -position, in particular the ⁇ -position, is substituted.
• R When R is substituted with substituents selected from the group halogen, it is preferably substituted with 1-8 fluoro or 1-3 chloro substituents.
• R When R is substituted with substituents from the group dC 4 -alkyl, it is preferably substituted by methyl or ethyl substituents, in particular methyl substituents.
• R When R is substituted with substituents from the group dC 4 -alkoxy, it is preferably substituted with 1 methoxy or ethoxy substituent.
• Suitable alcohols are, for example, 2,2,2-trifluoroethanol, 1,1,2,2-tetrafluoroethanol, 1,1,1,2,2,2-pentafluoroethanol, 1,1,1-trifluoro-2-propanol, 1,1 Dimethyl-1-ethanol, 2-propanol, 2,2,3,3,4,4,4-heptafluoro-1-butanol, 2,2,3,3,3-pentafluoro-1-propanol, 1-propanol , 2-butanol, 1, 1-dimethyl-1-propanol, iso-butanol, 3-methyl-2-butanol, 2-propyn-1-ol, 2,2-dimethyl-1-propanol, 3-pentanol, 1 Butanol, 2,3-dimethyl-2-butanol,
• Preferred alcohols are 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, isobutanol, 2-methyl-1-butanol, 3-methyl-1-butanol, or 2-methoxyethanol and particularly preferred are 1-propanol, 1 Butanol, 1-pentanol, isobutanol or 3-methyl-1-butanol.
• Alkylene carbonates which are suitable for the process according to the invention are alkylene carbonates of the general formula (II)
• alkylene carbonates are ethylene carbonate and propylene carbonate.
• the ring structure of the alkylene carbonate is broken up and the radicals R 1 and R 2 of the alkylene carbonate are each substituted by the radical R of the alcohol used. It is also possible to use a mixture of several alcohols, so that the radicals R 1 and R 2 are substituted by different radicals of the alcohols.
• the dialkyl carbonates formed in the transesterification are generally those of the general formula (III),
• R is the same or different and corresponds to the above definition of the radical R of the alcohol of formula (I).
• R is the same.
• the carbonates can be symmetrical or asymmetrical.
• the carbonates mentioned are a selection of the possible combinations of different alcohols.
• Dialkylcarbonates which can be prepared in the transesterification reaction are, for example, di- (2,2,2-trifluoroethyl) carbonate, di (1,1,2,2-tetrafluoroethyl) carbonate, di (1,1,2,2,2 Pentafluoroethyl) carbonate, di (1,1,1-trifluoro-2-propyl) carbonate, di-1, 1-dimethyl-1-ethyl carbonate, di-2-propyl carbonate, di- (2,2,3, 3,4,4,4-heptafluoro-1-butyl) carbonate, di (2,2,3,3,3-pentafluoro-1-propyl) carbonate, di-1-propyl carbonate, di-2-butyl carbonate, Di-1, 1-dimethyl-1-propyl carbonate, diisobutyl carbonate, di (3-methyl-2-butyl) carbonate, di (2-propyn-1-ol) carbonate, di (2,2-dimethyl 1-propyl
• Preferred dialkyl carbonates are di-1-propyl carbonate, di-1-butyl carbonate, di-1-pentyl carbonate, di-1-hexyl carbonate, diisobutyl carbonate, di-2-methyl-1-butyl carbonate, di-3-methylbutyl carbonate or di-2-methoxyethyl carbonate ,
• the dialkyl carbonate is particularly preferably di-1-propyl carbonate, di-1-butyl carbonate, di-1-pentyl carbonate, diisobutyl carbonate, di-3-methyl-1-butyl carbonate or di-2-methoxyethyl carbonate.
• radicals R 1 and R 2 are the same as described above for the alkylene carbonates.
• a dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing stream When the process, a dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing stream is supplied, it generally contains 0.5 to 70 wt .-% of dialkyl carbonate, 1 to 50 wt .-% of alkylene carbonate, 1 to 40 wt .-% of alkylene glycol and 10 to 95 wt .-% alcohol. More preferably, the stream contains 1 to 50 weight percent dialkyl carbonate, 2 to 30 weight percent alkylene carbonate, 2 to 30 weight percent alkylene glycol, and 20 to 90 weight percent alcohol. In particular, the stream contains 5 to 40% by weight of dialkyl carbonate, 5 to 30% by weight of alkylene carbonate, 2 to 15% by weight of alkylene glycol and 40 to 80% by weight of alcohol.
• the stream in particular in the case of a homogeneous catalyzed transesterification reaction, may contain less than 10% by weight, more preferably from 5 to 0.0001% by weight and in particular from 2 to 0.001% by weight of catalyst.
• FIG. 1 shows a flow chart of the method according to the invention in a first
• FIG. 2 is a flowchart of the method according to the invention in a second
• FIG. 1 shows a flow chart of the method according to the invention of a first embodiment.
• a dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream to be treated is fed to a first distillation stage.
• the first distillation stage comprises a dividing wall column 1.
• the feed of the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing material stream is designed as side feed 3 to dividing wall column 1.
• a dialkyl carbonate and alkylene glycol is by distillation Separated heteroazeotrope containing stream. This is removed via a side trigger 5.
• an alcohol-containing overhead stream 7 is obtained.
• a material stream containing homoazeotrophic alkylene carbonate and alkylene glycol is taken off as the bottom stream 9.
• the homo-azeotrope-forming alkylene carbonate and alkylene glycol-containing stream taken off as bottom stream 9 are fed to a second distillation stage 11.
• the second distillation stage 1 1 comprises a distillation column.
• the stream comprising alkylene carbonate and alkylene glycol is separated into a bottom stream 13 containing an alkylene carbonate and an overhead stream 15 containing alkylene glycol and dialkyl carbonate.
• the second distillation stage 1 1 is additionally fed dialkyl carbonate.
• the feed takes place in the embodiment shown here via a side inlet 17 above the inlet 9 of the mixture of alkylene glycol and alkylene carbonate.
• the obtained at the bottom of the second distillation stage 1 1 alkylene carbonate is recycled as well as the top of the Trennwandkolonnel resulting alcohol in a reactor 19 in which react the alkylene carbonate and the alcohol in a transesterification reaction to dialkyl carbonate and alkylene glycol.
• the reaction is an equilibrium reaction, so that the material containing the dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol, which is recycled to the dividing wall column 1, is taken from the reactor 19.
• Alcohol converted in the reaction is fed to the reactor 19 via a first feed 21 and reacted alkylene carbonate via a second feed 23.
• the alcohol can, as shown in FIG. 1, be fed into the reflux of the overhead stream 7 and the alkylene carbonate into the reflux of the alkylene carbonate from the second distillation stage 1 1. It is also possible to feed the individual streams separately into the reactor , However, it is preferred to mix all the streams fed into the reactor 19 in a mixing point and to introduce them together into the reactor 19. The mixture can be done simply by opening pipes into a central supply line into the reactor 19.
• the material stream taken off as a side draw 5 from the dividing wall column 1 and containing dialkyl carbonate and alkylene carbonate in the form of the heteroazeotrope is fed to a device for phase separation 25.
• a device for phase separation 25 for example, a settler can be used.
• the heteroazeotrope of dialkyl carbonate and alkylene glycol is separated into a first crude product stream 27 containing substantially dialkyl carbonate and a second crude product stream 29 containing substantially alkylene glycol.
• a portion of the first crude product stream 27 containing essentially dialkyl carbonate is branched off and passed via the inlet for dialkyl carbonate 17 into the second distillation stage 11.
• the first crude product stream 27 containing essentially dialkyl carbonate is passed into a distillation column 31 for further processing.
• the alkylene glycol separated off in the distillation column 31 is contained as an impurity in the first crude product stream 27 containing essentially dialkyl carbonate.
• the substantially crude alkylene glycol-containing second crude product stream 29 also contains dialkyl carbonate as an impurity, it is likewise fed to a distillation column 35.
• a distillation column 35 In the distillation column 35, an alkylene glycol-containing product stream 37 is separated and a substantially dialkyl carbonate-containing stream is recycled to the apparatus for phase separation 25.
• the recycle streams from the distillation columns 31, 35 can also be further mixed with the separated from the dividing wall column 1 dialkyl carbonate and alkylene glycol as a heteroaze otropic containing stream.
• the apparatus for phase separation 25 Also recirculated to the apparatus for phase separation 25 is the top of the second distillation stage 1 1 withdrawn alkylene glycol and dialkyl carbonate overhead stream.
• the material streams supplied in each case to the apparatus for phase separation 25 can be mixed before the feed line or fed as separate feeds. It is also possible to mix individual material streams and provide several feeds.
• the first distillation stage is designed in the form of a dividing wall column 1
• the first distillation column of the dialkyl carbonate, alkylene glycol, alkylene carbonate and alcohol-containing material stream is fed and separated into a dialkyl carbonate, alkylene glycol and alcohol containing overhead stream and a Homoazeotrop forming alkylene carbonate and alkylene glycol-containing bottom stream, wherein the Homoazeotrop forming alkylene carbonate and alkylene glycol-containing bottom stream of the second Stage 1 1 is supplied.
• the dialkyl carbonate, alkylene glycol and alcohol-containing top stream is passed into a second distillation column of the first distillation stage, in which this in the apparatus for phase separation 25 supplied dialkyl carbonate and alkylene glycol as a heteroazeotrope-containing material stream as the bottom stream and an alcohol-containing overhead stream, which returned to the reactor 19 becomes, is separated. Furthermore, it is possible to provide a reactive distillation in place of the separate reactor 19, wherein the reactive distillation of the alcohol and the alkylene carbonate are fed and produced to be separated dialkyl carbonate, alkylene carbonate, alkylene glycol and alcohol-containing stream in the reactive distillation and directly separated.
• FIG. 2 shows the method according to the invention in an alternative embodiment.
• the embodiment shown in Figure 2 differs from the embodiment shown in Figure 1, inter alia, in that the first distillation stage, a portion of the dialkyl carbonate-containing crude product stream 27 is supplied in the form of stream 17 as entraining agent.
• a stream 13 containing alkylene carbonate can already be separated off and no homoazeotrope of alkylene glycol and alkylene carbonate is obtained. Therefore, can be dispensed with the second distillation stage 1 1.
• FIG. 2 shows the first distillation stage with two distillation columns 39 and 41. Alternatively, it is also possible to replace the two distillation columns 39 and 41 shown in FIG. 2 by a dividing wall column 1.
• dialkyl carbonate-containing stream is fed to the dividing wall column in the feed and the dialkyl carbonate and alkylene glycol containing heteroazeotrope stream does not fall as the bottom of a second distillation column but, as shown in Figure 1, as a side take of the dividing wall column.
• Example 1 Percentages given in the examples are percentages by weight unless stated otherwise.
• Example 1 Percentages given in the examples are percentages by weight unless stated otherwise.
• the reaction effluent is passed into a dividing wall column which is operated at a top pressure of 80 mbar (absolute).
• the distillation is operated continuously at a bottom temperature of 170 ° C and a reflux ratio of 0.76 g / g. This gives 2.38 kg / h liquid bottoms product having a composition of 57.5% ethylene carbonate, 20.5% monoethylene glycol, 15.1% diisobutyl carbonate and 0.55% sodium isobutylate. The remainder consists predominantly of higher ethylene glycols.
• phase separation into a Diisobutylcarbonatreiche phase with 98.5% diisobutyl carbonate and in a monoethylene glycol-rich phase with 97.6% monoethyl englycol is carried out at 40 ° C.
• the monoethylene glycol-rich phase is pure-distilled with a mass flow of 0.95 kg / h in a column at a top pressure of 130 mbar and a bottom temperature of 139 ° C. This gives 0.93 kg / h of a liquid bottom stream with the composition of 99.9% monoethylene glycol and 0.1% ethylene carbonate. 0.03 kg / h of a vapor stream having the composition of 39% isobutanol, 40.1% diisobutyl carbonate and 20.9% monoethylene glycol are taken off at the top, condensed and recycled to the phase separation.
• the reaction takes place under the same conditions as described in Example 1.
• the reaction effluent, together with 4 kg / h of the diisobutyl carbonate-rich phase, is passed from the phase separator into a distillation column which is operated at a top pressure of 25 mbar.
• the distillation is operated continuously at a bottom temperature of 178 ° C and a reflux ratio of 0.44 g / g. 2.17 kg / h of a liquid bottom stream having a composition of 92.3% ethylene carbonate, 0.3% diisobutyl carbonate, 0.49% sodium isobutylate and residual higher ethylene glycols, which is recycled to the reactor, are obtained at the bottom of the column.
• the monoethylene glycol-rich phase from the phase separator is pure-distilled with a mass flow of 0.76 kg / h in a column at a top pressure of 130 mbar and a bottom temperature of 139 ° C. This gives 0.72 kg / h of a liquid bottom stream having the composition of 99.99% monoethylene glycol and 60 ppm of ethylene carbonate.
• 0.05 kg / h of a vapor stream with the composition 23.8% diisobutyl carbonate, 66% isobutanol and 10.2% monoethylene glycol are removed, condensed and recycled to the phase separation.
• the reaction is passed into a dividing wall column, which is operated at a top pressure of 150 mbar.
• the distillation is operated continuously at a bottom temperature of 152 ° C and a reflux ratio of 0.76 g / g.
• the column is operated at a top pressure of 70 mbar and a bottom temperature of 159 ° C. This gives 1, 2 kg / h of a liquid bottom stream having the composition of 99.9% ethylene carbonate and 0.1% catalyst and higher Ethyl- englykolen, which is recycled to the reactor. Part of the bottom stream is discharged to remove higher ethylene glycols from the system. 15.8 kg / h of a vapor stream having a composition of 93.5% of dipropyl carbonate, 6.4% of monoethylene glycol, 800 ppm of ethylene carbonate and 440 ppm of 1-propanol, which is condensed, and into the phase separation or, respectively, are obtained at the top of the column Return is returned to the column.
• the monoethylene glycol-rich phase from the phase separator is pure-distilled at a mass flow of 0.92 kg / h in a column at a top pressure of 100 mbar and a bottom temperature of 161 ° C.
• 0.89 kg / h of monoethylene glycol having a composition of 99.9% and 0.1% of ethylene carbonate are obtained at the bottom.
• 0.03 kg / h of a vapor stream having a composition of 89.6% dipropyl carbonate, 7.2% monoethylene glycol and 3.2% 1-propanol, which is condensed and recycled to the phase separation, are obtained at the top of the column.

Landscapes

• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Priority Applications (1)

Applications Claiming Priority (3)

Publications (1)

Family

ID=47351616

Family Applications (1)

Country Status (7)

Families Citing this family (8)

Family Cites Families (20)

• 2012
  • 2012-12-05 EP EP12799132.1A patent/EP2788315A1/de not_active Withdrawn
  • 2012-12-05 JP JP2014545236A patent/JP2015504855A/ja not_active Ceased
  • 2012-12-05 IN IN4151CHN2014 patent/IN2014CN04151A/en unknown
  • 2012-12-05 KR KR1020147018561A patent/KR20140113931A/ko not_active Application Discontinuation
  • 2012-12-05 WO PCT/EP2012/074478 patent/WO2013083618A1/de unknown
  • 2012-12-05 BR BR112014013557A patent/BR112014013557A2/pt not_active IP Right Cessation
  • 2012-12-05 CN CN201280069004.4A patent/CN104203899A/zh active Pending

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events