TW201827395A - A method of treating a carbonate stream - Google Patents

Abstract

A method of treating an organic carbonate stream comprising passing the organic carbonate stream through a fixed bed to remove contaminants and produce a less contaminated stream wherein the fixed bed comprises alumina or silica.

Description

 Method of treating carbonate stream    [Cross-Reference to Related Applications]  

This application claims the benefit of U.S. Provisional Application Serial No. Serial No. No. No. No. No. No. No

The present invention relates to a method of treating an organic carbonate stream to remove contaminants.

Alkylene carbonates such as ethylene carbonate are important starting materials for the production of acyclic dialkyl carbonates and monoalkylene glycols by reaction with alkanols. For example, ethylene carbonate and ethanol can be reacted to form diethyl carbonate and monoethylene glycol. Alkylene carbonates are also widely used as solvents and diluents in industrial processes such as dyes, fibers, plastics and batteries. In many applications, ethylene and propylene carbonate provide a safe and clean alternative to the more dangerous dipolar aprotic solvents. It is also used as a raw material for commodities such as cosmetics and pharmaceuticals.

Second, a non-cyclic dialkyl carbonate such as dimethyl carbonate or diethyl carbonate is an important chemical product. For example, it can be used as a starting material for producing a diaryl carbonate by reacting with an aromatic alcohol. For example, diphenyl carbonate can be produced by reacting a dialkyl carbonate with phenol.

Diphenyl carbonate is an important starting material in the commercial production of polycarbonate. Diphenyl carbonate can be polymerized into a polycarbonate with a dihydroxy aromatic compound such as bisphenol acetone. Diphenyl carbonate must have sufficient purity before it is reacted with the dihydroxy aromatic compound. This can be achieved by purifying the diphenyl carbonate or by ensuring that the starting material used to produce the diphenyl carbonate (e.g., ethylene carbonate and diethyl carbonate) is of sufficient purity.

In addition, ensuring that the dialkyl carbonate starting material is of sufficient purity also results in less side reactions and, therefore, higher yields and/or selectivity of the desired reaction.

No. 6,586,605 describes a process for contacting an alkylene carbonate with at least two solid adsorbents comprising carbon and inorganic cerium or alumina.

The present invention provides a method of treating an organic carbonate stream comprising passing an organic carbonate stream through a fixed bed to remove contaminants and produce a less contaminated stream, wherein the fixed bed comprises alumina or cerium oxide.

The invention further provides a process for producing diphenyl carbonate comprising: a) reacting carbon dioxide with ethylene oxide to form ethylene carbonate; b) reacting ethylene carbonate with ethanol to form carbonic acid in a transesterification reaction Diethyl ester and monoethylene glycol; and c) reacting diethyl carbonate with phenol in a transesterification and disproportionation reaction to form diphenyl carbonate, wherein ethylene carbonate, diethyl carbonate and diphenyl carbonate are obtained. One or more of them are removed by a fixed bed comprising alumina or cerium oxide.

The present invention provides a method of treating one or more organic carbonate streams. The treated organic carbonate may be one or more of alkylene carbonate, dialkyl carbonate, and/or carbonate. For example, the processing process can reduce the total halogen to an extremely low level, i.e., less than 0.3 ppm. With regard to diphenyl carbonate, this compound has a very stringent halogen specification of less than 300 ppbw of halogen because halogen is a known color former that causes color and other problems in the melt polymerization process used to produce the polycarbonate. Since the alkylene carbonate and the dialkyl carbonate are precursors used in the formation of diphenyl carbonate, any of these streams can be subjected to a processing step to reduce the level of contaminants.

Alkylene carbonate

In one embodiment, the treated organic carbonate stream comprises an alkylene carbonate. The alkylene carbonate can be prepared by any method known to those skilled in the art, which comprises reacting carbon dioxide with an alkylene oxide to produce a stream containing alkylene carbonate and impurities, and recovering from the stream. Alkylene carbonate. This reaction can be carried out in the presence of a catalyst. Suitable catalysts include quaternary ammonium halides, quaternary phosphonium halides, and metal halides. Additional catalysts are described in US 7,674,919.

In one embodiment, the alkylene carbonate can be prepared as described in US 7,674,919, which is incorporated herein by reference. This patent describes a process for preparing an alkylene carbonate comprising contacting a corresponding alkylene oxide with carbon dioxide in the presence of water, wherein the amount of water is at least 0.05 mol/mol alkylene oxide, and including hydrogen halide In the presence of a catalytic composition of a neutralized organic base, wherein the organic base comprises a carbon-based compound comprising one or more nitrogen atoms having at least one free electron pair and/or having at least one free electron pair Or a plurality of phosphorus atoms, and wherein the organic base has a pKa greater than 8.

In another embodiment, the alkylene carbonate can be prepared as described in US 7,488,835, incorporated herein by reference. This patent describes a process for the catalytic carboxylation of alkylene oxide with carbon dioxide in the presence of a catalytic composition and water, wherein the catalyst composition comprises an alkali metal halide and a macrocyclic chelating compound.

In another embodiment, the alkylene carbonate can be prepared as described in US 7,501,531, incorporated herein by reference. This patent describes a process for preparing an alkylene carbonate comprising contacting a corresponding alkylene oxide with carbon dioxide in the presence of a metal salt immobilized on a solid support, wherein the metal salt comprises a metal selected from the group consisting of Cation: according to the third cycle of the IUPAC nomenclature and the second, fourth and fourth and fourth to twelfth, fifth and second, fourth to seventh, and twelfth Group 14, and sixth cycle and Group 2 and Groups 4 to 6, and the metal salt comprises an anion selected from the group consisting of inorganic acids and anions of organic acids, and wherein the solid carrier contains quaternary ammonium, quaternary phosphonium, quaternary arsenic, and quaternary Ruthenium or unterminated cation.

Ethylene carbonate is infinitely soluble in water. The propylene carbonate can be dissolved in water at 25 ° C with up to 25.0 g of propylene carbonate per 100 g of water.

Dialkyl carbonate

In another embodiment, the treated organic carbonate stream comprises a dialkyl carbonate. The dialkyl carbonate can be prepared by any method known to those skilled in the art, which comprises producing an alkanol (e.g., ethanol) with an alkylene carbonate (e.g., ethylene carbonate) by a catalyst to produce Dialkyl carbonates (such as diethyl carbonate) and monoalkylene glycols (such as monoethylene glycol).

In one embodiment, the dialkyl carbonate can be prepared according to the process described in US Pat. No. 8,975,432, incorporated herein by reference. This patent describes a process for the preparation of alkanediols and dialkyl carbonates comprising: (a) reacting an alkylene carbonate with an alkanol in the presence of a transesterification catalyst to obtain a dialkyl carbonate. a reaction mixture of an unconverted alkanol, an alkanediol, an unconverted alkylene carbonate, and an alkoxyalkanol impurity; (b) subjecting the reaction mixture to distillation in a first distillation column to obtain a carbonic acid comprising a top stream of alkyl esters, alkanols and alkoxyalkanol impurities and a bottoms stream comprising an alkanediol and an alkylene carbonate; (c) subjecting the bottom stream from the first distillation column to distillation in the second distillation column Obtaining a top stream comprising an alkanediol and a bottoms stream comprising an alkylene carbonate; (d) from the presence of a catalyst to effect the reaction of the alkoxyalkanol impurity with the dialkyl carbonate to form a carbonate ether impurity The overhead stream of the first distillation column is subjected to distillation in a third distillation column to obtain a top stream comprising an alkanol and a bottoms stream comprising dialkyl carbonate and carbonate ether impurities; and (e) from the third distillation column The bottom stream is subjected to distillation in the fourth distillation column Obtaining a top stream comprising a dialkyl carbonate and a bottoms stream comprising dialkyl carbonate and carbonate ether impurities; and (f) recycling the bottom stream from the fourth distillation column to the first distillation column.

In another embodiment, the dialkyl carbonate can be prepared according to the process described in US Pat. No. 8,618,322, incorporated herein by reference. This patent describes a process for the preparation of alkanediols and dialkyl carbonates comprising: (a) reacting an alkylene carbonate with an alkanol in the presence of a transesterification catalyst to obtain a dialkyl carbonate. a reaction mixture of an unconverted alkanol, an alkanediol, and an unconverted alkylene carbonate; (b) subjecting the reaction mixture to distillation in a first distillation column to obtain a dialkyl carbonate and an alkanol a top stream and a bottoms stream comprising a dialkyl carbonate, an alkanol, an alkanediol, and an alkylene carbonate; (c) subjecting the bottom stream from the first distillation column to distillation in the second distillation column to obtain a carbon dioxide comprising a top stream of an alkyl ester and an alkanol and a bottoms stream comprising an alkanediol and an alkylene carbonate; (d) recovering the alkanediol from the bottom stream from the second distillation column; and (e) from the first and the The overhead stream of the second distillation column is subjected to distillation in a third distillation column to obtain a top stream comprising an alkanol and a bottoms stream comprising a dialkyl carbonate.

In the dialkyl carbonate, the alkyl groups may be the same or different, preferably the same. Further, preferably, and in the alkyl dialkyl carbonate, the alkyl group (the group may be linear, branched and/or cyclic) is a C1-8 alkyl group, more preferably C1. -6 alkyl, such as isopropyl, ethyl and methyl, suitably ethyl. Preferably, the dialkyl carbonate is dimethyl carbonate or diethyl carbonate, more preferably diethyl carbonate.

Industrially important dialkyl carbonates such as dimethyl carbonate, diethyl carbonate, dipropyl carbonate, di-n-butyl carbonate are all colorless liquids, and most of them have a pleasant odor. Dimethyl carbonate and diethyl carbonate are slightly soluble in water.

The dialkyl carbonate feed to be treated by the process of the present invention may include a dialkyl carbonate feed that does not meet specifications for maximum impurity levels.

Diaryl carbonate

In another embodiment, the treated organic carbonate stream comprises a diaryl carbonate. The diaryl carbonate can be prepared by any method known to those skilled in the art, which comprises reacting a dialkyl carbonate with an aryl alcohol (eg, phenol) to produce an alkyl aryl carbonate and Corresponding to the alkanol, the alkyl aryl carbonate is then disproportionated to produce a diaryl carbonate and a dialkyl carbonate. Further transesterification of the alkyl aryl carbonate with the aryl alcohol can also be carried out to obtain a diaryl carbonate and an alkyl alcohol.

The diaryl carbonate mentioned above may be a carbonate of the formula: R ¹ O(CO)OR ²

Wherein both R ¹ and R ² are aryl groups. Preferably, the aryl group is a phenyl group and the diaryl carbonate is diphenyl carbonate (DPC).

In one embodiment, the diaryl carbonate can also be subjected to conventional purification and recovery techniques prior to treatment. If the diaryl carbonate is produced from an aryl alcohol and a dialkyl carbonate, such purification and recovery techniques typically involve removal of unreacted aryl alcohol, dialkyl carbonate, by-product alkyl alcohol, and reaction intermediates. Alkyl aryl carbonate.

Preferably, the diaryl carbonate treated by the process of the invention is used as a starting material for the manufacture of polycarbonate.

In one embodiment, the diaryl carbonate can be prepared according to the process described in US Pat. No. 8,110,698, incorporated herein by reference. This patent describes a process for producing a diaryl carbonate comprising: feeding an aromatic hydroxy compound and a dialkyl carbonate to a first reaction zone comprising a solid transesterification catalyst; and The organometallic compound is fed to the first reaction zone, wherein the solid transesterification catalyst and the soluble organometallic compound each independently comprise a Group II to Group VI element.

In another embodiment, the diaryl carbonate can be produced by a process for producing a diaryl carbonate, the process comprising: reacting an epoxide with carbon dioxide in a first reaction zone to form a cyclic carbonate comprising a first reaction product; transesterifying the cyclic carbonate with ethanol in the second reaction zone in the presence of a first transesterification catalyst to form a second reaction product comprising diethyl carbonate and ethylene glycol; The second reaction product is separated to recover the first diethyl carbonate fraction and the first ethylene glycol fraction; at least a portion of the first diethyl carbonate fraction and the aryl hydroxy compound are in the third in the presence of the second transesterification catalyst Transesterification in the reaction zone to form a third reaction product comprising ethyl aryl carbonate and ethanol; separating the third reaction product to recover the ethyl aryl carbonate fraction and the first ethanol fraction; in the presence of a disproportionation catalyst At least a portion of the ethyl aryl carbonate fraction is disproportionated in the fourth reaction zone to form a fourth reaction product comprising diaryl carbonate and diethyl carbonate; the fourth reaction product is divided Recycling the diaryl carbonate fraction and the second diethyl carbonate fraction; recycling at least a portion of the first ethanol fraction to the second reaction zone; and recycling at least a portion of the second diethyl carbonate fraction to the third Reaction zone.

In another embodiment, the diaryl carbonate can be produced by a process for producing a diaryl carbonate, the process comprising: reacting ammonia with carbon dioxide in a first reaction zone to form a first reaction product comprising urea. And transesterifying urea and ethanol in a second reaction zone in the presence of a first transesterification catalyst to form a second reaction product comprising diethyl carbonate and ammonia; separating the second reaction product to recover the first carbonic acid a diethyl ester fraction and a first ammonia fraction; at least a portion of the first diethyl carbonate fraction is transesterified with the aryl hydroxy compound in the third reaction zone in the presence of a second transesterification catalyst to form an ethyl group comprising a third reaction product of an aryl carbonate and ethanol; separating a third reaction product to recover an ethyl aryl carbonate fraction and an ethanol fraction; and at least a portion of the ethyl aryl carbonate fraction in the presence of a disproportionation catalyst Disproportionation in the reaction zone to form a fourth reaction product comprising diaryl carbonate and diethyl carbonate; separating the fourth reaction product to recover the diaryl carbonate fraction and the second carbon Diethyl fraction; at least a portion of the ethanol fraction is recycled to a second reaction zone; diethyl carbonate and a second fraction is recycled to at least a portion of the third reaction zone.

In yet another embodiment, the diaryl carbonate can be prepared according to the process described in WO 2008/090107, which is incorporated herein by reference. This published patent application describes a process for preparing a diaryl carbonate by reacting an aromatic alcohol with a dialkyl carbonate which has been prepared by reacting an alkanol with an alkylene carbonate. The process comprises the steps of: (a) transferring an aromatic alcohol and a dialkyl carbonate to a first transesterification zone to obtain a diaryl carbonate, an alkanol, an unconverted dialkyl carbonate, and a first product stream of unconverted aromatic alcohol; (b) separating the first product stream into a diaryl carbonate-rich product stream, an aromatic-rich alcohol recycle stream, and an alcohol-containing, dialkyl carbonate, and aromatic alcohol a second recycle stream; (c) feeding an alkanol and an alkylene carbonate to the second transesterification zone to obtain an alkanediol and an unconverted alkanol and an unconverted dialkyl carbonate. a second product stream; (d) separating the alkanediol from the second product stream to obtain an alkanediol product stream and a mixture of a dialkyl carbonate and an unconverted alkanol; (e) making a dialkyl carbonate a mixture with an unconverted alkanol and a second refill comprising an alkanol, a dialkyl carbonate and an aromatic alcohol The loop is subjected to the same distillation to obtain an alkanol stream as a lower boiling fraction and a contaminated stream comprising a dialkyl carbonate and an aromatic alcohol as a higher boiling fraction; (f) recycling the alkanol stream of step e) to a second transesterification zone; and (g) delivering a contaminated stream comprising a dialkyl carbonate and an aromatic alcohol and an aromatic-rich alcohol recycle stream to the first transesterification zone.

The diaryl carbonate is a solid under ambient conditions. It is soluble in many organic solvents, especially polar solvents such as esters, ketones, ethers, alcohols and aromatic hydrocarbons.

Possible pollutant

Contaminants can include halogen or ethyl cellosolve. Contaminants can include organic chlorides such as 2-chloroethanol. Contaminants may also include organic bromides such as 2-bromoethanol and 1-bromo-2-propanol. Such contaminants may be derived from one or more catalysts used to prepare the organic carbonates described above or from one of the reactants used in the preparation.

In addition, monoethylene glycol and diethylene glycol can be considered as contaminants in the ethylene carbonate stream.

Handling one or more of these streams to remove contaminants

One or more of the organic carbonate streams described above and/or mixtures thereof may be treated to remove such contaminants or other impurities present in the organic carbonate stream. This treatment involves contacting the organic carbonate stream with a fixed bed comprising alumina or cerium oxide.

The alumina or cerium oxide may have a surface area of from 200 to 700 m ² /g. Alumina or cerium oxide may be present in the form of spheres, spherulites, cylinders, trilobes or quadralobe.

The process preferably removes at least 50% of the contaminants in the organic carbonate stream. In certain embodiments, the starting organic carbonate stream can be relatively pure, for example, the organic carbonate stream to be treated can contain less than 0.01 wt% impurities. For example, the organic carbonate stream to be treated can include less than 0.01 wt% halogen.

The fixed bed can be regenerated to remove accumulated impurities that have been adsorbed on the fixed bed. Additionally, more than one fixed bed can be used to allow for the regeneration of another bed while using one bed to treat the organic carbonate stream. In another embodiment, more than two fixed beds may be used, such that there may be additional supplies that may be used as spares or otherwise ensure that the organic carbonate stream can be processed at all times regardless of the required regeneration and/or other downtime. Fixed bed.

In one embodiment, an alkylene carbonate (ethylene carbonate) can be prepared by reacting carbon dioxide with an alkylene oxide (ethylene oxide). The ethylene carbonate can be reacted with an alkanol (ethanol) to produce a dialkyl carbonate (diethyl carbonate) and a monoalkylene glycol (monoethylene glycol). Diethyl carbonate is reacted with phenol to produce ethyl phenyl carbonate and ethanol. Ethyl phenyl carbonate is disproportionated with ethanol to produce diphenyl carbonate and diethyl carbonate. Further, transesterification of ethyl phenyl carbonate with phenol gives diphenyl carbonate and ethanol. The resulting diphenyl carbonate contains contaminants from the reaction steps carried out to produce diphenyl carbonate. The contaminant can comprise catalyst components and/or by-products formed during the reaction step.

The diphenyl carbonate is treated by contacting a diphenyl carbonate with a fixed bed comprising alumina or cerium oxide. The diphenyl carbonate can be further purified by passing the treated diphenyl carbonate through a distillation step to remove additional contaminants.

Instance

Example 1

In this example, it is passed through a fixed bed of alumina by a solution comprising diethyl bromoethanol, 2-chloroethanol and 1-bromo-2-propanol and having a bromine concentration of 1000 ppm of diethyl carbonate (DEC). deal with. Alumina is a 1.3 mm trilobal alumina extrudate having a surface area of 300 m ² /g. In a separate experiment, it was treated by the same DEC through a fixed bed of yttrium oxide. In both experiments, more than 85% of the bromine was adsorbed onto the solid adsorbent at low temperature (environment) for a minimum contact time (LHSV of 0.05 hr ^-1 ).

Example 2

The ethylene carbonate stream having less than 0.3 wt% MEG or DEG (dissolved in diethyl carbonate in a 1:1 ratio) is passed through a fixed bed of alumina. Alumina is a 1.3 mm trilobal alumina extrudate having a surface area of 300 m ² /g. Almost all MEG or DEG are adsorbed onto the alumina.

Claims (15)

 A method of treating an organic carbonate stream comprising passing the organic carbonate stream through a fixed bed to remove contaminants and produce a less contaminated stream, wherein the fixed bed comprises alumina or cerium oxide.   The method of claim 1, wherein the alumina or cerium oxide has a surface area of from 200 to 700 m ² /g.  The method of any one of claims 1 to 2, wherein the contaminant comprises a halogen or ethyl cellosolve.    The method of any one of claims 1 to 3, wherein the contaminant comprises an organic chloride.    The method of any one of claims 1 to 4, wherein the contaminant comprises 2-bromoethanol, 2-chloroethanol or 1-bromo-2-propanol.    The method of any one of claims 1 to 5, wherein the contaminant comprises monoethylene glycol or diethylene glycol.    The method of any one of claims 1 to 6, wherein the less contaminated stream has less than 50% of the contaminants in the organic carbonate stream.    The method of any one of claims 1 to 7, wherein the organic carbonate stream contains less than 0.01% by weight of a halogen.    The method of any one of claims 1 to 8, wherein the fixed bed comprises an extrudate or other bed of low pressure drop solids.    The method of any one of claims 1 to 9, wherein the organic carbonate stream comprises ethylene carbonate.    The method of any one of claims 1 to 10, further comprising regenerating the fixed bed to remove contaminants.    The method of claim 11, wherein two fixed beds are used such that one bed can be regenerated while contacting the organic carbonate stream.    A method of producing diphenyl carbonate, comprising: a. reacting carbon dioxide with ethylene oxide to form ethylene carbonate; b. reacting the ethylene carbonate with ethanol to form diethyl carbonate in a transesterification reaction And monoethylene glycol; and c. reacting the diethyl carbonate with phenol in a transesterification and disproportionation reaction to form diphenyl carbonate, wherein the ethylene carbonate, diethyl carbonate, and diphenyl carbonate are One or more of them are removed by a fixed bed comprising alumina or cerium oxide.    The method of claim 13, further comprising subjecting the diphenyl carbonate to a purification step after passing the diphenyl carbonate through the fixed bed.    The method of claim 14, wherein the purifying step comprises a distillation column.