Provided is a carbonate ester purification apparatus including a treatment part for mixing a first solution containing a carbonate ester and an acidic substance with an alcohol solution of a metal alcoholate to obtain a mixed solution containing a reaction product of the acidic substance and the metal alcoholate, a separation part for removing a metal salt contained in the reaction product from the mixed solution to obtain a second solution, and a distillation part for removing a component from the second solution, the component different in boiling point from the carbonate ester to obtain a carbonate ester solution, wherein a content of the metal alcoholate in the alcohol solution is 5 to 18 mass %.

An apparatus for separating dimethyl carbonate using pervaporation includes: an atmospheric distillation column and a high pressure distillation column distilling a mixture containing dimethyl carbonate and methanol and separating dimethyl carbonate from the mixture; and a pervaporation membrane module disposed between the atmospheric distillation column and the high pressure distillation column and allowing for permeation of the methanol to separate the methanol from the mixture, thereby reducing heat consumption and a process cost as compared to the case of only using an existing pressure swing distillation method.

An apparatus for separating dimethyl carbonate using pervaporation includes: an atmospheric distillation column and a high pressure distillation column distilling a mixture containing dimethyl carbonate and methanol and separating dimethyl carbonate from the mixture; and a pervaporation membrane module disposed between the atmospheric distillation column and the high pressure distillation column and allowing for permeation of the methanol to separate the methanol from the mixture, thereby reducing heat consumption and a process cost as compared to the case of only using an existing pressure swing distillation method.

An apparatus for separating dimethyl carbonate using pervaporation includes: an atmospheric distillation column and a high pressure distillation column distilling a mixture containing dimethyl carbonate and methanol and separating dimethyl carbonate from the mixture; and a pervaporation membrane module disposed between the atmospheric distillation column and the high pressure distillation column and allowing for permeation of the methanol to separate the methanol from the mixture, thereby reducing heat consumption and a process cost as compared to the case of only using an existing pressure swing distillation method.

The invention relates to a composition comprising a titanium or zirconium alkoxide or aryloxide, wherein the alkoxy group in the titanium or zirconium alkoxide is a group of formula R-0.sup.− wherein R is an alkyl group having 1 to 4 carbon atoms and the aryloxy group in the titanium or zirconium aryloxide is a group of formula Ar-0.sup.− wherein Ar is an aryl group having 6 to 12 carbon atoms, and wherein the composition additionally comprises 0.1 to 50 wt. % of an organic carbonate, based on the total weight of the composition. Further, the invention relates to a process for preparing such composition, comprising blending such titanium or zirconium alkoxide or aryloxide with an organic carbonate in such amounts that the resulting composition comprises 0.1 to 50 wt. % of the organic carbonate, based on the total weight of the composition. Still further, the invention relates to a process for preparing an aromatic carbonate, such as a diaryl carbonate, using said composition comprising a titanium or zirconium alkoxide or aryloxide; and to a process for making a polycarbonate from the diaryl carbonate thus prepared.

The invention relates to a composition comprising a titanium or zirconium alkoxide or aryloxide, wherein the alkoxy group in the titanium or zirconium alkoxide is a group of formula R-0.sup.− wherein R is an alkyl group having 1 to 4 carbon atoms and the aryloxy group in the titanium or zirconium aryloxide is a group of formula Ar-0.sup.− wherein Ar is an aryl group having 6 to 12 carbon atoms, and wherein the composition additionally comprises 0.1 to 50 wt. % of an organic carbonate, based on the total weight of the composition. Further, the invention relates to a process for preparing such composition, comprising blending such titanium or zirconium alkoxide or aryloxide with an organic carbonate in such amounts that the resulting composition comprises 0.1 to 50 wt. % of the organic carbonate, based on the total weight of the composition. Still further, the invention relates to a process for preparing an aromatic carbonate, such as a diaryl carbonate, using said composition comprising a titanium or zirconium alkoxide or aryloxide; and to a process for making a polycarbonate from the diaryl carbonate thus prepared.

A carbonate ester purification apparatus including a first distillation column in which an alcohol and a first solution containing a carbonate ester and formaldehyde, or a first solution containing a carbonate ester, formaldehyde and an alcohol is supplied to obtain a distillate containing the formaldehyde and the alcohol from a column top part while obtaining a carbonate ester solution with a lower content of formaldehyde than in the first solution from a column bottom part, a reactor having a catalyst for producing an acetal and/or a hemiacetal by reacting the formaldehyde to the alcohol and a reflux part refluxing a fluid containing the acetal and/or the hemiacetal to the first distillation column.

A carbonate ester purification apparatus including a first distillation column in which an alcohol and a first solution containing a carbonate ester and formaldehyde, or a first solution containing a carbonate ester, formaldehyde and an alcohol is supplied to obtain a distillate containing the formaldehyde and the alcohol from a column top part while obtaining a carbonate ester solution with a lower content of formaldehyde than in the first solution from a column bottom part, a reactor having a catalyst for producing an acetal and/or a hemiacetal by reacting the formaldehyde to the alcohol and a reflux part refluxing a fluid containing the acetal and/or the hemiacetal to the first distillation column.

A carbonate ester purification apparatus including a first distillation column in which an alcohol and a first solution containing a carbonate ester and formaldehyde, or a first solution containing a carbonate ester, formaldehyde and an alcohol is supplied to obtain a distillate containing the formaldehyde and the alcohol from a column top part while obtaining a carbonate ester solution with a lower content of formaldehyde than in the first solution from a column bottom part, a reactor having a catalyst for producing an acetal and/or a hemiacetal by reacting the formaldehyde to the alcohol and a reflux part refluxing a fluid containing the acetal and/or the hemiacetal to the first distillation column.

A method of producing high purity dimethyl carbonate through the reaction of carbon dioxide and methanol is provided. In the ammonia-based method ammonia and carbon dioxide react to produce urea. The urea is mixed with methanol for further reaction to produce dimethyl carbonate. Ammonia released in the process is recycled as a reactant to produce more urea. It is then reacted with methanol to produce dimethyl carbonate. An integrated reactive distillation process using side reactors is used for facilitating catalytic reaction in the method for producing high purity dimethyl carbonate. The process is further enhanced by enclosing multiple side reactors into a pressure vessel and incorporating thermal heat pump for recovery and reuse of latent heat within the process.