Provided is a method for preparing an asymmetric linear carbonate, the method comprising: subjecting two kinds of different symmetric linear carbonates to a transesterification reaction in the presence of a metal alkoxide catalyst to prepare an asymmetric linear carbonate, wherein the metal of the metal alkoxide is at least one selected from the group consisting of aluminum (Al), magnesium (Mg), germanium (Ge), gallium (Ga), cobalt (Co), calcium (Ca), hafnium (Hf), iron (Fe), nickel (Ni), niobium (Nb), molybdenum (Mo), lanthanum (La), rhenium (Re), scandium (Sc), silicon (Si), tantalum (Ta), tungsten (W), yttrium (Y), zirconium (Zr) and vanadium (V). Also provided is an asymmetric linear carbonate including the metal alkoxide catalyst.

Provided is a method for preparing an asymmetric linear carbonate, the method comprising: subjecting two kinds of different symmetric linear carbonates to a transesterification reaction in the presence of a metal alkoxide catalyst to prepare an asymmetric linear carbonate, wherein the metal of the metal alkoxide is at least one selected from the group consisting of aluminum (Al), magnesium (Mg), germanium (Ge), gallium (Ga), cobalt (Co), calcium (Ca), hafnium (Hf), iron (Fe), nickel (Ni), niobium (Nb), molybdenum (Mo), lanthanum (La), rhenium (Re), scandium (Sc), silicon (Si), tantalum (Ta), tungsten (W), yttrium (Y), zirconium (Zr) and vanadium (V). Also provided is an asymmetric linear carbonate including the metal alkoxide catalyst.

The present invention provides a method for fixing carbon dioxide gas as a carbonyl compound represented by formula (3) as depicted by FIG. 1 and comprising, purging of carbon dioxide in a solution of a nucleophile represented by the formula (1) in presence of a solvent at a temperature ranging from 40 Degree Celsius to 35 Degree Celsius, followed by adding a reagent at temperature ranging from 40 degree to 35 degree and thereafter adding another nucleophile represented by the formula (2) to obtain carbonyl compound represented by formula (3). The present invention can be advantageously used to obtain commercially important carbonyl compounds and clean unwanted carbon dioxide gas from the atmosphere and industrial effluents.

##STR00001##

The present invention provides a method for fixing carbon dioxide gas as a carbonyl compound represented by formula (3) as depicted by FIG. 1 and comprising, purging of carbon dioxide in a solution of a nucleophile represented by the formula (1) in presence of a solvent at a temperature ranging from 40 Degree Celsius to 35 Degree Celsius, followed by adding a reagent at temperature ranging from 40 degree to 35 degree and thereafter adding another nucleophile represented by the formula (2) to obtain carbonyl compound represented by formula (3). The present invention can be advantageously used to obtain commercially important carbonyl compounds and clean unwanted carbon dioxide gas from the atmosphere and industrial effluents.

##STR00001##

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.

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.