Disclosed is a high yield, high selectivity and high conversion method to produce Dimethyl Carbonate (DMC) from carbon dioxide (CO.sub.2) and methanol (MeOH) using optimized concentration of ethylene oxide as water scavenger. The method provides an alternative and optimized solution towards the problem of formation of water in DMC synthesis by reporting optimal feed ratio and scavenger to MeOH feed ratio. The disclosure also discloses an optimal pressure condition that could have significant impact on economy of compression of the feed to the DMC reactor.

Disclosed is a high yield, high selectivity and high conversion method to produce Dimethyl Carbonate (DMC) from carbon dioxide (CO.sub.2) and methanol (MeOH) using optimized concentration of ethylene oxide as water scavenger. The method provides an alternative and optimized solution towards the problem of formation of water in DMC synthesis by reporting optimal feed ratio and scavenger to MeOH feed ratio. The disclosure also discloses an optimal pressure condition that could have significant impact on economy of compression of the feed to the DMC reactor.

The present invention relates to the technical field of chemical engineering, and in particular to a linear carbonate and a preparation method thereof, which includes one or more of compounds of structural formula 1 below:

##STR00001##

wherein R.sub.1 and R.sub.2 are respectively selected from one of alkyl groups containing 1˜4 carbon atoms;

a hydroxyl concentration of the linear carbonate is no more than 100 ppm, and a free acid conversion rate of a solution with a concentration of 1 mol/L as formulated from the linear carbonate and lithium hexafluorophosphate is less than 1.2 after storage under 25° C. for 30 days. An acidity conversion rate was reduced when lithium hexafluorophosphate is dissolved in the linear carbonate by controlling the hydroxyl concentration, the energy density, discharge capacity, safety performance and service life of a battery can be improved when it's electrolyte solution contains the linear carbonate.

The invention relates to a process wherein a dialkyl carbonate stream containing an ether alkanol impurity is subjected to extractive distillation using an extraction solvent to obtain a top stream comprising dialkyl carbonate and a bottom stream comprising the ether alkanol impurity and the extraction solvent, wherein the extraction solvent is an organic compound containing one or more ester moieties and/or ether moieties which organic compound does not contain a hydroxyl group. Further, the invention relates to a process for making a diaryl carbonate, comprising reacting an aryl alcohol with a stream containing a dialkyl carbonate from which stream an ether alkanol impurity has been removed in accordance with the above-described process.

The invention relates to a process wherein a dialkyl carbonate stream containing an ether alkanol impurity is subjected to extractive distillation using an extraction solvent to obtain a top stream comprising dialkyl carbonate and a bottom stream comprising the ether alkanol impurity and the extraction solvent, wherein the extraction solvent is an organic compound containing one or more ester moieties and/or ether moieties which organic compound does not contain a hydroxyl group. Further, the invention relates to a process for making a diaryl carbonate, comprising reacting an aryl alcohol with a stream containing a dialkyl carbonate from which stream an ether alkanol impurity has been removed in accordance with the above-described process.

A method and system for membrane-assisted production of high purity concentrated dimethyl carbonate by the reaction of carbon dioxide and methanol is provided. Carbon dioxide is recovered from flue gas or other dilute streams from industrial processes by a membrane and subsequent conversion takes place to an intermediate methyl carbamate by reacting of carbon dioxide with ammonia and methanol. For high-purity carbon dioxide obtained by one of the carbon capture technologies or by a process (such as, for example, ethanol fermentation process) the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to methyl carbamate by reacting with ammonia and methanol. The methyl carbamate is further reacted with methanol for conversion to dimethyl carbonate. An integrated reactive distillation process using side reactors is used for facilitating the catalytic reaction in the subject method for producing high purity dimethyl carbonate.

A method and system for membrane-assisted production of high purity concentrated dimethyl carbonate by the reaction of carbon dioxide and methanol is provided. Carbon dioxide is recovered from flue gas or other dilute streams from industrial processes by a membrane and subsequent conversion takes place to an intermediate methyl carbamate by reacting of carbon dioxide with ammonia and methanol. For high-purity carbon dioxide obtained by one of the carbon capture technologies or by a process (such as, for example, ethanol fermentation process) the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to methyl carbamate by reacting with ammonia and methanol. The methyl carbamate is further reacted with methanol for conversion to dimethyl carbonate. An integrated reactive distillation process using side reactors is used for facilitating the catalytic reaction in the subject method for producing high purity dimethyl carbonate.

A method and system for membrane-assisted production of high purity concentrated dimethyl carbonate by the reaction of carbon dioxide and methanol is provided. Carbon dioxide is recovered from flue gas or other dilute streams from industrial processes by a membrane and subsequent conversion takes place to an intermediate methyl carbamate by reacting of carbon dioxide with ammonia and methanol. For high-purity carbon dioxide obtained by one of the carbon capture technologies or by a process (such as, for example, ethanol fermentation process) the membrane reactor is replaced with a catalytic reactor for direct conversion of carbon dioxide to methyl carbamate by reacting with ammonia and methanol. The methyl carbamate is further reacted with methanol for conversion to dimethyl carbonate. An integrated reactive distillation process using side reactors is used for facilitating the catalytic reaction in the subject method for producing high purity dimethyl carbonate.

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 %.

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 %.