Method and device for co-producing dimethyl carbonate and dimethyl oxalate

Abstract

The invention discloses a method and a device for co-preparing di(C1-3) alkyl carbonate and di(C1-3) alkyl oxalate. The method comprises the following steps of: a) separating a product of a di(C1-3) alkyl carbonate synthesis reactor into a first liquid phase and a first gas phase; b) separating a product of a di(C1-3) alkyl oxalate synthesis reactor into a second liquid phase and a second gas phase; c) conveying the first liquid phase to a first rectifying tower from the tower top, conveying the combined first gas phase and second gas phase to the first rectifying tower from the middle lower part of the tower, conveying the second liquid phase to the first rectifying tower from the tower bottom, and generating basically pure di(C1-3) alkyl oxalate fraction from the bottom of the first rectifying tower during rectifying; d) separating the overhead fraction produced in the first rectifying tower into a third liquid phase and a third gas phase; and e) conveying the third liquid phase to a second rectifying tower from the middle part of the tower, and generating basically pure di(C1-3) alkyl carbonate from the bottom of the second rectifying tower. Only three rectifying towers are designed in the whole process through reasonable process design, so the energy requirement and operation expense are effectively reduced, and the equipment investment expense is saved.

Description

technical field [0001] The invention relates to a method and a device for coproducing dimethyl carbonate and dimethyl oxalate from carbon monoxide, methanol and oxygen. It belongs to the technology of preparing dimethyl carbonate and dimethyl oxalate by oxidative carbonylation of methanol. technical background [0002] Dimethyl carbonate (DMC) is an important organic synthesis intermediate with low toxicity. It is a "green" chemical product with development prospects. It can replace toxic substances such as phosgene to synthesize polycarbonate, and can be used in gasoline Additives etc. [0003] Dimethyl oxalate (DMO) is an intermediate product in the synthesis of ethylene glycol by oxidative carbonylation of methanol. Japan UBE Company (EP0046598, 1982; EP0086370, 1983) and U.S. Union Carbide Corporation (EP0057630, 1982) have announced the preparation of dimethyl oxalate or diethyl oxalate by means of the CO coupling reaction that occurs with methyl nitrite or ethyl nitr...

AI Technical Summary

Problems solved by technology

The use of methanol washing inevitably requires the addition of at least one methanol recovery tower to separate DMC and recover methanol, which will inevitably lead to high energy consumption for separation

[0014] For the catalytic reaction of DMC, owing to be accompanied by by product DMO, for separating DMC and DMO, open patent " carbon monoxide low-pressure synthetic dimethyl carbonate technological process " (publication number CN1227839A) adopts DMO to wash DMC product as extraction agent, but this Only DMC products can be obtained, and high-purity DMO products cannot be obtained

[0015] In addition, because the gas generated after regeneration in the MN regeneration system contains a certain amount of water, the published patent "A method for synthesizing dimethyl oxalate and producing dimethyl carbonate as a by-product" (publication number CN101190884A) uses methanol washing To remove the water, but this will lead to a higher content of methanol in the cycle gas, which is unfavorable for the subsequent carbonylation reaction

Images