Method for separating dimethyl carbonate

Abstract

The invention relates to a method for separating dimethyl carbonate. The method adopts an oxidative esterification reactor, ahigh low boiling fraction removaltower, a linaethol recovery tower, a low boiling fraction removaltower, an alkaline bath, a methyl alcohol recovery tower and a dimethyl carbonate separating tower to separate methanol and dimethyl carbonate. By adopting the method, the process energy consumption is reduced while the quality of products is ensured, and the method can be used for industrial production of dimethyl carbonate separation in the dimethyl oxalate synthesis process.

Description

technical field [0001] The invention relates to a method for separating dimethyl carbonate, especially for the process of synthesizing dimethyl oxalate using coal-based synthesis gas, natural gas, coke oven gas, blast furnace gas, calcium carbide furnace tail gas, etc. as raw materials. Qualified dimethyl carbonate product is obtained, and methanol is recycled by alkali washing at the same time. Background technique [0002] In the process of synthesizing dimethyl oxalate (DMO), methyl nitrite and CO undergo a gas-phase catalytic coupling reaction on the catalyst to generate DMO, and at the same time, there is a side reaction to generate dimethyl carbonate (DMC). The reaction equation is as follows: [0003] 2CH 3 ONO+2CO→(COOCH 3 ) 2 +2NO [0004] The main side effects are: [0005] 2CH 3 ONO+2CO→CO(OCH 3 ) 2 +2NO [0006] The by-product methyl formate (MF) is also formed in the presence of hydrogen. The reaction equation is as follows: [0007] [0008] Both...

AI Technical Summary

Problems solved by technology

Although the double-tower pressure swing rectification process does not need to add extractant, it needs two rectification towers to carry out the separation operation continuously, and the obtained high-concentration DMC yield is low, and the azeotrope of MeOH and DMC extracted at the top of the DMC separation tower is still low. It needs to be sent to the atmospheric tower to continue separation, so that the total amount of azeotrope at the top of the tower in the atmospheric tower and DMC separation tower increases, and the amount of effective separation of DMC is small, which increases energy consumption

CN101381309B separates DMC from the DMC-MeOH mixed solution by vacuum azeotropic rectification-pressurized azeotropic rectification double-tower process, and makes MeOH reclaimed, recycles, and this method needs vacuuming equipment, and does not carry out effective Heat integration, high energy consumption

However, researchers believe that the extraction efficiency of ethylene glycol is low, and it is not suitable for the extraction agent of DMC-MeOH mixture (Ind. Eng. Chem. Res. 2010, 49, 735-749)

Among them, the extraction and rectification separation process also needs to add an extractant separation tower for the separation of the extractant and MeOH. The operation process is complicated and the heat load is high.

[0015] CN102442903A thinks that the extraction and rectification double-tower process needs to add and recover the extractant, the operation process is complicated, the heat load is high, and the pressure-swing rectification double-tower process effectively separates DMC with less amount, which increases energy consumption

But the above process is a batch process, which is not suitable for industrialized large-scale production; the mass ratio of MeOH and DMC in the top component of the control separation tower is equal to 3:1, and the operating pressure of pressurized rectification is 0.75MPa. The control is relatively simple, and due to the addition of The pressure of rectification is low, which leads to the increase of mixed liquid circulation and increases the energy consumption of separation

Images