Method for preparing dimethyl ether with high purity by syngas one-step method

Abstract

The invention relates to a method for preparing dimethyl ether with high purity by a syngas one-step method; dimethyl ether synthesized by the syngas one-step method is divided into a liquid phase and a gas phase after being condensed, the gas phase enters the lower part of an absorption tower, water is used to absorb dimethyl ether and carbon dioxide, the mixed gas returns to a synthesis system to continue reacting; a liquid phase condensate and an absorption solution are combined to form a liquid phase mixture which enters the lower part of a dimethyl ether rectification column, and dimethyl ether is discharged from the upper part of the rectification column in a siding way; non-condensable gas is discharged from the top of the rectification column and then enters the lower part of the absorption tower; the dimethyl ether rectification column bottom liquid phase product enters the lower part of a methanol rectification column, methanol is output from the top of the rectification column in a siding way and then enters the upper part of a methanol dehydrating tower, and the product after the methanol dehydration enters the lower part of the absorption tower; the methanol rectification column bottom liquid phase product is pure water, which can be used as an adsorbent; the invention can adopt a fixed bed reactor, a fluidized bed reactor or a three-phase slurry reactor to carry out reaction, and the purity of the prepared dimethyl ether can reach above 99.99%, thus having industrial value and better application prospect.

Description

【Technical field】 [0001] The invention relates to the technical field of chemical industry, in particular to a method for preparing high-purity dimethyl ether from synthesis gas in one step. 【Background technique】 [0002] Using coal as raw material to produce dimethyl ether through synthesis gas is a non-petroleum resource route with extremely important significance. [0003] At present, DME is produced from synthesis gas at home and abroad, and the reaction product is a multi-component mixture. To obtain DME products that meet the purity requirements of industrial grades, corresponding refining and separation must be carried out. Compared with methanol dehydration to produce dimethyl ether, the separation process of unreacted synthesis gas and methanol and carbon dioxide produced in the process of producing dimethyl ether from synthesis gas is more complicated. [0004] Chinese patent document CN 1215716 discloses a separation method of dimethyl ether, which is characteri...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are: large water consumption, and the by-product carbon dioxide in the separation process has not been further separated and utilized

The disadvantage of this process is that the utilization of energy is not reasonable: on the one hand, a large amount of external energy needs to be consumed in the separation process;

The purity of the dimethyl ether and methanol products produced by this separation method can only reach about 98%, and only alcohol ether fuels can be produced instead of industrial-grade pure dimethyl ether and methanol products.

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