DMM2 preparation process and system

Abstract

The invention discloses a DMM2 preparation process. The DMM2 preparation process includes that methylal and water are taken as reaction materials, methyl alcohol generated from reaction as well as partially unconverted water and the methylal in the materials are continuously steamed out in azeotropy at the tower top of a catalytic-distillation tower under catalytic distillation of the catalytic-distillation tower, the DMM2 generated from reaction enters the tower bottom of the catalytic-distillation tower to obtain reaction liquid with different DMM2 concentrations, and a DMM2 product is obtained after the reaction liquid is extracted and separated in distillation; mass fraction of the water in the reaction materials is 0.1-15%, and conversion rate of the water is 5-100%; reaction temperature of the catalytic-distillation tower is 40-200DEG C, reaction pressure is 0.1-3.0MPa, and reflux ratio is 0.2-10. The DMM2 can be generated in highly selective reaction, the process method is simple in procedure, the materials are cheap and easy to obtain, problems that existing various polymethoxy dimethyl ether production routes for producing the DMM2 are quite difficult and complicated in process are solved, the production process of the DMM2 is greatly shortened, and investment and energy consumption are remarkably lowered.

Description

technical field [0001] The invention belongs to the technical field of chemical production technology, and mainly relates to a preparation technology and system of polymethoxy dimethyl ether dimer, namely DMM2. Background technique [0002] my country's resource endowment of "rich coal, poor oil, and little gas" determines the country's industrial policy of vigorously supporting and developing clean coal chemical industry and its downstream products. Polyoxymethylene dimethyl ether uses methanol as a raw material, which can act as a bridge between coal chemical industry and petrochemical industry. The development of advanced polyoxyl dimethyl ether production methods and devices is conducive to saving crude oil energy. For my country Energy storage and energy security have important strategic significance. [0003] The general structural formula of polyoxymethylene dimethyl ether is CH 3 O(CH 2 O)nCH 3 , referred to as DMMn or PODEn, etc., is currently recognized as an ox...

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Problems solved by technology

Patent CN201410008770.0 discloses a production device system and production process of polyoxymethylene dimethyl ether, the reaction product of which is treated by the adsorption deacidification system, the first to the third rectification tower system and the adsorption dehydration system, respectively to obtain DMM2 and DMM3~4 are two products, the whole process is complicated, the adsorption deacidification and dehydration system needs to be regenerated repeatedly, a large amount of DMM2 is circulated, the yield of DMM2 as a product is significantly lower than that of DMM3~4, and it still contains formaldehyde and other impurity components

Patent CN201310684776.5 discloses a preparation process device and method of polyoxymethylene dimethyl ether. The reaction products are separated by flash evaporation, primary and secondary extraction to obtain DMM2~5 products respectively, and a large amount of extractant is used to circulate , also has the disadvantages of complex process and low yield of DMM2

[0007] Above-mentioned technological method is not the technological process that obtains DMM2 as main product, and its main product is all DMM3~5 or DMM3~8, and in the mixed reaction liquid flowing out of reactor, the DMM2 component that content is second only to methylal needs a large amount of The circulation between the reaction system and the separation system requires high energy consumption and high-quality DMM2 products cannot be separated. In order to obtain a small amount of DMM2 products, it is generally necessary to use physical or chemical methods to remove formaldehyde from the mixed reaction solution. The process flow Long, there is intermittent operation equipment, it is easy to generate solid waste, the utilization rate of formaldehyde is low, and the yield of DMM2 is significantly lower than that of DMM3~5 or DMM3~8

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