Improved method for preparing methyl methacrylate

Abstract

Tert-butyl alcohol / isobutene is used as a raw material to be oxidized to generate methylacrolein, and the methylacrolein is oxidized and esterified to produce methyl methacrylate; methacrylic acid byproduct is treated and purified to prepare methacrylate, and the organic salt can be used as an auxiliary material of a dispersing agent and a coating. Through optimization of process parameters, generation of the by-products is reduced, the yield and efficiency of the method are improved, and the method has the advantages of simple process, low cost, cleanness, environmental protection and the like.

Description

technical field [0001] The invention relates to a simplified preparation and purification process of methacrolein and an improved method for preparing methyl methacrylate through oxidative esterification. Background technique [0002] Methyl methacrylate (MMA), as an important chemical polymerization monomer, can generate polymethyl methacrylate through self-polymerization and copolymerization to generate multiple copolymers of methyl methacrylate. In addition, methyl methacrylate can also be combined with various The transesterification reaction of alcohols produces various special esters based on methacrylic acid, which has great industrial application value. [0003] At present, the main processes for the industrial production of methyl methacrylate include the traditional acetone cyanohydrin method and isobutylene oxidation method. Compared with the acetone cyanohydrin method, the isobutylene oxidation method uses the C4 resource of the refinery as the raw material, and...

AI Technical Summary

Problems solved by technology

But the problem that exists is 1) when aldol ratio reduces, and material circulation reduces, productive rate declines

2) In addition, reaction by-products such as carbon dioxide, methyl formate, and dimethacrolein cannot be avoided

[0009] In addition, in the prior art, Evonik Rohm Co., Ltd. patents CN105683148A and CN108124444A directly combine the Mannich reaction and oxidative esterification reaction. The disadvantages of this method are 1) the water in the crude methacrolein product Increased content leads to an increase in methacrylic acid, a by-product of the oxidative esterification step

3) Formaldehyde in the Mannich reaction has a reducing effect, which may damage the oxidative esterification catalyst, thus shortening the life of the catalyst

4) In addition, formaldehyde-formed oligomers (paraformaldehyde) react with methacrolein during the oxidative esterification, resulting in a subsequently stable and insoluble polymer that can adsorb onto the catalyst reducing its activity , blocking the reaction device, causing the continuous reaction to stop

The disadvantage of this method is that a large amount of sulfuric acid that can corrode equipment must be added

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