Method of efficiently preparing alpha,beta-unsaturated carboxylic acids or esters

Abstract

The invention discloses a method of efficiently preparing alpha,beta-unsaturated carboxylic acids or esters, and belongs to the technical field of industrial catalysis in petrochemical engineering. Formaldehyde or sources thereof and carboxylic acids or esters are subjected to a gas-solid phase reaction under the existence of a gamma-Al2O3 catalyst supported by a K-sourced or Cs-sourced precursor, and under the existence of an alcohol as appropriate. The carboxylic acids or esters which are reactants have a general formula that is R3-CH2-COOR4, wherein the R4 is hydrogen or alkyl, and the R3 is hydrogen, alkyl or aryl. The prepared alpha,beta-unsaturated carboxylic acids or esters comprise acrylic acid, alkyl acrylic acid, 2-butenoic acid, cyclohexene-1-carboxylic acid, maleic acid, itaconic acid, fumaric acid, and alkyl esters and methylene-substituted lactones of the acrylic acid, the alkyl acrylic acid, the 2-butenoic acid, the cyclohexene-1-carboxylic acid, the maleic acid, the itaconic acid and the fumaric acid. The sources of the formaldehyde comprise trioxymethylene, formalin and methylal. The method has advantages of high yield, high selectivity, wide sources of catalyst supporters, low cost, simple and convenient catalyst preparation processes, and the like.

Description

technical field [0001] The invention belongs to the technical field of industrial catalysis in petrochemical industry, and relates to a method for preparing α, β-unsaturated carboxylic Acids or esters, especially acrylic acid or esters (such as alkacrylic acid or alkyl alkacrylic acid esters, especially (meth)acrylic acid or alkyl (meth)acrylates), in particular, but not exclusively, It is about a method for preparing (meth)acrylic acid or its alkyl ester (such as methyl methacrylate) by condensation of propionic acid or its alkyl ester and formaldehyde or its source in the presence of a catalyst. In particular, the invention relates to a process for the manufacture of methacrylic acid (MAA) and methyl methacrylate (MMA). [0002] Background technique [0003] α, β-unsaturated carboxylic acid or ester can be represented by the formula R 3 ?CH 2 ?COOR 4 The carboxylic acid or ester is prepared by reacting with a suitable source of formaldehyde, wherein R 4...

AI Technical Summary

Problems solved by technology

When the molar ratio of propionic acid and formaldehyde is 1:2, based on propionic acid, the selectivity of methyl methacrylate and methacrylic acid is as high as 85.2%, and the highest yield is only 23.3%. The effect is better, but the disadvantage is still There is methyl methacrylate hydrolysis product methacrylic acid, which will increase the difficulty and cost of subsequent separation, and reduce the yield of the main product methyl methacrylate

Images