Method for preparing methyl methacrylate by aldol condensation of methyl acetate and formaldehyde

Abstract

The invention provides a method for preparing methyl methacrylate by aldol condensation of methyl acetate and formaldehyde, and belongs to the technical field of preparation of methyl methacrylate. The method comprises the following steps: preheating methyl acetate, returned methyl propionate, a formaldehyde source, methanol, water and oxygen-containing fluidized gas as materials, enabling the materials to enter a fluidized-bed reactor, under the action of a catalyst bed material in an internal-circulation fluidized bed, generating aldol condensation reaction to produce MMA, and finishing regeneration of a catalyst. The method provided by the invention has the beneficial effects that by utilization of the characteristic of internal-circulation movement of the fluidized-bed material, a little amount of oxygen is introduced at the lower part of the fluidized bed to form a local oxygen-containing area to carry out periodical regeneration on the catalyst bed material, so that the serious side reaction in the presence of a large amount of oxygen and insufficient and non-uniform regeneration of the fluidized-bed material are avoided, regeneration of the catalyst in the aldol condensationreaction is realized, the catalyst can maintain high activity for a long term, and the catalyst utilization efficiency is improved; the problems of inactivation and short service life of a catalyst due to easy carbon deposition in the aldol condensation process of the methyl acetate, the methyl propionate and the formaldehyde are solved.

Description

technical field [0001] The invention belongs to the technical field of methyl methacrylate preparation, in particular to a method for preparing methyl methacrylate through aldol condensation of methyl acetate and formaldehyde. Background technique [0002] Methyl methacrylate (MMA) is an important organic chemical raw material, widely used in the production of organic glass (PMMA), PVC additives, coatings and other fields. The traditional industrial production technology of MMA is the acetone cyanohydrin method (ACH method). This route uses highly toxic hydrocyanic acid as a raw material, and is mostly produced with acrylonitrile equipment. The reaction process consumes a large amount of sulfuric acid, which requires high equipment materials and side effects. A large amount of ammonium bisulfate is produced, the process is long, and the pressure on environmental protection is high. At present, the newly developed MMA synthesis technology includes isobutylene method (C4 meth...

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Problems solved by technology

It is also reported that domestic production capacity of polyvinyl alcohol (PVA) will exceed 1.7 million tons in 2018, and nearly 2.8 million tons of methyl acetate will be produced as a by-product. The PVA industry generally adopts the technical scheme of hydrolyzing methyl acetate to produce acetic acid and methanol. The consumption is high and the process is complicated. If this part of production capacity can be effectively utilized, the production cost of polyvinyl alcohol can be reduced and environmental pollution can be reduced.

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