Method for synthesizing trioxymethylene by methanol through condensation, oxidation and polycondensation

Abstract

The invention relates to a method for synthesizing trioxymethylene by methanol through condensation, oxidation and polycondensation. According to the invention, methanol and dilute formaldehyde with concentration of 5-30% separated from a trioxymethylene apparatus are taken as raw materials to synthesize methylal with concentration of 85-99.9%; methylal and air are subjected to catalyst oxidation to generate formaldehyde through an iron molybdenum method, through refining water and methylal unit tower waste water absorption, a formaldehyde aqueous solution with concentration of 70% is generated; high-concentration formaldehyde is introduced into a trioxymethylene synthetic tower, and the trioxymethylene is synthesized under existence of a strong-acid cation exchange resin catalyst, and trioxymethylene with content of 99.9% can be obtained through steps of rectification and concentration, extraction, rectification, and purifying. The method solves the problems of low conversion rate, selectivity and low yield during a trioxymethylene production process, solves the problems of low catalyst reaction efficiency and corrosivity, and solves the problems of complex technology and high energy consumption. The method provides good raw materials for producing PODE, and realization of industrialization of PODE can solve the problem of excess production capacity of methanol in our country.

Description

technical field [0001] The invention relates to a method for synthesizing trioxane with methanol through condensation, oxidation and polycondensation processes. In particular, it relates to a catalyst using a strongly acidic styrene-based cation exchange resin. It belongs to the technical field of chemical synthesis. Background technique [0002] Paraformaldehyde (TOX) and many related industries are extremely important links in the carbon-one chemical industry chain. First of all, paraformaldehyde is the raw material for preparing polyoxymethylene (POM) engineering plastics. POM is one of the three major engineering plastics in the world, and the domestic demand is increasing day by day. At the same time, paraformaldehyde can replace formaldehyde and is widely used in the preparation of bulk chemicals and fine chemicals, including disinfectants, antibacterials, fumigants, insecticides, and adhesives. The raw material can also be used to synthesize isooctyl thioglycolate ...

AI Technical Summary

Problems solved by technology

But no matter what type of catalyst is used above, the biggest problem of these methods for synthesizing paraformaldehyde based on aqueous formaldehyde solution is that the formaldehyde solution needs to be concentrated to more than 65%, and the paraformaldehyde yield in the reaction phase is very low (under the above conditions When sulfuric acid and ionic liquid are used as catalysts, the equilibrium concentration of paraformaldehyde in the reaction kettle liquid is only about 1.8% and 2.5% respectively (mass percentage), and formic acid, methyl formate, etc. are generated at the same time, so it must be produced by reactive distillation process Paraformaldehyde

This type of process also generally has the problem of recovery and treatment of dilute formaldehyde. The recovery of dilute formaldehyde basically adopts a distillation scheme, which has a large recovery volume, high energy consumption, high requirements for equipment materials, and large investment.

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