Method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane

Abstract

The invention relates to a method for preparing polyformaldehyde through co-production of trioxymethylene and dioxolane. The method comprises the following steps of: synthesizing ethylene glycol and formaldehyde in a trioxymethylene crude product into hemiacetal, performing separation, and synthesizing dioxolane, thereby simplifying the subsequent separation and refining process of the dealdehydedtrioxymethylene crude product. According to the process, the amount of dilute aldehyde in the polyformaldehyde monomer preparation process is reduced, the energy consumption of the preparation process is reduced, and the product quality of the polyformaldehyde monomer is improved.

Description

technical field [0001] The disclosure relates to a process for preparing polyoxymethylene through the joint production of paraformaldehyde and dioxane, and specifically relates to the production field of polyoxymethylene. Utilize ethylene glycol and formaldehyde in the crude paraformaldehyde to synthesize hemiacetal, which is used to synthesize dioxane after separation, and the subsequent separation and purification process of the dealdehydeized crude paraformaldehyde is simplified. Background technique [0002] Polyoxymethylene is one of the five major engineering plastics in the world. my country has become the largest producer and consumer of polyoxymethylene in the world. At the same time, polyoxymethylene is an important branch of C1 chemistry in the coal chemical industry. Advantages of mass production. However, the current situation of the domestic POM production industry is "big but not strong", the production equipment technology is backward, the product structure i...

AI Technical Summary

Problems solved by technology

The current process generally adopts the method of crystallization or extraction to carry out preliminary separation of the synthetic product, plus the refining of rectification, but it is still unable to obtain paraformaldehyde with ultra-purity or close to 100% purity. At the same time, the extraction process introduces new solvents, resulting in The separation system is more complicated, resulting in energy consumption and dilute aldehyde recovery difficulties, and often requires a separate dilute aldehyde recovery unit for recovery

[0014] Second, in the existing and above-mentioned paraformaldehyde preparation process, there are difficulties of large amount of dilute aldehyde and high recovery energy consumption. For example, every ton of paraformaldehyde produced will produce about 4 tons of 15% dilute formaldehyde

Therefore, the dehydration of formaldehyde solution is a complicated physical and chemical process, which leads to the extremely high energy consumption of rectification and recovery of dilute aldehyde

[0016] Third, dioxane can form an azeotrope with water, with an azeotropic point of 70-73°C and a water content of 6.7%, making separation difficult. At the same time, due to the presence of formaldehyde, the local concentration in the separation unit is too high, and formaldehyde polymers are easily formed , resulting in clogging of the pipes of the distillation tower equipment, and the presence of formic acid, which easily corrodes the equipment and pipes

Low efficiency, high difficulty, high energy consumption and high pollution

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