A kind of recovery method of formaldehyde in prenol system synthesized by supercritical method

Abstract

The invention discloses a method of recovering formaldehyde from a supercritical method prenyl alcohol synthesis system. According to the method, formaldehyde-containing 3-alcohol crude product which is obtained by supercritical reactions is subjected to continuous rectification under a normal pressure; formaldehyde and a little of 3-alcohol are directly produced from the tower top; formaldehyde is enriched continuously and carries out self-polymerization to form polymer (solid) adhered on the internal wall of a condenser; then the formaldehyde polymer is separated by a scraper and a cold filtering method; and 3-alcohol obtained by tower top filtering and 3-alcohol in the tower bottom are dehydrated, weight-reduced, and rectified to carry out purification. By adopting the method, the formaldehyde content of 3-alcohol crude product can be reduced to less than 0.01%, the product becomes qualified, at the same time, the recovered formaldehyde polymer can be used as a raw material, and the waste is converted into valuable resource. The technology can remove formaldehyde without adding any alkaline chemical reagent, the cost is saved, and the discharged wastewater is greatly reduced. The method is green and environmentally-friendly, has a lower cost, and can be widely used in industry.

Description

technical field [0001] The invention relates to a new recovery method for formaldehyde in a prenol system synthesized by a supercritical method, which belongs to the field of fine chemicals. Background technique [0002] Prenol is an important intermediate in the synthesis of citral fragrances, vitamin products and pyrethroid pesticides, and its isomer 3-methyl-3-buten-1-ol (hereinafter referred to as 3-position alcohol) can be used in the synthesis Polycarboxylate concrete superplasticizer. The traditional preparation method of isopentenol is to obtain the 3-position alcohol through Prins condensation or carbonyl-ene reaction with formaldehyde (or paraformaldehyde) and isobutylene as raw materials, and then further isomerization. The method mainly includes two synthetic routes of adding an acid-base catalyst and a catalyst-free route. Wherein the Prins method of synthesizing 3-alcohol by acid-base catalysis, although product yield reaches more than 94%, added a large amou...

AI Technical Summary

Problems solved by technology

However, the existence of formaldehyde in the system makes the phenomenon of "blocking tower" often occur when the product is rectified

On the other hand, residual formaldehyde will make the quality of the 3-alcohol product unqualified, such as causing subsequent reaction catalyst poisoning, etc.

By adopting the method of chemical reaction (such as adding alkaline reagent) to remove formaldehyde, formaldehyde in the product can be removed, but because the alkaline reagent and aldehyde are consumed by chemical equivalents and cannot be recovered, the production cost is obviously increased; on the other hand, chemical The reaction produces a large amount of waste water, and the environmental cost is also significantly increased

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