Preparation method of high-purity 2,6-di-tert-butyl p-cresol

Abstract

The invention relates to a preparation method of high-purity 2,6-di-tert-butyl p-cresol, and belongs to the technical field of organic chemical synthesis. According to the method, ethanol and water are recrystallized twice, so that the purity of the product is improved, and the purity of the target product BHT can reach 99.99% or above; besides, water and ethanol separated from the primary motherliquor through the rectifying tower can be recycled, the rectified mother liquor is guided into a crystallization system to be recycled, and the yield of 2,6-di-tert-butyl-p-cresol is increased; meanwhile, the BHT concentration of the secondary mother liquor is detected, recrystallization is conducted, and the yield of BHT reaches 99.89% or above. Secondly, under the catalytic action of the modified mesoporous silica supported Nb / Mo / Cu three-metal active center catalyst, the conversion rate of mixed cresol and the selectivity of di-tert-butyl cresol are greatly improved, and the conversion rate of the raw materials is further improved under the synergistic effect of ultrasonic cavitation.

Description

technical field [0001] The invention relates to a preparation method of high-purity 2,6-di-tert-butyl-p-cresol, which belongs to the technical field of organic chemical synthesis. Background technique [0002] 2,6-Di-tert-butyl-p-cresol (BHT) is a common phenolic antioxidant widely used in food processing, feed additives, petroleum products, plastics and rubber, etc. It is a multi-purpose, non-coloring , The largest amount of phenolic antioxidants. [0003] At present, the production process of isobutylene and p-cresol under the action of a catalyst to produce the antioxidant BHT is mostly used at home and abroad. The catalyst has experienced the evolution of liquid concentrated sulfuric acid and solid sulfonic acid. Chinese patent CN 103694085B reports that p-cresol and isobutanol are used as raw materials, and concentrated sulfuric acid is added as a catalyst to synthesize the antioxidant BHT; this method not only produces a large amount of waste water, but the synthesis ...

AI Technical Summary

Problems solved by technology

Chinese patent CN 103694085B reports that p-cresol and isobutanol are used as raw materials, and concentrated sulfuric acid is added as a catalyst to synthesize antioxidant BHT; this method not only produces a large amount of waste water, but the synthesis efficiency is low, and the use of concentrated sulfuric acid catalyst seriously corrodes the equipment

Chinese patent CN102311318A has reported using p-cresol and isobutylene as raw materials, adding p-arylsulfonic acid as a catalyst to synthesize 2,6-di-tert-butyl p-cresol; Wastewater by-products, but arylsulfonic acid will also cause greater corrosion to the reactor. In addition, the cost of using p-cresol as a raw material is relatively high

[0004] And the existing solid catalyst, such as Chinese patent CN107737605A, has reported that any modified molecular sieve in ammonium phosphate, ammonium hydrogen phosphate, and ammonium dihydrogen phosphate is used as a carrier to support active component A and active component B, wherein the The molecular sieve is Hβ molecular sieve, hydrogen mordenite, HY molecular sieve, USY molecular sieve, REY molecular sieve or SAPO-5 molecular sieve, active component A is Co, Cu, Ni or Fe, active component B is phosphotungstic acid, silicotungstic acid , phosphomolybdic acid, silicomolybdic acid, and sodium tungstate, but there are still problems of low conversion rate of raw materials and low selectivity of products

[0005] At present, there is still the problem that mixed cresols (m-cresol and p-cresol) are not easy to separate. As reported in Chinese patent CN102898281A, mixing m-p-cresol and isobutylene in catalyst sulfuric acid or solid S-ZrO 2 The alkylation reaction is carried out under the catalysis of the catalyst, and after rectification, three products of 2,6-di-tert-butyl-p-cresol, m-cresol and 6-tert-butyl-m-cresol are co-produced, but the patent still There is a problem of corroding equipment when sulfuric acid is used, and S-ZrO is used 2 When the conversion rate of raw materials is low, the problem of low selectivity of 2,6-di-tert-butyl-p-cresol and 4,6-di-tert-butyl-m-cresol

[0006] The purification process of BHT generally adopts the solvent crystallization method at present, as CN110759815A reports adopting the mode purification BHT of salt water crystallization and alcohol water crystallization once, yet some BHT can not be reclaimed in salt water and alcohol water, cause BHT yield to reduce

[0007] Therefore, at present, liquid catalysts still have relatively large corrosivity, and solid catalysts still have the problems of low conversion rate of raw materials and low product selectivity. In addition, solvent crystallization is commonly used in the purification of 2,6-di-tert-butyl-p-cresol. Problems of low yield and low product purity of BHT products