Catalyst for alkylation separation of m-cresol and p-cresol and separation method

Abstract

The invention relates to a novel catalyst for alkylation separation of m-cresol and p-cresol and a separation method. Imidazole type ionic liquid 4-(3-methyl-1-imidazol)-1-butyl sulfonic acid hydrogen sulfate with the purity of 99% is taken as the catalyst for alkylation reaction of cresol. A cresol mixture and an alkylation reagent, namely methyl tert-butyl ether perform hydrocarbyl substitution reaction to generate di-tert-butyl substitutes (4, 6-di-tert-butyl-m-cresol and 2, 6-di-tert-butyl-p-cresol) of m-cresol and p-cresol with greater boiling point difference. The di-tert-butyl substitutes are separated by utilizing a rectification method according to the boiling point difference between the two, and then tert-butyl groups in the di-tert-butyl substitutes of the cresol are removed to obtain pure m-cresol and p-cresol so as to achieve the purpose of separating the m-cresol and the p-cresol. The transformation rate of the m-cresol after the reaction is 85-89%, the transformation rate of the p-cresol is 78-81%, and alkylation products are 6-tert-butyl-m-cresol, 2-tert-butyl-p-cresol, 4, 6-di-tert-butyl-m-cresol and 2, 6-di-tert-butyl-p-cresol.

Description

technical field [0001] The invention relates to a separation and purification method for m-cresol and p-cresol, in particular to a novel catalyst and separation method for alkylating and separating m-p-cresol, belonging to the field of chemical mass transfer and separation. Background technique [0002] m-cresol and p-cresol are important organic synthesis intermediates. Mixed cresols are a by-product of coal chemical industry. Since m-cresol has an atmospheric boiling point of 202.2°C and p-cresol has an atmospheric boiling point of 201.9°C, the boiling points of the two are very close, and it is difficult to separate them by conventional distillation methods. Crystallization and alkylation are two commonly used methods for the separation of m-p-cresol. Crystallization method, such as the process of preparing high-purity p-cresol from Chinese patent CN1130618A crude p-cresol, is a process for preparing high-purity p-cresol with crude p-cresol as a raw material. Fractional...

AI Technical Summary

Problems solved by technology

But the alkylation process in the traditional alkylation method has many disadvantages

Traditional alkylation catalyst liquid acid (sulfuric acid, phosphoric acid, etc.) is very corrosive to equipment, and after alkylation, it needs to be washed with alkali and water to remove the residual acid. If the acid is not removed, the product will be The dehydrogenation reaction occurs in the rectification process, which brings a series of problems, increases the production cost, the catalyst cannot be recycled well, and the side reactions cannot be well controlled, making it difficult to separate the product

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