Method for preparing pure p-cresol and pure m-cresol by separating industrial mixed p-cresol and m-cresol

Abstract

The invention relates to a method for preparing pure p-cresol and pure m-cresol by separating industrial mixed p-cresol and m-cresol. In specific, the invention relates to a method for preparing pure p-cresol and pure m-cresol through a complexion separation method by taking industrial mixed p-cresol and m-cresol as the raw material. Compared with the separation method in the prior art, the method provided by the invention can obtain p-cresol product and m-cresol product at a time and comprises the advantages that through the coupling of separation processes of p-cresol and m-cresol, the proportion of p-cresol and m-cresol in the m-cresol extraction raw material is increased, the residual p-cresol and m-cresol are separated in a circulatory manner, and the extraction efficiency of m-cresol is improved to the greatest extent; three wastes are not generated in the whole separation process, the operation is carried out under ordinary pressure, the requirement on equipment is low, and the method belongs to an environment-friendly and green separation technological method.

Description

technical field [0001] The present invention relates to a kind of method that separates inter-industrial p-cresol to prepare pure p-cresol and pure m-cresol. A method for preparing pure p-cresol and pure m-cresol. Background technique [0002] The three isomers of cresol (o-cresol, p-cresol and m-cresol) are all important chemical raw materials, but because of their very close properties, especially p-cresol and m-cresol, the two The normal pressure boiling point difference of cresol is only 0.5 degrees, it is difficult to separate by rectification, crystallization separation and extractive distillation will consume a lot of energy, low efficiency and high cost. The cresol produced by refining crude phenol in coal chemical industry or chemical synthesis is basically a mixture of m-cresol and p-cresol. Most of this m-p-cresol mixture is used for the production of low value-added applications such as polyester enameled wire field, failing to make full use of the value of m-c...

AI Technical Summary

Problems solved by technology

Among them, the azeotropic distillation method is in the presence of sodium p-cresolate, p-cresol can be distilled out with water azeotropically, but this method consumes too much energy; the high-pressure crystallization separation method requires a pressure of 100-300 MPa, which requires too much equipment. High, the investment is too large; the molecular sieve adsorption separation method is difficult to select and prepare molecular sieves, and the adsorption capacity is limited, and less is used; the alkylation separation method requires alkylation and dealkylation, high vacuum distillation, etc., and the equipment is relatively Complex, large investment and high cost; the chelate-like separation method is simple to operate, the raw materials are easy to obtain, and various raw materials can be recycled

[0004] It is known that there are some prior art, such as "Liaoning Chemical Industry" 1977, 04, 8-13; Chemical Research and Application, Volume 15, No. 6, 871-872; patent documents US3855195, CN1127241A, JP1287049A, etc. relate to compound separation method to separate m-cresol and p-cresol, but the ultimate goal of the separation is only to separate m-cresol or p-cresol as a single product, and the remaining m-p-cresol does not mention further processing scheme, if the fraction cannot be further purified, it is not economical to sell it at a low price in the form of a mixture

None of the above-mentioned articles or patents involves an integrated full-flow process for obtaining m-cresol products and p-cresol products at the same time through one separation