Method for dimethylbenzene and trimethylbenzene by alkylating benzene and methanol

Abstract

The invention relates to a method for dimethylbenzene and trimethylbenzene by alkylating benzene and methanol, which comprises steps as follows: (1) raw material benzene is mixed with cyclic benzene, methylbenzene and partial dimethylbenzene recovered from rectification, the mixture is heated and gasified to reaction temperature, the mixture and methanol enter an alkylating reactor, and alkylating reaction is performed in the presence of an acidic catalyst to obtain a product mixture of methylbenzene, dimethylbenzene, trimethylbenzene and the like; the unreacted benzene and generated methylbenzene and partial dimethylbenzene return to continue reaction with methanol so as to generate C8+ aromatic hydrocarbons; (2) the mixed aromatic hydrocarbons from the alkylating reactor enter a methylbenzene removal tower to be rectified and separated, the mixture of benzene, methylbenzene and water at the tower top is cooled and subjected to oil-water separation, the oil phase returns to the alkylating reactor for circular reaction, and the water phase is recycled after treatment; oil at the tower bottom enters a dimethylbenzene rectification tower to be rectified and separated, part of mixed dimethylbenzene obtained from the tower top returns to the reactor, and the rest is used as the product; and oil at the tower bottom enters a trimethylbenzene rectification tower to be rectified, thereby obtaining the mixed trimethylbenzene product at the tower top.

Description

technical field [0001] The invention belongs to the field of organic chemical synthesis, in particular to a method for preparing xylene and trimethylbenzene by alkylation of benzene and methanol. Background technique [0002] Xylene and trimethylbenzene are important chemical raw materials and have a wide range of uses. Among them, p-xylene is mainly used to produce terephthalic acid, and then produce ethylene terephthalate, a raw material for polyester. Meta-xylene is used to produce isophthalic acid, and o-xylene is used to produce phthalic anhydride, which in turn produces various plastic plasticizers. [0003] With the development of fine chemical industry in recent years, various isomers of trimethylbenzene have been widely used. [0004] Trimethylbenzene can be used to synthesize trimellitic anhydride (partial anhydride), and many high value-added fine chemical products can be synthesized from partial anhydride (TMA). Non-toxic alkyd resin, epoxy resin curing agent,...

AI Technical Summary

Problems solved by technology

[0014] There are many reports about the alkylation of benzene or toluene and methanol to produce xylene with methanol as the alkylating agent, but there is no report on the technology of producing trimethylbenzene by the alkylation of benzene and methanol

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