Method for preparing paraxylene from toluene and methanol

Abstract

The invention relates to a method for preparing paraxylene from toluene and methanol. Full mixing of an aromatic hydrocarbon raw material and an alkylation reagent is guaranteed by employing a plurality of tandem circulating fluidized bed reactors for reactions and arranging a gas-phase mixer at the inlet of each reactor. The raw material toluene all enters from a first reactor; the alkylation reagent methanol is divided into a plurality of parts which separately enter via the reaction inlets and are uniformly mixed with toluene-containing material flow in corresponding mixers, and then the obtained mixtures enter corresponding reactors for a reaction; each fluidized bed reactor is equipped with an individual reactivator; a catalyst cyclically flows between the reactors and corresponding reactivators; and through adjustment of the circulation amount of the catalyst, optimal desired carbon formation of the catalyst is controlled, and continuous regeneration of the catalyst with carbon deposits in the reactions is realized. The method provided by the invention is applicable to industrial production process for preparing p-xylene through alkylation of toluene and methanol.

Description

technical field [0001] The invention relates to a method for preparing p-xylene from toluene and methanol. Background technique [0002] As an important basic chemical, p-xylene is mainly used for the production of purified terephthalic acid, and then for the production of polyester; in addition, it can also be used as a raw material for the production of pharmaceuticals, fragrances, inks and other industries. In recent years, with the rapid development of my country's polyester industry, the output of p-xylene has increased rapidly, but it still cannot meet the needs of the downstream PTA industry. In 2012, my country imported 6.28 million tons of p-xylene. In 2013, the import volume was 9.25 million tons. In 2014, the import volume reached 11 million tons, and the import dependence was as high as 52.4%. In the past ten years, my country's p-xylene import The volume is increasing year by year, and the import dependence is basically maintained at more than 40%. [0003] At ...

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Problems solved by technology

In addition, the amount of carbon deposited on the catalyst in the reactor also has a significant impact on the reaction results. An appropriate amount of carbon deposited can improve the selectivity of the target product p-xylene, but too high a carbon deposited reduces the activity of the catalyst and affects the conversion rate of raw materials; Therefore, controlling the appropriate carbon deposition amount of the catalyst in the reactor is also a key factor affecting the reaction result

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