Method for preparing dimethylbenzene through methylation and transalkylation

Abstract

The invention relates to a method for preparing dimethylbenzene through methylation and transalkylation, and mainly aims to solve the problems that the yield of dimethylbenzene is determined by the link relative ratio of methyl benzene in raw materials, and when a heavy aromatic raw material is insufficient, the output of the dimethylbenzene is low and a lot of byproduct benzene is generated at the same time in the existing toluene disproportionation or toluene disproportionation and transalkylation technologies. The problems are well solved by adopting the technical scheme which is s follows: the method comprises the following steps of: by using a methylation agent and aromatic hydrocarbons which has less than 12 Cs and does not contain or only contains a small amount of dimethylbenzene as raw materials, under the condition that the reaction temperature is 300-500 DEG C, the reaction pressure is between the normal pressure and 10.0MPa and the weight space velocity of the raw materials is 0.3-10h<-1>, contacting the raw materials with a solid acid catalyst to ensure that an alkylation reaction is performed on methanol and the aromatic hydrocarbons, and performing transalkylation among the aromatic hydrocarbons to obtain the dimethylbenzene. The method can be used in industrial production of dimethylbenzene.

Description

technical field

[0001] The invention relates to a method for producing xylene through methylation and transalkylation. Background technique

[0002] Xylene is one of the main basic organic raw materials in the petrochemical industry, and has a wide range of uses in many chemical production fields such as chemical fibers, synthetic resins, pesticides, medicines, and plastics.

[0003] Industrially, xylene is mainly obtained by separation of catalytic reforming, catalytic cracking, coking process products and pyrolysis gasoline, and can also be produced by toluene disproportionation, benzene and carbon nine alkyl transfer, or by toluene and C 9-10 A and other heavy aromatics derived from methyl transfer.

[0004] In recent years, there have been many research reports on catalysts for toluene disproportionation and / or transalkylation to produce xylene at home and abroad. U.S. Patent No. 5,475,179 discloses a catalyst for the disproportionation of toluene, which is SiO 2 The ...