System and method for preparing durene by utilization of toluene and methanol

Abstract

The invention discloses a system and a method for preparing durene by the utilization of toluene and methanol. The problems such as limited sources of raw materials, high cost of raw materials, low yield of durene, low purity of durene and the like existing in the durene preparation technologies in the prior art are solved. The prepared durene has high yield and high purity. The technical scheme comprises the following steps: preheating toluene and methanol and introducing the preheated toluene and methanol into an alkylation reactor, and reacting at the reaction temperature of 350-400 DEG C at the reaction pressure of 2.0-5.0 MPa at the mass space velocity of 1-5 h<-1> for the reaction retention time of 1-5 s by using an HZSM-5 molecular sieve catalyst as a reaction catalyst; removing moisture and dry gas by oil-water separation of the reaction liquid, removing toluene, mixed xylenes and mixed trimethylbenzenes by rectifying the oil phase, and cooling for crystallization so as to obtain pure durene.

Description

technical field [0001] The invention belongs to the field of petrochemical synthesis, and in particular relates to a system and method for preparing durene by using toluene and methanol. Background technique [0002] Durene, that is, 1,2,4,5-tetramethylbenzene, is an important fine chemical raw material, and is an important raw material for medicine, powder coating matting agent, dye, pesticide, and surfactant. The most important use is to produce pyromellitic dianhydride and further produce polyimide. Polyimide has the advantages of thermal oxidation stability and good insulation, and is widely used in aerospace, electrical insulation, atomic energy industry, satellite, nuclear submarine, microelectronics and other precision machinery. [0003] At present, the production process of durene mainly includes: C10 component crystallization separation method, trimylene isomerization method, trimylene chloromethylation method, trimylene gas phase isomerization disproportionation ...

AI Technical Summary

Problems solved by technology

The process of crystallization and separation of carbon ten components is complicated, the yield of durene is low, and the source of raw materials for heavy aromatics rich in durene is limited, which cannot meet the market demand of downstream homoanhydride or polyimide; The process of producing durene also has the defects of limited source of raw materials, catalyst deactivation, and insufficient stability; the method of methylation of methylbenzene with methanol and the method of chloromethylation of methylbenzene have high raw material costs, limited sources, and the use of Catalyst activity, selectivity and stability are unsatisfactory, corrosion is serious, and the environment is polluted; the reaction conditions of the gas-phase isomerization and disproportionation of p-trimethylbenzene are harsh, and industrialization has not yet been realized; the research on the alkylation reaction of benzene / toluene with methanol as raw material is in the domestic market. It mainly produces p-xylene, and there are few related studies on the production of durene; the method of producing durene from methanol or synthesis gas has many by-products, the degree of alkylation is difficult to control, and the catalyst is easily deactivated.

[0004] Although the relevant technology has disclosed the use of methanol and toluene as raw materials to prepare trimethylbenzene and tetramethylbenzene, in this method, it has shown that durene has good selectivity, but the yield of durene is between Below 10%, the yield of durene is low, the utilization rate of raw materials is low, the preparation cost of durene is high, and it is difficult to realize industrial production

[0005] Therefore, the raw materials for the preparation of durene mainly come from naphtha cracking or catalytic reforming of aromatics. With the increasing shortage of petroleum resources, the raw materials for the preparation of durene are subject to more and more restrictions.

[0006] To sum up, there is still a lack of effective solutions for problems such as limited sources of raw materials, high cost of raw materials, low yield of durene, and low purity of durene in the prior art.

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