Study On Aromatic Hydrocarbon Catalysts Coupling Methanol With Low Carbon Hydrocarbons

Aromatics are important petrochemical raw materials.They are often used in synthetic rubber,fibers,resins,etc.,and have a wide range of applications.At present,the process of co-production of methanol and low-carbon hydrocarbons from non-petroleum resources such as coal and natural gas has gradually become a new green and sustainable process.However,the main problem restricting the development of this process is the choice of catalyst.HZSM-5 zeolite Due to its unique three-dimensional microporous topology,molecular sieves have good shape selectivity,large specific surface area,strong acidity,and good hydrothermal performance.They have been widely used in the petrochemical field,but they have not been modified acid HZSM-5.Zeolite molecular sieve catalysts have low selectivity to aromatics and are easily deactivated.Therefore,this paper mainly uses HZSM-5 as a carrier.Through research on its modification,a better performance coupling aromatization catalyst is obtained,and its reaction mechanism is preliminary explored.In this paper,using ZSM-5 molecular sieve as the carrier,the supported metal oxide catalyst X%M₂O_n/ZSM-5 was prepared by ion exchange method and equal volume impregnation method.The evaluation results examined the effects of carrier silicon-aluminum ratio,active component types,metal oxide loading and other conditions on the catalyst aromatization reaction performance.The results are as follows:when the carrier silicon-aluminum ratio is 50,the molecular sieve exhibits good catalysis Performance,the methanol conversion rate is 99%,the n-pentane conversion rate is 93%,the oil phase yield is 22%,the aromatic hydrocarbon yield in the product is 60%,and the xylene selectivity is 24%;when the active component is selected M5₂O_n,and its loading is1%,the methanol conversion rate is 99%,n-pentane conversion rate is 83%,the oil phase yield is 32%,the aromatics yield in the product is 67%,and the xylene selectivity is 32%.The effects of process conditions such as reaction temperature,pressure and volume space velocity on the catalytic performance of 1-M5₂O_n/ZSM-5 catalyst were investigated by a single factor experiment method.The results showed that the optimal process conditions for the coupling of methanol and low-carbon hydrocarbons to produce aromatics It is reaction temperature 400?,pressure 1.0MPa,volume space velocity 2h^-1,methanol conversion rate under this condition is 99%,n-pentane conversion rate is 83%,oil phase yield is 32%,aromatic content is 74%The selectivity of xylene is 38%,the stability of the catalyst is good,and it has good economic benefits.It can be used in the industrial coupling of methanol and low-carbon hydrocarbons to produce aromatics.Finally,the catalytic mechanism of the coupling reaction of methanol and n-pentane to produce aromatics was preliminarily explored.The results showed that the coupling reaction of methanol and n-pentane to produce aromatics conformed to the mechanism of the hydrocarbon pool.