Four types of NiMo/(Al2O3+molecular sieve)catalysts were prepared using HY,Beta,ZSM-5 and MOR zeolites as acidic components and n-butylbenzene as the model compound.Then the hydrocracking reaction of n-butylbenzene was investigated on a high pressure fixed-bed micro-reactor.On this basis,the effects of zeolite types on the conversion rate of n-butylbenzene and the distribution of dealkylation/broken side-chain reaction,cyclization and dehydrogenation are systematically investigated.The results show that at the temperature of 340-400 ℃,pressure of 4.0 MPa,volume ratio of hydrogen to n-butylbenzene of 500 and reaction time of 2 h,n-butylbenzene mainly underwent dealkylation/broken side-chain reaction and cyclization reaction;over the four catalysts,the increase of temperature is beneficial to the transformation of n-butylbenzene and the dealkylation/broken side-chain reaction,and able to inhibit the cyclization and dehydrogenation reactions.When the conversion of n-butylbenzene is similar(about 46％),the type of zeolite can significantly affect the yield and distribution of the products,especially the light aromatic mixture(BTEX)of benzene,toluene,ethylbenzene and xylene.The BTEX selectivity of NiMo/(Al2O3+HY),NiMo/(Al2O3+Beta)and NiMo/(Al2O3+MOR)catalysts with 12-MR structure are high and up to 40.41％,37.04％and 43.65％,respectively.By contrast,the selectivity of BTEX over NiMo/(Al2O3+ZSM-5)catalyst with 10-MR structure is only 19.30％.The total acid amount of the zeolites is also an important factor affecting the BTEX selectivity,and the selectivity of BTEX is higher over the NiMo/(Al2O3+MOR)catalyst with the lowest total acid amount.
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