关键词: 沸石催化, ZSM-5, 汽油降烯烃;芳构化, 异构化

Abstract: Here, aggregated ZSM-5 zeolite nanocrystals were directly synthesized by the hydrothermal synthesis method without using any mesopore templates. The combination modification methods for the prepared ZSM-5 zeolite were developed via the introduction of hydrothermal treatment with ammonia solution and impregnation of La and P elements, in order to adjust the acidic properties of zeolite and then to improve the catalytic performance of the 1-hexene isomerization and olefin reduction of heavy FCC gasoline, respectively. After the modification of bulk HZSM-5 zeolite with hydrothermal treatment using 0.4% mass fraction ammonia solution and the impregnation of 3% mass fraction La2O3 and 0.5% mass fraction phosphorus, the amount of weak acid, strong acid, Br?nsted acid (B acid) and the ratio of B acid amount to Lewis acid (L acid) amount decreased, and the amount and fraction of mediumstrong acid in total acid increased. The modified ZSM-5 exhibits good catalytic performance in olefin isomerization. For the conversion of 1-hexene, the volume fraction of olefin in the product is only 1.8%, and the yield of iso-paraffin is as high as 44.8%, which is 17.8 percentages higher than that of the industrial catalyst. Moreover, the volume fractions of iso-alkane and aromatics of gasoline over the prepared catalyst are higher than those of industrial catalysts, and the loss of octane number is also smaller in the olefin reduction of heavy FCC gasoline.

Key words: zeolite catalysis, ZSM-5 olefin reduction of gasoline, aromatization, isomerization