MFI型分子筛在正丁烷催化热裂解制备低碳烯烃反应中的性能研究

Study on MFI-Type Zeolites for Catalytic Thermal Cracking of Butane to Produce Light Olefins

轻质烷烃催化热裂解是生产乙烯和丙烯的重要途径。本工作采用水热合成法制备不同Al含量的MFI型分子筛,并采用水热合成法和机械球磨法分别制备了Ba掺杂的高硅ZSM-5分子筛催化剂,研究了其催化正丁烷热裂解反应性能。结果表明:高硅ZSM-5分子筛中Al含量的减少降低了催化剂表面酸性位的数量和强度,抑制了低碳烯烃通过氢转移反应生成烷烃副产物的活性,提高了低碳烯烃的收率。与低硅铝比的ZSM-5分子筛相比,高硅的ZSM-5分子筛表现出更高的低碳烯烃收率。向高硅ZSM-5分子筛中掺杂质量分数为1%的Ba可进一步弱化催化剂表面酸性,抑制氢转移反应,提高低碳烯烃收率。采用机械球磨法制备的Ba/ZSM-5催化剂上乙烯和丙烯的单程收率最高可达54.02%。

Catalytic pyrolysis of light alkanes to produce light olefins is a crucial approach for enhancing alkane utilization efficiency and generating high value-added ethylene and propylene.The reaction network is intricate,with hydrogen transfer reactions significantly influencing products distribution.This study is devoted to elucidate the effect of hydrogen transfer activity on olefin selectivity,and prepare alkanes catalytic pyrolysis catalysts with high selectivity and yield of low carbon olefin.In this study,MFI zeolite catalysts with varying aluminum contents were synthesized through hydrothermal method,secondly,Ba doped high-silica ZSM-5 were synthesized through hydrothermal method and mechanical ball-milling method.It was observed that reducing aluminum content in zeolite led to a decrease in both the amount and strength of acid sites,thereby inhibiting the generation of alkane byproducts from light olefins via hydrogen transfer reactions and increasing the yield of light olefins.Compared to low silicon-aluminum ratios ZSM-5 zeolite,high-silica ZSM-5 zeolite exhibited higher yields of light olefins.Doping 1%Ba into high-silica ZSM-5 zeolite further attenuated surface acidity,suppressed hydrogen transfer reactions,and enhanced the production of light olefins.The Ba/ZSM-5 catalyst prepared by mechanical ball-milling method yielded a remarkable 54.02%yield of ethylene and propylene.