酸性对HZSM-5催化剂上丙烯齐聚反应性能的影响OA

HZSM-5 zeolite catalysts with different Si/Al ratios were synthesized by the hydrothermal method.The catalytic performance of these HZSM-5 zeolites with varying Si/Al ratios in propylene oligomerization was investigated.The structure,composition,and acidity of the catalysts were analyzed using XRD,SEM,N2 physisorption-desorption,NH3-TPD and so on.A comparative study was conducted on the catalytic performance in propylene oligomerization over HZSM-5 with different Si/Al ratios(30,50,90 and 120).The results indicate that as the Si/Al ratio increases,the catalyst acidity decreases,and the temperature for maximum liquid oil yield from propylene oligomerization shifts to higher temperatures,specifically 360,380,440 and 460 ℃,respectively.This study focuses on elucidating the relationship between the acidity of HZSM-5 zeolites with different Si/Al ratios and the product distribution as well as the reaction pathways in propylene oligomerization.The research indicates that HZSM-5 zeolites with lower Si/Al ratios possess higher acid site density,which favors the occurrence of propylene oligomerization,with the reaction products primarily consisting of olefins.In contrast,HZSM-5 catalysts with higher Si/Al ratios are more conducive to further reactions of propylene and the primary olefinic products from oligomerization,such as cyclization,aromatization and hydrogen transfer.Consequently,the product distribution is broader,encompassing olefins,cycloalkanes,aromatics,and alkanes.