ZnHZSM－5上脱氢环化芳构化过程的探讨

Study on Dehydrocyclization and Aromatization Process over ZnHZSM 5 Catalyst

以正己烷、环己烷、甲基环戊烷、１－己烯和环己烯等分子探针反应，考察了单Ｂ酸型ＨＺＳＭ－５、Ｚｎ－Ｌ酸型ＺｎＮａＺＳＭ－５和双中心型ＺｎＨＺＳＭ－５（Ｂ酸和Ｚｎ－Ｌ酸）催化剂的性能，探讨了Ｂ酸中心和Ｚｎ－Ｌ酸中心在芳构化过程中的作用．实验结果表明，Ｂ酸中心有利于环化，Ｌ酸中心有利于脱氢芳构化．单具Ｂ酸或Ｚｎ－Ｌ酸中心催化剂上，直链烃分子的芳构化性能较差，当两种中心同时存在时，双功能互相促进，加快芳构化过程．

The catalytic behavior of single Brnsted acid center model catalyst HZSM 5, single zinc Lewis acid center model catalyst ZnNaZSM 5 and double center model catalyst ZnHZSM 5 have been investigated using n hexane,cyclohexane,methylcyclohexane,1 hexene and cyclohexene respectively, and the different roles of Brnsted acid centers and zinc Lewis acid centers in aromatization have been discussed. Brnsted acid centers promote the cyclization of alkene and zinc Lewis acid centers promote the dehydrogenation of alkanes and alkenes. The aromatization of aliphatic alkanes or alkenes on the catalysts solely with Brnsted acid centers or zinc Lewis acid centers shows a low conversion and a low selectivity to aromatics. When both Brnsted acid centers and zinc Lewis acid centers are present in the same catalyst, the cyclization and the dehydrogenation promotes each other to achieve a high rate of aromatization. The different aromatization paths of different C 6 molecules have also been discussed.