在ZSM－5分子筛上引入Zn、Ga物种对乙烷芳构化的影响

Aromatization of Ethane on ZSM-5 Zeolite Catalysts Promoted by Zn、Ga

报道了在Ｚｎ、Ｇａ改性的ＺＳＭ－５分子筛上进行乙烷芳构化与乙烯芳构化反应的结果，并考察了反应温度对Ｚｎ－ＺＳＭ－５催化剂乙烷芳构化性能的影响和催化剂Ｇａ－ＺＳＭ－５的焙烧时间对其性能的影响等。试验结果表明：（１）乙烷脱氢活化步骤是乙烷芳构化反应的控制步骤，Ｚｎ、Ｇａ物种对乙烷脱氢活化起着至关重要的作用，并且ｚｎ物种的作用大于Ｇａ物种。Ｚｎ、Ｇａ物种还能促进聚合环化物脱氢向芳烃转化：（２）升高反应温度对乙烷脱氢活化和聚合环化物脱氢有利，同时会使聚合环化物的裂解反应速度增加，因而在乙烷芳构化反应中存在最佳温度；（３）延长焙烧时间，有利于乙烷的活化及乙烯、Ｃ＿３等芳构化中间产物向芳烃的转化。

Aromatization of ethane or ethene on ZSM-5 zeolite catalysts promoted by Zn, Ga wasstudied in this paper. Effects of reaction telnperature and calcining time of catalysts on thecatalysts perforlnance were also investigated.According to the experin1ental results,someconclusins could be drawn as follows:(1)Dehydrogenation of ethane is the rate determiningstep of ethane arolnatization reaction; Zn and Ga have an important effect on the ethanedehydrogenation, and Zn is more effective than Ga.(2)Dehydrogenation of ethane andpolycyclic colnpounds is favored by increasing reaction temperature,which also increases thecracking reaction of polycyclic compounds,There is an optimum temperature in the ethaliearomatization reaction.(c)Increase in calcination time of catalysts enhances thetransfotlm-ation of ethane,ethene and other intermediates into aromatic hydrocarbons.