脱铝八面沸石的催化行为——非晶格铝的影响

Catalytic Characterization of the Dealuminized Faujusite ——Effect of the Nonframework Aluminiun

经水热处理和SiCl_4处理得到了两个系列的脱铝Y沸石USY(W)和USY(T).经X射线衍射分析、化学分析和ESCA研究确定USY(W)中包含有非晶格铝.通过TPD、IR研究发现,沸石中非晶格铝屏蔽了沸石中的强酸中心,同时产生部分弱酸中心。经异丙苯裂化反应和DTA实验发现非晶格铝的存在虽使反应活性降低,但却提高了抗积碳能力。

By hydrothermal treatment or silicon tetrachloride reaction at a high temperature, we have succeeded in reducing the content of Al atom in zeolite HY and obtained two series of deafuminized Y zeolite named as USY(W) containing nonframework Al and USY(T). USY(W) and USY(T) were characterized by TPD. IR and ESCA. The results shows that the nonframework Al in the USY ( W ) screens the strong acid sites of the surface and produces weak acid sites.The effects of Si/Al ratio and nonframework Al on the cumene- cracking activity of dealuminated zeolite were examined. The results shows that the higher the Si/Al is, the smaller the catalytic activity is. Besides, the nonframework Al in the USY(W) exerts a influence on the catalytic activity of zeolite in cumene-cracking and coking. The catalytic activity of zeolite decreases with the formation of non-framework Al and the coking amount reduces obviously.