Alumination of ZSM-5 Type Zeolite with AlCl3

Abstract

Abstract The alumination of highly siliceous HZSM-5 type zeolites with AlCl 3 was studied. The introduction of aluminium into the zeolitic framework was confirmed by Si and Al MAS NMR and ir measurements. A considerable amount of aluminium was also introduced into non-framework sites. Alumination at 623 K proceeded through the reaction of hydroxyl nests with AlCl 3 , while at 923 K mainly through the substitution of silicon in the framework by aluminium in AlCl 3 . The solid acid properties of the aluminated HZSM-5 were examined by NH 3 -TPD and pyridine-ir spectroscopies. Strong acid sites including both Brønsted and Lewis acid sites were generated together with the acid sites of normal strength observed for ordinary HZSM-5. Part of these strong acid sites would be produced via the enhancement of Brønsted acid sites by Lewis acid sites.