Acidity of Beta zeolite determined by TPD of ammonia and ethylbenzene disproportionation

The acidity of Beta zeolites with Si/Al ratios ranging from 18 to 33 was de termined using appropriate temperature programmed desorption of ammonia con ditions and their catalytic behavior was evaluated by disproportionation of ethylbenzene. Samples with greater Si/Al ratios presented higher acid stre ngth by retaining ammonia at higher temperatures and showed a higher ethylb enzene disproportionation activity per aluminum atom. These results indicat e that as the aluminum content in zeolite Beta is reduced in that range, th e strength of the associated acid sites increases. (C) 1999 Elsevier Scienc e B.V. All rights reserved.