STUDIES ON ACIDITY OF ANHYDROUS LaHY ZEOLITE BY IN-SITU IR AND MAS-NMR METHOD

Acidity of La3+-exchanged HY zeolite has been studied by the measurements of adsorption on the in-situ IR system and MAS-NMR method. The results show that, 1, The IR bands at 3631 and 3558 cm(-1) are all assigned to hydroxyl group of strong acidic sites. The band at 3531 cm(-1) is assigned to nonacidic hydroxyl group, since it has no interaction with ammonia. It is possible that two hydroxyl groups coordinate with one La3+ directly, the band at 3520 cm(-1) is assigned to weak acidic hydroxyl group, because it has weak interaction with ammonia, and one hydroxyl group may coordinate with one La3+ directly. 2, The hydroxyl group at 3638 cm(-1), which is in supercage of HY Zeolite, is of heterogeneity of acidity resulting from silicon atoms with different numbers of coordinated Aluminium.