11-P-21 - Study on the acidity of modified HY zeolites prepared by combination of chemical dealumination and hydrothermal treatment

Abstract

Publisher Summary This chapter presents study on the acidity of modified HY zeolites prepared by the combination of chemical dealumination and hydrothermal treatment. Acidity of modified HY zeolites prepared by the combination of chemical dealumination and hydrothermal treatment has been characterized by infrared (IR), magic angle spinning nuclear magnetic resonance (MAS NMR), and n-butylamine titration. The results show that by increasing the level of dealumination, the total amount of acid sites decreased while the strongest acid sites increased. The strength population profile of acid sites reveal that only the aluminum atoms associated with the stronger acid sites are extracted from the framework during the dealumination steps. These results are correlated with the population of Si(nAl) groupings obtained from the spectra of 29 Si MAS NMR. The acidity changes at each step of preparation procedure are also discussed.