Characterization of titanium-modified USY zeolites and their catalytic performance on n-heptane cracking

Titanium-modified USY zeolites were prepared by impregnation of USY zeolites with tetra-butoxide titanium and post synthesis treatment with (NH4)(2)TiF6. The samples before and after modification were characterized by X-ray diffraction, Raman spectroscopy, UV-DRS, FTIR and NH3-TPD. The results indicate that the titanium species are highly dispersed over USY zeolites, and that the states of titanium over zeolites are dependent on the modification conditions. Extra strong Bronsted acid sites which resulted from interaction between titanium species and their neighboring hydroxyl groups of zeolites appeared on Ti-modified USY zeolites, and the catalytic activity in n-heptane cracking was enhanced after titanium modification for USY zeolites. (C) 2001 Elsevier Science B.V. All rights reserved.