Abstract: The effect of ZSM-5 composition on catalytic performance of the supported PtSn/ZSM-5 catalyst for propane dehydrogenation was studied using a microreactor combined with infrared spectroscopy of adsorbed pyridine, temperature-programmed desorption of NH3, thermogravimetry, H2 chemisorption, and temperature-programmed reduction. The results showed that the ZSM-5 composition exerted great influence on the catalytic performance of PtSn/ZSM-5 for propane dehydrogenation. With the increase of SiO2/Al2O3 molar ratio in theZSM-5support, the numbers of both total and stronger acidic sites decreased. When the SiO2/Al2O3 molar ratio in the ZSM-5 support increased from 45 to 108, the catalytic activity increased, and the amount of coke formed on the catalyst surface decreased. When the SiO2/Al2O3 molar ratio in the ZSM-5 support was higher than 304, the interaction of Sn species with the ZSM-5 support became weaker, and the ratio of Sn0 species in the catalyst increased after reduction in H2, resulting in the decrease of H2 uptake and catalytic activity of the PtSn/ZSM-5 catalyst for propane dehydrogenation.

Key words: platinum, tin, ZSM-5 zeolite, supported catalyst, propane, dehydrogenation, propylene