Synergistic mechanism between Brønsted acid site and active cerium species in hydride transfer reaction over CeY zeolites

Abstract

In this study, cyclohexene was used as a representative of olefin and catalyzed by CeY zeolites in a fixed-bed reactor under mild conditions, and the influence of Ce species in hydride transfer reaction over CeY zeolites was evaluated. CeY zeolites show more excellent hydride transfer properties than HY zeolite. Based on the results of almost identical Brønsted acid properties but not the product distributions for 0.075CeY and 0.075CeY(DC) samples, it should be suggested that the Brønsted acid strength and density are not the deciding factors to the hydride transfer reaction. A unique band at 1442 cm−1in situ FTIR spectroscopy spectra are assigned to pyridine complexes bonded to a class of active Ce species that could reversibly migrate from the core of SOD cages to its 6-rings mouth towards the supercages. These results provide valuable information that these active Ce species should play a synergistic role with the Brønsted acid sites in enhancing the hydride transfer reaction with a bimolecular mechanism over CeY zeolites.