Highly selective methanol-to-olefin reaction on pyridine modified H-mordenite

Abstract

The effects of the acid site in main channels of MOR zeolites on their product selectivity and deactivation in the MTO (methanol to olefin) reactions were investigated. The catalytic analysis demonstrates that the pyridine modified MOR zeolite yielded high selectivity (> 65.3%) of C2=-C4=, although the conversion dropped from 100% to 54%. Furthermore, both the catalytic lifetime of MOR and the stability of yielding the lower olefins were increased from less than 30min to more than 120min after the modification with pyridine. 1H MAS NMR on MOR and modified MOR shows that the acid sites in main channel do not benefit the productivity of lower olefins and catalysts’ lifetime. It can be concluded from ex-situ 13C CP MAS NMR that the deposit species during the MTO reaction depend on the pore sizes, and the formation of large alkyl aromatic species more likely occurs in the 12-ring main channels rather than the 8-ring side pocket.