Extra-Framework Aluminum-Assisted Initial C-C Bond Formation in Methanol-to-Olefins Conversion on Zeolite H-ZSM-5

Surface methoxy species bound to an extra-framework Al (SMS-EFAL) was unambiguously identified by advanced C-13-{Al-27} double-resonance solid-state NMR technique in the methanol-to-olefins reaction on H-ZSM-5 zeolite. The high reactivity of the SMS-EFAL leads to the formation of surface ethoxy species and ethanol as the key intermediates for ethene generation in the early reaction stage. A direct route for the initial C-C bond formation in ethene was proposed and corroborated by density functional theory calculations.