Origin of extra-stable multinuclear zinc species riveted into siliceous zeolite for efficient propane dehydrogenation

Zn-based catalysts are promising for direct propane dehydrogenation (PDH) to propylene owing to their cheaper and environment-friendly features but are subjected to serious depletion of active Zn component under working conditions. Herein, we successfully open a “black box” for the origin of active Zn speciations confined within the silicalite-1 (S-1) zeolite by thermogravimetric-mass spectrometry analysis and in-situ Fourier transform infrared spectroscopy. Guided by this, single-site, multinuclear and nanometer hydroxylated ZnOx species are separately encapsulated into the channels of S-1 zeolite by the controllable transformation of intermediate Zn(OH)x with assistant of vicinal- and nest-silanols. Delightfully, synthetic m-ZnOx@S-1 catalyst enables enviable propylene formation rate (50.8 mmol∙gcat−1∙h−1) and propylene selectivity (>96 %) in the PDH reaction. Most importantly, initial activity revives as before and without Zn loss after 7 regeneration cycles. This exceptional PDH performance is benefited from low-coordination and extra-stable multinuclear ZnOx species that can greatly lower the dehydrogenation barrier, favoring the PDH pathway to further produce propylene and hydrogen. These findings elucidate the potential of Zn-based zeolite catalysts for the development of PDH reaction and afford value-filled opportunities in alternative PDH catalyst optimization.