Boosting Propane Dehydrogenation by the Regioselective Distribution of Subnanometric CoO Clusters in MFI Zeolite Nanosheets.

Abstract

Direct dehydrogenation of propane (PDH) has already been implemented worldwide in industrial processes to produce value-added propylene. The discovery of earth-abundant and environmentally friendly metal with high activity in C-H cleavage is of great importance. Co species encapsulated within zeolite are highly efficient for catalyzing direct dehydrogenation. However, exploring a promising Co catalyst remains a nontrivial target. Direct control of the regioselective distribution of Co species in the zeolite framework through altering their crystal morphology gives opportunities to modify the metallic Lewis acidic features, thus providing an active and appealing catalyst. Herein, we achieved the regioselective localization of highly active subnanometric CoO clusters in straight channels of siliceous MFI zeolite nanosheets with controllable thickness and aspect ratio. The subnanometric CoO species were identified by different types of spectroscopies, probe measurements, and density functional theory calculations, as the coordination site for the electron-donating propane molecules. The catalyst showed promising catalytic activity for the industrially important PDH with propane conversion of 41.8% and propylene selectivity higher than 95% and was durable during 10 successive regeneration cycles. These findings highlight a green and facile method to synthesize metal-containing zeolitic materials with regioselective metal distribution and also to open up a future perspectives for designing advanced catalysts with integrated advantages of the zeolitic matrix and metal structures.