Regioselective Distribution of Zinc Hydroxyl within Straight Channels in MFI Zeolite Nanosheets for Propane Dehydrogenation
Xiangqi Liu, Xintong Lv, Weiyu Song, Guanghui Zhang, Xinwen Guo
Abstract
Direct dehydrogenation of propane (PDH) is an important industrial process to produce propylene. Transition-metal oxides encapsulated within zeolites (TM@Zeolite) are promising nonprecious and nontoxic alternatives for commercial Pt and CrOx-based PDH catalysts, and it is of great interest to further optimize the catalytic performance of TM@Zeolite. This study describes a facile dual-ligand-directed synthetic strategy that achieves the in situ introduction of Zn sites and morphology modulation of the catalysts. The optimized ZnO@MFI-P catalyst yields a propylene formation rate of 57.9 mmol propylene ·g cat –1 ·h –1 at 580 °C with a propylene selectivity over 95%, which is superior to bulk ZnO@MFI-B, as well as the state-of-the-art Zn-based PDH catalysts. The combined theoretical and experimental efforts evidence that the MFI-P with preferential exposure of straight channels benefits the regioselective distribution of Zn species within the straight channels. This contributes to the formation of isolated [ZnOH] species and the derived [ZnH] sites, therefore facilitating propane activation toward efficient PDH performance over the ZnO@MFI-P catalyst.