Suppressed Active Site Loss by Y-Doped ZnO/Silicalite-1 for Superior CO₂ Oxidative Propane Dehydrogenation Performance by Microwave Catalysis

Abstract

Compared to energy-intensive propane direct dehydrogenation, oxidative propane dehydrogenation by CO 2 (CO 2 −ODHP) significantly reduces the energy consumption of the alkane dehydrogenation process and eliminates CO 2 . However, CO 2 −ODHP faces the challenges of low reaction efficiency at low temperatures and poor product selectivity at high temperatures in the conventional reaction mode. Microwave catalysis offers a new approach to achieve efficient reactions at lower temperatures and further reduce energy consumption, but the key is to develop highperformance microwave catalysts. Cheap and nontoxic ZnO-based catalysts have emerged as promising candidates, but the loss of active components is severe due to reduced ZnO to evaporated metal Zn during reaction. Herein, we developed suppressed active site loss by doping Y into ZnO/Silicalite-1 as a novel microwave catalyst for CO 2 −ODHP. The 5Zn−Y/Silicalite-1 + SiC microwave catalyst showed high performance with C 3 H 8 conversion of 76% and C 3 H 6 selectivity of 89% under microwave irradiation at 550 °C. However, propane conversion was only 29% under conventional reactions. Among low-cost base metal catalysts, its activity level is one of the highest. Microwave irradiation can effectively gather microwave energy and improve energy utilization efficiency. The 5Zn−Y/Silicalite-1 + SiC microwave catalyst achieved better CO 2 conversion (27%) than ZnO/Silicalite-1 + SiC (17%). Moreover, the 5Zn−Y/Silicalite-1 + SiC microwave catalyst has good stability and performance, which is attributed to the reduction of 38.79% Zn loss after Y doping. The activation energy of the catalyst for CO 2 −ODHP was significantly reduced from 98.3 to 57.4 kJ/mol by microwave irradiation. Microwave irradiation is a more energy-efficient method compared to conventional reaction for the same propane conversion. This approach highlights the great potential and advantages of multiphase catalytic reactions under microwave irradiation.