Microwave catalytic oxidative dehydrogenation of propane by CO2 over ZnK/Silicalite-1 catalysts by acid treatment

The oxidative dehydrogenation of propane by carbon dioxide (CO2-ODHP) is an effective method for the sustainable production of propylene and CO2 resource utilization. However, using non-precious metals to achieve high propane conversion while maintaining high selectivity at low temperatures is still a huge challenge. Furthermore, the microwave-catalyzed CO2-ODHP has received little attention. Herein, we have developed a novel high-efficient Zn-based microwave catalyst for CO2-ODHP by doping alkali metal K and simple acid leaching. Interestingly, the doping with K and acid leaching greatly improved the catalytic performance. More surprisingly, the activity of (1.0)-ZnK/S-1+SiC microwave catalyst in microwave mode was significantly higher than that in conventional mode. An amazingly high C3H8 conversion of 69.80% and C3H6 selectivity of 93.38% is achieved under microwave irradiation. In sharp contrast, the conventional mode showed only 19.67% C3H8 conversion and 95.34% C3H6 selectivity. Meanwhile, the conversion of CO2 was significantly enhanced by doping K. In addition, the spent microwave catalyst with acid leaching showed lower carbon accumulation (1.17%) than the spent Zn/S-1+SiC microwave catalyst without acid leaching and doping K (2.20%). It is found microwave irradiation achieved high-efficient oxidative dehydrogenation of propane at low temperatures through reduced apparent activation energy of the catalyst (118.9 → 70.3 kJ/mol). This work paves the way for non-precious metal and environment-friendly catalysts for high-efficient CO2 oxidative propane dehydrogenation. The established strategy for adjusting acid/base and particle size is expected to extend preparing other catalysts.