Enhanced microwave-catalytic performance for CO2 oxidative propane dehydrogenation by acidified and Bi-doped ZnO-based microwave catalysts

The oxidative dehydrogenation of propane by carbon dioxide (CO2-ODHP) has great potential in producing propylene. Resource utilization of CO2 will be the dominant trend in the future to mitigate environmental problems and cope with the growth in energy demand. However, simultaneously achieving high propane conversion, high propylene selectivity, and high CO2 conversion at low temperatures remains challenging. Herein, we report a novel efficient microwave catalyst (1.0-Zn4Bi1/Silicalite-1+SiC) by doping Bi on ZnO/Silicalite-1 and then acid treatment. The (1.0)-Zn4Bi1/Silicalite-1+SiC microwave catalyst exhibited 92 % C3H8 conversion, 84 % C3H6 selectivity, and 45 % CO2 conversion under microwave mode, significantly better than under the thermocatalysis (without microwave: 27 % C3H8 conversion, 92 % C3H6 selectivity, and 14 % CO2 conversion). The CO2 capture capacity was improved by adding Bi to ZnO/Silicalite-1. In addition, acid modification increased the propane and CO2 conversion by 1.9 and 1.3 times, respectively. Notably, acid treatment enriched the pore structure of the catalysts, altered surface acidity and alkalinity, and promoted C3H8 and CO2 activation and C3H6 desorption. In particular, the acid treatment enriches the state of the presence of Zn species in the catalyst. Microwave irradiation reduces the apparent activation energy of the catalytic system and accelerates the removal of coke from the catalyst surface. Microwave catalysis can activate CO2 and propane at lower temperatures than thermocatalysis. [Display omitted] •High propane conversion and propylene selectivity in propane dehydrogenation by microwave irradiation.•Basicity of catalysts altered by Bi-doping.•Nitric acid modification improved the dehydrogenation performance of the catalyst.•Microwave irradiation reduces graphitization of coke on catalyst surfaces.