Highly effective microwave catalytic oxidative dehydrogenation of propane by CO2 over V-La-doped dendritic mesoporous silica-based microwave catalysts

Abstract

The great potential of the oxidative dehydrogenation of propane by CO2 (CO2-ODHP) reaction in facilitating propylene production from propane and elimination of CO2 has attracted much attention. However, the challenge of the oxidative dehydrogenation of propane by CO2 (CO2-ODHP) reaction is the high thermodynamic stability of CO2, which requires high temperature for activation but the predominance of propane cracking reactions at high temperatures leads to difficulties in maintaining high selectivity for propylene at high conversion rates. Herein, a new and effective method for CO2-ODHP by microwave catalysis has been developed. Meanwhile, a novel vanadium-lanthanum-doped three-dimensional dendritic mesoporous silica nanospheres (V-La-MSNS) based microwave catalyst is synthesized by the in situ growth approach. Importantly, the propane conversion increases from 2% in conventional reaction mode (CRM) to 13% in microwave catalytic reaction mode (MCRM) at 500 °C, with the propylene selectivity still remained at a high level. The catalyst exhibits good stability and reproducibility in microwave catalytic reaction mode. Besides, the doping of La in V-MSNS can dramatically increase the catalytic activity. More importantly, the apparent activation energy of the V-La-MSNS + SiC microwave catalyst drops from 132.7 kJ/mol in the CRM to 71.4 kJ/mol in the MCRM, indicating a significant microwave direct catalytic effect. This work presents a new method for high-efficient catalytic CO2-ODHP reaction under microwave irradiation.