Relationship of catalytic performance and catalyst structure evolution based on pressurized CH4-CO2 reforming reaction over carbon-supported Co-Ir alloy catalysts

Research on pressurized methane dry reforming (DRM) is of great significance for the integration with downstream F-T synthesis processes and reducing gas compression costs. However, the increase in pressure leads to severe coking, which limits the stable operation of the process. Developing Co-based bimetallic catalysts doped with a small amount of noble metals is one of the important approaches to improving the catalysts’ coking resistance and catalytic performance, thereby alleviating this issue. In this work, a carbon-supported Co-Ir bimetallic catalyst doped with 0.2 wt% Ir (denoted as Co-0.2Ir/C) was developed. Structural characterizations confirmed the formation of Co-Ir alloy, with the metal particles on the catalyst being highly dispersed and having an average particle size of 4.82 nm. Under the reaction conditions of 800 °C, 0.5 MPa, and 30,000 mL g cat -1 h −1 , the incorporation of Ir effectively enhanced the initial catalytic activity of the catalyst and achieved stable operation for 100 h, with final CH 4 and CO 2 conversion reaching 73.9 % and 82.8 %, respectively. In addition, this study focused on the structural changes of the catalyst during the induction period, confirming the dynamic evolution laws of metal particle redispersion and amorphous carbon graphitization. These findings explain the dynamic variation phenomenon where the conversion of CH 4 and CO 2 first increased significantly and then gradually stabilized during the reaction. This study provides certain guiding significance for the development of relatively low-cost carbon-supported metal catalysts, the realization of stable operation of DRM under pressurized conditions, and the clarification of the structure–activity relationship of such catalysts in the DRM reaction.