Investigation of the Resistance of Metal Sintering and Coke Deposition for Structure-Evolved Char Supported Co-Based Catalysts in the Dry Reforming of Methane at Elevated Pressure

Operating the pressurized catalytic dry reforming of methane (DRM) reaction is promising for industrial applications; however, two of the most challenging problems are serious coke deposition and metal sintering, especially under high temperature. Designing a catalyst with a small metal particle size, strong metal–support interaction (MSI), high migration rate of oxygen species, and moderate basicity can be effective to solve these problems. In this work, we prepared Ce and La promoted Co/C catalysts and compared their structural properties, catalytic activity, and stability with Co/C. The results show that 4 wt % Ce promoted Co/C (Co-4Ce/C) exhibits a small average metal particle size of 3.87 nm, larger specific surface area (396 m2/g), stronger MSI, higher reduction degree of active metal, larger content of surface chemical adsorbed oxygen, and medium basicity (0.286 mmol/g), providing better catalytic performance with stable CH4 conversion, CO2 conversion, and H2/CO ratio values of 78.0%, 85.8% and 0.77, respectively, for 100 h of reaction under 800 °C, 0.5 MPa, and 30,000 mL·gcat–1·h–1. Only a slight increase of metal particle size as well as a lower amount of deposited carbon were observed on the reacted catalyst, well explaining its good stability. Moreover, the carbon nanotube structure was detected on the surface of Co-4Ce/C, indicating the formation of a kind of more stable carbon-based catalyst. At last, a bifunctional activation mechanism was proposed based on the analysis of in situ diffuse reflectance infrared Fourier transform spectroscopy, which can illustrate the shorter induction period and its enhanced activity. Overall, the Co-4Ce/C exhibits excellent resistance of metal sintering and carbon deposition and would be attractive for the catalytic DRM reaction, especially under an elevated pressure.