Highly stable activity of cobalt based catalysts with tungsten carbide-activated carbon support for dry reforming of methane: Role of tungsten carbide

Although tungsten carbide (WC) has similar properties, it is easily oxidized and deactivated during dry methane reforming (DRM). Therefore, it is of great significance to investigate the influence of carburizing atmosphere on the structure and properties of the prepared tungsten carbide material. Here, using ammonium metatungstate as the tungsten source and activated carbon (AC) as the matrix, under different carburizing atmospheres, a tungsten carbide-activated carbon (WC-AC) composite support was prepared through in-situ reduction and carbonization technology. After further loading cobalt (Co) and cerium (Ce), a series of Co-Ce/WC-AC catalysts were prepared. The catalytic performance for dry reforming was investigated. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (H2-TPR) and Thermogravimetric (TG) were used to characterize the crystal phase, microstructure and chemical composition of different samples. The results show that the main component of tungsten carbide prepared in a carburizing atmosphere containing CH4 was bitungsten carbide (W2C); tungsten carbide prepared in a pure hydrogen carburizing atmosphere was composed of W2C and WC. After loading Co and Ce, the catalytic activity and stability of catalysts containing WC are significantly improved compared with those mainly containing W2C. Due to the presence of WC, the interaction between the metal and the carrier was enhanced, thereby improving the dispersibility and oxidation resistance of the active component Co species. At the same time, WC was helpful to transform Co3+ to Co2+ and Ce4+ to Ce3+ on the surface and inner of catalyst, which was conducive to the enrichment of chemically adsorbed oxygen on the catalyst surface and the formation of oxygen vacancies. It promoted the adsorption and activation of CO2, and improved the anti-carbon deposition performance of the catalyst.