Carbon Monoxide Desorption and Reduction Studies of Graphitic Carbon Nitride Supported Nickel Catalysts for CO Methanation

Graphitic carbon nitride (g‐C3N4) has attracted much attention due to its unique polymeric structure of carbon and nitrogen in the form of heptazine units. In this study, a nickel catalyst supported on graphitic carbon nitride was prepared by a facile impregnation method. Ni/g‐C3N4 desorption and reduction behaviors with carbon monoxide (CO) were investigated by temperature‐programmed desorption (TPD) and reduction (TPR). The chemisorption study of reduction and desorption behaviors of CO molecules on Ni/g‐C3N4 catalyst is essential for CO methanation reaction. The as‐prepared Ni/g‐C3N4 catalyst was also characterized by X‐ray diffraction (XRD), N2 physisorption, and X‐ray photoelectron spectroscopy (XPS). It was found that the utilization of g‐C3N4 as a catalyst support enhances the complete reduction of Ni species and CO desorption. This can be attributed to the role of g‐C3N4 support as a reducing agent for Ni, as well as its basicity owing to the richness of nitrogen functional group. The good performance of Ni/g‐C3N4 catalyst towards CO methanation can be ascribed to the improvement in adsorption and activation of CO molecules on the active sites and the number of surface basic sites. The addition of g‐C3N4 support to Ni catalyst improved the surface basicity, which can be demonstrated from the strong desorption of CO on active sites of the catalyst. The good performance of Ni/g‐C3N4 catalyst towards CO methanation can be attributed to the enhanced adsorption and activation of CO molecules on the active sites and the number of surface basic sites.