Highly Stable Ni/N-C-DS Dry Reforming Methane Catalyst and Its Structure–Activity Relationship

Dry reforming of methane (DRM) reaction has attracted much attention due to its important implications for the environment and energy. The nonprecious metallic nickel is a promising active metal in DRM catalysts because of its low price and high activity. However, nickel-based catalysts are prone to deactivation due to sintering and carbon deposition, which is the main factor limiting the industrial application of the DRM reaction. Herein, a highly stable DRM catalyst has been developed, which was a highly dispersed nickel-based catalyst Ni/N-C-DS (Ni supported on N–C support prepared by the double-solvent (DS) method), prepared by impregnating Ni2+ into the cavities of ZIF-8 using the double-solvent method (DS), followed by a one-step carbonization process. The results showed that the Ni/N-C-DS catalyst exhibited smaller metallic Ni nanoparticles, more dispersed Ni species, and richer pore structures. At a reaction temperature of 800 °C, the Ni/N-C-DS catalyst exhibited satisfactory DRM catalytic activity and stability, with CH4 and CO2 conversion rates reaching 82 and 85%, respectively. The H2/CO ratio approached 1, and no deactivation was observed during 300 h of continuous operation. A thorough study of the catalyst’s structure–activity relationship revealed that the high dispersion of Ni0 in the Ni/N-C-DS catalyst was the main source of high activity for the DRM reaction, while the high stability in the later stage (80–300 h) of the DRM reaction was mainly attributed to the synergistic effect between the in situ reduced Ni0 and the initially highly dispersed Ni0.