Enhancing the Activity and Stability for Methane Dry Reforming over a Ni/CeO 2 Catalyst by a Comodification Strategy Using Silicon and Cobalt

Dry reforming of methane (DRM) converts greenhouse gases (CH4/CO2) into H2/CO, which can be utilized for subsequent energy applications. To achieve high activity with nickel catalysts, the reaction temperature tends to exceed 800 °C, posing a severe challenge to the long-term stability of the catalysts. In this study, we prepared a novel nickel-cobalt bimetallic catalyst supported on silicon-modified CeO2. The representative Ni–Co/0.5SiCe catalyst exhibited enhanced CH4 and CO2 conversions of 71% and 80%, respectively, and practically remained stable for at least 50 h at 700 °C. The silicon reduced the CeO2 crystallite size, enhancing the dispersion of nickel particles, and thereby improving CH4 adsorption. The silicon modification increased the oxygen vacancies in CeO2, providing pathways for reactive oxygen species to eliminate coke. The cobalt formed a stable Ni–O–Co structure with nickel particles. Cobalt oxides increased the electron density of the nickel catalyst, thereby weakening the strength of the C═O bond and thus promoting CO2 adsorption. This made coke nucleation more difficult and altered the type of coke. Furthermore, the enhanced Ni–CeO2 interaction and stable Ni–O–Co structure inhibited the sintering of nickel particles, thereby enhancing catalyst stability. This study offers new insights into the design of efficient Ni/CeO2-based catalysts for the DRM reaction.