Insights into Low-Temperature CO ₂ Methanation over Ni/Molecular Sieve Catalysts

CO2 methanation has been considered as a promising method for carbon capture and utilization (CCU), and the lowering of the reaction temperature has become a key focus in current research. Herein, Ni-based catalysts supported on molecular sieves (β, HZSM-5, NaY, and Y) are prepared, and techniques including BET, XRD, H2-TPR, CO2-TPD, NH3-TPD, and XPS are employed to characterize them. Ni/β(Si/Al ∼ 12.5) reached 71.1% CO2 conversion and 97.2% CH4 selectivity at 325 °C, much lower than the corresponding temperature on other catalysts, which may be attributed to the moderate metal–support interactions and medium Ni particles tuned by the support. In situ DRIFTS indicated that formate and CO pathways coexisted during the reaction process over Ni/β(Si/Al ∼ 12.5), and the CO route with linear and bridge CO* as intermediates was predominant above 325 °C, increasing both CO2 conversion and CH4 selectivity. These findings may offer valuable insights into support selection and a mechanistic understanding.