A novel W-doped Ni-Mg mixed oxide catalyst for CO₂ methanation

Novel Ni-W-Mg mixed oxide catalysts (NiWMgO_x) were prepared by homogeneous precipitation and attempted for the methanation of CO₂. Adding W remarkably promoted the activity with improved stability, anti-CO-poisoning ability and resistance against coke formation compared to the undoped NiMgO_x catalyst. The superior reactivity of monodentate formate towards hydrogenation than that of bidentate formate species was identified by DRIFTS analysis and the formation of more active monodentate formate species was indisputably facilitated by W additives, leading to the greatly enhanced catalytic activity. H₂-TPR and CO₂-TPD characterization showed that doping W increased the number of stable CO₂ adsorption sites and helped in anchoring the Ni sites as a result of strengthened Ni-Mg interaction, both of which were responsible for the enhanced CO₂ methanation activity and the improved resistance against sintering.