The effect of heat treatment on the performance of the Ni/(Zr-Sm oxide) catalysts for carbon dioxide methanation

► CO 2 methanation on the catalyst prepared from an aqueous ZrO 2 sol with Sm(NO 3) 3 and Ni(NO 3) 2. ► Rapid methanation with almost 100% methane selectivity and no CO formation. ► The active catalyst is Ni supported on tetragonal ZrO 2 stabilized by inclusion of Sm 3+. ► The activity increase with Sm 3+ content, that is, oxygen vacancies in tetragonal ZrO 2 lattice. The active catalysts for methane formation from the gas mixture of CO 2 + 4H 2 with almost 100% methane selectivity were prepared by reduction of the oxide mixture of NiO and ZrO 2 prepared by calcination of aqueous ZrO 2 sol with Sm(NO 3) 3 and Ni(NO 3) 2. The 50 at%Ni-50 at%(Zr-Sm oxide) catalyst consisting of 50 at%Ni-50 at%(Zr + Sm) with Zr/Sm = 5 calcined at 650 or 800 °C showed the highest activity for methanation. The active catalysts were Ni supported on tetragonal ZrO 2, and the activity for methanation increased by an increase in inclusion of Sm 3+ ions substituting Zr 4+ ions in the tetragonal ZrO 2 lattice as a result of an increase in calcination temperature. However, the increase in calcination temperature decreased BET surface area, metal dispersion and hydrogen uptake due to grain growth. Thus, the optimum calcination temperature existed.