Enhanced low-temperature CO2 methanation over Ni/ ZrO2-Al2O3 catalyst: Effect of Al addition on catalytic performance and reaction mechanism

It is desirable but challenging to obtain high CO2 conversion in low-temperature CO2 methanation and elucidate the reaction mechanism on nickel-based catalysts. In this work, we incorporated Al into Ni/ZrO2 to form nickel-based catalysts supported by ZrO2-Al2O3 composite support. The addition of the appropriate amount of Al increased the dispersion of metal Ni on the catalyst surface, promoted the activation and dissociation of H2, and thus significantly improved the activity of CO2 methanation at low-temperature (< 300 °C). The CO2 methanation on nickel-based catalysts supported on ZrO2-Al2O3 composite supports all follow the formate reaction pathway. Since adding Al removes the ability of ZrO2 to activate H2, the active sites of the catalyst change from the surrounding support to the support-Ni interface, which improves the efficiency of the hydrogenation reaction of the active intermediate.