Abstract
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•Local electron density of metal Ni could be regulated by the crystal phase of ZrO2 support.•Ni/m-ZrO2 presented faster CO2 methanation at low-temperature than Ni/c-ZrO2.•Ni/m-ZrO2 exhibited high oxygen vacancies and strong electronic metal-support interactions.•The formate is the key intermediate for CO2 methanation over Ni/ZrO2.•Both the experiments and DFT calculation determine the structure–activity relationship.
CO2 methanation is a promising route for converting CO2 into a marketable natural gas. The major challenge of this process is to enhance CO2 methanation catalytic activity at low temperature. This work showcases a supported-catalysts phase engineering strategy to overcome the challenge. We report a ∼ 24% decrease in the activation energy of methanation reaction over Ni/monoclinic-ZrO2 due to the optimization of ZrO2 crystal phases and thus turnover frequency of CO2 methanation at 240 °C increases by ∼ 116% than Ni/cubic-ZrO2. Both experimental characterizations and theoretical calculations confirm the high local electron density of Ni over Ni/monoclinic-ZrO2, a key factor to present superior performance for CO2 methanation, resulting from its high oxygen vacancies and electronic metal-support interactions. This is beneficial to the adsorption and dissociation of H2 and the hydrogenation of formate intermediate. Hence our work might open an avenue for rational design of advanced low-temperature CO2 hydrogenation catalysts via a phase engineering strategy.