CO2 hydrogenation to methane over Ni/ZrO2 and Ni/CeO2 catalysts: experimental and DFT studies

In this paper, performance of ZrO2 and CeO2 supported Ni catalysts on CO2 hydrogenation reaction was investigated in continuous flow reactor. The results revealed that Ni/ZrO2 catalyst exhibited superior performance compared to Ni/CeO2, with a CO2 conversion rate of 71.84%, a CH4 formation rate of 21.03 mmol g−1 h−1, and excellent reaction stability at 400 °C. And the activation energy of Ni/ZrO2 was lower than that of Ni/CeO2. N2 adsorption–desorption, SEM, XRD, XPS, CO2-TPD and O2-TPO analysis results suggest that Ni/ZrO2 is a multi-stage pore material, which has slit holes formed by the accumulation of sheet-like particles, as well as a superior dispersion of Ni on ZrO2. Moreover, Ni/ZrO2 shows higher alkalinity and remarkable resistance to carbon accumulation. DFT calculations demonstrated that CO2 can be more easily adsorbed on ZrO2 surface, and one O-terminus of CO2 is closer to top sites of ZrO2, which is favorable for electron transfer and promotes the activation of CO2.