Effect of the ZrO2–Al2O3 solid solution on the performance of Ni/ZrO2–Al2O3 catalysts for CO2 methanation

Abstract

The conversion of CO₂ into value-added chemicals has attracted a lot of attention, not only reducing the concentration of CO₂ in the air, but also generating chemicals and fuels, which are of great importance to solve the growing environmental and energy problems. Ni catalysts with different Zr/Al ratios were prepared by co-precipitation and impregnation for CO₂ methanation. The activity test results showed that almost 100% CH₄ selectivity and 82.6% CO₂ conversion were obtained at a reaction temperature of 350 °C when the Zr/Al ratio was 1. The physicochemical properties of the catalysts were investigated using XRD, N₂ adsorption–desorption, H₂-TPR, H₂-TPD, CO₂-TPD, XPS and TEM, and the surface-generating substances and methanation reaction mechanism of the catalysts were explored using in situ DRIFTS characterisation. The experimental results show that the addition of Al₂O₃ to Ni/ZrO₂ weakens the Ni–ZrO₂ interaction and promotes the reduction and dispersion of NiO through the solid solution bonding of ZrO₂–Al₂O₃. The in situ DRIFTS results show that there are more formate adsorbed species on the surface of the Ni/ZrO₂–Al₂O₃ catalyst compared to the Ni/ZrO₂ catalyst, which is the main formation substance for CO₂ methanation.