Improvement in the activity of Ru/ZrO2 for CO2 methanation by the enhanced hydrophilicity of zirconia

Increasing interests in the supported Ru catalysts for CO methanation can be recently found in the literature. In this work, we demonstrated that the enhanced surface hydrophilicity of ZrO via air plasma treatment has significant effects on the properties of Ru/ZrO catalyst for CO methanation. At the same CO conversions, the reaction temperature over the catalysts on ZrO with enhanced hydrophilicity is 20–70 °C lower than those on untreated ZrO. The catalyst characterization confirms that the enhanced hydrophilicity leads to more hydroxyl groups and oxygen vacancies on the support, which further promotes CO adsorption and activation, facilitating the conversion of CO to HCO* and HCOO* in formate pathway. The enhanced hydrophilicity also causes a high Ru dispersion with stronger electronic interaction between Ru and ZrO, which forms more interfacial active sites and improves the adsorption and dissociation of H, promoting the linear-CO-Ru adsorption in CO* pathway.