Plasma-assisted Ru/Zr-MOF catalyst for hydrogenation of CO2 to methane

As an important type of metal-organic framework (MOF), Zr-MOF shows excellent CO2 adsorption performance. In this work, a Zr-MOF was synthesized by a solvothermal method and adopted to support Ru through simple incipient-wetness impregnation. Then the Ru/Zr-MOF was applied for CO2 hydrogenation (V-H2: V-CO2 = 4:1) with the assistance of dielectric barrier discharge (DBD) plasma. The hydrogenation of CO2 results showed that methane was produced selectively under the synergistic effect between plasma and the Ru/Zr-MOF catalyst, and the selectivity and yield of methane reached 94.6% and 39.1%, respectively. The XRD and SEM analyses indicate that the basic crystalline phase structure and morphology of the Zr-MOF and Ru/Zr-MOF remained the same after DBD plasma treatment, suggesting that the catalysts are stable in plasma. The guest molecules in the pores of the Zr-MOF are removed and the Ru3+ ions are reduced to metallic Ru-0 in the reduction atmosphere according to the BET and XPS results, which are responsible for the high performance of plasma with the Ru/Zr-MOF catalyst. In situ optical emission spectra of pure plasma, plasma with Zr-MOF, and plasma with Ru/Zr-MOF were measured, and the active species of C, H and CH for CO2 hydrogenation were detected. The plasma-assisted Ru/Zr-MOF exhibited high catalytic activity and stability in CO2 hydrogenation to methane, and it has great guiding significance for CO2 hydrogenation by using plasma and MOF materials.