Reverse water-gas shift in a packed bed DBD reactor: Investigation of metal-support interface towards a better understanding of plasma catalysis

Palladium-loaded ZnO (Pd/ZnO) catalyst was synthesized by co-precipitation method and evaluated for plasma-catalytic reverse water-gas shift (RWGS) reaction. A CO 2 conversion of 32.5 % was achieved on “Pd/ZnO + Plasma”, and was around two times higher than that of “ZnO + Plasma” (17.3 %). Catalyst characterization by X-ray diffraction, high-resolution transmission electron microscopy, temperature-programmed reduction and quasi in situ X-ray photoelectron spectroscopy revealed the possible formation of ZnO x @PdZn (ZnO x decorated PdZn alloy) at the interface of Pd active phase and ZnO support. The role of ZnO x @PdZn in plasma-catalytic CO 2 conversion was systematically investigated by plasma-excited CO 2 temperature-programmed desorption and in situ Fourier transform infrared spectroscopy. It was found that ZnO x @PdZn at Pd-ZnO interface improved significantly plasma-catalytic CO 2 conversion by promoting the production of bidentate carbonate and bidentate formate species. In situ Raman spectroscopy studies proved that the ZnO x @PdZn remained largely intact during the RWGS process. Our in situ spectroscopic findings thus unveil that the ZnO x @PdZn at Pd-ZnO interface favors the activation of CO 2 , and, consequently, leads to a higher plasma-catalytic performance for CO 2 conversion.