Enhanced CO2 hydrogenation to light hydrocarbons on Ni-based catalyst by DBD plasma

Abstract

The high thermal stability of CO2 makes its conversion low in conventional thermal catalysis. Comparatively, non-equilibrium plasma technique provides an efficient way for CO2 hydrogenation under mild reaction conditions. Introducing effective catalysts to the dielectric barrier discharge (DBD) plasma reactor may further improve CO2 hydrogenation performance. In this way, the interaction between plasma and catalysts is important to contribute CO2 hydrogenation performance. Considering Ni-based catalyst is active for CO2 hydrogenation, we used three different kinds of carrier materials including CeO2, γ-Al2O3 and ZSM-5 as supports to prepare nickel-based catalysts by incipient impregnation in this paper. The supported Ni catalysts were tested for the plasma-induced CO2 hydrogenation to CH4 and C2+ hydrocarbons in the DBD-plasma reactor. It was found that the 15Ni/CeO2 catalyst achieved the best CO2 conversion of 85.7% and nearly 100% CH4 selectivity at 300 °C due to its high reducibility and CO2 chemisorption capacity. In addition, a significant synergistic effect was found between DBD plasma and catalyst. The performance of plasma-catalysis was considerably better than that of thermal catalysis plus pure plasma reaction, and the synergistic effects were enhanced with increase of reaction temperature. Moreover, the mechanism of the synergistic effect was proposed by analyzing the optical emission spectroscopy (OES) of DBD plasma, which provides a theoretical basis for further optimizing and application of plasma-catalysis for CO2 hydrogenation reaction.