Plasma-Catalytic CO2 Hydrogenation at Low Temperatures

Abstract

A coaxial packed-bed dielectric barrier discharge (DBD) reactor has been developed for plasma-catalytic CO₂ hydrogenation at low temperatures and atmospheric pressure. Reverse water-gas shift reaction and carbon dioxide methanation have been found dominant in the plasma CO₂ hydrogenation process. The results show that the H₂/CO₂ molar ratio significantly affects the CO₂ conversion and the yield of CO and CH₄. The effect of different γ-Al₂O₃ supported metal catalysts (Cu/γ-Al₂O₃, Mn/γ-Al₂O₃, and Cu-Mn/γ-Al₂O₃) on the performance of the CO₂ hydrogenation has been investigated. Compared with the plasma CO₂ hydrogenation without a catalyst, the combination of plasma with these catalysts enhances the conversion of CO₂ by 6.7%-36%. The Mn/γ-Al₂O₃ catalyst shows the best catalytic activity for CO production, followed by the Cu-Mn/γ-Al₂O₃ and Cu/γ-Al₂O₃ catalysts. The presence of the Mn/γ-Al₂O₃ catalyst in the plasma process significantly increases the yield of CO by 114%, compared with the plasma reaction in the absence of a catalyst. In addition, we find that combining plasma with the Mn/γ-Al₂O₃ catalyst significantly enhances the energy efficiency of CO production by 116%, whereas packing the Cu/γ-Al₂O₃ catalyst into the DBD reactor only increases the energy efficiency of CO production by 52%.