Plasma-Catalytic CO2Hydrogenation at Low Temperatures

A coaxial packed-bed dielectric barrier discharge (DBD) reactor has been developed for plasma-catalytic CO ₂ hydrogenation at low temperatures and atmospheric pressure. Reverse water-gas shift reaction and carbon dioxide methanation have been found dominant in the plasma CO ₂ hydrogenation process. The results show that the H ₂ /CO ₂ molar ratio significantly affects the CO ₂ conversion and the yield of CO and CH ₄ . The effect of different γ-Al ₂ O ₃ supported metal catalysts (Cu/γ-Al ₂ O ₃ , Mn/γ-Al ₂ O ₃ , and Cu-Mn/γ-Al ₂ O ₃ ) on the performance of the CO ₂ hydrogenation has been investigated. Compared with the plasma CO ₂ hydrogenation without a catalyst, the combination of plasma with these catalysts enhances the conversion of CO ₂ by 6.7%-36%. The Mn/γ-Al ₂ O ₃ catalyst shows the best catalytic activity for CO production, followed by the Cu-Mn/γ-Al ₂ O ₃ and Cu/γ-Al ₂ O ₃ catalysts. The presence of the Mn/γ-Al ₂ O ₃ 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-Al ₂ O ₃ catalyst significantly enhances the energy efficiency of CO production by 116%, whereas packing the Cu/γ-Al ₂ O ₃ catalyst into the DBD reactor only increases the energy efficiency of CO production by 52%.