Plasma-Catalytic CO2 Hydrogenation 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%.