Atmospheric Pressure Non-Thermal Plasma Activation of CO2 in a Packed-Bed Dielectric Barrier Discharge Reactor

Abstract

Direct conversion of CO₂ into CO and O₂ is performed in a packed-bed dielectric barrier discharge (DBD) non-thermal plasma reactor at low temperatures and atmospheric pressure. The maximum CO₂ conversion of 22.6 % is achieved when BaTiO₃ pellets are fully packed into the discharge gap. The introduction of γ-Al₂ O₃ or 10 wt % Ni/γ-Al₂ O₃ catalyst into the BaTiO₃ packed DBD reactor increases both CO₂ conversion and energy efficiency of the plasma process. Packing γ-Al₂ O₃ or 10 wt % Ni/γ-Al₂ O₃ upstream of the BaTiO₃ bed shows higher CO₂ conversion and energy efficiency compared with that of mid- or downstream packing modes because the reverse reaction of CO₂ conversion-the recombination of CO and O to form CO₂ -is more likely to occur in mid- and downstream modes. Compared with the γ-Al₂ O₃ support, the coupling of the DBD with the Ni catalyst shows a higher CO₂ conversion, which can be attributed to the presence of Ni active species on the catalyst surface. The argon plasma treatment of the reacted Ni catalyst provides extra evidence to confirm the role of Ni active species in the conversion of CO₂ .

Keywords: carbon dioxide conversion; non-thermal plasmas; plasma chemistry; plasma treatment of catalysts; supported catalysts.