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-Al2O3 or 10 wt % Ni/γ-Al2O3 catalyst into the BaTiO3 packed DBD reactor increases both CO2 conversion and energy efficiency of the plasma process. Packing γ-Al2O3 or 10 wt % Ni/γ-Al2O3 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-Al2O3 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.