Plasma-catalytic hybrid reactor: Application to methane removal

Methane oxidation was investigated in a pulsed dielectric barrier discharge at atmospheric pressure coupled with Pd/Al2O3 catalysts. Comparison between plasma, catalytic, and plasma-catalysis (both inplasma and post-plasma catalysis) systems were performed in the temperature range of 25-500 degrees C and specific input energy up to 148 J/L. For plasma-alone experiments, CH4 conversion reached a maximum of 67% and the main products obtained were CO, CO2, O-3, and HNO3. The plasma catalytic treatment leads to an increase of the CH4 oxidation even at low temperature. It is evidenced that, compared to plasma alone, both Al2O3 and Pd/Al2O3 catalysts coupled plasma discharge increase the CH4 conversion. Moreover, for all plasma-catalytic systems, the CH4 conversion plots were shifted toward lower temperature as the specific input energy increases. Although the difference is low, the in-plasma catalysis configuration seems to be more efficient compared to post-plasma catalysis. In all cases, CH4 oxidation in presence of Pd/Al2O3 catalyst becomes more selective in CO2 formation than the reaction in plasma alone. (C) 2015 Elsevier B.V. All rights reserved.