(69d) Plasma-Enhanced Catalysis of CO2 Reforming of Propane on Ni/γ-Al2O3 Catalyst

CO₂ reforming of propane was studied in dielectric barrier discharge (DBD) plasma and in the association of plasma with Ni/γ-Al₂O₃ catalyst. The main products of the reaction in DBD plasma were hydrogen, carbon monoxide, and a large amount of hydrocarbons, indicating that the reforming reaction could occur in DBD plasma without catalysts. And C-C coupling and cracking reactions also play important roles. The presence of propane and CO₂ promote the conversion of each other through the attachment of a series of radicals generated by the plasma. When the reaction was performed in association of plasma with Ni/γ-Al₂O₃ catalyst, the activation temperature of the catalyst was reduced, and synergistic function between plasma and the catalyst was obtained. It is suggested that vibrationally excited molecules and radicals produced by the plasma are responsible for the enhancement of reactant conversions in the association reaction mode, compared to the summed results in pure catalytic and pure plasma mode. Both excited species produced by gas-phase plasma and the interaction of plasma with the solid surface of the catalyst through surface discharge are probable to induce the decrease of the activation temperature of the catalyst. The inhibition of methanation reaction in the association mode is mainly due to the further reaction of excited methane with CO₂ to produce H₂ and CO. And the synergistic function between the plasma and the catalyst leads to the improvement of the selectivity of preferable H₂ and CO in the association mode compared to that in pure plasma or pure catalytic modes.