Plasma-catalytic dry reforming of the CH4 in dielectric barrier discharge: Synergistic effect at low temperatures

Summary form only given. Recently, the combination of non-thermal plasma and catalyst for fuel production from CH4 reforming has attracted considerable interest^1,2. The interactions between plasma and catalyst become very complex when the catalyst is directly placed in the plasma^1,3. The integration of plasma and catalysis could generate a synergistic effect, which provides a unique way to separate the activation steps from the selective reactions. A coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma-catalytic dry reforming of CH₄ into syngas over different Ni/γ-Al₂O₃ catalysts. Three different packing methods are introduced to investigate the influence of catalysts packed in the plasma area on the physical properties of the discharge and consequent plasma-catalytic chemical reactions. Compared to the fully packing method, which strongly shifts the discharge mode due to a significant reduction in the discharge volume¹, partially packing the Ni/γAl₂O₃ catalyst either in radial or in axial direction into the discharge region still shows strong filamentary discharge and significantly enhances the physical and chemical interactions between the plasma and catalyst. Optical emission spectra of the discharge have demonstrated the presence of reactive species (CO, CH, C₂, CO₂⁺ and N₂⁺) in the plasma dry reforming reaction. The synergistic effect resulting from the integration of the plasma and catalyst is clearly observed when a 10 wt% Ni/γ-Al₂O₃ catalyst in flake form calcined at 300°C is partially packed in the plasma, showing both the CH₄ conversion (56.4%) and H₂ yield (17.5%) are almost doubled. The synergy of plasma-catalysis also contributes to a significant enhancement in the energy efficiency of gas conversion. This syn- rgistic effect from the combination of low temperature plasma and solid catalyst can be attributed to both strong plasma-catalyst interactions and high activity of the Ni/γ-Al₂O₃ catalyst calcined at low temperature.