Non-equilibrium plasma-assisted dry reforming of methane over shape-controlled CeO2 supported ruthenium catalysts

In this report, CeO2 and SiO2 supported 1 wt% Ru catalysts were synthesized and studied for dry reforming of methane (DRM) by introducing non-thermal plasma (NTP) in a dielectric barrier discharge (DBD) fixed bed reactor. From quadrupole mass spectrometer (QMS) data, it is found that introducing non-thermal plasma in thermo-catalytic DRM promotes higher CH4 and CO2 conversion and syngas (CO + H-2) yield than those under thermal catalysis only conditions. According to the H-2-TPR, CO2-TPD, and CO-TPD profiles, reducible CeO2 supported Ru catalysts presented better activity compared to their irreducible SiO2 supported Ru counterparts. For instance, the molar concentrations of CO and H-2 were 16% and 9%, respectively, for plasma-assisted thermo-catalytic DRM at 350 degrees C, while no apparent conversion was observed at the same temperature for thermo-catalytic DRM. Highly energetic electrons, ions, and radicals under non-equilibrium and non-thermal plasma conditions are considered to contribute to the activation of strong C-H bonds in CH4 and C-O bonds in CO2, which significantly improves the CH4/CO2 conversion during DRM reaction at low temperatures. At 450 degrees C, the 1 wt% Ru/CeO2 nanorods sample showed the highest catalytic activity with 51% CH4 and 37% CO2 conversion compared to 1 wt% Ru/CeO2 nanocubes (40% CH4 and 30% CO2). These results clearly indicate that the support shape and reducibility affect the plasma-assisted DRM reaction. This enhanced DRM activity is ascribed to the surface chemistry and defect structures of the CeO2 nanorods support that can provide active surface facets, higher amounts of mobile oxygen and oxygen vacancy, and other surface defects.