Plasma-catalytic reforming of biogas into syngas over Ni-based bimetallic catalysts

Biogas reforming to syngas is an attractive route for the efficient utilization of biogas. In this work, plasma-catalytic dry reforming of biogas into value-added fuels and chemicals over Ni-based bimetallic catalysts was achieved using dielectric barrier discharge (DBD). The coupling DBD with 10Ni3Co exhibited the best reaction performance, reflected by the highest gas conversion, main gas product yield and selectivity, and fuel production efficiency (FPE). This hybrid process also favored the suppression of carbon deposition on the catalyst surface and the reduction of energy cost for both gas conversion and product formation. The maximum CO2 and CH4 conversion (29.8% and 49.1%) was obtained when the discharge power was 60 W, while a low discharge power (30 W) led to the highest FPE of 12.3%. By using Ni-based catalysts, we were able to tune the product distribution, favoring the generation of C3-C4 hydrocarbons and syngas while reducing the production of C2 hydrocarbons, with 10Ni3Co providing the most favorable results. Compared to other spent catalysts, the lowest carbon deposition (2.9%) was detected on the spent 10Ni3Co after 150 min of plasma reforming. Catalyst characterizations and density functional theory (DFT) calculations showed that the 10Ni3Co catalyst was superior due to a combination of factors such as a higher specific surface area, improved capability to adsorb CO2, strong interactions between the metals and the support, enhanced reducibility and the formation of a Ni-Co alloy. Furthermore, a simplified kinetics model was developed to better understand the effects of Ni-based bimetallic catalysts on the overall energy constant for the conversion of reactants in plasma-catalytic reforming of biogas.