The Influence of High-Energy Faceted TiO₂ Supports on Co and Co−Ru Catalysts for Dry Methane Reforming

The reforming of methane from biogas has been proposed as a promising method of CO₂ utilization. Co-based catalysts are promising candidates for dry methane reforming. However, the main constraints limiting the large-scale use of Co-based catalysts are deactivation through carbon deposition (coking) and sintering due to weak metal-support interaction. We studied the structure-function properties and catalytic behavior of Co/TiO₂ and Co−Ru/TiO₂ catalysts using two different types of TiO₂ supports, commercial TiO₂ and faceted non-stoichiometric rutile TiO₂ crystals (TiO₂*). The Co and Ru metal particles were deposited on TiO₂ supports using a wet-impregnation method with the percentage weight loading of Co and Ru of 5% and 0.5%, respectively. The materials were characterized using SEM, STEM-HAADF, XRD, XPS and BET. The catalytic performance was studied using the CH₄ : CO₂ ratio of 3 : 2 to mimic the methane-rich biogas composition. Our results indicate that the addition of Ru to Co catalysts supported on TiO₂* reduces carbon deposition and influences oxygen mobility. Co and Co−Ru catalysts supported on TiO₂* has superior activity with the highest conversion of CO₂ and CH₄ of 34.7% and 23.5%, respectively. Despite the improved performance, the Co−Ru/TiO₂* catalyst has limited stability due to the proliferation of nanoparticle growth and TiO_x layers on the surface of the nanoparticles indicating the prevalence of the strong-metal support interaction.