TiO₂ Supported RuRe Nanocatalysts for Soot Oxidation: Effect of Re and the Support Nature

Catalytic combustion of hazardous particulate matter (soot) generated by automobile engines is a primary method of their elimination. Ruthenium-based catalysts are a promising alternative for traditional noble metal (Pt, Pd) based systems; however, their relatively poor thermal stability hinders wide applications. In this study, we synthesized a novel, highly active, and stable catalyst for soot oxidation containing bimetallic RuRe nanoparticles supported on TiO₂. The RuRe NPs were synthesized by colloidal, microwave-assisted polyol method and deposited on rutile or anatase TiO₂. The effect of rhenium content and the nature of TiO₂ support on the performance of RuRe nanoparticles (NPs) in the soot oxidation under air atmosphere was investigated. Bimetallic RuRe/TiO₂ nanocatalysts exhibited higher activity in the soot oxidation than Ru/TiO₂ systems, and the rutile supported 2 wt% Ru–0.4 wt% Re nanocatalyst (Ru/Re atomic ratio of 9:1) showed the best catalytic performance (T₅₀ = 340 °C and T₉₀ < 400 °C). All studied nanocatalysts were stable under reaction conditions in the consecutive catalytic tests. The exceptional catalytic performance of bimetallic RuRe NPs is explained by the synergy effect between ruthenium, rhenium, and TiO₂. Graphical Abstract: [Figure not available: see fulltext.]