Decomposition of N₂O by Ruthenium Catalysts – RuO₂ as Active Phase on Non-Reducible Supports

Ruthenium has been supported on specifically chosen non-reducible supports (Al₂O₃, SiO₂, Al₂O₃-SiO₂ mixed oxides, Mg/ZnAl₂O₄ spinel, and AlF₃), and these catalysts have been tested in the decomposition of nitrous oxide, N₂O, to identify the catalytically active phase of ruthenium. Pure, bulk ruthenium dioxide, RuO₂, and isolated Ru surface complexes have been synthesized and investigated for comparison. The catalysts were characterized by X-ray diffraction, H₂ chemisorption, N₂ physisorption, temperature-programmed reduction, and desorption (TPR/TPD) and in situ infrared spectroscopy (IR). All aimed experiments strongly indicate that the decomposition of N₂O occurs on ruthenium dioxide, RuO₂, instead of metal particles. H₂ pre-reduction to Ru metal has inhibitory effects for all oxygen-containing supports. The activity increases with the dispersion of ruthenium oxide. Bulk RuO₂ showed the best catalytic performance.