Reactions and catalytic properties of ruthenium dioxide hydrate with aqueous solutions of cerium(IV)

Abstract

The redox catalytic properties of ruthenium dioxide hydrate (RuO₂·xH₂O) were studied using a test system of Ce⁴⁺ in 0.5 mol dm^–3H₂SO₄. In powder form RuO₂·xH₂O appeared a poor redox catalyst unless bound to an inert support, such as titanium dioxide (TiO₂). This was attributed to the production of ruthenium tetraoxide (RuO₄), which was observed with RuO₂·xH₂O and a RuO₂·xH₂O–TiO₂ mixture but not with a TiO₂-bound RuO₂ catalyst. In the absence of a catalyst, or when TiO₂ or Al₂O₃ were used, no decay of the Ce⁴⁺ was observed (t > 200 h).