Effects of preparation conditions on catalytic activity of Ru/AC catalyst to reduce bromate ion in water

The effects of Ru precursor, Ru loading and calcination conditions on the properties and catalytic activities of ruthenium catalysts supported on activated carbon (Ru/AC) to remove bromate ion in water were investigated. A series of Ru/AC catalysts were prepared by the impregnation method and were characterized. From the examination of X-ray photoelectron spectra, RuO2 was deemed as the major active component on the Ru/AC catalysts to reduce bromate ion. The Ru precursors have significant effect on the activities of Ru/AC catalysts, due mainly to that (NH4)2RuCl6 was prone to generate metallic Ru, while RuCl3·3H2O could form RuO2. It was also found that calcination of Ru/AC in pure nitrogen gas favored the RuO2 formation compared with those calcined in vacuum and 1.5 vol.% H2/N2. The maximum bromate reduction efficiency around 95 % can be successfully achieved by Ru/AC prepared when the Ru loading, calcination temperature and time were 0.1 wt.%, 900 °C, and 3 h, in order, in a pure N2 atmosphere. From the characterization of catalysts, it was found that the excellent performance of Ru/AC would benefit from two aspects: one is that the structure and texture of the support carbon was strengthened during the calcination process, and the other is that an even distribution of RuO2 particles was obtained.