Interfacial structure-governed SO2 resistance of Cu/TiO2 catalysts in the catalytic oxidation of CO

Abstract

Three types of Cu–Ti interfacial structures have been fabricated by using different preparation methods. The mechanism regarding the interfacial effect on oxidation of CO and resistance to SO₂ has been elaborated. It is proposed that an O vacancy-steered catalytic oxidation of CO prevails over an in situ Cu-doped TiO₂ (DT) catalyst while a lattice O-initiated one proceeds on the other two catalysts that are obtained via solvent free and mechanical mixing methods. The former catalyst exhibits a strong Cu–Ti interface due to the high dispersion of copper species on TiO₂ and partial incorporation of Cu²⁺ into the TiO₂ matrix. This not only creates rich O vacancies, enhances O mobility and thus leads to superior redox ability of DT, hence promoting CO oxidation, but also restricts the interaction of SO₂ with strongly-anchored Cu²⁺ species and thus increases the SO₂ tolerance of DT. Meanwhile, the latter two catalysts have aggregated CuO either above or inside TiO₂, which leads to rapid sulfation of CuO and deactivation of the catalysts.