HCl catalytic oxidation over Ru/Ti-Sn oxide catalysts: The influence of supports’ crystal and surface structures on catalytic performance

RuO 2 supported on rutile TiO 2 or SnO 2 has been proved extremely effective for catalyzing the oxidation of HCl into Cl 2 . The supports play a crucial role in the catalyst systems. In this work, Ti-Sn oxides with different Sn/(Sn + Ti) molar ratios (0–0.2) were synthesized by a facile co-precipitation method as supports. The corresponding Ru/Ti-Sn oxide catalysts were investigated in HCl catalytic oxidation and systematically characterized to elucidate the role of Ti-Sn oxide supports on the process. The diffraction, spectroscopy and microscopy results reveal the crystal and surface structures of supports and catalysts. Among all the RuO 2 /Ti 1-x Sn x O 2 catalysts, RuO 2 /Ti 0.97 Sn 0.03 O 2 exhibits the best catalytic activity of 2.6 g Cl 2 ·g cat -1 ·h −1 with only 0.5% Ru loading and excellent stability on stream. Differed from the previous understanding, Ti 0.8 Sn 0.2 O 2 support containing the most rutile phase shows unsatisfying performance. The excessive Sn content renders more crystal disorder and volatile substrate, inevitably lowering the dispersion and stabilization of RuO 2 active phase. However, moderate Sn addition induces well-dispersed SnO 2 and rutile TiO 2 film, facilitating the dispersion of RuO 2 phase on the support surface with more active oxygen species. A large number of oxygen vacancies on Ti 0.97 Sn 0.03 O 2 can act as an active oxygen reservoir and boost catalytic performance.