Stable and efficient Ru/TiO2-ZrO2 catalysts for catalytic wet air oxidation of phenolsulfonic acid wastewater treatment

Catalytic wet air oxidation (CWAO) technology can efficiently treat organic wastewater, but the performance of existing catalysts, especially its stability, is far from industrial applications. In this study, ZrO₂ was used to modify TiO₂ support to form the stable Ru/TiO₂-ZrO₂ catalysts. It was found that the Ru/TiO₂-ZrO₂ catalysts showed excellent performance for catalytic wet air oxidation of phenolsulfonic acid wastewater. They gave high total organic carbon (TOC) conversions (>90%) and remained stable in 5 consecutive running in the Ti/Zr ratio range from 9∶1 to 7∶3. On the other hand, TOC conversion decreased from 99.1% to 65.3% in 5 consecutive cycles for the conventional Ru/TiO₂ catalyst. The characterization results of XRD, BET, XPS, H₂-TPR and ICP-OES indicated that ZrO₂ can enter the lattice of TiO₂ to form TiO₂-ZrO₂ solid solution, which prevented the transformation of TiO₂ from anatase to rutile. In addition, the modification of ZrO₂ strengthened the interaction between Ru and the support, which effectively inhibited the leaching of Ru metal. The stable support structure and good anti-loss performance are the main reasons for the excellent reaction performance of Ru/TiO₂-ZrO₂ catalyst.