LAUSR

The extensive use of selective catalytic reduction (SCR) catalysts will afford many spent SCR catalysts. The mass fraction of the titanium component is over 80% in spent SCR catalysts, but currently, it is usually thrown away without proper recycling. This work aims to develop a clean, green, and economical approach to recovering titanium and regenerating TiO2 photocatalysts from spent SCR catalysts based on the conversion of the titanium component. This titanium component is converted into metastable α-Na2TiO3 with high efficiency (>98%) using a NaOH molten salt method, and the optimal conditions were found to be a roasting temperature of 550 °C, a NaOH-to-spent-SCR-catalysts mass ratio of 1.8:1, a roasting time of 10 min, and a NaOH concentration of 60–80 wt %. And a possible chemical reaction mechanism is proposed. A subsequent hydrothermal treatment of α-Na2TiO3 regenerates TiO2 photocatalysts with high purity (>99.0%) that can satisfy commercial requirements. In addition, the present iron element con...