Iron removal and titanium dioxide support recovery from spent V2O5-WO3/TiO2 catalyst

Iron seriously affects the quality of TiO2 support recovered from spent selective catalytic reduction (SCR) catalyst. In this paper, the iron removal and TiO2 support recovery from spent SCR catalyst were studied. The experiment results suggested that iron exists on the surface and bulk structure of a spent SCR catalyst. The iron deposited on the surface of the spent SCR catalyst was removed by ultrasonic cleaning. The iron remaining in the bulk structure of the spent SCR catalyst was primarily Fe(III) and was adequately removed by NaOH activation and acid washing. The NaOH activation process considerably increased the specific surface area of the spent SCR catalyst. Subsequently, iron was efficiently dissolved through the synergistic effect of sulfuric acid and ascorbic acid. Sulfuric acid dissolved iron in the form of Fe3+, and ascorbic acid promoted iron dissolution by reducing Fe3+ to Fe2+. After the recovery process, 97.1% of the iron in the spent SCR catalyst was removed, and anatase TiO2 was recovered from the spent SCR catalyst. The recovered anatase TiO2 can be used as support material to produce fresh SCR catalyst.