Photocatalytic oxidation process for treatment of gas phase benzene using Ti3+ self-doped TiO2 microsphere with sea urchin-like structure

Abstract

Photocatalytic oxidation processes (PCO processes) are a promising technology for controlling the pollution of working environments, namely, the low concentrations of volatile organic compounds (VOCs) generated in industrial processes, and improving the efficiency of this process is an important issue. In this study, the photocatalytic oxidation of gas-phase benzene was carried out with TiO2 microspheres with a sea-urchin-like structure, and the effect of Ti3+ self-doping on the catalytic performance of TiO2 was investigated in detail. The structures and properties were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, UV–visible diffuse reflectance spectroscopy, electron spin resonance, scanning electron microscopy, and high-resolution transmission electron microscopy. Ti3+ ions were formed in TiO2 microspheres by heating under vacuum, which improved the catalytic performance of TiO2 for the complete oxidation of benzene to CO2 and CO. The photoelectrochemical measurements showed that the incorporation of Ti3+ into TiO2 microspheres reduced electron-hole recombination and increased the light absorption capacity, which contributed to improving the photocatalytic activity. In situ FTIR spectroscopic studies revealed that in the benzene oxidation process, Ti3+ self-doped TiO2 microspheres suppressed the formation of strongly bound byproduct compounds on the TiO2 surface, which affected the rate of benzene oxidation. Thus, the Ti3+ self-doped TiO2 microspheres are effective catalysts for efficient use of UV light and suppression of catalyst deactivation during benzene oxidation.