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Volatile organic compounds (VOCs) cause the major air pollution concern. In this study, a series of ZSM-5 supported transition metals were prepared by impregnation method. They were combined with vacuum UV (VUV) photo-oxidation in a continuous-flow packed-bed reactor and used for the degradation of benzene, a typical toxic VOCs. Compared with VUV photo-oxidation alone, the introduction of catalysts can greatly enhance benzene oxidation under the help of O 3 , the by-products from VUV irradiation, via ozone-assisted catalytic oxidation (OZCO). The catalytic activity of transition metals towards benzene oxidation followed the order: Mn > Co > Cu > Ni > Fe. Mn achieved the best catalytic activity due to the strongest capability for O 3 catalytic decomposition and utilization. Benzene and O 3 removal efficiency reached as high as 97% and 100% after 360 min, respectively. O 3 was catalytically decomposed, generating highly reactive oxidants such as OH and O for benzene oxidation. [ABSTRACT FROM AUTHOR]

Vacuum ultraviolet (VUV) irradiation was used to improve photocatalytic degradation of gaseous benzene. A multi-functional photocatalyst of 0.1%Mn/TiO 2 /ZSM-5 was developed by a modified sol-gel method for the elimination and utilization of O 3 , the by-product generated from VUV irradiation. O 3 was completely removed and efficiently used to enhance catalytic oxidation of benzene via ozone-assisted catalytic oxidation (OZCO). Under VUV irradiation, benzene removal efficiency was stably kept at 100% over 0.1%Mn/TiO 2 /ZSM-5, however, it was only about 50% and much O 3 was residual over commercial TiO 2 (P25). 0.1%Mn/TiO 2 /ZSM-5 perfectly synergized with VUV irradiation. It provides more efficient pathways besides photocatalytic oxidation, for benzene degradation. The possible mechanism of benzene degradation over 0.1%Mn/TiO 2 /ZSM-5 with VUV irradiation was proposed. This is the first report of an efficient photocatalyst with superior performance for O 3 elimination and utilization. [ABSTRACT FROM AUTHOR]

Volatile organic compounds (VOCs) present a great risk to the atmospheric environmental as well as the public health and safety. In this study, a series of TiO 2 /zeolites catalysts were synthesized by sol-gel method. They showed much better photocatalytic activity for benzene degradation under UV irradiation compared with commercial TiO 2 (P25), which suffered from typical catalyst deactivation. Vacuum ultraviolet (VUV) irradiation was used to further enhance photocatalytic oxidation of benzene. The VUV-PCO process obtained much higher benzene removal efficiency (nearly 100%) than conventional UV-PCO (less than 10%). Besides photocatalytic oxidation, photolysis and ozone-assisted catalytic oxidation was also involved in the VUV-PCO process and they contributed much to benzene degradation. Most of the removed benzene was oxidized into CO 2 . Among the prepared photocatalysts, TiO 2 /ZSM-5 with Si/Al ratio of 200 obtained the best catalytic activity due to its appropriate porous structure and framework, which led to superior capacity for benzene absorption and ozone decomposition. [ABSTRACT FROM AUTHOR]