Promotional role of Mn doping on catalytic oxidation of VOCs over mesoporous TiO2 under vacuum ultraviolet (VUV) irradiation

Volatile organic compounds (VOCs) are the crucial precursors to the formation of fine particulate matter and photochemical smog. Photocatalytic oxidation (PCO) under vacuum ultraviolet (VUV) irradiation has attracted increasing interest for VOCs degradation owing to its strong oxidation capability and excellent stability. However, the generation of O-3 from VUV irradiation causes secondary pollution and needs to be addressed. In this study, the Mn doped mesoporous TiO2 (Mnimeso-TiO2) was developed and first combined with VUV irradiation to remove O-3 as well as enhance benzene degradation via O-3-assited catalytic oxidation. Results indicate that the Mn doped TiO2 exhibited a much higher benzene removal efficiency (82%) than undoped one (70%) and commercial TiO2 P25 (48%). The O-3 by-product can be completely eliminated by Mnimeso-TiO2 and contributed to benzene removal efficiency of about 34%. The excellent performance was attributed to the formation of highly reactive oxidizing species such as O(D-1), O(P-3), hydroxyl radicals (center dot OH) via catalytic decomposition of O-3 over oxygen vacancy sites of Mn oxides. Mnimeso-TiO2 cooperated well with VUV and such a VUV-PCO process is very promising for VOCs degradation. (C) 2017 Elsevier B.V. All rights reserved.