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Study on the decomposition of trace benzene over V2O5-WO3/TiO2-based catalysts in simulated flue gas
Citation:
Lee, C., B. Gullett, S. Lu, R. Zhao, W. Stevens, AND Y. Zhao. Study on the decomposition of trace benzene over V2O5-WO3/TiO2-based catalysts in simulated flue gas. APPLIED CATALYSIS B: ENVIRONMENTAL. Elsevier Science Ltd, New York, NY, 147:322-329, (2014).
Impact/Purpose:
V2O5-WO3/TiO2 based catalysts, that have been used for destruction of a wide variety of organic hazardous air pollutants(HAPs), were modified by our collaborators at Zhejiang University, China by adding other active metals. Bench-scale tests were performed at APPCD with the Zhejiang University visiting scientist using our state-of-the art resonance enhanced multiphoton ionization-time of flight mass spectrometry (REMPI-TOFMS) to evaluate the modified catalysts for decomposition of chlorobenzene (ClBz), a typical HAP produced from waste combustion. The effects of various parameters such as vanadium content of the catalyst, the catalyst support, and reaction temperature on decomposition of ClBz were evaluated. Test results suggested that ClBz decomposition efficiency was significantly enhanced when nano-TiO2 instead of conventional TiO2 was used as the catalyst support. No promotion effects were found in the ClBz decomposition process when two active metals, CuO and CeO2, were added to the catalysts. The kinetics for decomposition of ClBz and benzene, another typical HAPs, promoted by V2O5–WO3/TiO2-based catalyst were analyzed and compared. Two different active sites were found likely involved in the decomposition of the two HAPs. The nano-TiO2 support used in the catalysts greatly facilitated the breaking of C-Cl bond in ClBz and resulting in significantly higher efficiency for decomposition of ClBz compared to that for benzene.
Description:
Commercial and laboratory-prepared V2O5–WO3/TiO2-based catalysts with different compositions were tested for catalytic decomposition of chlorobenzene （ClBz） in simulated flue gas. Resonance enhanced multiphoton ionization-time of flight mass spectrometry (REMPI-TOFMS) was employed to measure real-time, trace concentrations of ClBz contained in the flue gas before and after the catalyst. The effects of various parameters, including vanadium content of the catalyst, the catalyst support, as well as the reaction temperature on decomposition of ClBz were investigated. The results showed that the ClBz decomposition efficiency was significantly enhanced when nano-TiO2 instead of conventional TiO2 was used as the catalyst support. No promotion effects were found in the ClBz decomposition process when the catalysts were wet-impregnated with CuO and CeO2. Tests with different concentrations (1,000, 500, and 100 ppb) of ClBz showed that ClBz-decomposition efficiency decreased with increasing concentration, unless active sites were plentiful. A comparison between ClBz and benzene decomposition on the V2O5–WO3/TiO2-based catalyst and the relative kinetics analysis showed that two different active sites were likely involved in the decomposition mechanism and the V=O and V-O-Ti groups may only work for the degradation of the phenyl group and the benzene ring rather than the C-Cl bond.
