Development of new vanadium-based oxide catalysts for decomposition of chlorinated aromatic pollutants.

Supported transition metal oxides and vanadium-containing multi-metallic oxides were investigated to develop new catalysts for the catalytic destruction of highly toxic polychlorinated aromatic pollutants such as polychlorinated benzenes, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and/or biphenyls (PCBs) from waste gases. The decomposition of 1,2-dichlorobenzene (Cl2Bz) was chosen as a model reaction. Titania-supported vanadium catalyst (VOx/TiO2) showed the highest activity and stability among the binary oxides tested even in the presence of water vapor. The optimum loading of vanadia was 5 wt %, corresponding to half a monolayer, suggesting that the active species are tetrahedral vanadyl species on titania. Characterizations of the VOx/TiO2 catalysts were carried out with XRD, laser Raman spectroscopy, and TPR. Multi-metallic VOx/TiO2 catalysts prepared by incorporating Mo, W, or Cr showed enhanced activities for Cl2Bz oxidation. Among the tested catalysts, V-Mo-Ox/TiO2 catalysts wash-coated on the cordierite honeycomb showed a good activity for the decomposition of the toxic PCDDs/PCDFs in the flue gas emitted from a municipal solid waste incinerator (MSWI).