Catalytic conversions of polychlorinated benzenes and dioxins with low-chlorine using V2O5/TiO2

Abstract

Chlorinated benzene, especially 1,2-dichlorobenzene (1,2-DCB), has been widely used as one of surrogate compounds of dioxin to find the noble methods to control dioxin. However, the relationship between the catalytic activity of dioxin surrogate compound and dioxin has not been understood quite well. In this work, we used a vanadium based catalyst (V2O5/TiO2) to compare catalytic activity of chlorinated benzenes and dibenzo-p-dioxins with low-chlorine content using the lab-scale system. We investigated the catalytic conversions of low-chlorinated dioxins, [2-monochlorodibenzo-p-dioxin (2-MCDD), 2,3-dichlorodibenzo-p-dioxin (2,3-DCDD)] and polychlorinated benzenes [1,2-DCB, 1,2,3,4-tetrachlorobenzene (1,2,3,4-TeCB), pentachlorobenzene (PeCB), hexachlorobenzene (HCB)] using a V2O5/TiO2 catalyst to understand quantitative relationship between dioxin and benzene with the chlorination level. The catalytic decomposition of chlorinated aromatic compounds was following 1,2-DCB > 1,2,3,4-TeCB > 2-MCDD > PeCB >= 2,3-DCDD > HCB. It might be more reasonable that PeCB or HCB should be used as the dioxin surrogate compound rather than 1,2-DCB. Also, we investigated the effect of both O-2 content and space velocity (SV) on the catalytic decomposition of 1,2-DCB in the presence of V2O5/TiO2 catalyst because these factors should be considered significantly in combustion facilities to control various pollutants. The decomposition of 1,2-DCB shows dependency on the SV while the effect of oxygen content on the catalytic decomposition is negligible in the range of 5-20%.