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Environmental Engineering Research 2000;5(4): 183-191.
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| CATALYTIC DECOMPOSITION OF o-DICHLOROBENZENE IN AIR OVER TiO2-BASED POWDER CATALYSTS |
| Zhidong Jiang, Bong-Soek Gil, Chang-Mo Nam, and Jong-Shik Chung† |
| Department of Chemical Engineering/School of Environmental Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea |
Corresponding Author:
Jong-Shik Chung ,
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Received: June 6, 2000; Accepted: October 7, 2000. |
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| ABSTRACT |
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Oxidative decomposition of 1,2-dichlorobenzene (o-DCB), which is structurally similar to the more toxic dioxin compounds, was conducted over titania-supported transition metal oxides (CrOx/VOx) and noble metal catalysts (Pt/Pd). Noble metal catalysts exhibited much higher activity than transition metal oxides for 300ppmv o-DCB fed in dry air, but meanwhile generated substantial amount of heavy by-products, especially in Pd/TiO2. With large amount of water present in feed, deactivation happened in all catalysts except Pd. Severe deactivation accompanied by erosion of Cr occurred when feed contained 10vol.% moisture. With 5vol.% moisture in feed, activity of Pt(2) (or metal/support = 2wt.%) and V(10) was reduced by 70°C and 20°C, respectively. In contrast, Pd(l) was activated with generation of less amount of by-products under wet-feed condition. The additive effect of tungsta was probed with W doped TiO2>2 support, or W(20). After doping of 20wt.% W, a big reduction of activity was found in V(10) and Cr(10) catalysts, but for Pd(l) catalysts, the activity reduced only at low temperatures. Also, W helped to suppress the selectivity to heavy by-products in Pd catalyst at high temperature range. Combining V and Pd at a proper ratio on W-doped TiO2 support, a higher activity than their physically mixed V/W(20) and Pd/W(20) catalysts was obtained, which can be ascribed to the synergy effect between Pd and V. Though further modification is desirable, the V(5)-Pd(0.5)/W(20) has already exhibited the ability to decompose completely the o-DCB and its by-products at a lower temperature than other catalysts tested in the presence of 5vol.% steam. |
| Keywords:
decomposition | noble metal | o-dichlorobenzene | titania-supported | vanadia |
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