Xiaole 2019. Efficient elimination of chlorinated organics on a phosphoric acid modified CeO2 catalyst: a hydrolytic destruction route. Environmental Science and Technology 53 (21) , pp.

Municipal solid waste incineration and the iron and steel smelting industry can simultaneously discharge NO x and chlorinated organics, particularly polychlorinated dibenzo-pdioxins and polychlorinated dibenzofurans (PCDD/Fs). Synergistic control of these pollutants has been considered among the most cost-effective methods. This work combined experimental and computational methods to investigate the reaction characteristics of a catalytically synergistic approach and gives the first insight into the effect of arsenic (As) on the multipollutant conversion efficiency, synergistic reaction mechanism, and toxic byproduct distribution over a commercial V 2 O 5 −WO 3 /TiO 2 catalyst. The loaded As 2 O 3 species were shown to distinctly decrease the formation energy of an oxygen vacancy at the V−O− V site, which likely contributed to the extensive formation of more toxic polychlorinated byproducts in the synergistic reaction. The As 2 O 5 species strongly attacked neighboring VO sites forming the As−O−V bands. Such an interaction deactivated the deNO x reaction, but led to excessive NO being oxidized into NO 2 that greatly promoted the V 5+ −V 4+ redox cycle and in turn facilitated chlorobenzene (CB) oxidation. Subsequent density functional theory (DFT) calculation further reveals that both the As 2 O 3 and As 2 O 5 loadings can facilitate H 2 O adsorption on the V 2 O 5 −WO 3 /TiO 2 catalyst, leading to competitive adsorption between H 2 O and CB, and thereby deactivate the CB oxidation with water stream.

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Ru-based catalysts have been extensively employed for the catalytic destruction of chlorinated volatile organic compounds (VOCs), but their versatility for other routine VOCs’ destruction has been less explored. Herein, we show that Ru-decorated SnO2/CeO2 mixed oxides can sustain H2O and HCl poisonings and are endowed with extraordinary versatility for a wide range of VOCs’ destruction. Selective adsorption of Ru on the cassiterite SnO2 and CeO2 nanorods through a Coulomb force can rationally tune the oxidation and dechlorination centers on decorated catalysts, where the epitaxial growth of RuO x on top of SnO2 is endowed with excellent dechlorination ability and that on CeO2 is functional as an oxidation center; the latter could also activate H2O to provide sufficient H protons for HCl formation. Our developed Ru/SnO2/CeO2 catalyst can steadily destruct mono-chlorobenzene, ortho-dichlorobenzene, trichloroethylene, dichloromethane, epichlorohydrin, N-hexane, ethyl acetate, toluene, and their mixtures at an optimum temperature of 300 °C, and its monolithic form is also functional at this temperature with few dioxins being detected in the off-gas. Our results imply that the Ru-decorated SnO2/CeO2 catalyst can meet the demands of regenerative catalytic oxidation for the treatment of a wide range of VOCs from industrial exhausts.

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