Abstract
ABSTRACTCatalytic decomposition of PCDD/Fs (Polychlorinated dibenzo-p-dioxins and furans) over nano-TiO2 based V2O5/CeO2 catalyst is investigated at 180°C based on a stable PCDD/Fs generating system. Step impregnation method is used to prepare the powder catalyst, and catalyst characterization is conducted by XRD and TPR. Effects of oxygen, water vapour and sulphur dioxide on PCDD/Fs destruction are studied in terms of destruction efficiency. Oxygen plays a positive role on PCDD/Fs destruction by accelerating the conversion of V4+Ox and V5+Ox, Ce3+Ox and Ce4+Ox. The destruction efficiencies of PCDD/Fs increase from 67.6% to 77.8% with oxygen contents increasing from 11 vol.% to 21 vol.%. In the absence of oxygen, PCDD/Fs can still be destroyed with destruction efficiency of 33.7% due to the lattice oxygen atoms stored by V2O5 and CeO2. Water vapour negatively affects the destruction of PCDD/Fs by competitive adsorption. On the other hand, negative destruction efficiencies of TCDD and TCDF are observed in the presence of water, and the values become lower with water vapour contents increasing. This result demonstrates water vapour facilitates the removal of Cl- present on the catalyst surface. SO2 inhibits the activity of catalyst by poisoning active sites of catalyst. With SO2 concentration increasing from 0 to 100 ppm, destruction efficiencies of PCDD/Fs significantly decrease from 67.6% to 51.9%. Finally, catalyst regeneration is also investigated at 180°C in the presence of oxygen. Most of PCDD/Fs residues in the catalyst will be destroyed, and catalyst is regenerated without PCDD/Fs contaminated.
Highlights
Incineration, rapidly reducing waste volume and recovering heat, has become the preferred technology for municipal solid waste disposal
In the absence of oxygen, PCDD/Fs can still be destroyed with destruction efficiency of 33.7% due to the lattice oxygen atoms stored by V2O5 and CeO2
Negative destruction efficiencies of TCDD and TCDF are observed in the presence of water, and the values become lower with water vapour contents increasing
Summary
Incineration, rapidly reducing waste volume and recovering heat, has become the preferred technology for municipal solid waste disposal. Dioxins and other aromatic compounds emission from incinerators are proved to be harmful for human health, and the extensive development of incinerators is rejected by society (Gao et al, 2009; Yan et al, 2011; Cheruiyot et al, 2015; Li et al, 2015; Tiwari et al, 2015). Various feasible and effective technologies for the control of dioxins emission are eagerly developing to prevent harmful influence. V2O5-WO3/TiO2 catalyst is originally designed for the removal of NOx by selective catalytic reduction (SCR), and found to be useful for the decomposition of PCDD/Fs (Liljelind et al, 2001; Finocchio et al, 2006). Vanadium oxide is identified as the active sites and presents a best oxidative activity compared to other metal oxides, for instance, CrOx, MnOx, and FeOx
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