Catalytic Decomposition of PCDD/Fs over Nano-TiO2 Based V2O5/CeO2 Catalyst at Low Temperature

Catalytic decomposition of PCDD/Fs (Polychlorinated dibenzo-p-dioxins and furans) over nano-TiO2 based V2O5/CeO2 catalyst is investigated at 180 degrees 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 degrees 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.