- 2. 安徽工业大学
- 3. 安徽工业大学冶金工程学院
摘要: V2O5-WO3/TiO2（VWTi）催化剂可以同时脱除铁矿烧结烟气中的NOx和二噁英，但复杂的烟气成分会导致催化剂失活。采用浸渍法对VWTi 催化剂进行ZnCl2，ZnO和ZnSO4中毒实验。在模拟烧结烟气条件下，研究了不同形态Zn中毒对VWTi 催化剂上同时脱除NOx和二噁英（CB作为模拟物）活性的影响，并分析了中毒前后催化剂表面活性物质理化性质。结果表明：负载不同Zn物种对催化剂同时脱除NOx和CB均具有失活作用。Zn物种会造成催化剂表面颗粒轻微团聚，表面酸性位点数量减少，表面V的还原性减弱，表面化学吸附氧比例和n(V5+)/n(V4+)物质的量比值降低。SO42-的引入为NH3和CB的吸附转化提供新的酸性位点。再生实验结果表明：酸洗可以一定程度上恢复中毒催化剂的催化活性，但水洗不能恢复中毒催化剂的活性。最后，提出了烧结烟气中不同形态Zn对VWTi 催化剂的中毒机理。
The poisoning effect of Zn on Simultaneous Removal of NOx and PCDD/Fs over V2O5-WO3/TiO2 catalysts for iron ore sintering flue gas
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Abstract: The flue gas from iron ore sintering process is one of the largest sources of nitrogen oxide (NOx) and dioxins emission in industries. The V2O5-WO3/TiO2 (VWTi) catalyst can simultaneously remove NOx and dioxins, but the complex flue gas composition will cause the catalyst deactivation. In this study, ZnCl2, ZnO and ZnSO4 poisoning experiments on VWTi catalyst were carried out by the wet impregnation method. The effects of different zinc speacies on simultaneous removal of NOx and dioxin (chlorobenzene (CB) was used as the dioxins simulant) from VWTi catalyst were studied under simulated conditions of iron ore sintering flue gas. The surface physicochemical properties of the fresh and poisoned catalysts were characterized to reveal the deactivation mechanism. The results show that the loading of different Zn species had inactivation effect on the simultaneous removal of NOx and CB on the catalysts, and the poisoning effect was more obvious with the increase of Zn content. Zinc species caused a slight agglomeration of particles on the surface of catalysts, a decrease in the number of surface acid sites, a reduction in the reducibility of surface vanadium species, and a decrease in the surface chemisorption oxygen ratio and the molar ratio of n(V5+)/n(V4+). The introduction of SO42- could create some new acid sites for adsorption and conversion of HN3 and CB. The results of regeneration experiments confirm that dilute sulfuric acid solution washing was an effective method for recovering the catalytic activity, but the water washing failed to restore the activity. Finally, a possible poisoning mechanism of the VWTi catalysts in the flue gas from iron ore sintering process was proposed.