Arsenic, a toxic component in coal-fired flue gas, is poisonous to the commercial selective catalytic reduction (SCR) denitrification catalysts. To unveil the arsenic poisoning mechanism on commercial SCR catalysts, fresh and 1 year used arsenic-poisoned plate-type V₂O₅–MoO₃/TiO₂ catalysts from a coal-fired power plant in the Inner Mongolia Province of China were systematically analyzed with SCR activity and characterization experiments. The results indicated that the plate-type V₂O₅–MoO₃/TiO₂ catalysts possessed a certain ability to resist arsenic poisoning. The average denitrification efficiency of the poisoned catalysts was maintained over 70% at 350 °C, even though the arsenic content was as high as 7 wt %, compared to the denitrification efficiency of 87.35% for the fresh catalyst. Characterization results indicated that both physical and chemical factors resulted in the deactivation of catalysts by arsenic. The surface area and amount of surface acid sites of the used catalysts decreased, which inhibited the adsorption of ammonia. The redox capacity of the used catalysts also decreased as a result of the increase of tetravalent vanadium (V⁴⁺) and the decrease of surface chemisorbed oxygen. Furthermore, catalysts at different installation positions in the SCR system had different denitrification activities and deactivation mechanisms. The major deactivation factor for the catalysts in the top layer was physical blockage, while the chemical deactivation was dominant for the catalysts in the middle layer.

中文翻译：

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燃煤电厂砷中毒工业V ₂ O ₅ -MoO ₃ / TiO ₂选择性催化还原催化剂的失活机理

砷是燃煤烟气中的一种有毒成分，对商业选择性催化还原（SCR）脱氮催化剂有毒。为了揭示商业SCR催化剂上的砷中毒机理，系统分析了来自内蒙古燃煤电厂的新鲜和1年使用过的砷中毒板式V ₂ O ₅ -MoO ₃ / TiO ₂催化剂进行SCR活性和表征实验。结果表明，平板型V ₂ O ₅ –MoO ₃ / TiO ₂催化剂具有一定的抗砷中毒能力。中毒催化剂的平均反硝化效率在350°C时保持在70％以上，尽管砷含量高达7 wt％，而新鲜催化剂的反硝化效率为87.35％。表征结果表明，物理和化学因素均导致砷使催化剂失活。所用催化剂的表面积和表面酸中心的量减少，这抑制了氨的吸附。使用的催化剂的氧化还原能力也由于四价钒（V ⁴⁺）并减少表面化学吸附的氧气。此外，SCR系统中不同安装位置的催化剂具有不同的反硝化活性和失活机理。顶层催化剂的主要失活因素是物理阻滞，而中间层催化剂的化学失活占主导。