Abstract:

NH₃ selective catalytic reduction (SCR) technology has high denitration efficiency, excellent selectivity and good usefulness. It is thus the mainstream method of NO _x removal in coal-fired power plants. V₂O₅/TiO₂ catalyst is widely used due to its high denitration activity and sulfur resistance in the medium temperature range (300—450℃). However, SO₃, NH₃ and water vapor in the flue gas would produce ammonium bisulfate (ABS) and ammonium sulfate (AS). Due to the capillary condensation at low temperature, ABS would deposit on the surface of V₂O₅/TiO₂ catalyst and the activity will be reduced. In order to avoid the catalyst poisoning at low temperature, we analyzed the formation mechanism of ABS on the catalyst surface, the harm to the catalyst and the research progress of anti ABS poisoning by catalyst modification, and found that the improvement measures mainly focus on inhibiting the ABS formation and promoting its decomposition. Finally, the promotion of the anti ABS poisoning performance of SCR denitration catalyst at low temperature by reasonably adjusting the catalyst's physical structure such as wall thickness, pore diameter and isolation layer, and by adding additives such as MoO₃, BaO, Nb₂O₅, Fe₂O₃, CeO₂ and SiO₂ were summarized, which could provide some theoretical guidance for the future research in this area.

Key words: V₂O₅/TiO₂ catalyst, catalyst support, selective catalytic reduction, SO₂ oxidation, ammonium kisulfate

摘要：

NH₃选择性催化还原（SCR）技术具有较高的脱硝效率、优良的选择性和实用性，是当前燃煤电厂去除NO _x 的主流方法。其中V₂O₅/TiO₂催化剂在中温段（300~450℃）具有较高的脱硝活性和抗硫性，被广泛应用。但是，烟气中的SO₃、NH₃和水蒸气会发生反应生成硫酸氢铵（ABS）和硫酸铵（AS），其中硫酸氢铵在低温条件下因毛细冷凝现象沉积在V₂O₅/TiO₂催化剂表面致其中毒，活性降低。为了改善低温条件下催化剂中毒问题，本文通过分析ABS在催化剂表面的生成机理、对催化剂的危害及催化剂抗ABS中毒改性研究进展，发现钒钛系脱硝催化剂抗ABS中毒改进措施主要集中在抑制硫酸氢铵生成、促进硫酸氢铵分解两方面。最后，总结了合理调控催化剂壁厚、孔径和隔离层等物理结构以及添加MoO₃、BaO、Nb₂O₅、Fe₂O₃、CeO₂、SiO₂等助剂对低温条件下SCR脱硝催化剂抗ABS中毒性能的促进作用，为未来提高低温条件下SCR脱硝催化剂抗ABS中毒性能的研究提供了一定的理论指导。

关键词: V₂O₅/TiO₂催化剂, 催化剂载体, 选择性催化还原, SO₂氧化, 硫酸氢铵