用于燃气轮机的钼改性高钒SCR脱硝催化剂

由于燃机烟气具有浓度低、NO2及H2O含量高等特点,传统催化剂难以直接用于其脱硝处理。文章针对高钒SCR脱硝催化剂低温活性好、宽温域、抗水性好等优势,开展高钒催化剂性能与反应机理的研究。采用浸渍法制备了一系列不同钒、钼添加量的催化剂。结果表明钒、钼的添加量(质量分数)分别为3%和4%时,催化剂具有最佳的脱硝性能,在220~440℃保持95%以上的脱硝效率。该催化剂具有较好的抗水性,O2浓度对催化性能的影响不大,NOx浓度过高或过低时,脱硝效率有所降低,烟气中适量NO2的存在对催化性能有促进作用。表征结果显示,该催化剂具有较大的比表面积,活性组分均匀分散,Bronsted酸和Lewis酸位显著增加。

钨改性高钒SCR脱硝催化剂的性能研究

高钒催化剂因其活性高、活性温度窗口宽、抗性强等特点,受到广泛关注。本文采用浸渍法,制备了一系列不同钨含量改性的 高钒催化剂,并再较宽的温度范围内进行了相应的催化剂活性测试,结合改性后催化剂的比表面积及孔容孔径的表征分析,对其改性机理 进行讨论和分析。结果表明钨的最佳添加量为 6 wt.%,在 220℃~440℃条件下,催化剂可以保持 95%以上的脱硝效率。

钨对高钒燃气脱硝催化剂的改性及SCR反应历程研究

针对燃气工况特点,以高钒SCR脱硝催化剂为研究对象,采用共浸渍法添加钨进行改性,考察了V_2O_5-WO_3/Ti O_2催化剂的SCR脱硝活性,表征了WO_3掺杂对V_2O_5氧化还原能力和酸性位的影响,并研究了该类型催化剂的SCR反应历程。结果表明:对于高钒脱硝催化剂,WO_3掺杂可以显著拓宽催化剂在280～440℃内的活性区间,但无法大幅提高催化剂的最高脱硝效率。活性温度区间得以拓宽的主要原因是WO_3掺杂后与V_2O_5发生强相互作用,在TiO_2表面形成V—O—W物种并提高V^(5+)物种比例,从而增加表面Br■nsted酸和Lewis酸位。在SCR脱硝反应中,催化剂表面酸性位对NH_3的吸附和活化是反应决速步骤,其后与气相NO反应,由气相中O_2补缺催化剂活化NH_3过程中消耗的晶格氧或—OH氧。

Carbon nanotubes loaded with vanadium oxide for reduction NO with NH_3 at low temperature

The catalytic activity of carbon nanotubes-supported vanadium oxide(V_2O_5/CNTs) catalysts in the selective catalytic reduction(SCR) of NO with NH_3 at low temperatures(<250℃) was investigated.The effects of V_2O_5loading,reaction temperature,and presence of SO_2 on the SCR activity were evaluated.The results show that V_2O_5/CNTs catalysts exhibit high activity for NO reduction with NH_3 at low-temperatures.The catalysts also show very high stability in the presence of SO_2.More interestingly,their activities are significantly promoted instead of being poisoned by SO_2.The promoting effect of SO_2 is distinctly associated with V_2O_5 loading,particularly maximized at low V_2O_5 loading,which indicated the role of CNTs support in this effect.The promoting effect of SO_2 at low temperatures suggests that V_2O_5/CNTs catalysts are promising catalytic materials for low-temperature SCR reactions.