具有吸附-分解NOx功能的多酸催化新体系研究

采用乙醚萃取法、浸渍法制备了具有吸附-分解NO_x功能的多酸催化新体系，并对其进行了IR、XRD、TEM表征，在固定床催化反应器中考察了体系对NO_x的吸附与分解性能。结果表明,钨系杂多酸优于钼系，H₃PMo_12-xW_xO₄₀（x=1、3、6、12）随着取代钼的钨原子数目增多，对NO_x的吸附能力增强；二氧化钛、碳纳米管均为磷钨酸（HPW）的优良载体，后者对体系有明显的增效作用；TiO₂经500℃煅烧后，以磷钨酸水溶液为浸渍剂，HPW负载量为20%时，制得的HPW/TiO₂体系的脱硝性能最佳，对NO_x的吸附率可达62.8%；混酸（V_HNO3∶ V_H2SO4=1∶3）能在碳纳米管上引入含氧基团使其在水中的分散性能增强，以水为浸渍溶剂、混酸改性后的碳纳米管为载体制得的HPW/CNT催化体系优于乙醇为浸渍溶剂制备的该催化体系，当HPW负载量为70%时，前者对NO_x的吸附率可达73.5%。通过GC-MS检测确认了吸附质催化分解为N₂的有效性。

New catalyst systems of heteropoly compounds as functional material for the adsorption-decomposition of NO_x

Several catalysts of heteropoly compounds (HPCs) with the performance of NO_x adsorption-decomposition were prepared by means of ethanol-extraction and impregnation. The catalysts were characterized by IR, XRD and TEM and evaluated in a fixed bed reactor. The results showed that tungsten containing HPCs were superior to molybdenum containing HPCs for NO_x adsorption; with the increase of the number of molybdenum atoms substituted by tungsten in H₃PMo_12-xW_xO₄₀（x=1、3、6、12）, its NO_x adsorption efficiency increased. Titania and carbon nanotube (CNT) were good supports for H₃PW₁₂O₄₀(HPW); CNT performed better than titania on the adsorption of NO_x. When TiO₂ was calcinated at 500℃ and the HPW loading was 20%, the NO_x adsorption efficiency of HPW/TiO₂ reached 62.8%. Mixed HNO₃/H₂SO₄ with a volume ratio of 1∶ 3 could produce functional groups such as COO- and C-O on the surface of CNT, which could enhance the dispersion of CNT in the aqueous solution. HPW/CNT catalyst prepared with HNO₃/H₂SO₄ modified CNT as support and using water as impregnation solvent was superior to that using ethanol as impregnation solvent; with the HPW loading of 70%, the adsorption efficiency of NO_x by HPW/CNT reached 73.5%. The process effectiveness for NO_x decomposition into N₂ was confirmed by GC-MS analysis.