具有吸附-分解NO_x功能的多酸催化新体系研究

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

采用乙醚萃取法、浸渍法制备了具有吸附-分解NOx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NOx的吸附与分解性能。结果表明,钨系杂多酸优于钼系,H3PMo12-xWxO40(x=1、3、6、12)随着取代钼的钨原子数目增多,对NOx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NOx的吸附率可达62.8%;混酸(VHNO3∶VH2SO4=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NOx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。

Several catalysts of heteropoly compounds （HPCs） with the performance of NOx adsorptiondecomposition 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 NOx adsorption ; with the increase of the number of molybdenum atoms substituted by tungsten in H3 PMo12-xWxO40 （x = 1 ,3,6,12） , its NOx adsorption efficiency increased. Titania and carbon nanotube （CNT） were good supports for H3 PW12 040 （ HPW ） ; CNT performed better than titania on the adsorption of NOx. When TiO2 was calcinated at 500 ℃ and the HPW loading was 20% , the NOx adsorption efficiency of HPW/TiO2 reached 62.8%. Mixed HNOa/H2SOg 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 NOx by HPW/CNT reached 73.5%. The process effectiveness for NOx decomposition into N2 was confirmed by GC-MS analysis.