Highly Selective PdCu/Amorphous Silica鈭扐lumina (ASA) Catalysts for Groundwater Denitration

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• 作者：Yongbing Xie ; Hongbin Cao ; Yuping Li ; Yi Zhang ; John C. Crittenden
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：May 1, 2011
• 年：2011
• 卷：45
• 期：9
• 页码：4066-4072
• 全文大小：865K
• 年卷期：v.45,no.9(May 1, 2011)
• ISSN：1520-5851

文摘

Catalytic nitrate reduction is a promising technology in groundwater purification. In this study, PdCu bimetallic catalysts supported on an industrial amorphous silica鈭抋lumina (ASA) were synthesized and used to simulate catalytic removal of nitrate in groundwater. The catalysts exhibited very high activity and the highest catalytic selectivity toward N₂O and N₂ was 90.2%. The optimal Pd/Cu weight ratio was four. Relatively low reduction temperature was found benefit the catalytic stability and 300 掳C was the appropriate reduction temperature during catalyst preparation. With an average particle size 5.4 nm, the metal particles were very uniformly distributed on the catalyst surface prepared with the codeposition method. This kept the catalyst more stable than the PdCu/Al₂O₃ catalyst with larger metal particles. According to XRD, TEM, and XPS results, the metals maintained zero-valence but aggregated by about 2 nm during the denitration reaction, which caused gradual deactivation of the catalysts. Little leaching of Cu and Pd from the catalyst might also have a slightly negative impact to the stability of the catalysts. A simple treatment was found to redistribute the particles on the deactivated catalysts, and high catalytic activity was recovered after this process.