Nano-Au/CeO2 catalysts for CO oxidation: Influence of dopants (Fe, La and Zr) on the physicochemical properties and catalytic activity
Nano-Au/CeO2 catalysts for CO oxidation: Influence of dopants (Fe, La and Zr) on the physicochemical properties and catalytic activity
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DOI：
10.1016/j.apcatb.2013.08.035
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发表时间：
2014
影响因子：
22.1
通讯作者：
Putla Sudarsanam;Baithy Mallesham;P. S. Reddy;Dennis Großmann;W. Grünert;B. M. Reddy
中科院分区：
文献类型：
--
作者：
Putla Sudarsanam;Baithy Mallesham;P. S. Reddy;Dennis Großmann;W. Grünert;B. M. Reddy
本文研究了不同掺杂剂对纳米au / ceo2催化剂的理化性质和CO氧化催化性能的影响。因此，利用超高稀水溶液通过易共沉淀法将Fe3+、La3+和Zr4+等多种金属离子掺入到铈晶格中。采用阴离子吸附法在不添加碱、还原剂和保护剂的情况下制备了Au/ ceo_2掺杂催化剂。采用XRD、BET比表面积、ICP-AES、TG-DTA、FT-IR、TEM、UV-vis DRS、Raman、XPS和TPD等技术对其进行了理化表征。与纯CeO2相比，掺杂CeO2表现出更小的晶粒尺寸、更高的BET表面积和更多的氧空位。XRD和TEM研究证实，这些显著的性能对金的粒度有有利的影响。XPS结果表明，Au以金属态存在，Ce以+3和+4氧化态存在。将Zr掺入Au/ ceo2中，由于存在更多的Ce3+离子和氧空位，导致了较高的CO氧化活性。相反，由于Au/ ceo2 - la2o3催化剂表面存在碳酸盐物质，因此la掺杂产生了相反的效果，阻碍了CO氧化所必需的活性位点。结果表明，碳酸盐种类的富集在很大程度上取决于支撑体的酸碱性质。金催化剂的催化性能在很大程度上取决于载体的性质。
The present investigation was undertaken to know the influence of different dopants on the physicochemical properties and catalytic behavior of nano-Au/CeO2catalyst for CO oxidation. Accordingly, various metal ions namely, Fe3+, La3+and Zr4+were incorporated into the ceria lattice by a facile coprecipitation approach using ultra-high dilute aqueous solutions. An anion adsorption method was used to prepare the Au/doped-CeO2catalysts in the absence of any base, reducing and protective agents. The physicochemical characterization was performed by XRD, BET surface area, ICP-AES, TG-DTA, FT-IR, TEM, UV–vis DRS, Raman, XPS and TPD techniques. Doped CeO2exhibited smaller crystallite size, higher BET surface area and larger amount of oxygen vacancies than the pure CeO2. These remarkable properties showed a beneficial effect toward gold particle size as confirmed by XRD and TEM studies. XPS results revealed that Au is present in the metallic state and Ce in both +3 and +4 oxidation states. Incorporation of Zr into the Au/CeO2resulted in high CO oxidation activity attributed to the presence of more Ce3+ions and oxygen vacancies. In contrast, the La-incorporation caused an opposite effect due to the presence of carbonate species on the surface of Au/CeO2–La2O3catalyst, which blocked the active sites essential for CO oxidation. It was shown that accumulation of carbonate species strongly depends on the acid–base properties of the supports. The catalytic performance of Au catalysts is highly dependent on the nature of the support.