Auδ+>Au0；pH值為8條件下制備的催化劑Au3+含量高、比表面積大，催化性能最好；高溫焙燒使氧化態(tài)金還原的同時(shí)也使載體比表面積嚴(yán)重縮小，催化活性顯著下降；紫外線(xiàn)照射可以引起Au3+的逐漸還原以及Au0顆粒的生長(zhǎng)，其催化失活作用弱于高溫焙燒。"/>

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Analysis of the Active Au Species on Au/α-Fe2O3 Catalyst
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Analysis of the Active Au Species on Au/α-Fe2O3 Catalyst
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National Natural Science Foundation of China (20777046, 21077064); Specialized Research Fund for the Doctoral Program of Higher Education of China (20070003027)

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    摘要:

    采用沉積沉淀法制備了CO低溫氧化Au/α-Fe2O3催化劑，利用X射線(xiàn)衍射（XRD）、X射線(xiàn)光電子能譜（XPS）、BET比表面測(cè)定、程序升溫還原（H2-TPR）等表征技術(shù)，對(duì)比了制備過(guò)程pH值的微小變化、焙燒及光線(xiàn)照射對(duì)催化劑結(jié)構(gòu)及催化性能的影響，探明了Au/α-Fe2O3催化劑的活性物種。結(jié)果表明，110 ℃處理的Au/α-Fe2O3催化劑表面同時(shí)存在Au3+、Au0以及過(guò)渡態(tài)Auδ+（0<δ<1），它們對(duì)CO氧化的活性順序?yàn)锳u3+>Auδ+>Au0；pH值為8條件下制備的催化劑Au3+含量高、比表面積大，催化性能最好；高溫焙燒使氧化態(tài)金還原的同時(shí)也使載體比表面積嚴(yán)重縮小，催化活性顯著下降；紫外線(xiàn)照射可以引起Au3+的逐漸還原以及Au0顆粒的生長(zhǎng)，其催化失活作用弱于高溫焙燒。

    Abstract:

    Au/α-Fe2O3 catalysts for CO oxidation were prepared by chemical coprecipitation at different pH values, and the as-prepared samples were calcined or UV (λ=254 nm) irradiated, respectively. The structure was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption and desorption analysis (BET) and temperature programmed reduction (H2-TPR), and the active Au species on the catalysts was investigated. The results show that Au3+, Auδ+（0≤δ≤1）and Au0 coexist on the surface of Au/α-Fe2O3 catalysts treated at 110 °C, and their activity order is Au3+> Auδ+> Au0. The sample prepared at pH=8 shows the best catalytic performance since it has more Au3+ species and high specific surface area. High temperature calcination can cause serious deactivation due to the reduction of Au3+ and Auδ+ species, together with the decrease of the specific surface area of α-Fe2O3. UV irradiation can also cause the reduction of oxidative Au species and the growth of Au particle.

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尉繼英,張振中,張 蘭,孟弼芳,江 鋒. Analysis of the Active Au Species on Au/α-Fe2O3 Catalyst[J].稀有金屬材料與工程,2012,41(3):377~382.[Wei Jiying, Zhang Zhenzhong, Zhang Lan, Meng Bifang, Jiang Feng. Analysis of the Active Au Species on Au/α-Fe2O3 Catalyst[J]. Rare Metal Materials and Engineering,2012,41(3):377~382.]
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  • 收稿日期:2011-11-30
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