Chlorine Residue in the Au/γ-Al2O3 Prepared by AuCl3 Impregnation—an EXAFS Analysis
Chlorine Residue in the Au/γ-Al2O3 Prepared by AuCl3 Impregnation—an EXAFS Analysis
复制标题
AuCl3 浸渍制备的 Au/γ-Al2O3 中的氯残留——EXAFS 分析
DOI：
10.1023/a:1025710730878
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发表时间：
2003
影响因子：
2.8
通讯作者：
Jyhfu Lee
中科院分区：
文献类型：
--
作者：
Chih;Shawn D. Lin;Jyhfu Lee
EXAFS（扩展X射线吸收精细结构）分析表明，在AuCl 3浸渍和真空干燥的新鲜Au/γ-Al 2 O3催化剂中，金主要以氧的形式存在于其最近的配位壳层中。氦热处理后，氯原子出现在金的近邻中，随着处理温度从323 K升高到473 K，氯原子的数量增加。在He的作用下，直到473 K都没有观察到还原态的Au物种.然而，在373 K及以上的CO氧化过程中，金被还原。前驱体AuCl 3通过与表面羟基的键合而存款在γ-Al 2 O3表面。该催化剂在573 K时CO转化率接近100%，但在≤373 K时活性很低。余氯和还原程度都不能解释低温下的低活性。
From EXAFS (extended X-ray absorption fine structure) analysis, gold was found to have mainly oxygen in its nearest coordination shell in the fresh Au/γ-Al2O3catalyst prepared by AuCl3impregnation and vacuum drying at room temperature. After thermal treatment under helium, chlorine appeared within the nearest neighbors of gold and more chlorine showed up as the treatment temperature was increased from 323 to 473 K. No reduced Au species was observed up to 473 K under He. However, the gold became reduced during CO oxidation at 373 K and above. The precursor AuCl3was found to deposit on γ-Al2O3via bonding to surface hydroxyl groups. This catalyst showed nearly 100% CO conversion at 573 K, but a very low activity at ≤373 K under the conditions used in this study. Neither the residual chlorine nor the extent of reduction can explain the low activity at lower temperatures.