On the potential role of hydroxyl groups in CO oxidation over Au/Al2O3
On the potential role of hydroxyl groups in CO oxidation over Au/Al2O3
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DOI：
10.1016/s0926-860x(02)00533-1
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发表时间：
2003-03-31
影响因子：
5.5
通讯作者：
Kung, HH
中科院分区：
文献类型：
--
作者：
Costello, CK;Yang, JH;Kung, HH
本文研究了在H_2或H_2O存在下，Au/γ-Al_2 O_3催化剂上CO稳态氧化反应的氘同位素效应以及预处理对未焙烧催化剂的影响。在室温下含有1%CO、0.5%O-2和40.5%H-2的反应进料中，CO氧化表现出1.4 +/-0.2的氘同位素效应（k（H）/k（D））。D-2氧化的速率也慢于H-2的氧化，使得CO氧化的选择性在D-2存在下为86%，而在H-2存在下为77%。相反，在含有1%CO、0.5%O-2和1.5%H2OH2的进料中没有氘同位素效应，在再生CO氧化反应失活的催化剂方面也比D-2更有效，而H2O和D2 O同样有效。这种差异是由于H_2 ~-或H_2O在CO氧化过程中阻止催化剂失活的机理不同。未煅烧的Au/γ-Al 2 O 3是相当不活泼的。在100 ℃下用H-2和H_2O的混合物处理可以激活它，尽管单独用H-2或H_2O处理无效。的意见是一致的模型的活性位点组成的金属Au原子和一个阳离子Att的合奏，一个羟基。(C)2002 Elsevier Science B. V.保留所有权利。
The deuterium isotope effect in the steady state CO oxidation rate over Au/gamma-Al2O3 in the presence of H-2 or H2O and the effect of pretreatment on an uncalcined catalyst were studied. In a reaction feed containing 1% CO, 0.5% O-2, and 40.5% H-2 at room temperature, CO oxidation exhibited a deuterium isotope effect (k(H)/k(D)) of 1.4 +/- 0.2. The rate of D-2 oxidation was also slower than the oxidation of H-2, such that the selectivity for CO oxidation was 86% in the presence of D-2 versus 77% in the presence of H-2. In contrast, there was no deuterium isotope effect in a feed containing 1% CO, 0.5% O-2, and 1.5% H2OH2 was also more effective in regenerating a CO oxidation reaction deactivated catalyst than D-2, whereas H2O and D2O were equally effective. The difference was attributed to the different mechanisms with which H-2 or H2O prevented deactivation of the catalyst during CO oxidation. An uncalcined Au/gamma-Al2O3 was rather inactive. It could be activated by treatment with a mixture of H-2 and H2O at 100degreesC, although treatment by either H-2 or H2O alone was ineffective. The observations are consistent with the model of the active site consisting of an ensemble of metallic Au atoms and a cationic Att with,a hydroxyl group. (C) 2002 Elsevier Science B.V. All rights reserved.