Cesium promotion in styrene epoxidation on silver catalysts.
Cesium promotion in styrene epoxidation on silver catalysts.
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DOI：
10.1021/ja9055849
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发表时间：
2010-01
影响因子：
15
通讯作者：
Ling Zhou;C. Gorin;R. Madix
中科院分区：
文献类型：
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作者：
Ling Zhou;C. Gorin;R. Madix
少量铯在Ag(110)面上的吸附使苯乙烯的部分氧化产物从苯乙醛和苯基酮重定向为环氧苯乙烷。铯稳定草金属环中间体，并阻碍其转化为导致其他产物的中间体。铯似乎不会对中间体的成键产生任何电子效应。Cs的低覆盖率导致了整个清洁的Ag(110)表面的(1×2)缺行重构和Cs重构的Ag(110)表面的(3×5)表面氧化物结构。这种(3×5)有序表面氧化物被叠加在铯诱导重建产生的Ag(111)微面上，导致了与扩展的(111)表面非常相似的选择性和反应性。这些研究揭示了在银催化剂上，铯在苯乙烯环氧化反应中结构效应的微观来源。
The adsorption of a small amount of cesium on Ag(110) redirects the partial oxidation products of styrene from phenylacetaldehyde and phenylketene to styrene oxide. The cesium stabilizes the oxametallacycle intermediate and hinders its transformation to the intermediate that leads to the other products. Cesium does not appear to create any electronic effects on the bonding of the intermediates. Low coverages of cesium induce a (1 x 2) missing-row reconstruction of the entire clean Ag(110) surface and a (3 x 5) surface oxide structure on the cesium-reconstructed Ag(110) surface. This (3 x 5)-ordered surface oxide is superimposed on the Ag(111) microfacets produced by the cesium-induced reconstruction, which leads to selectivity and reactivity very similar to those of the extended (111) surface. These studies provide insight into the microscopic origins of the structural effects of cesium in styrene epoxidation on silver catalysts.