n-butane hydrogenolysis on planar and faceted Pt/W(111) surfaces
n-butane hydrogenolysis on planar and faceted Pt/W(111) surfaces
复制标题
平面和多面 Pt/W(111) 表面上的正丁烷氢解
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
T. Madey
中科院分区：
文献类型：
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作者：
R. A. Campbell;J. Guan;T. Madey
通过正丁烷氢解反应（一种已知的结构敏感反应），研究了Pt/ W（111）平面和刻面表面的表面结构与反应活性之间的关系。在气相沉积Pt（>1.3 ML）并在750 K以上退火后，W（111）表面重构形成具有[211]取向的金字塔小面。氢解动力学的平面和小面的表面被发现是相当不同的。平坦表面对乙烷形成具有更高的选择性和更高的反应速率。对平面表面的表观活化能为33 ± 4 kJ/mol，对覆盖有20 nm小面的表面的表观活化能为76 ± 6 kJ/mol。表面上的四重配位（C4）位点的浓度与产生的乙烷量之间似乎存在相关性。C4浓度通过改变刻面尺寸（退火温度）来改变。结果表明C4位上存在不同的中间体，如表观活化能、反应速率和总选择性的差异所证明的。
The Relationship between surface structure and reactivity is investigated by means ofn-butane hydrogenolysis, a known structure sensitive reaction, for planar and faceted Pt/ W(111) surfaces. The W(111) surface reconstructs to form pyramidal facets with [211] orientation upon vapor deposition of Pt (>1.3 ML) and annealing above 750 K. The hydrogenolysis kinetics over the planar and the faceted surface are found to be quite different. The planar surface has a higher selectivity towards ethane formation and a higher reaction rate. The apparent activation energies are found to be 33 ± 4 kJ/mol for the planar surface and 76 ± 6 kJ/mol for a surface covered with ∼ 20 nm facets. There appears to be a correlation between the concentration of fourfold coordination (C4) sites on the surface and the amount of ethane produced. The C4 concentration is altered by changing the facet size (annealing temperature). The results indicate the presence of a different intermediate on the C4 sites as evidenced by the differences in the apparent activation energy, the reaction rate and the overall selectivity.