Reactions of 1-propanol and propionaldehyde on Rh(111)
Reactions of 1-propanol and propionaldehyde on Rh(111)
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1-丙醇和丙醛在 Rh(111) 上的反应
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
M. Barteau
中科院分区：
文献类型：
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作者：
N. F. Brown;M. Barteau
用程序升温脱附(TPD)和高分辨电子能量损失谱(HREELS)研究了丙醇和丙醛在清洁的Rh(111)表面上的反应。本研究的主要重点是确定乙醇和乙醛分解过程中涉及的反应途径和中间产物。丙氧基中间体是由正丙醇解离形成的，在147K的HREEL谱中很容易分离出来，在226K左右发生脱羰反应，形成吸附的碳氢化合物碎片和吸附的CO。在该伯醇的分解过程中，没有检测到醛或酰基中间体。1-丙醇在Rh(111)表面分解生成CO、H[sub2]和表面碳。相反，丙醛吸附在Rh(111)表面分解生成乙烷、CO、H[sub2]和表面碳。在145K，HREELS观察到了[ETA][SUP2](C，O)-丙醛。到251K时，发生了一定程度的脱羰基反应，生成桥键CO和乙基物种。用HREELS在301K观察到丙醛低温脱羰生成的乙基物种的一部分加氢生成乙烷，其余的脱氢生成乙叉。乙叉脱氢生成乙炔，最终分解为碳和氢。丙醇和丙醛反应路径的惊人差异与乙醇和乙醛在Rh(111)表面分解的观察结果一致，表明该表面较高的醇盐分解可能是沿烷基链的C-H断裂，而不是[α]-碳。参考文献36，图8，表4。
Temperature programmed desorption (TPD) and high resolution electron energy loss spectroscopy (HREELS) were used to investigate the reactions of 1-propanol and propionaldehyde on the clean Rh(111) surface. The principal emphasis of this study was to determine the reaction pathways and intermediates involved in alcohol and aldehyde decomposition. Propoxide intermediates were formed by the dissociation of 1-propanol; these were easily isolated in the HREEL spectrum at 147 K. Decarbonylation occurred at ca. 226 K, resulting in the formation of adsorbed hydrocarbon fragments and adsorbed CO. No aldehyde or acyl intermediates were detected during the course of the decomposition of this primary alcohol. 1-Propanol decomposed on the Rh(111) surface to produce CO, H[sub 2], and surface carbon. In contrast, propionaldehyde adsorbed on Rh(111) decomposed to form ethane, as well as CO, H[sub 2], and surface carbon. At 145 K, [eta][sup 2](C,O)-propionaldehyde was observed by HREELS. By 251 K, some decarbonylation had occurred to yield bridge-bonded CO and ethyl species. A portion of the ethyl species formed by low temperature decarbonylation of propionaldehyde was hydrogenated to ethane, while the rest dehydrogenated to form ethylidynes, observed at 301 K by HREELS. Ethylidyne species dehydrogenated to acetylides which ultimately decomposed to carbon and hydrogen. Themore » surprising divergence of reaction pathways for propanol and propionaldehyde is consistent with observations for ethanol and acetaldehyde decomposition on Rh(111) and suggests that higher alkoxide decomposition on this surface may involve C-H scission along the alkyl chain, rather than at the [alpha]-carbon. 36 refs., 8 figs., 4 tabs.« less