Role of defects in the adsorption of aliphatic alcohols on the TiO2(110) surface
Role of defects in the adsorption of aliphatic alcohols on the TiO2(110) surface
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DOI：
10.1021/jp020729p
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发表时间：
2002-10-17
影响因子：
3.3
通讯作者：
Madix, RJ
中科院分区：
文献类型：
--
作者：
Farfan-Arribas, E;Madix, RJ
用TPRS和XPS研究了脂肪醇在TiO_2（110）表面吸附过程中的缺陷作用。通过电子轰击产生点缺陷（氧空位），以最小化对表面造成的结构损伤。乙醇、正丙醇和异丙醇在室温下解离吸附在TiO2（110）表面，形成醇盐和氢氧化物基团。吸附醇盐从表面在两个不同的反应通道。大约一半的醇盐物种在345 K与羟基基团重新结合，并作为母体醇解吸。其余的醇盐基团在高于550 K的温度下进行反应以产生相应的醛、烯烃和醇。点缺陷的产生增加了醇盐覆盖率，并将产物分布向高温通道移动，有利于醇盐分解而不是重组。在分解产物中，当表面上存在缺陷时，以脱氢和重组过程为代价促进脱水产物（烯烃）的形成。烯烃脱附的活化能随氧空位数的增加而降低。不同的结合位点的醇盐物种提出负责两个不同的反应通道。
The role of defects in the adsorption of aliphatic alcohols on TiO2(110) was studied by means of TPRS and XPS. Point defects (oxygen vacancies) were created by electron bombardment in order to minimize the structural damage inflicted to the surface. Ethanol, n-propanol, and 2-propanol adsorbed dissociatively on the TiO2(110) surfaces at room temperature, forming alkoxide and hydroxide groups. Adsorbed alkoxides evolved from the surface in two different reaction channels. About half of the alkoxide species recombined at 345 K with hydroxyl groups and desorbed as the parent alcohols. The rest of the alkoxide groups underwent reactions to produce the corresponding aldehydes, alkenes, and alcohols at temperatures above 550 K. The creation of point defects increased the alkoxide coverage and shifted the product distribution toward the high-temperature channel, favoring alkoxide decomposition over recombination. Within the decomposition products, formation of the dehydration product (alkene) was promoted at the expense of dehydrogenation and recombination processes when defects were present on the surface. The activation energy for alkene desorption decreased with increasing number of oxygen vacancies. Different binding sites for the alkoxide species are proposed to be responsible for the two distinct reaction channels.