Kinetic study on photocatalytic hydrogenation of acetophenone derivatives on titanium dioxide
Kinetic study on photocatalytic hydrogenation of acetophenone derivatives on titanium dioxide
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DOI：
10.1039/c3cy00879g
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发表时间：
2014-01-01
影响因子：
5
通讯作者：
Miyabe, Hideto
中科院分区：
文献类型：
--
作者：
Kohtani, Shigeru;Kamoi, Yuna;Miyabe, Hideto
苯乙酮（AP）衍生物在二氧化钛（Degussa P25，TiO 2）催化剂上的光催化氢化反应具有良好的化学效率。最大反应速率（k（max））和表观吸附常数（K-LH）照射下，从Langmuir-Hinshelwood动力学分析。Kmax值随AP衍生物还原电位（E-red）的降低而降低，KLH值分布在280-780 L mol（-1）之间。其中，简单的AP表现出最大的紫外线照射的TiO 2表面上的吸附性。此外，它被证明，在表面缺陷Ti（Ti-st）网站上的TiO 2上捕获的电子实际上氢化AP衍生物。反应电子的量也显示出随着E-red值的降低而减少的趋势，与对k（max）的依赖性雅阁。这些结果表明，在浅Ti-st态积累的电子容易参与AP衍生物的氢化，而那些被困在较深的状态几乎不与底物反应。结果支持了TiO 2光催化氢化反应中通过Ti-st位的电子转移反应模型。
Acetophenone (AP) derivatives were photocatalytically hydrogenated to afford the corresponding secondary alcohols with excellent chemical efficiencies on titanium dioxide (Degussa P25, TiO2) under UV light irradiation. Maximum reaction rates (k(max)) and apparent adsorption constants (K-LH) under irradiation were obtained from the Langmuir-Hinshelwood kinetic analysis. The kmax values showed a tendency to decrease with the decreasing reduction potentials (E-red) of the AP derivatives, while the KLH values were distributed in the range of 280-780 L mol(-1). Among these, simple AP exhibited the greatest adsorptivity upon the UV irradiated TiO2 surface. Additionally, it was demonstrated that the electrons trapped at surface defect Ti (Ti-st) sites on the TiO2 actually hydrogenated the AP derivatives. The amount of reacted electrons also showed a tendency to decrease with decreasing E-red values, in accord with the dependence on k(max). These results indicate that the electrons accumulated at shallow Ti-st states easily participate in the hydrogenation of AP derivatives, whereas those trapped at deeper states hardly react with the substrates. The results strongly support the electron transfer reaction model via the Ti-st sites in the photocatalytic hydrogenation on TiO2.