Simultaneous production of aromatic aldehydes and dihydrogen by photocatalytic dehydrogenation of liquid alcohols over metal-loaded titanium(IV) oxide under oxidant- and solvent-free conditions
Simultaneous production of aromatic aldehydes and dihydrogen by photocatalytic dehydrogenation of liquid alcohols over metal-loaded titanium(IV) oxide under oxidant- and solvent-free conditions
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DOI：
10.1016/j.apcata.2012.09.051
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发表时间：
2013-01
影响因子：
5.5
通讯作者：
Kazuya Imamura;Hikaru Tsukahara;Kenta Hamamichi;Naoko Seto;K. Hashimoto;H. Kominami
中科院分区：
文献类型：
--
作者：
Kazuya Imamura;Hikaru Tsukahara;Kenta Hamamichi;Naoko Seto;K. Hashimoto;H. Kominami
研究了载金属氧化钛（IV）在乙腈（CH3CN）悬浮液中不同条件下芳香族醇的光催化转化。在负载铂的氧化钛（Pt-TiO2）的CH3CN悬浮液中，以1:1的摩尔比同时制备苯甲醛（PhCHO）和氢气（H2）， BnOH在366nm处以38%的表观量子效率进行了定量转化。在脱氧条件下脱氢PhCHO的产率（>99%）远高于在有氧条件下BnOH脱氢生成水而非H2的产率（53%）。在Pt-TiO2的CH3CN悬浮液中有意加入少量的水，氢化反应速率急剧降低。在有空气和有水的条件下进行的对照实验表明，无氧条件对BnOH向PhCHO的定量转化很重要，即无氧条件下的反应不产生水和活性氧，这分别导致BnOH和PhCHO的反应速率急剧下降和不良氧化。即使在无溶剂条件下，pt - tio2颗粒悬浮在BnOH中，也可以光催化脱氢生成PhCHO。应用脱氧条件下的光催化加氢反应将各种芳香醇转化为相应的醛类。
Photocatalytic conversion of aromatic alcohols in acetonitrile (CH3CN) suspensions of metal-loaded titanium(IV) oxide under various conditions was examined. Benzaldehyde (PhCHO) and hydrogen (H2) were simultaneously produced with a molar ratio of 1:1 from benzyl alcohol (BnOH) in CH3CN suspensions of platinum-loaded titanium(IV) oxide (Pt–TiO2) under deaerated conditions and BnOH was converted quantitatively with high apparent quantum efficiency of 38% at 366nm. The yield of PhCHO in dehydrogenation under deaerated conditions (>99%) was much higher than that (53%) obtained by dehydrogenation of BnOH in the presence of oxygen accompanying the formation of water instead of H2. When a small amount of water was intentionally added to the CH3CN suspension of Pt–TiO2, reaction rates of hydrogenation drastically decreased. Control experiments carried out under air and in the presence of water indicated that an oxygen-free condition was important for quantitative conversion of BnOH to PhCHO in two points, i.e., the reaction under oxygen-free conditions yields no water and active oxygen, that caused drastic decrease in the reaction rate and undesired oxidation of BnOH and PhCHO, respectively. Photocatalytic dehydrogenation of BnOH to PhCHO occurred even in a solvent-free condition in which Pt–TiO2particles were suspended in BnOH. Photocatalytic hydrogenation under deaerated conditions was applied for conversions of various aromatic alcohols to corresponding aldehydes.