Photocatalytic reduction of nitrobenzenes to aminobenzenes in aqueous suspensions of titanium(IV) oxide in the presence of hole scavengers under deaerated and aerated conditions
Photocatalytic reduction of nitrobenzenes to aminobenzenes in aqueous suspensions of titanium(IV) oxide in the presence of hole scavengers under deaerated and aerated conditions
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DOI：
10.1039/c0cp02279a
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发表时间：
2011-01-01
影响因子：
3.3
通讯作者：
Kominami, Hiroshi
中科院分区：
文献类型：
--
作者：
Imamura, Kazuya;Iwasaki, Shin-ichi;Kominami, Hiroshi
研究了不同条件下含孔洞清除剂的氧化钛（TiO2）水悬浮液中硝基苯光催化还原为相应的氨基苯。在脱氧条件下，甲酸（FA）存在下光催化还原间硝基苯磺酸（m-NBS），酸性悬浮液中几乎可以定量生成间氨基苯磺酸（m-ABS）， FA作为孔洞清除剂的利用率高达99%。在有和没有FA的酸性条件下，m-ABS都没有发生再氧化。m-ABS的高收率可以解释为FA作为空穴清除剂的强能力，以及在酸性悬浮液中还原的官能团（铵基，-NH3+）可能排斥质子化的，即带正电的TiO2表面，从而避免m-ABS的再氧化。利用溶剂热法合成的不同物理性质的TiO2样品，在不同温度下煅烧后，研究了TiO2样品的物理性质对m-ABS产率的影响。吸附m-NBS的量与m-ABS收率呈线性相关，表明TiO2对m-NBS的吸附能力是m-NBS有效光催化还原为m-ABS的关键因素之一。该光催化体系可用于在草酸作为空穴清除剂存在下将氨基硝基苯还原为相应的二氨基苯（DAB）。m-ABS和DAB的产率很高，即使在有氧的情况下也能得到。
Photocatalytic reduction of nitrobenzenes to corresponding aminobenzenes in aqueous suspensions of titanium(IV) oxide (TiO2) containing hole scavengers under various conditions was examined. In photocatalytic reduction of m-nitrobenzenesulfonic acid (m-NBS) in the presence of formic acid (FA) under deaerated conditions, m-aminobenzenesulfonic acid (m-ABS) was produced almost quantitatively in acidic suspensions and high efficiency (> 99%) in FA utilization as a hole scavenger was achieved. No re-oxidation of m-ABS occurred in acidic conditions both in the presence and absence of FA. The high yield of m-ABS was explained by strong ability of FA as a hole scavenger and possible repulsion of the reduced functional group (ammonium group, -NH3+) from the protonated, i.e., positively charged TiO2 surface in acidic suspensions avoiding re-oxidation of m-ABS. Using TiO2 samples of various physical properties, which had been synthesized by a solvothermal method and post-calcination at various temperatures, effects of physical properties of the TiO2 samples on m-ABS yield were also investigated. A linear correlation between the amount of m-NBS adsorbed and the m-ABS yield was observed, suggesting that ability of TiO2 for m-NBS adsorption is one of the key factors for effective photocatalytic reduction of m-NBS to m-ABS. This photocatalytic system can be applied for reduction of aminonitrobenzenes to corresponding diaminobenzenes (DAB) in the presence of oxalic acid as a hole scavenger. High yields of m-ABS and DAB were achieved even when the reactions were performed in the presence of oxygen.