Nitrogen-Doped Activated Carbon as Metal-Free Catalysts Having Various Functions
Nitrogen-Doped Activated Carbon as Metal-Free Catalysts Having Various Functions
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DOI：
10.3390/c3040031
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发表时间：
2017-10
期刊：
影响因子：
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通讯作者：
S. Fujita;H. Yoshida;M. Arai
中科院分区：
文献类型：
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作者：
S. Fujita;H. Yoshida;M. Arai
氮掺杂的碳材料作为无金属催化剂已经获得越来越多的关注。本文简要介绍了氮掺杂活性炭（N-AC）在碱催化的Knoevenagel缩合和酯交换反应，氧杂蒽和醇的有氧氧化反应，硝基苯、3-硝基苯乙烯、苯乙烯和苯乙炔与肼的转移氢化反应中的应用研究进展。掺杂氮物种以不同的结构存在于AC表面。例如，吡啶型氮物种似乎参与了Knoevenagel缩合和氧杂蒽氧化的活性位点，而石墨型氮物种似乎参与了醇的氧化。与这些反应不同的是，硝基苯加氢反应的活性中心同时涉及表面氮和氧物种。N-AC对乙烯基和乙炔基的转移氢化反应几乎没有活性，但对硝基苯参与的氢化反应有催化作用。N-AC与常规催化剂的比较表明，N-AC可替代常规固体碱催化剂和负载型金属催化剂用于Knoevenagel缩合和氧化反应。
Nitrogen-doped carbon materials have been gaining increasing interest as metal-free catalysts. In this article, the authors have briefly introduced their recent studies on the utilization of nitrogen-doped activated carbon (N-AC) for several organic synthesis reactions, which include base catalyzed reactions of Knoevenagel condensation and transesterification, aerobic oxidation of xanthene and alcohols, and transfer hydrogenation of nitrobenzene, 3-nitrostyrene, styrene, and phenylacetylene with hydrazine. Doped-nitrogen species existed on the AC surface in different structures. For example, pyridine-type nitrogen species appear to be involved in the active sites for Knoevenagel condensation and for the oxidation of xanthene, while graphite-type nitrogen species appear to be involved for the oxidation of alcohols. Being different from these reactions, both surface nitrogen and oxygen species are involved in the active sites for the hydrogenation of nitrobenzene. N-AC was practically inactive for the transfer hydrogenation of vinyl and ethynyl groups, but it can catalyze those hydrogenation reactions assisted by co-existing nitrobenzene. Comparison of N-AC with conventional catalysts shows that N-AC can alternate with conventional solid base catalysts and supported metal catalysts for the Knoevenagel condensation and oxidation reactions.