Metal–organic frameworks as selectivity regulators for hydrogenation reactions
Metal–organic frameworks as selectivity regulators for hydrogenation reactions
复制标题
DOI：
10.1038/nature19763
复制
发表时间：
2016-10
期刊：
影响因子：
64.8
通讯作者：
Meiting Zhao;Kuo Yuan;Yun Wang;Guodong Li;Jun Guo;L. Gu;Wenping Hu;Huijun Zhao;Z. Tang
中科院分区：
文献类型：
--
作者：
Meiting Zhao;Kuo Yuan;Yun Wang;Guodong Li;Jun Guo;L. Gu;Wenping Hu;Huijun Zhao;Z. Tang
由于天然来源有限，香料、香水和制药行业对不饱和酒精的广泛需求是通过碳氧基(优先于碳-碳基)的选择性氢化从α，β不饱和醛中生产出来的。然而，开发用于这种转化的有效催化剂是具有挑战性的，因为从热力学上讲，碳-碳基的加氢是受欢迎的。这一困难尤其与多相催化剂的一个主要类别有关：金属氧化物负载的金属纳米颗粒。这些体系一般不能显著提高对热力学不利反应的选择性，因为只有与金属氧化物载体直接接触的纳米颗粒的边缘具有选择性催化性能；大多数暴露的纳米颗粒表面没有、。这激发了金属有机骨架(MOF)的使用，将金属纳米颗粒包裹在其层内或通道内，以影响整个纳米颗粒表面的活性，同时由于材料的多孔性质，保持了反应物和产品的有效传输。在这里，我们发现MOF还可以作为α，β-不饱和醛加氢反应的有效选择性调节剂。将铂纳米颗粒夹在由含有Fe3+、Cr3+或两者的金属结点的MOF组成的内核和外壳之间(称为MIL-101；参考文献，)，可以得到稳定的催化剂，高效地转化一系列α，β不饱和醛，并显著提高对不饱和醇的选择性。计算表明，MOF金属中心与碳-氧而不是碳-碳基的优先相互作用使得前者被嵌入的铂纳米颗粒加氢是热力学上有利的反应。我们预计，我们的基本设计策略将允许开发其他选择性多相催化剂，用于重要但具有挑战性的转化。
Owing to the limited availability of natural sources, the widespread demand of the flavouring, perfume and pharmaceutical industries for unsaturated alcohols is met by producing them from α,β-unsaturated aldehydes, through the selective hydrogenation of the carbon–oxygen group (in preference to the carbon–carbon group). However, developing effective catalysts for this transformation is challenging,,,,,, because hydrogenation of the carbon–carbon group is thermodynamically favoured. This difficulty is particularly relevant for one major category of heterogeneous catalyst: metal nanoparticles supported on metal oxides. These systems are generally incapable of significantly enhancing the selectivity towards thermodynamically unfavoured reactions, because only the edges of nanoparticles that are in direct contact with the metal-oxide support possess selective catalytic properties; most of the exposed nanoparticle surfaces do not,,,,,. This has inspired the use of metal–organic frameworks (MOFs) to encapsulate metal nanoparticles within their layers or inside their channels, to influence the activity of the entire nanoparticle surface while maintaining efficient reactant and product transport owing to the porous nature of the material,,,. Here we show that MOFs can also serve as effective selectivity regulators for the hydrogenation of α,β-unsaturated aldehydes. Sandwiching platinum nanoparticles between an inner core and an outer shell composed of an MOF with metal nodes of Fe3+, Cr3+or both (known as MIL-101; refs , , ) results in stable catalysts that convert a range of α,β-unsaturated aldehydes with high efficiency and with significantly enhanced selectivity towards unsaturated alcohols. Calculations reveal that preferential interaction of MOF metal sites with the carbon–oxygen rather than the carbon–carbon group renders hydrogenation of the former by the embedded platinum nanoparticles a thermodynamically favoured reaction. We anticipate that our basic design strategy will allow the development of other selective heterogeneous catalysts for important yet challenging transformations.