N-containing covalent organic frameworks as supports for rhodium as transition-metal catalysts in hydroformylation reactions
N-containing covalent organic frameworks as supports for rhodium as transition-metal catalysts in hydroformylation reactions
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DOI：
10.1016/j.micromeso.2016.03.010
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发表时间：
2016-06
影响因子：
5.2
通讯作者：
M. Pilaski;J. Artz;H. Islam;A. Beale;R. Palkovits
中科院分区：
文献类型：
--
作者：
M. Pilaski;J. Artz;H. Islam;A. Beale;R. Palkovits
含氮官能团的多孔交联聚合物是一类很有前途的过渡金属催化剂固定化材料。这些高度多孔的材料是使用自下而上的方法从含配体的构建块构建的。利用含二腈的单体，在高温下在熔融氯化锌中形成高度多孔的共价三嗪框架（CTF）。含有大量可接近的氮配位位点，金属物种可以稳定在这些材料中。材料的孔隙率可以根据所使用的单体结构单元和合成条件进行调整。通过将铑物质固定在骨架内，然后预活化，Rh@CTF材料适合作为1-辛烯的无溶剂加氢裂化中的催化剂。这些Rh@CTF催化剂的活性不如常规的均相基准催化剂;然而，它们的活性和选择性明显优于可比的碳基催化剂。可以建立载体材料的孔隙率和极性与观察到的催化活性之间的相关性。此外，CTF基催化剂可以很容易地回收，无需进一步处理，只需逐渐失活即可进行多达五次运行。活性物质的浸出已被深入研究，以阐明在固定化催化剂的这一相当具有挑战性的反应中金属-载体相互作用的强度。
Porous cross-linked polymers containing nitrogen donor functionalities are a promising class of materials for the immobilization of transition metal catalysts. These highly porous materials are built from ligand-containing building blocks using a bottom-up approach. Utilizing dinitrile containing monomers, highly porous covalent triazine frameworks (CTFs) are formed at elevated temperatures in molten zinc chloride. Containing a large number of accessible nitrogen coordination sites, metal species can be stabilized within these materials. The materials' porosity can be tuned, depending on the monomeric building block used and synthesis conditions. By immobilizing rhodium species within the framework followed by pre-activation, Rh@CTF materials are suitable as catalysts in the solvent-free hydroformylation of 1-octene. These Rh@CTF catalysts are not as active as conventional homogeneous benchmark catalysts; however, their activity and selectivity clearly outperform comparable carbon-based catalysts. A correlation between porosity and polarity of the support material and the observed catalytic activity could be established. Furthermore, CTF-based catalysts could be recycled easily with no further treatment for up to five runs with just a gradual deactivation. The leaching of active species has been studied intensively to elucidate the strength of the metal-support-interactions in this rather challenging reaction for an immobilized catalyst.