Deformable Metal-Organic Framework Nanosheets for Heterogeneous Catalytic Reactions
Deformable Metal-Organic Framework Nanosheets for Heterogeneous Catalytic Reactions
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用于多相催化反应的可变形金属有机框架纳米片
DOI：
10.1021/jacs.0c02272
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发表时间：
2020-05-20
影响因子：
15
通讯作者：
Wang, Tie
中科院分区：
文献类型：
--
作者：
Huang, Chuanhui;Guo, Zhihong;Wang, Tie
催化剂表面附近的动态状态可以显着影响催化过程，因为总反应速率取决于产物附着和反应物脱离的质量速度。作为一种主要的扩散机制，分子扩散被认为是一个缓慢的过程，会抑制反应物与多相催化剂之间的快速接触，从而降低催化转化效率。在此，我们报告了一种可以打破这种停滞层以促进向催化剂表面的质量传输的策略，其中封装在软金属有机框架（MOF）纳米片中的钯纳米立方体（NC）用作氢化反应的催化剂。软 MOF 支持渲染可变形特征，以增强 Pd NC 上的质量传输，这对于提高催化剂性能至关重要。结合数值模拟，我们确定了由流动流体的剪切力驱动的可变形 MOF，与包含不可变形 MOF 的对应系统相比，染料吸附和催化转化率分别提高了 5 倍和 3 倍。催化效率随MOF纳米片长距比设计呈现火山型趋势，长距比为2:1时催化效率达到最大值。该技术提供了独特的机会，可以在对多相催化反应有更深入的机理理解的基础上设计概念验证的自推进催化。
The dynamic status near the surface of a catalyst can significantly affect the catalytic process, because the overall reaction rate depends on the mass velocity of product attachment and reactant detachment. As a dominant diffusion mechanism, molecular diffusion is known as a slow process that inhibits the fast contact between the reactants and the heterogeneous catalyst, which depresses catalytic conversion efficiency. Herein, we report a strategy that can break such a stagnant layer to facilitate the mass transport toward the catalyst surface, wherein Pd nanocubes (NCs) encapsulated in soft metal-organic framework (MOF) nanosheets are used as catalysts for the hydrogenation reactions. The soft MOF supports render deformable features to enhance mass transport across the Pd NCs, which is vital to enhance the catalyst performance. In combination with numerical simulations, we identify the deformable MOF driven by the shear force of flowing fluid to increase dye adsorption and catalytic conversion by 5- and 3-fold, respectively, as compared to a counterpart system containing nondeformable MOFs. The catalytic efficiency presents a volcano-type trend with the length-to-spacing ratio of MOF nanosheet being designed and reaches the maximum with a length-to-spacing ratio of 2:1. This technique provides unique opportunities to design a proof-of-concept self-propelled catalysis on the basis of a greater mechanistic understanding of heterogeneous catalytic reactions.