Dai Jingjing, Zhang Hongbo
School of Materials Science and Engineering and National Institute for Advanced Materials, Tianjin Key Laboratory for Rare Earth Materials and Applications, Nankai University, Tianjin, 300350, China.
Small. 2021 Jun;17(22):e2005334. doi: 10.1002/smll.202005334. Epub 2021 Mar 16.
Micro/meso-porous crystalline materials with a well-defined pore structure, such as zeolites, carbon nanotubes, and metal-organic frameworks, are of great significance in the development of catalytic systems for scientific and industrial demands. The confinement effect aroused by pore features of porous crystalline materials has triggered great interest in heterogeneous catalysis. Catalytic reactions in confined spaces exhibit unique behaviors compared to those observed on bulk materials. More interestingly, chemical reactivity can be modulated in different ways by the confinement effect, despite the fact that the mechanism on how the confinement effect changes the reaction remains unclear. In this review, a systematic discussion and fundamental understanding is provided concerning the concept of confinement effect, highlighting the impact of confinement effects on diffusion, adsorption/desorption, and catalytic reaction in typical micro/meso-porous crystalline materials, including zeolites, carbon nanotubes, and metal-organic frameworks. Relevant studies demonstrate that confinement effect affords not only shape selectivity against reactants/products, but also modulates surface electron distribution of active species confined within porous environments, thereby successively affecting the catalytic reactivity, selectivity, and stability. This review provides a useful guide for researchers attempting to design excellent porous crystalline catalysts based on the concept of confinement effect in heterogeneous catalysis.
具有明确孔结构的微/介孔晶体材料，如沸石、碳纳米管和金属有机框架，在满足科学和工业需求的催化体系开发中具有重要意义。多孔晶体材料的孔特征所引发的限域效应在多相催化领域引起了极大的关注。与在块状材料上观察到的催化反应相比，在受限空间内的催化反应表现出独特的行为。更有趣的是，尽管限域效应改变反应的机制尚不清楚，但限域效应可以通过不同方式调节化学反应性。在这篇综述中，我们对限域效应的概念进行了系统的讨论并提供了基本的理解，重点阐述了限域效应在典型的微/介孔晶体材料（包括沸石、碳纳米管和金属有机框架）中对扩散、吸附/脱附以及催化反应的影响。相关研究表明，限域效应不仅对反应物/产物具有形状选择性，还能调节受限在多孔环境中的活性物种的表面电子分布，从而依次影响催化反应活性、选择性和稳定性。这篇综述为试图基于多相催化中的限域效应概念设计优异多孔晶体催化剂的研究人员提供了有用的指导。
