Liu Zhiqiang, Yuan Jiamin, van Baten Jasper M, Zhou Jian, Tang Xiaomin, Zhao Chao, Chen Wei, Yi Xianfeng, Krishna Rajamani, Sastre German, Zheng Anmin
State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, and Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China.
University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
Sci Adv. 2021 Mar 12;7(11). doi: 10.1126/sciadv.abf0775. Print 2021 Mar.
In separation and catalysis applications, adsorption and diffusion are normally considered mutually exclusive. That is, rapid diffusion is generally accompanied by weak adsorption and vice versa. In this work, we analyze the anomalous loading-dependent mechanism of -xylene diffusion in a newly developed zeolite called SCM-15. The obtained results demonstrate that the unique system of "continuum intersecting channels" (i.e., channels made of fused cavities) plays a key role in the diffusion process for the molecule-selective pathways. At low pressure, the presence of strong adsorption sites and intersections that provide space for molecule rotation facilitates the diffusion of -xylene along the direction. Upon increasing the molecular uptake, the adsorbates move faster along the direction because of the effect of continuum intersections in reducing the diffusion barriers and thus maintaining the large diffusion coefficient of the diffusing compound. This mechanism synergistically improves the diffusion in zeolites with continuum intersecting channels.
在分离和催化应用中，吸附和扩散通常被认为是相互排斥的。也就是说，快速扩散通常伴随着弱吸附，反之亦然。在这项工作中，我们分析了对二甲苯在一种新开发的名为SCM - 15的沸石中异常的负载依赖性扩散机制。所得结果表明，独特的“连续相交通道”（即由融合空腔构成的通道）系统在分子选择性路径的扩散过程中起关键作用。在低压下，强吸附位点和为分子旋转提供空间的交叉点的存在促进了对二甲苯沿 方向的扩散。随着分子吸附量的增加，由于连续交叉点在降低扩散势垒从而保持扩散化合物的大扩散系数方面的作用，被吸附物沿 方向移动得更快。这种机制协同改善了在具有连续相交通道的沸石中的扩散。
