Exploring the hierarchy of transport phenomena in hierarchical pore systems by NMR diffusion measurement
Exploring the hierarchy of transport phenomena in hierarchical pore systems by NMR diffusion measurement
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DOI：
10.1016/j.micromeso.2012.06.049
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发表时间：
2012-12-01
影响因子：
5.2
通讯作者：
Ryoo, Ryong
中科院分区：
文献类型：
--
作者：
Mehlhorn, Dirk;Valiullin, Rustem;Ryoo, Ryong
脉冲场梯度技术的NMR（PFG NMR）适用于探索分子扩散在不同的NaCaA沸石试样，特别是在样品中含有“分级”的孔系统，其中微孔穿过中孔。选择乙烷（能够渗透微孔和中孔）和环己烷（无法渗透微孔）作为客体分子，并有目的地改变通过温度变化和孔阻塞的中孔中的可及性和流动性，在两个孔隙空间中的扩散率分别测量彼此。它示出的中孔的存在下，可能会引起显着增强的晶内扩散系数，而堵塞的中孔减少了一个数量级的晶内扩散系数。(C)2012 Elsevier Inc. All rights reserved.
The pulsed field gradient technique of NMR (PFG NMR) is applied for exploring molecular diffusion in different specimens of zeolite NaCaA, notably in samples containing "hierarchical" pore systems where the micropores are traversed by mesopores. Choosing ethane (capable of permeating both micro- and mesopores) and cyclohexane (unable to penetrate the micropores) as guest molecules and varying purposefully the accessibility and mobility in the mesopores by temperature variation and pore blocking, the diffusivities in the two pore spaces are measured separately from each other. It is shown that the presence of the mesopores may give rise to dramatically enhanced intracrystalline diffusivities while a blockage of the mesopores reduces the intracrystalline diffusivities by an order of magnitude. (C) 2012 Elsevier Inc. All rights reserved.