Diffusion pathways of benzene, toluene and p-xylene in MFI
Diffusion pathways of benzene, toluene and p-xylene in MFI
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DOI：
10.1016/j.micromeso.2009.01.025
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发表时间：
2009-10-01
影响因子：
5.2
通讯作者：
Lercher, J. A.
中科院分区：
文献类型：
--
作者：
Gobin, O. C.;Reitmeier, S. J.;Lercher, J. A.
通过解耦粒径效应和晶内扩散的频率响应方法研究了烷基取代芳香族分子在H-ZSM-5中的扩散。对于平均直径超过5μm的沸石晶体，随着芳族分子长宽比的增加，沸石孔中的传输对整体传输产生显着影响，导致各向异性扩散。苯的扩散几乎是各向同性的，而对二甲苯在ZSM-5的直通道和正弦通道系统中的扩散过程表现出显着差异。苯的各向同性扩散是基于其在两个通道系统之间重新定向而没有大障碍的能力而合理化的。对于对二甲苯，通道之间的切换只能通过能量上不利的旋转运动来实现，从而导致两个通道系统之间切换的可能性较低。 (C) 2009 Elsevier Inc. 保留所有权利。
The diffusion of alkyl-substituted aromatic molecules in H-ZSM-5 was investigated by means of the frequency response method decoupling particle size effects and intracrystalline diffusion. For zeolite crystals above 5 mu m average diameter, the transport in the zeolite pores exerts a significant effect on the overall transport causing anisotropic diffusion as the aspect ratio of the aromatic molecules increases. Diffusion of benzene is nearly isotropic, while p-xylene shows marked differences between the diffusive processes in the straight and sinusoidal channel system of ZSM-5. The isotropic diffusion of benzene is rationalized on the basis of its ability to reorient between the two channel systems without major hindrances. For p-xylene, switching between the channels is only possible by energetically unfavorable rotational motions leading to a low probability for changing between both channel systems. (C) 2009 Elsevier Inc. All rights reserved.