Diffusion pathways of benzene, toluene and p-xylene in MFI

O. C. Gobin; S. J. Reitmeier; A. Jentys; J. A. Lercher

doi:10.1016/j.micromeso.2009.01.025

Diffusion pathways of benzene, toluene and p-xylene in MFI

O. C. Gobin
, S. J. Reitmeier
, A. Jentys
, J. A. Lercher

Technical University of Munich

Research output: Contribution to journal › Article › peer-review

44 Scopus citations

Abstract

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 μm 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.

Original language	English
Pages (from-to)	3-10
Number of pages	8
Journal	Microporous and Mesoporous Materials
Volume	125
Issue number	1-2
DOIs	https://doi.org/10.1016/j.micromeso.2009.01.025
State	Published - 1 Oct 2009

Keywords

Aromatics
Frequency response
Intra-crystalline diffusion
MFI-type zeolites
Particle size distribution

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10.1016/j.micromeso.2009.01.025

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title = "Diffusion pathways of benzene, toluene and p-xylene in MFI",

abstract = "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 μm 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.",

keywords = "Aromatics, Frequency response, Intra-crystalline diffusion, MFI-type zeolites, Particle size distribution",

author = "Gobin, \{O. C.\} and Reitmeier, \{S. J.\} and A. Jentys and Lercher, \{J. A.\}",

note = "Funding Information: The financial support from the Deutsche Forschungsgemeinschaft DFG under project JE260-7/1 and JE260-8/1 is acknowledged. Stephan J. Reitmeier acknowledges the {\textquotedblleft}Studienstiftung des Deutschen Volkes{\textquotedblright} for the financial support by a PhD scholarship. For the possibility to perform the DLS measurements the authors are grateful to Michael Paul from the Sch{\"u}th group. The authors are also grateful to Martin Neukamm for conducting the SEM measurements, and for the fruitful discussions in the framework of the network of excellence IDECAT and the Bavarian graduate school NanoCat (S.R.). ",

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doi = "10.1016/j.micromeso.2009.01.025",

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AU - Gobin, O. C.

AU - Reitmeier, S. J.

AU - Jentys, A.

AU - Lercher, J. A.

N1 - Funding Information: The financial support from the Deutsche Forschungsgemeinschaft DFG under project JE260-7/1 and JE260-8/1 is acknowledged. Stephan J. Reitmeier acknowledges the “Studienstiftung des Deutschen Volkes” for the financial support by a PhD scholarship. For the possibility to perform the DLS measurements the authors are grateful to Michael Paul from the Schüth group. The authors are also grateful to Martin Neukamm for conducting the SEM measurements, and for the fruitful discussions in the framework of the network of excellence IDECAT and the Bavarian graduate school NanoCat (S.R.).

PY - 2009/10/1

Y1 - 2009/10/1

N2 - 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 μm 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.

AB - 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 μm 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.

KW - Aromatics

KW - Frequency response

KW - Intra-crystalline diffusion

KW - MFI-type zeolites

KW - Particle size distribution

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DO - 10.1016/j.micromeso.2009.01.025

M3 - Article

AN - SCOPUS:67651114129

SN - 1387-1811

VL - 125

SP - 3

EP - 10

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

IS - 1-2

ER -

Diffusion pathways of benzene, toluene and p-xylene in MFI

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Keywords

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