A comparative study of diffusion of benzene/p-xylene mixtures in MFI particles, pellets and grown membranes

R. Kolvenbach; N. Al-Yassir; S. S. Al-Khattaf; O. C. Gobin; J. H. Ahn; A. Jentys; J. A. Lercher

doi:10.1016/j.cattod.2011.01.037

A comparative study of diffusion of benzene/p-xylene mixtures in MFI particles, pellets and grown membranes

R. Kolvenbach, N. Al-Yassir, S. S. Al-Khattaf, O. C. Gobin, J. H. Ahn, A. Jentys^*, J. A. Lercher

^*Corresponding author for this work

King Fahd University of Petroleum & Minerals

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

13 Scopus citations

Abstract

The transport and separation of mixtures between benzene and p-xylene in pellets prepared by pressing of ZSM-5 powder and a dense supported (crystalline) Silicalite-1 membrane were compared to isolated ZSM-5 crystallites. The kinetics of the transport in the pressed pellet and the grown membrane determined in a Wicke-Kallenbach cell (313-403 K; partial pressure range 200-2300 Pa) differed significantly from those measured for isolated ZSM-5 particles with the pressure modulation frequency response technique (343-403 K; partial pressure 30 Pa). In a pressed pellet, the transport was of Knudsen type leading to high fluxes of 10^-4 mol/m² s and identical permeances for benzene and p-xylene. The diffusion coefficient in a pressed pellet exceeded that in particles, in which the transport was controlled by intracrystalline diffusion and the pore entrance step, by 8 orders of magnitude. The flux across a grown Silicalite-1 membrane was two orders of magnitude lower and the permeability of p-xylene was 2.6-5 times higher than that of benzene. The change in diffusivity in the membrane compared to the particles results from the higher surface coverage of p-xylene.

Original language	English
Pages (from-to)	147-157
Number of pages	11
Journal	Catalysis Today
Volume	168
Issue number	1
DOIs	https://doi.org/10.1016/j.cattod.2011.01.037
State	Published - 20 Jun 2011

Bibliographical note

Funding Information:
The financial support from the Deutsche Forschungsgemeinschaft DFG under project JE260-8/1 is acknowledged. Robin Kolvenbach acknowledges the “Fonds der chemischen Industrie” for financial support by a Ph.D. scholarship. The authors are also grateful to Martin Neukamm for conducting the SEM measurements, and for the fruitful discussions in the framework of the center of excellence IDECAT.

Funding Information:
The authors acknowledge the support from Ministry of Higher Education, Saudi Arabia for the establishment of the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals (KFUPM).

Keywords

Aromatic molecules
Knudsen diffusion
Pressure modulation frequency response
Silicalite-1 membranes
Stefan-Maxwell diffusion
Wicke-Kallenbach experiments
ZSM-5

ASJC Scopus subject areas

Catalysis
General Chemistry

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10.1016/j.cattod.2011.01.037

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title = "A comparative study of diffusion of benzene/p-xylene mixtures in MFI particles, pellets and grown membranes",

abstract = "The transport and separation of mixtures between benzene and p-xylene in pellets prepared by pressing of ZSM-5 powder and a dense supported (crystalline) Silicalite-1 membrane were compared to isolated ZSM-5 crystallites. The kinetics of the transport in the pressed pellet and the grown membrane determined in a Wicke-Kallenbach cell (313-403 K; partial pressure range 200-2300 Pa) differed significantly from those measured for isolated ZSM-5 particles with the pressure modulation frequency response technique (343-403 K; partial pressure 30 Pa). In a pressed pellet, the transport was of Knudsen type leading to high fluxes of 10-4 mol/m2 s and identical permeances for benzene and p-xylene. The diffusion coefficient in a pressed pellet exceeded that in particles, in which the transport was controlled by intracrystalline diffusion and the pore entrance step, by 8 orders of magnitude. The flux across a grown Silicalite-1 membrane was two orders of magnitude lower and the permeability of p-xylene was 2.6-5 times higher than that of benzene. The change in diffusivity in the membrane compared to the particles results from the higher surface coverage of p-xylene.",

keywords = "Aromatic molecules, Knudsen diffusion, Pressure modulation frequency response, Silicalite-1 membranes, Stefan-Maxwell diffusion, Wicke-Kallenbach experiments, ZSM-5",

author = "R. Kolvenbach and N. Al-Yassir and Al-Khattaf, \{S. S.\} and Gobin, \{O. C.\} and Ahn, \{J. H.\} and A. Jentys and Lercher, \{J. A.\}",

note = "Funding Information: The financial support from the Deutsche Forschungsgemeinschaft DFG under project JE260-8/1 is acknowledged. Robin Kolvenbach acknowledges the “Fonds der chemischen Industrie” for financial support by a Ph.D. scholarship. The authors are also grateful to Martin Neukamm for conducting the SEM measurements, and for the fruitful discussions in the framework of the center of excellence IDECAT. Funding Information: The authors acknowledge the support from Ministry of Higher Education, Saudi Arabia for the establishment of the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals (KFUPM). ",

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AU - Al-Yassir, N.

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AU - Gobin, O. C.

AU - Ahn, J. H.

AU - Jentys, A.

AU - Lercher, J. A.

N1 - Funding Information: The financial support from the Deutsche Forschungsgemeinschaft DFG under project JE260-8/1 is acknowledged. Robin Kolvenbach acknowledges the “Fonds der chemischen Industrie” for financial support by a Ph.D. scholarship. The authors are also grateful to Martin Neukamm for conducting the SEM measurements, and for the fruitful discussions in the framework of the center of excellence IDECAT. Funding Information: The authors acknowledge the support from Ministry of Higher Education, Saudi Arabia for the establishment of the Center of Research Excellence in Petroleum Refining and Petrochemicals at King Fahd University of Petroleum and Minerals (KFUPM).

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N2 - The transport and separation of mixtures between benzene and p-xylene in pellets prepared by pressing of ZSM-5 powder and a dense supported (crystalline) Silicalite-1 membrane were compared to isolated ZSM-5 crystallites. The kinetics of the transport in the pressed pellet and the grown membrane determined in a Wicke-Kallenbach cell (313-403 K; partial pressure range 200-2300 Pa) differed significantly from those measured for isolated ZSM-5 particles with the pressure modulation frequency response technique (343-403 K; partial pressure 30 Pa). In a pressed pellet, the transport was of Knudsen type leading to high fluxes of 10-4 mol/m2 s and identical permeances for benzene and p-xylene. The diffusion coefficient in a pressed pellet exceeded that in particles, in which the transport was controlled by intracrystalline diffusion and the pore entrance step, by 8 orders of magnitude. The flux across a grown Silicalite-1 membrane was two orders of magnitude lower and the permeability of p-xylene was 2.6-5 times higher than that of benzene. The change in diffusivity in the membrane compared to the particles results from the higher surface coverage of p-xylene.

AB - The transport and separation of mixtures between benzene and p-xylene in pellets prepared by pressing of ZSM-5 powder and a dense supported (crystalline) Silicalite-1 membrane were compared to isolated ZSM-5 crystallites. The kinetics of the transport in the pressed pellet and the grown membrane determined in a Wicke-Kallenbach cell (313-403 K; partial pressure range 200-2300 Pa) differed significantly from those measured for isolated ZSM-5 particles with the pressure modulation frequency response technique (343-403 K; partial pressure 30 Pa). In a pressed pellet, the transport was of Knudsen type leading to high fluxes of 10-4 mol/m2 s and identical permeances for benzene and p-xylene. The diffusion coefficient in a pressed pellet exceeded that in particles, in which the transport was controlled by intracrystalline diffusion and the pore entrance step, by 8 orders of magnitude. The flux across a grown Silicalite-1 membrane was two orders of magnitude lower and the permeability of p-xylene was 2.6-5 times higher than that of benzene. The change in diffusivity in the membrane compared to the particles results from the higher surface coverage of p-xylene.

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KW - Knudsen diffusion

KW - Pressure modulation frequency response

KW - Silicalite-1 membranes

KW - Stefan-Maxwell diffusion

KW - Wicke-Kallenbach experiments

KW - ZSM-5

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DO - 10.1016/j.cattod.2011.01.037

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SN - 0920-5861

VL - 168

SP - 147

EP - 157

JO - Catalysis Today

JF - Catalysis Today

IS - 1

ER -

A comparative study of diffusion of benzene/p-xylene mixtures in MFI particles, pellets and grown membranes

Abstract

Bibliographical note

Keywords

ASJC Scopus subject areas

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