Adsorption of dimethyl ether (DME) on zeolite molecular sieves

Jai B. Lad; Yassir T. Makkawi

doi:10.1016/j.cej.2014.07.001

Adsorption of dimethyl ether (DME) on zeolite molecular sieves

Jai B. Lad, Yassir T. Makkawi^*

^*Corresponding author for this work

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

Abstract

In recent years there has been growing interest in the use of dimethyl ether (DME) as an alternative fuel. In this study, the adsorption of DME on molecular sieves 4Å (Mol4A) and 5Å (Mol5A) has been experimentally investigated using the volumetric adsorption method. Data on the adsorption isotherms, heats of adsorption, and adsorption kinetic have been obtained and used to draw conclusions and compare the performance of the two adsorbents. Within the conditions considered, the adsorption capacity of Mol5A was found to be around eight times higher than the capacity of Mol4A. Low temperature adsorption and thermal pre-treatment of the adsorbents in vacuum were observed to be favourable for increased adsorption capacity. The adsorption isotherms for both adsorbent were fitted to the Freundlich model and the corresponding model parameters are proposed. The adsorption kinetic analysis suggest that the DME adsorption on Mol5A is controlled by intracrystalline diffusion resistance, while on Mol4A it is mainly controlled by surface layering resistance with the diffusion only taking place at the start of adsorption and for a very limited short time. The heats of adsorption were calculated by a calorimetric method based on direct temperature measurements inside the adsorption cell. Isosteric heats, calculated by the thermodynamic approach (Clasius-Clapeyron equation), have consistently shown lower values. The maximum heat of adsorption was found to be 25.9kJmol^-1 and 20.1kJmol^-1 on Mol4A and Mol5A, respectively; thus indicating a physisorption type of interactions.

Original language	English
Pages (from-to)	335-346
Number of pages	12
Journal	Chemical Engineering Journal
Volume	256
Early online date	8 Jul 2014
DOIs	https://doi.org/10.1016/j.cej.2014.07.001
Publication status	Published - 15 Nov 2014

Bibliographical note

NOTICE: this is the author’s version of a work that was accepted for publication in Chemical engineering journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Lad, J. B., & Makkawi, Y. T. Adsorption of dimethyl ether (DME) on zeolite molecular sieves. Chemical engineering journal, Vol. 256 (2014) http://dx.doi.org/10.1016/j.cej.2014.07.001

Funding: EPSRC CASE EP/J501797/1

Keywords

adsorption
adsorption kinetics
DME
heat of adsorption
isotherm
molecular sieves

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10.1016/j.cej.2014.07.001

Adsorption of dimethyl ether (DME) on zeolite molecular sieves
NOTICE: this is the author’s version of a work that was accepted for publication in Chemical engineering journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Lad, J. B., & Makkawi, Y. T. Adsorption of dimethyl ether (DME) on zeolite molecular sieves. Chemical engineering journal, Vol. 256 (2014) http://dx.doi.org/10.1016/j.cej.2014.07.001
Accepted author manuscript, 997 KB

Cite this

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title = "Adsorption of dimethyl ether (DME) on zeolite molecular sieves",

abstract = "In recent years there has been growing interest in the use of dimethyl ether (DME) as an alternative fuel. In this study, the adsorption of DME on molecular sieves 4{\AA} (Mol4A) and 5{\AA} (Mol5A) has been experimentally investigated using the volumetric adsorption method. Data on the adsorption isotherms, heats of adsorption, and adsorption kinetic have been obtained and used to draw conclusions and compare the performance of the two adsorbents. Within the conditions considered, the adsorption capacity of Mol5A was found to be around eight times higher than the capacity of Mol4A. Low temperature adsorption and thermal pre-treatment of the adsorbents in vacuum were observed to be favourable for increased adsorption capacity. The adsorption isotherms for both adsorbent were fitted to the Freundlich model and the corresponding model parameters are proposed. The adsorption kinetic analysis suggest that the DME adsorption on Mol5A is controlled by intracrystalline diffusion resistance, while on Mol4A it is mainly controlled by surface layering resistance with the diffusion only taking place at the start of adsorption and for a very limited short time. The heats of adsorption were calculated by a calorimetric method based on direct temperature measurements inside the adsorption cell. Isosteric heats, calculated by the thermodynamic approach (Clasius-Clapeyron equation), have consistently shown lower values. The maximum heat of adsorption was found to be 25.9kJmol-1 and 20.1kJmol-1 on Mol4A and Mol5A, respectively; thus indicating a physisorption type of interactions.",

keywords = "adsorption, adsorption kinetics, DME, heat of adsorption, isotherm, molecular sieves",

author = "Lad, {Jai B.} and Makkawi, {Yassir T.}",

note = "NOTICE: this is the author{\textquoteright}s version of a work that was accepted for publication in Chemical engineering journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Lad, J. B., & Makkawi, Y. T. Adsorption of dimethyl ether (DME) on zeolite molecular sieves. Chemical engineering journal, Vol. 256 (2014) http://dx.doi.org/10.1016/j.cej.2014.07.001 Funding: EPSRC CASE EP/J501797/1",

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AU - Lad, Jai B.

AU - Makkawi, Yassir T.

N1 - NOTICE: this is the author’s version of a work that was accepted for publication in Chemical engineering journal. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Lad, J. B., & Makkawi, Y. T. Adsorption of dimethyl ether (DME) on zeolite molecular sieves. Chemical engineering journal, Vol. 256 (2014) http://dx.doi.org/10.1016/j.cej.2014.07.001 Funding: EPSRC CASE EP/J501797/1

PY - 2014/11/15

Y1 - 2014/11/15

N2 - In recent years there has been growing interest in the use of dimethyl ether (DME) as an alternative fuel. In this study, the adsorption of DME on molecular sieves 4Å (Mol4A) and 5Å (Mol5A) has been experimentally investigated using the volumetric adsorption method. Data on the adsorption isotherms, heats of adsorption, and adsorption kinetic have been obtained and used to draw conclusions and compare the performance of the two adsorbents. Within the conditions considered, the adsorption capacity of Mol5A was found to be around eight times higher than the capacity of Mol4A. Low temperature adsorption and thermal pre-treatment of the adsorbents in vacuum were observed to be favourable for increased adsorption capacity. The adsorption isotherms for both adsorbent were fitted to the Freundlich model and the corresponding model parameters are proposed. The adsorption kinetic analysis suggest that the DME adsorption on Mol5A is controlled by intracrystalline diffusion resistance, while on Mol4A it is mainly controlled by surface layering resistance with the diffusion only taking place at the start of adsorption and for a very limited short time. The heats of adsorption were calculated by a calorimetric method based on direct temperature measurements inside the adsorption cell. Isosteric heats, calculated by the thermodynamic approach (Clasius-Clapeyron equation), have consistently shown lower values. The maximum heat of adsorption was found to be 25.9kJmol-1 and 20.1kJmol-1 on Mol4A and Mol5A, respectively; thus indicating a physisorption type of interactions.

AB - In recent years there has been growing interest in the use of dimethyl ether (DME) as an alternative fuel. In this study, the adsorption of DME on molecular sieves 4Å (Mol4A) and 5Å (Mol5A) has been experimentally investigated using the volumetric adsorption method. Data on the adsorption isotherms, heats of adsorption, and adsorption kinetic have been obtained and used to draw conclusions and compare the performance of the two adsorbents. Within the conditions considered, the adsorption capacity of Mol5A was found to be around eight times higher than the capacity of Mol4A. Low temperature adsorption and thermal pre-treatment of the adsorbents in vacuum were observed to be favourable for increased adsorption capacity. The adsorption isotherms for both adsorbent were fitted to the Freundlich model and the corresponding model parameters are proposed. The adsorption kinetic analysis suggest that the DME adsorption on Mol5A is controlled by intracrystalline diffusion resistance, while on Mol4A it is mainly controlled by surface layering resistance with the diffusion only taking place at the start of adsorption and for a very limited short time. The heats of adsorption were calculated by a calorimetric method based on direct temperature measurements inside the adsorption cell. Isosteric heats, calculated by the thermodynamic approach (Clasius-Clapeyron equation), have consistently shown lower values. The maximum heat of adsorption was found to be 25.9kJmol-1 and 20.1kJmol-1 on Mol4A and Mol5A, respectively; thus indicating a physisorption type of interactions.

KW - adsorption

KW - adsorption kinetics

KW - DME

KW - heat of adsorption

KW - isotherm

KW - molecular sieves

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DO - 10.1016/j.cej.2014.07.001

M3 - Article

AN - SCOPUS:84904866506

SN - 1385-8947

VL - 256

SP - 335

EP - 346

JO - Chemical Engineering Journal

JF - Chemical Engineering Journal

ER -

Adsorption of dimethyl ether (DME) on zeolite molecular sieves

Abstract

Bibliographical note

Keywords

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