Optimizing flexible zeolite Rho for unrivalled argon purification

Magdalena M. Lozinska; Elliott L. Bruce; Veselina M. Georgieva; Elizabeth M.  Feverston; Shubhra J.  Bhadra; Garret C.  Lau; Timothy C.  Golden; Erin M.  Sorensen; Roger D.  Whitley; Ronald I.  Smith; Paul A. Wright; William J.  Casteel Jr

doi:10.1016/j.micromeso.2025.113502

Optimizing flexible zeolite Rho for unrivalled argon purification

Magdalena M. Lozinska, Elliott L. Bruce, Veselina M. Georgieva, Elizabeth M. Feverston, Shubhra J. Bhadra, Garret C. Lau, Timothy C. Golden, Erin M. Sorensen, Roger D. Whitley, Ronald I. Smith, Paul A. Wright^*, William J. Casteel Jr^*

^*Corresponding author for this work

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

Abstract

The preparation of pure Ar from air requires removal of O₂ from a crude Ar stream produced by cryogenic distillation. Whereas their similar boiling points make further separation by distillation expensive, the difference in their molecular sizes makes separation by flexible zeolites an attractive route to kinetic separation. Modifying the cation content of the flexible and cubic zeolite Rho enables precise tuning of a single window size for unprecedented kinetic separation of O₂ from Ar. Li-Rho (unit cell Li_9.8Al_9.8Si_38.2O₉₆) is a very selective adsorbent due to its small pore size, but the highly distorted framework results in very slow O₂diffusion. By replacing some of the Li⁺ with H⁺, Cs⁺, or Zn²⁺, the window can be enlarged and in some cases the window cation occupancy reduced, increasing O₂ diffusion rates whilst retaining high O₂/Ar selectivity. The optimum unit cell composition among those examined was found to be Li_6.2Zn_1.8-Rho (O₂/Ar selectivity = 813, D/r²(O₂) = 0.37 s^-1).

Original language	English
Article number	113502
Number of pages	8
Journal	Microporous and Mesoporous Materials
Volume	387
Early online date	22 Jan 2025
DOIs	https://doi.org/10.1016/j.micromeso.2025.113502
Publication status	Published - 1 Apr 2025

Keywords

Argon purification
Kinetic separation O₂/Ar
Lithium zeolite Rho

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10.1016/j.micromeso.2025.113502Licence: CC BY

Lozinska_2025_MandMM_Optimizing-zeolite-Rho-argon-purification_CC
© 2025 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
Final published version, 3.22 MBLicence: CC BY

Light Element Analysis Facility (LEAF): Light Element Analysis Facility (LEAF)
Irvine, J. T. S. (PI), Baker, R. (CoI) & Miller, D. N. (CoI)
EPSRC
5/04/20 → 4/04/23
Project: Standard
Cation-Controlled Gating for Zeolites: Cation-Controlled Gating for Selective Gas Adsorption over Adaptable Zeolites
Wright, P. A. (PI)
EPSRC
1/11/16 → 31/01/20
Project: Standard
fLEXICCS ACCOUNT P WRIGHT: Versatile Adsorption Processes for the Capture of Carbon Dioxide from Industrial Sources - FlexICCS
Wright, P. A. (PI)
EPSRC
1/09/16 → 30/04/21
Project: Standard

Optimizing Flexible Zeolite Rho for Unrivalled Argon Purification (dataset)
Lozinska, M. M. (Creator), Bruce, E. L. (Creator), Georgieva, V. M. (Creator), Feverston, E. M. (Creator), Bhadra, S. J. (Creator), Lau, G. C. (Creator), Golden, T. C. (Creator), Sorensen, E. M. (Creator), Whitley, R. D. (Creator), Smith, R. I. (Creator), Wright, P. A. (Creator) & Casteel Jr, W. J. (Creator), University of St Andrews, 28 Jan 2025
DOI: 10.17630/c2e58789-0f2c-40c7-8653-f2fe1cdf7a10
Dataset

File
In situ neutron powder diffraction study of carbon dioxide adsorption on an adaptable zeolite
Wright, P. (Creator), Lozinska, M. (Creator), Georgieva, V. (Creator) & Smith, R. (Creator), ISIS Facility, 2018
DOI: 10.5286/isis.e.rb1820563, https://topcat.isis.stfc.ac.uk/doi/INVESTIGATION/90782158/
Dataset

Cite this

Lozinska, M. M., Bruce, E. L., Georgieva, V. M., Feverston, E. M., Bhadra, S. J., Lau, G. C., Golden, T. C., Sorensen, E. M., Whitley, R. D., Smith, R. I., Wright, P. A., & Casteel Jr, W. J. (2025). Optimizing flexible zeolite Rho for unrivalled argon purification. Microporous and Mesoporous Materials, 387, Article 113502. https://doi.org/10.1016/j.micromeso.2025.113502

@article{38340aa3e5c34fe787985826c42be30c,

title = "Optimizing flexible zeolite Rho for unrivalled argon purification",

abstract = "The preparation of pure Ar from air requires removal of O2 from a crude Ar stream produced by cryogenic distillation. Whereas their similar boiling points make further separation by distillation expensive, the difference in their molecular sizes makes separation by flexible zeolites an attractive route to kinetic separation. Modifying the cation content of the flexible and cubic zeolite Rho enables precise tuning of a single window size for unprecedented kinetic separation of O2 from Ar. Li-Rho (unit cell Li9.8Al9.8Si38.2O96) is a very selective adsorbent due to its small pore size, but the highly distorted framework results in very slow O2 diffusion. By replacing some of the Li+ with H+, Cs+, or Zn2+, the window can be enlarged and in some cases the window cation occupancy reduced, increasing O2 diffusion rates whilst retaining high O2/Ar selectivity. The optimum unit cell composition among those examined was found to be Li6.2Zn1.8-Rho (O2/Ar selectivity = 813, D/r2(O2) = 0.37 s-1).",

keywords = "Argon purification, Kinetic separation O₂/Ar, Lithium zeolite Rho",

author = "Lozinska, {Magdalena M.} and Bruce, {Elliott L.} and Georgieva, {Veselina M.} and Feverston, {Elizabeth M.} and Bhadra, {Shubhra J.} and Lau, {Garret C.} and Golden, {Timothy C.} and Sorensen, {Erin M.} and Whitley, {Roger D.} and Smith, {Ronald I.} and Wright, {Paul A.} and {Casteel Jr}, {William J.}",

note = "Funding: The authors thank the EPSRC for (FLEXICCS–Flexible Industrial Carbon Capture (EP/N024613/1; M.M.L. and P.A.W.), CationControlled Gating for Selective Gas Adsorption over Adaptable Zeo lites (EP/N032942/1; PAW and VMG) for funding and an NPIF PhD scholarship for ELB: EP/R512199/1). Experiments at the ISIS Neutron and Muon Source were supported by beamtime allocations RB1820563 and XB1890041 from the Science and Technology Facilities Council. Dr Alessandro Turrina (Johnson Matthey Technology Centre) is thanked for providing as-prepared Na,Cs-Rho material. Dr Julia L. Payne (University of St. Andrews) is thanked for assistance with sample preparation for NPD analysis. The authors acknowledge the SEM-EDS spectroscopy equipment funding (EPSRC Light Element Analysis Facility Grant: EP/ T019298/1).",

year = "2025",

month = apr,

day = "1",

doi = "10.1016/j.micromeso.2025.113502",

language = "English",

volume = "387",

journal = "Microporous and Mesoporous Materials",

issn = "1387-1811",

publisher = "Elsevier",

}

TY - JOUR

T1 - Optimizing flexible zeolite Rho for unrivalled argon purification

AU - Lozinska, Magdalena M.

AU - Bruce, Elliott L.

AU - Georgieva, Veselina M.

AU - Feverston, Elizabeth M.

AU - Bhadra, Shubhra J.

AU - Lau, Garret C.

AU - Golden, Timothy C.

AU - Sorensen, Erin M.

AU - Whitley, Roger D.

AU - Smith, Ronald I.

AU - Wright, Paul A.

AU - Casteel Jr, William J.

N1 - Funding: The authors thank the EPSRC for (FLEXICCS–Flexible Industrial Carbon Capture (EP/N024613/1; M.M.L. and P.A.W.), CationControlled Gating for Selective Gas Adsorption over Adaptable Zeo lites (EP/N032942/1; PAW and VMG) for funding and an NPIF PhD scholarship for ELB: EP/R512199/1). Experiments at the ISIS Neutron and Muon Source were supported by beamtime allocations RB1820563 and XB1890041 from the Science and Technology Facilities Council. Dr Alessandro Turrina (Johnson Matthey Technology Centre) is thanked for providing as-prepared Na,Cs-Rho material. Dr Julia L. Payne (University of St. Andrews) is thanked for assistance with sample preparation for NPD analysis. The authors acknowledge the SEM-EDS spectroscopy equipment funding (EPSRC Light Element Analysis Facility Grant: EP/ T019298/1).

PY - 2025/4/1

Y1 - 2025/4/1

N2 - The preparation of pure Ar from air requires removal of O2 from a crude Ar stream produced by cryogenic distillation. Whereas their similar boiling points make further separation by distillation expensive, the difference in their molecular sizes makes separation by flexible zeolites an attractive route to kinetic separation. Modifying the cation content of the flexible and cubic zeolite Rho enables precise tuning of a single window size for unprecedented kinetic separation of O2 from Ar. Li-Rho (unit cell Li9.8Al9.8Si38.2O96) is a very selective adsorbent due to its small pore size, but the highly distorted framework results in very slow O2 diffusion. By replacing some of the Li+ with H+, Cs+, or Zn2+, the window can be enlarged and in some cases the window cation occupancy reduced, increasing O2 diffusion rates whilst retaining high O2/Ar selectivity. The optimum unit cell composition among those examined was found to be Li6.2Zn1.8-Rho (O2/Ar selectivity = 813, D/r2(O2) = 0.37 s-1).

AB - The preparation of pure Ar from air requires removal of O2 from a crude Ar stream produced by cryogenic distillation. Whereas their similar boiling points make further separation by distillation expensive, the difference in their molecular sizes makes separation by flexible zeolites an attractive route to kinetic separation. Modifying the cation content of the flexible and cubic zeolite Rho enables precise tuning of a single window size for unprecedented kinetic separation of O2 from Ar. Li-Rho (unit cell Li9.8Al9.8Si38.2O96) is a very selective adsorbent due to its small pore size, but the highly distorted framework results in very slow O2 diffusion. By replacing some of the Li+ with H+, Cs+, or Zn2+, the window can be enlarged and in some cases the window cation occupancy reduced, increasing O2 diffusion rates whilst retaining high O2/Ar selectivity. The optimum unit cell composition among those examined was found to be Li6.2Zn1.8-Rho (O2/Ar selectivity = 813, D/r2(O2) = 0.37 s-1).

KW - Argon purification

KW - Kinetic separation O₂/Ar

KW - Lithium zeolite Rho

U2 - 10.1016/j.micromeso.2025.113502

DO - 10.1016/j.micromeso.2025.113502

M3 - Article

SN - 1387-1811

VL - 387

JO - Microporous and Mesoporous Materials

JF - Microporous and Mesoporous Materials

M1 - 113502

ER -

Optimizing flexible zeolite Rho for unrivalled argon purification

Abstract

Keywords

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Projects

Light Element Analysis Facility (LEAF): Light Element Analysis Facility (LEAF)

Cation-Controlled Gating for Zeolites: Cation-Controlled Gating for Selective Gas Adsorption over Adaptable Zeolites

fLEXICCS ACCOUNT P WRIGHT: Versatile Adsorption Processes for the Capture of Carbon Dioxide from Industrial Sources - FlexICCS

Datasets

Optimizing Flexible Zeolite Rho for Unrivalled Argon Purification (dataset)

In situ neutron powder diffraction study of carbon dioxide adsorption on an adaptable zeolite

Cite this