Using small angle neutron scattering to explore porosity, connectivity and accessibility, towards optimised hierarchical solid acid catalysts
Using small angle neutron scattering to explore porosity, connectivity and accessibility, towards optimised hierarchical solid acid catalysts
The significant interest in developing hierarchical materials to overcome the traditional limitations of microporous catalysts, has led to a wide range of synthesis protocols being developed. In this work we modify traditional synthetic procedures known to yield highly crystalline microporous materials, by adding a hydrocarbon surfactant, leading to the formation of hierarchical solid-acid zeotypes; silicoaluminophosphates. We show for the first time, that small angle neutron scattering can build a qualitative description of the porosity in hierarchical materials, probing the exact nature of the micropores and mesopores within our system, that can be adapted to any hierarchical system. When combined with positron annihilation lifetime spectroscopy and porosimetry measurements we gain greater insight by exploring the accessibility and interconnectivity of the micropores and mesopores. We show that by varying the quantity of mesoporogen the size and nature of the mesopores can be finely tuned. Further, small angle neutron scattering reveals that mesopores are lined with a silica layer, that strongly influences the accessibility of the micropores. As such we show that our hierarchical materials contain distinct micropores housing stronger Brønsted acid sites, whilst the mesopores are lined with weaker silanol groups. This is complemented with a catalytic study focussing on n-butane isomerisation and ethanol dehydration that highlights the advantages and disadvantages of this design and further probes the influence of these bimodal porous systems on catalytic performance.
22822-22834
Potter, Matthew E.
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Oakley, Alice E.
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Le Brocq, Joshua J.M.
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Riley, Lauren N.
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Carravetta, Marina
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King, Stephen M.
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Doherty, Cara M.
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Vandegehuchte, Bart D.
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Raja, Robert
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20 September 2023
Potter, Matthew E.
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Oakley, Alice E.
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Le Brocq, Joshua J.M.
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Riley, Lauren N.
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Carravetta, Marina
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King, Stephen M.
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Doherty, Cara M.
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Vandegehuchte, Bart D.
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Raja, Robert
74faf442-38a6-4ac1-84f9-b3c039cb392b
Potter, Matthew E., Oakley, Alice E., Le Brocq, Joshua J.M., Riley, Lauren N., Carravetta, Marina, King, Stephen M., Doherty, Cara M., Vandegehuchte, Bart D. and Raja, Robert
(2023)
Using small angle neutron scattering to explore porosity, connectivity and accessibility, towards optimised hierarchical solid acid catalysts.
Journal of Materials Chemistry A, 11 (42), .
(doi:10.1039/d3ta04763f).
Abstract
The significant interest in developing hierarchical materials to overcome the traditional limitations of microporous catalysts, has led to a wide range of synthesis protocols being developed. In this work we modify traditional synthetic procedures known to yield highly crystalline microporous materials, by adding a hydrocarbon surfactant, leading to the formation of hierarchical solid-acid zeotypes; silicoaluminophosphates. We show for the first time, that small angle neutron scattering can build a qualitative description of the porosity in hierarchical materials, probing the exact nature of the micropores and mesopores within our system, that can be adapted to any hierarchical system. When combined with positron annihilation lifetime spectroscopy and porosimetry measurements we gain greater insight by exploring the accessibility and interconnectivity of the micropores and mesopores. We show that by varying the quantity of mesoporogen the size and nature of the mesopores can be finely tuned. Further, small angle neutron scattering reveals that mesopores are lined with a silica layer, that strongly influences the accessibility of the micropores. As such we show that our hierarchical materials contain distinct micropores housing stronger Brønsted acid sites, whilst the mesopores are lined with weaker silanol groups. This is complemented with a catalytic study focussing on n-butane isomerisation and ethanol dehydration that highlights the advantages and disadvantages of this design and further probes the influence of these bimodal porous systems on catalytic performance.
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d3ta04763f
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Accepted/In Press date: 20 September 2023
e-pub ahead of print date: 20 September 2023
Published date: 20 September 2023
Additional Information:
Funding Information:
MEP, AOE, JJMLB, MC and RR acknowledge the TotalEnergies “Consortium on metal nanocatalysts” project for funding. The authors would like to thank the Science & Technology Facilities Council for the provision of neutron beamtime (experiment RB1920060, DOI: 10.5286/ISIS.E.RB1920060-1). This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union's Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement no. 654000. CMD acknowledges the Veski Inspiring Women fellowship for support. ICP analysis was performed at the National Oceanography Centre, Southampton with the kind help of Dr Matthew Cooper. SEM imaging was performed at the Biological Imaging Unit at Southampton General Hospital.
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Local EPrints ID: 483742
URI: http://eprints.soton.ac.uk/id/eprint/483742
ISSN: 2050-7488
PURE UUID: 42acff1f-74b7-4cbf-8218-d3437a37b106
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Date deposited: 03 Nov 2023 18:06
Last modified: 18 Mar 2024 03:04
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Contributors
Author:
Alice E. Oakley
Author:
Joshua J.M. Le Brocq
Author:
Lauren N. Riley
Author:
Cara M. Doherty
Author:
Bart D. Vandegehuchte
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