Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours

Hessam Jahangiri; Amin Osatiashtiani; Miloud Ouadi; Andreas Hornung; Adam Lee; Karen Wilson

doi:10.3390/catal9100841

Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours

Hessam Jahangiri, Amin Osatiashtiani, Miloud Ouadi, Andreas Hornung, Adam Lee, Karen Wilson

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

Abstract

Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 ^◦C and 400 ^◦C. Turnover frequencies were proportional to Ga loading, reaching ~6 min ⁻¹ at 400 ^◦C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Brønsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation.

Original language	English
Article number	841
Journal	Catalysts
Volume	9
Issue number	10
DOIs	https://doi.org/10.3390/catal9100841
Publication status	Published - 11 Oct 2019

Bibliographical note

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Funding: EPSRC (EP/K036548/2, EP/K014676/1, EP/N009924/1), the Royal Society Industry Fellowship.

Keywords

Bio-oil
Ketonisation
Pyrolysis
Turnover frequencies (TOFs)

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10.3390/catal9100841Licence: CC BY 3.0

Acetic Acid Ketonisation
© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Final published version, 1.34 MBLicence: CC BY 3.0

Cite this

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title = "Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours",

abstract = "Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 ◦C and 400 ◦C. Turnover frequencies were proportional to Ga loading, reaching ~6 min −1 at 400 ◦C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Br{\o}nsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation. ",

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AU - Jahangiri, Hessam

AU - Osatiashtiani, Amin

AU - Ouadi, Miloud

AU - Hornung, Andreas

AU - Lee, Adam

AU - Wilson, Karen

N1 - © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). Funding: EPSRC (EP/K036548/2, EP/K014676/1, EP/N009924/1), the Royal Society Industry Fellowship.

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N2 - Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 ◦C and 400 ◦C. Turnover frequencies were proportional to Ga loading, reaching ~6 min −1 at 400 ◦C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Brønsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation.

AB - Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 ◦C and 400 ◦C. Turnover frequencies were proportional to Ga loading, reaching ~6 min −1 at 400 ◦C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Brønsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation.

KW - Bio-oil

KW - Ketonisation

KW - Pyrolysis

KW - Turnover frequencies (TOFs)

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Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours

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