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 journalArticle

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 languageEnglish
Article number841
JournalCatalysts
Volume9
Issue number10
DOIs
Publication statusPublished - 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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