Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours
by
Hessam Jahangiri 1,2,3
, Amin Osatiashtiani 3, Miloud Ouadi 1, Andreas Hornung 1,4,5, Adam F. Lee 6,* and Karen Wilson 6,*
Hessam Jahangiri 1,2,3, Amin Osatiashtiani 3, Miloud Ouadi 1, Andreas Hornung 1,4,5, Adam F. Lee 6,* and Karen Wilson 6,*
1
School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, UK
2
School of Water, Energy and Environment, Cranfield University, Cranfield MK43 0AL, UK
3
European Bioenergy Research Institute, Aston University, Birmingham B4 7ET, UK
4
Fraunhofer UMSICHT, Fraunhofer Institute for Environmental, Safety and Energy Technology, An der Maxhütte 1, 92237 Sulzbach-Rosenberg, Germany
5
Friedrich-Alexander University Erlangen-Nuremberg, Schlossplatz 4, 91054 Erlangen, Germany
6
Applied Chemistry & Environmental Science, RMIT University, Melbourne, VIC 3000, Australia
*
Authors to whom correspondence should be addressed.
Catalysts 2019, 9(10), 841; https://doi.org/10.3390/catal9100841
Received: 19 September 2019 / Revised: 4 October 2019 / Accepted: 5 October 2019 / Published: 11 October 2019
(This article belongs to the Special Issue Sustainable Catalytic Conversion of Biomass for the Production of Biofuels and Bioproducts)
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.
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Keywords:
pyrolysis; ketonisation; bio-oil; turnover frequencies (TOFs)
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MDPI and ACS Style
Jahangiri, H.; Osatiashtiani, A.; Ouadi, M.; Hornung, A.; Lee, A.F.; Wilson, K. Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours. Catalysts 2019, 9, 841.
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