On the influence of Si: Al ratio and hierarchical porosity of FAU zeolites in solid acid catalysed esterification pretreatment of bio-oil

Amin Osatiashtiani, Begoña Puértolas, Caio C.S. Oliveira, Jinesh C. Manayil, Brunella Barbero, Mark Isaacs, Chrysoula Michailof, Eleni Heracleous, Javier Pérez-Ramírez, Adam F. Lee, Karen Wilson*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


A family of faujasite (FAU) zeolites with different Si:Al ratio, and/or hierarchical porosity introduced via post-synthetic alkaline desilication treatment, have been evaluated as solid acid catalysts for esterification pretreatments of pyrolysis bio-oil components. Acetic acid esterification with aliphatic and aromatic alcohols including methanol, anisyl alcohol, benzyl alcohol, p-cresol and n-butanol was first selected as a model reaction to identify the optimum zeolite properties. Materials were fully characterised using N2 porosimetry, ICP, XRD, XPS, FT-IR, pyridine adsorption, NH3 TPD, In-situ ATR and inverse gas chromatography (IGC). IGC demonstrates that the surface polarity and hence hydrophobicity of FAU decreases with increased Si:Al ratio. Despite possessing a higher acid site loading and acetic acid adsorption capacity, high Al-content FAU possess weaker acidity than more siliceous catalysts. Esterification activity increases with acid strength and decreasing surface polarity following the order FAU30>FAU6>FAU2.6. The introduction of mesoporosity through synthesis of a hierarchical HFAU30 material further enhances esterification activity through improved acid site accessibility and hydrophobicity. Methanol was the most reactive alcohol for esterification, and evaluated with HFAU30 for the pretreatment of a real pyrolysis bio-oil, reducing the acid content by 76% under mild conditions.
Original languageEnglish
Pages (from-to)331-342
Number of pages12
JournalBiomass Conversion and Biorefinery
Issue number3
Early online date5 Apr 2017
Publication statusPublished - 1 Sept 2017

Bibliographical note

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Funding: EPSRC (EP/K000616/2, EP/G007594/4, EP/K036548/2, EP/N009924/1 and Leadership Fellowship); Royal Society
(Industry Fellowship); and EC FP7/2007–2013 (604307).

Underpinning data can be found at 10.17036/researchdata.aston.ac.uk.00000216.


  • esterification
  • bio-oil
  • pyrolysis
  • heterogeneous catalysis


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