Production of sustainable aviation fuel intermediates by Pd/C catalysed alkylation of combinations of fermentation-derived oxygenates

Abstract

Sustainable Aviation Fuel (SAF) is a complex mixture of hydrocarbons, consisting of linear and branched alkanes along with cyclic and aromatic compounds. In this study, an optimised catalytic system formed by Pd/C and the base K₃PO₄ was examined for the alkylation of different combinations of ketones (acetone and butanone) and alcohols (ethanol, 1-butanol, and isopropanol), all obtainable through fermentation of renewable carbon sources. Conversion of the reactants towards desired longer-chained ketone products serving as intermediates for SAF was consistently above 90% for all combinations involving primary alcohols at higher temperatures, with selectivities towards the desired products as high as 80%. Acetone primarily provided intermediates for linear alkanes, whereas butanone was found to be a promising ketone for alkylation, providing intermediates for long branched alkanes after dialkylation on both the methyl and the less reactive ethyl side chain. In perspective, the catalytic system seems promising for making blends of SAF substrates with high selectivity from fermentation-derived oxygenate mixtures.