Production of bio-renewable jet-fuel via aldol-condensation and HDO processes of lignocellulosic platform molecules

Production of bio-renewable jet-fuel via aldol-condensation and HDO processes of lignocellulosic platform molecules

Geopolitical and environmental concerns currently faced by humanity have given rise to extensive research activities focused on the production of transport fuels and valuable bioproducts, specifically taking advantage of renewable resources as opposed to fossil ones. Among such renewable energy resources, there is a solid consensus in lignocellulosic biomass as one of the most promising bio-based feedstocks for the production of not only biofuels but also a wide variety of biomass-derived chemicals, most desirably without competing with food crops, fodder, and natural habitats.Among them, furanic compounds (such as furfural, 5-hydroxymethlyfurfural) and ketones (such as acetone, 2-butanone) are readily available chemicals, which can be produced from biomass hydrolytic processes (Biofine, Dibanet, etc.). Aldehydes and ketones can react by aldol condensation and afford higher added-value products. The aldol condensation proceeds in the presence of either basic or acidic catalysts. While the most effective industrially available methods rely on using liquid bases (NaOH or KOH) or mineral acid (H2SO4) as catalysts, these catalysts constitute a major environmental threat due to wastewater production and equipment corrosion. To address this issue, new industrially viable catalysts must be developed.

Building units of the majority of natural plant biomass mainly consists of short-chain monosaccharides (typically C5 and C6 sugars), together with complex lignin molecules. Such components contain a considerable amount of oxygen, usually leading, after mechanical, thermal and/or chemo-catalytic processing, to products having poor fuel properties, or for limited applications in organic chemistry. To overcome this limitation, strategies for increasing the hydrocarbon chain length and reduce the oxygen content are being analysed and developed, based on new biomass up-grading concepts. The combination of aldol condensation and hydrodeoxygenation (HDO) transformations would allow obtaining high energy-content biofuels, with the adequate chain length and structure for use in the range of jet fuel.
In this context, the main goal of the proposed research line is the optimization of the production of precursor molecules in the jet-fuel range (C8-13), especially aimed to reduce the carbon footprint of air transport. The research would be focused on the aldol condensation of biomass-derived furfural with different ketones, especially those also of renewable origin, seeking to optimize the catalytic system (nature and concentration of active sites, selection of the support, optimization of reaction conditions, etc.). Furthermore, HDO reaction is contemplated as way of reducing the oxygen content of the final biofuel.