Thermochemical and catalytic processes for the sustainable production of biofuels through biomass conversion

The environmental impact of fossil fuel exploitation has driven the research interest in biomass as a renewable and sustainable carbon source. This thesis investigates chemical and thermochemical conversion strategies for the valorisation of waste and low-value biomass into biofuels and value-added chemicals, within an integrated biorefinery framework. The first part of the work focuses on the synthesis of ethyl levulinate (EL) via acid-catalysed ethanolysis of hexose-based model substrates and real waste biomasses from the food supply chain. EL was subsequently evaluated as a bio-additive for gasoline in a spark-ignition engine, and as a reactive intermediate for the synthesis of a bio-based alternative to bisphenol A. The second part addresses the valorisation of hemicellulose-derived furfural through transfer hydrogenation to furfuryl alcohol, employing ethanol as both solvent and hydrogen donor in the presence of non-noble metal catalysts based on Aluminium and Zirconium complexes. Finally, the oxy-steam gasification of pulp and paper mill sludge is investigated as a thermochemical valorisation strategy, carried out in a downdraft fixed-bed gasifier, targeting the production of hydrogen-rich syngas and the characterisation of the resulting solid by-products.