Synthesis of the bio-blendstock butyl levulinate: from model sugars to a real waste

Alkyl levulinates (ALs) are strategic bio-products within the bio-refinery process, finding applications as fragrances, plasticizers, intermediate for chemicals and oxygenated bio-fuels. In particular for the latter application, butyl levulinate (BL) represents an interesting compound, thanks to its promising fuel properties (low solubility in water, good solubility in Diesel fuel, contribution to the reduction of CO and soot emission) and its feasible synthesis. In the present work, the BL synthesis has been carried out starting directly from model sugars (glucose and microcrystalline cellulose) and a waste cellulosic biomass, namely a paper powder (PP) produced downstream of a papermill process. For this purpose, cheap diluted sulfuric acid has been used as catalyst, working at high substrate loading (high-gravity approach), aiming at the realisation of an economically sustainable process that allows the achievement of high BL concentration. Yields up to about 40 mol% have been achieved, working at the optimum feedstock loading of 14 wt%, which is higher than the majority of the values reported up to now.