Valorization of Cynara Cardunculus L. to chemicals and biofuels

As the petroleum reserves are running out and at the same time the environmental deterioration is continuing, it is of fundamental importance to explore alternative resources to traditional fuels for the production of chemicals and fuels. Hydrolysis of lignocellulosic biomass is an efficient way to produce valuable platform chemicals, such as levulinic acid (LA), whose derivatives find increasing application as bio-fuels, intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this scenario, the ability to employ as starting material residual or waste biomass is an added value and fits with the concept of circular economy. In this research, the acid-catalized hydrolysis of residual Cynara Cardunculus L. (cardoon), remaining after seeds removal for oil exploitation, has been investigated. The residual cardoon has been employed as received and after steam explosion treatment, resulting in a feedstock enriched in cellulose. Since both types of cardoon represent material with low value, the investigation has been carried out adopting the High Gravity approach, using biomass loadings as higher as possible in order to achieve the maximum LA concentration in the hydrolyzed with an appreciable conversion yield. High values of LA molar yield, up to about 50%, have been obtained, working on non pre-treated biomass. When cellulose-rich steam-explosed cardoon was adopted, significantly better results were reached adopting both microwave reactor and batch autoclave. Moreover, our preliminary studies on the direct alcoholysis of cardoon demonstrate the possibility to direct production of the corresponding alkyl levulinates with good yield. The very interesting achieved results of this work indicate that such biomass is a promising feedstock for the sustainable production of LA and alkyl levulinates, paving the way towards a real circular economy.