Valorization of Cynara Cardunculus L. to chemicals and biofuels

Hydrolysis of lignocellulosic biomass is an efficient way to produce valuable biobased platform chemicals, such as levulinic acid, whose derivatives find increasing applications as bio-fuels, intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this research, the acid-catalyzed hydrolysis of waste residue of Cynara Cardunculus L. (cardoon), remaining after seeds removal for oil exploitation, was investigated. The cardoon residue was employed as received and after steam explosion treatment, being the last a feedstock enriched in cellulose. Since both types of cardoon represent material with low value, the investigation was carried out adopting the High Gravity approach, using biomass loadings as higher as possible in order to achieve the maximum levulinic acid concentration in the hydrolyzates with an appreciable yield. Also the effect of main reaction parameters, such as catalyst type and loading, reaction time, temperature and heating methodology, on the hydrolysis performance was assessed. Levulinic acid molar yields up to 53mol% and levulinic acid concentrations up to 62 g/L were reached. In addition, formic acid, which is also a valuable compound, was always co-produced. Moreover, our preliminary studies on one-pot alcoholysis of cardoon in n-butanol demonstrate the possibility of direct production of the corresponding butyl levulinate with good yield. The very interesting achieved results of this work indicate that such waste biomass is a promising feedstock for the sustainable production of levulinic acid and alkyl levulinates, paving the way towards a real circular economy.