Production of levulinic acid and n-butyl levulinate from the waste biomasses grape pomace and Cynara Cardunculus L.

Nowadays, the transformation of lignocellulosic biomass into added-value products, such as bio-based platform chemicals and fuels, is attracting great attention. In this research, the acid-catalyzed hydrolysis of waste grape pomace and Cynara Cardunculus L. (cardoon), remained after wine and oil exploitation respectively, to levulinic acid was investigated. The grape pomace residue was employed as received, whereas the cardoon one was used both as received and after the steam explosion treatment, becoming enriched in cellulose. Since waste biomasses are low value materials, this investigation was performed adopting the High Gravity approach, using biomass loadings as higher as possible in order to achieve the maximum product concentration in the hydrolyzates, while maintaining an appreciable yield. Under the optimized reaction conditions, starting from grape pomace residue, the levulinic acid yield and concentration of 49.5 mol% and 8.5 g/L were reached respectively, whereas, from pre-treated cardoon residue, levulinic acid yields and concentrations up to 53 mol% and 62 g/L were attained, highlighting cardoon as the most suitable feedstock. On this basis, one-pot alcoholysis of pre-treated cardoon in n-butanol to n-butyl levulinate was successfully performed. In summary, waste cardoon resulted a promising feedstock for the sustainable production of both levulinic acid and alkyl levulinates, paving the way towards a circular economy.