Sustainable Exploitation of Residual Cynara cardunculus L. to Levulinic Acid and n-Butyl Levulinate

Anna Maria Raspolli Galletti,Valentina Coccia,Franco Cotana,Claudia Antonetti,Nicola Di Fidio,Domenico Licursi,Serena Ciorba

doi:10.3390/catal11091082

Abstract

Hydrolysis and butanolysis of lignocellulosic biomass are efficient routes to produce two valuable bio-based platform chemicals, levulinic acid and n-butyl levulinate, which find increasing applications in the field of biofuels and for the synthesis of intermediates for chemical and pharmaceutical industries, food additives, surfactants, solvents and polymers. In this research, the acid-catalyzed hydrolysis of the waste residue of Cynara cardunculus L. (cardoon), remaining after seed removal for oil exploitation, was investigated. The cardoon residue was employed as-received and after a steam-explosion treatment which causes an enrichment in cellulose. The effects of the main reaction parameters, such as catalyst type and loading, reaction time, temperature and heating methodology, on the hydrolysis process were assessed. Levulinic acid molar yields up to about 50 mol % with levulinic acid concentrations of 62.1 g/L were reached. Moreover, the one-pot butanolysis of the steam-exploded cardoon with the bio-alcohol n-butanol was investigated, demonstrating the direct production of n-butyl levulinate with good yield, up to 42.5 mol %. These results demonstrate that such residual biomass represent a promising feedstock for the sustainable production of levulinic acid and n-butyl levulinate, opening the way to the complete exploitation of this crop.

Highlights

Renewable resources have garnered increasing interest due to the shortage of petroleum, recurring rise in its price and environmental deterioration associated with its consumption, including pollutant by-products and greenhouse gases emission
European Union has recently incremented the renewable component of fuels and Italian legislation requires that 10% of fuels on sale in Italy are made of biofuel by 2020 [1,2]
The steam-explosion pretreatment is a high-pressure and high-temperature physical process that has been widely used for biomasses in the last decades [29], since it allows increased availability of cellulose of the raw lignocellulosic matrix for further processing

Summary

Introduction

Renewable resources have garnered increasing interest due to the shortage of petroleum, recurring rise in its price and environmental deterioration associated with its consumption, including pollutant by-products and greenhouse gases emission. It is worthy of notice that methane, a greenhouse gas 25 times more powerful than carbon dioxide, is emitted during the decomposition of organic material in landfills [3,4] In this scenario, the simple thermal-valorization and the chemical conversion of nonedible biomass to exploitable biomolecules should be developed and implemented, possibly avoiding any conflict with the food chain. The simple thermal-valorization and the chemical conversion of nonedible biomass to exploitable biomolecules should be developed and implemented, possibly avoiding any conflict with the food chain In this regard, the ability to employ residual or waste biomasses as starting materials using water or a bioalcohol as reactants/reaction media represents an added value that fits well with the concept of green chemistry. The nonedible lignocellulosic residues of this crop are reduced to a size of

Methods

Results

Conclusion