Levulinic acid production from sugarcane bagasse: the role of acidity in 1-allyl-3-methylimidazolium ionic liquids

Abstract

The transition toward a sustainable bio-economy necessitates the efficient valorization of lignocellulosic biomass, such as sugarcane bagasse (SCB), into high-value platform chemicals like levulinic acid (LA). Chemo-catalytic conversion of cellulosic biomass to high value-added biochemicals remains challenging due to the low process efficiency and low recovered yields of the catalysts from the utilized methods, but catalytic transformations utilizing ionic liquids (ILs) offer a sophisticated and effective strategy that can be utilized for evaluating the impact of the IL’s acidity strength on the overall transformation process of SCB to produce levulinic acid (LA). In this study, we explored the use of 1-allyl-3-methylimidazolium-based ionic liquids [hydrogen sulfate (HSO 4 ) and dodecyl sulfate (DOS)] as catalysts in a transformation process using the benchtop Parr reactor under varied reaction conditions designed using the Box–Behnken method. The results show that the more acidic the catalyst, the more effective the chemo-catalytic method and the higher the yield produced. In the screening experiments, DOS-based IL was more selective toward the production of LA (75.5%) from glucose when compared to the pristine (Cl-based, 63.2%) and HSO 4 -based (72.7%) catalysts. Based on these results, optimization studies were carried out using the DOS-based ionic liquid (IL) as the catalyst and SCB as the feedstock, and the optimal LA yield obtained was 46.7%. These optimal conditions were also utilized to study the reusability of the IL, and the resultant LA yields demonstrate the impressive performance of [1-allyl-3-mim][DOS] as its acidic property, robust recyclability, and great potential enable it to be applied in biomass valorization to produce useful biochemicals.