Highly active and scalable SO3H functionalized carbon catalyst synthesized from bagasse for transformation of bio-based platform chemicals into fuel precursors and its in-depth characterization studies

Abstract

Scalable synthesis of SO3H functionalized carbon from sugar industry waste (bagasse) and detailed structural characterization and activity were reported. The incorporation of SO3H functionality groups on the carbon surface and the growth of the aromatic carbon framework was supported by FT-IR and 13C CP-MAS NMR analysis. The hydrothermally synthesized carbon exhibited total acidity of 5 mmol/g and uniform distribution of sulphur on the surface of carbon. The synthesized catalyst was found to be efficient for the acetalization, alkylation and alcoholysis reactions and exhibits excellent stability during the reactions. Various bio-derived carbonyl compounds were demonstrated by the solvent-free acetalization of bio-derived glycerol gives 50–100% conversion and 52–98% selectivity towards solketal derivatives at room temperature. The synthesized catalyst's reactivity was better than the commercially used Brønsted/Lewis acids. Furthermore, the SO3H functionalized carbon was also used for alcoholysis followed by ring-opening of furfuryl alcohol, giving 67–98% selectivity towards alkyl levulinates with complete conversion of furfuryl alcohol. The mechanistic pathway suggests that the alcoholysis reaction goes through three different intermediates (2-alkoxymethylfuran, 4,5,5-trialkoxypentan-2-one, and 5-hydroxy-4,5-dialkoxypentan-2-one) to produce the alkyl levulinates. Additionally, the catalyst was tested for solvent-free condensation of 2-methylfuran with various carbonyl compounds to selectively produce an excellent yield of fuel precursors (for C12-C15 hydrocarbons) at 60 °C. The catalyst was reused up to four cycles with 14% loss in the conversion of furfural for acetalization of glycerol, and negligible losses in the alkylation of 2-methylfuran were observed.