Efficient synthesis of furfural from waste biomasses by sulfonated crab shell-based solid acid in a sustainable approach

As one of key biobased chemicals, furfural can be manufactured from the hydrothermal transformation of hemicelluloses in biomass, which is widely utilized in manufacturing furans, plastics, polymers, rubbers, resins, synthetic fibers, medicine, biofuels and other additives. In this work, one eco-friendly and sustainable approach for transforming waste lignocellulosic biomass to furfural was established in one-pot reaction manner. Crab shells (CRSs), which are derived from discarded seafood bio-waste, are known as one kind of naturally renewable and abundant bioresource. Using the pretreated CRS as support, a biobased heterogeneous chemocatalyst Sn-CFCRS was successfully prepared by carbonization followed by sulfonation, which was utilized to transform waste lignocellulosic biomass into furfural. The structure and morphology of the as-prepared chemocatalyst was examined and the acidity was measured. Deep eutectic solvent choline chloride:malic acid (DES ChCl:MA) (pKa=3.46) was chosen to assist Sn-CFCRS for catalysis of biomass. The catalytic performances were evaluated by one-pot transformation of various biomasses to furfural. Sn-CFCRS (2.4 wt%) transformed 75 g/L corncob into 117.1 mM furfural (65.6% yield) at 180 °C after 10 min in ChCl:MA−water (1:9, v/v) containing 50 mM CaCl2. This established sustainable process shows high potential application for valorization of biomass into furfural by utilizing biobased chemocatalyst in a benign reaction medium.