Efficient valorization of biomass-derived furfuryl alcohol to butyl levulinate using a facile lignin-based carbonaceous acid

The preparation and application of biorenewable carbon-based catalyst are attracting increasingly attention in the field of green and sustainable chemistry. Here, a facile and low-cost lignosulfonate-based carbonaceous solid acid (LSS) was availably prepared via directly sulfonating lignosulfonate that was from sulfite pulping industry, and used to catalyze biomass-derived furfuryl alcohol to yield versatile butyl levulinate. The fabrication and properties of LSS were highly sensitive to the sulfonation conditions (i.e., lignosulfonate-to-H2SO4 ratio and temperature). The physicochemical properties of the as-prepared LSS were well characterized using BET surface area, acid–base titration, SEM, XRD, FT-IR, XPS, and TGA techniques. The LSS contained –SO3H, –COOH and phenolic –OH groups and was ideal to perform the reaction of furfuryl alcohol with n-butanol to obtain butyl levulinate in yield higher than 95% at 110 °C for 8 h with catalyst dosage of 15 g/L. Meanwhile, the catalyst deactivated increasingly with a recycle number that was attributed to the adsorption of formed polymeric by-products on the active catalyst sites, and the slightly deactivated catalyst after plain sulfonation treatment was found to remain active with an almost unchanged product yield in consecutive cycles. This work highlights an economic, eco-friendly, sustainable and promising protocol for catalytic upgrading of bio-based compounds.