Lignin-based solid acid catalyst for cellulose residue conversion into levulinic acid in biphasic system

Phosphoric acid-activated lignin-based solid acid catalysts (PLSA) were prepared from lignosulfonate by phosphoric acid activation, carbonation, and sulfonation. The physicochemical properties of catalysts were determined by SEM, N2 adsorption-desorption, FT-IR, XRD, XPS and element analysis. Masses of phosphorous-containing group were grafted on catalyst surface during phosphoric acid activation and carbonation to provide sites for subsequent -SO3H substitution. PLSA could efficiently convert cellulose residue into levulinic acid. The effects of reaction temperature, residue time, catalyst loading, substrate concentration, solvent and catalyst stability were investigated and optimized. Using PLSA as catalyst, 67.9 mol% LA yield was obtained from 4 g cellulosic residue at 190 ℃ in 150 min in MIBK/H2O-NaCl. Overall, this work provides a valuable basis for the application of lignin-based solid acid in biomass valorization. [Display omitted] •Lignosulfonate was used as carbon support in solid acid catalyst.•Phosphoric acid-activation and carbonization favor for better pore structure.•-SO3H substituted the phosphoric acid group on carbon surface by grafting.•67.93% levulinic acid yield was achieved in MIBK/H2O-NaCl.