Efficient conversion of cellulose to glucose using lignite-derived solid acid catalyst

Cellulosic biomass, as the most abundant renewable resource on Earth, holds great potential for achieving carbon neutrality through efficient valorization, where its hydrolysis to glucose represents a critical initial step. Conventional methods relying on homogeneous acids face limitations such as poor catalyst recycling and significant environmental issues. Carbon-based solid acids (CSAs) for cellulose hydrolysis have emerged as promising alternative, yet, their synthesis often requires high-temperature calcination to construct stable aromatic frameworks, leading to complex and energy-intensive processes. In this study, we propose a novel approach of utilizing the inherent aromatic structure of lignite for synthesizing lignite-derived solid acids (LSAs). We found that lignite was successfully sulfonated directly at low temperature without prior calcination. The synthesized LSAs which possess abundant sulfonic and weak acid sites, proved rapid and efficient hydrolysis of cellulose, resulting in high glucose yield of 57.4 % in just 45 min at 190 °C. In situ Fourier-transform infrared (FTIR) analysis further revealed the weakening of hydrogen bonds and cleavage of glycosidic bonds in cellulose facilitated by LSAs. This work provides a sustainable and low-carbon way for the integrated valorization of lignite and cellulosic biomass.