Highly efficient hydrolysis of cellulose to high-concentration glucose using synergistic Brønsted/Lewis acid catalysis system under mild conditions

ZnCl 2 /H 3 PO 4 combines H-bond disruption and synergistic Brønsted/Lewis acid catalysis for glycosidic bond cleavage. • Cellulose is hydrolyzed to glucose in 10 min with a 94.8 mol% yield and 130 mg/mL concentration. • Solvent shows promise for converting glucose to 5-HMF without solid catalysts or energy-intensive pretreatments. Glucose and 5–hydroxymethylfurfural (5–HMF) are attractive platforms for sustainable biomass valorization, yet cellulose conversion remains limited by substrate concentration, reaction conditions, and complex catalyst designs. Here, we report an acidic bifunctional solvent system (ZnCl 2 –H 3 PO 4 ) that can both disrupt cellulose structure and promote rapid in situ cascade hydrolysis to glucose and 5–HMF. In this system, ZnCl 2 (a Lewis acid) facilitates protonation of the β–1,4–glycosidic oxygen, while H 3 PO 4 (a Brønsted acid) accelerates Zn 2+ desolvation, together reducing cellulose crystallinity, activating C–O–C bonds, and lowering the energy barrier for carbocation formation. Under mild conditions (65°C), the process reaches completion within 10 min, achieving 94.8 mol% glucose (with a high concentration ∼ 130 mg/mL). Furthermore, this bifunctional solvent shows promise for converting the released glucose into 5–HMF by leveraging ZnCl 2 for isomerization and H 3 PO 4 for dehydration. This approach avoids the high temperatures and elaborates catalyst architectures typical of conventional acid hydrolysis, offering a streamlined route to efficient cellulose conversion. Download: Download high-res image (150KB) Download: Download full-size image