3-47: Porous polymer as cellulase-mimetic catalyst for saccharification of lignocellulose

Hydrolysis of cellulose to glucose is the most critical step in bioconversion of lignocellulosic biomass to fuels and chemicals. Cellulases and homogenous acids are widely used for cellulose hydrolysis. However, cellulases can only be used at moderate conditions and need longer time to achieve satisfactory cellulose hydrolysis. Homogenous acids can tolerate higher temperature above 100 °C, but they have limitations and issues in equipment corrosion, recycling and wastewater treatment. To address these issues, heterogeneous solid acids have recently drawn a lot of attention for hydrolyzing cellulose. Traditional solid acid catalysts such as sulfonated carbon and resin, however, are not as effective as homogenous acids and cellulases in hydrolyzing cellulose because they have poor access/affinity to cellulose. In this study, a series of porous polymers were synthesized for cellulose hydrolysis. These cellulase-mimetic solid acids have carboxyl, hydroxyl and halides as cellulose-binding groups and sulfonic acid as cellulose-hydrolytic groups. It was found that these synthesized catalysts could hydrolyze microcrystalline cellulose (Avicel) and ball-milled (2 h) Avicel to glucose by 50% and 80%, respectively, in 24 h at 120 °C. When applied to ball-milled (2 h) biomass such as spruce and corn stover, about 50% glucose yield was achieved in 24 h at 120 °C.