Conversion of Cellulose to High Yield Glucose in Water over Sulfonated Mesoporous Carbon Fibers with Optimized Acidity

Hydrolysis of cellulose to high yield glucose in water remains challenging owing to the limited acidity and contact to substrate for sulfonated carbons. Herein, we report a unique sulfonated mesoporous carbon fiber with optimized acidity prepared by pyrolysis of FeCl3-impregnated wipe fiber followed by acid treatment. The Bronsted acidity (especially for SO3H) is produced by sulfonation of magnetic carbon fiber intermediate while the Lewis acidity is originated from small Fe3O4 nanoparticles and defects remained. The balanced Bronsted and Lewis acidity combined with hydrophilic functionalities, was simultaneously tailored by varing the Fe/wipe fiber (WF) feed ratio and pyrolysis temperature, to change the porous structure of final catalysts. As expected, the elaborately fabricated MCF-SO3H-20-500 (20% of Fe/WF feed ratio and pyrolysis at 500 oC) delivers 66.0% of glucose yield as cellulose is completely converted. This is the highest glucose yield achieved by hydrolysis of untreated cellulose in water over a sulfonated carbon catalyst. The optimized Bronsted and Lewis acidity is mainly responsible for the directional conversion of cellulose to glucose, and rich hydrophilic functionalities and superior mesoporous structure of the catalyst facilitate contact to cellulose and mass transfer. This investigation will open new avenues to design high-performance carbon sulfoacid catalysts towards cellulose hydrolysis.