Roles of water and aluminum sulfate for selective dissolution and utilization of hemicellulose to develop sustainable corn stover-based biorefinery

The roles of water and aluminum sulfate (Al 2 (SO 4 ) 3 ) in one-step selective catalytic transformation of hemicellulose in corn stover were investigated. At 130 °C, 90.2 wt% hemicellulose contained was selectively dissolved and further converted to 85.1 wt% xylose in the presence of Al 2 (SO 4 ) 3 , while keeping cellulose (92.1 wt%) and lignin (88.4 wt%) insignificantly converted. The hemicellulose hydrolysate could be further transformed to lactic acid with the yield of 82.2 wt% using Lactobacillus plantarum via fermentation. H 2 O formed hydrogen bonds with the intermolecular linkages connecting hemicellulose with cellulose and lignin in corn stover, which was helpful to dissolve hemicellulose. The hydrolysis of Al 2 (SO 4 ) 3 formed H + (Brønsted acid), which enhanced selectively the conversion of hemicellulose to xylose. While the active Lewis acid [Al(OH) 2 (H 2 O) x ] + , formed from the hydrolysis of Al 2 (SO 4 ) 3 , could promote the selective dissolution of hemicellulose. The aluminum species could also form complex compounds with –OH 1 and C 1 –O 6 of xylan unit by hydrogen bonds, promoting the production of xylose, as well as inhibiting its further degradation. These findings provided new strategies to develop a low-cost and sustainable corn stover-based biorefinery by understanding and controlling complex reaction networks in biomass conversion.