A novel hemicellulose and lignin-first process for corn stover valorization catalyzed by Al2(SO4)3 in GBL/H2O co-solvent was developed in this study. In 25% GBL/H2O at 160 °C, Al2(SO4)3 assisted H2O in breaking down intermolecular linkages of corn stover. The hydrolysis of Al2(SO4)3 could produce H+, [Al(OH)2(H2O)x]+ and SO42−. With the solvation of GBL, the H+ and [Al(OH)2(H2O)x]+ from Al2(SO4)3 hydrolysis increased the co-conversion and dissolution of hemicellulose (96.9 wt%) and lignin (68.0 wt%), while the AlHSO4(OH)2H2O species formed by combining with [Al(OH)2(H2O)x]+ and SO42− was found to inhibit cellulose conversion (88.7 wt% kept). Expecting for H+ from Al2(SO4)3 hydrolysis, the formed AlHSO4(OH)2H2O was found to be the catalytic active species for the cleavage of glycosidic bonds in hemicellulose to produce xylose, and also acted as a “stabilizer” to prevent the further degradation of xylose to improve its yield (87.6%, based on the weight of hemicellulose). Al2(SO4)3 selectively promoted lignin depolymerization to lower Mw oligomers, as well as monophenols (11.20%) with high selectivity of 70.0% to VG and VP via Cα-OH dehydration and -Cγ(=O)-OH decarboxylation reaction. The obtained cellulose-rich residues show great potential for further use within many industrial processes. The developed process is recyclable, giving important insights to design new approaches for corn stover valorization.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)