The effect of Ru/C and MgCl2 on the cleavage of inter- and intra-molecular linkages during cornstalk hydrolysis residue valorization

The cleavage of linkages of lignocellulose is important for its valorization. The linkage cleavage of cornstalk hydrolysis residue was investigated over catalysts (Ru/C + MgCl 2 ) in EtOAc/H 2 O solvents. The results show that almost hydrogen bonds, C–C bonds, ether and ester bonds in the matrix of lignin and cellulose were broken, accompanying 80.6% of lignin and 98.5% of cellulose conversion, and obtaining 37.5% of aromatic monomers and 28.8% of lignin oligomers. In the reaction system, biphasic EtOAc/H 2 O solvents exhibited an effect on cleaving the intermolecular linkages between lignin and cellulose. MgCl 2 showed limited abilities of breaking the α-O-4 and β-O-4 linkages in lignin and limited β-1, 4-glycosidic and hydrogen bonds in cellulose were cleaved over Ru/C catalyst. The cleavage of C–O linkages (α-O-4, β-O-4, 4-O-5) and C–C bonds (α-β, β-5) in lignin were mainly dependent on Ru/C catalyst. Much C–O and the stubborn C–C linkages of β-5, β-1 and 5-5 were significantly disrupted by the synergistic effect between MgCl 2 and Ru/C. However, MgCl 2 exhibited great contribution to breakage of β-1, 4-glycosidic linkage, hydrogen bonds and sugar ring of cellulose. The linkage of β-1, 4-glycosidic, hydrogen bonds and C–C in C5/C6 sugars were significantly broken. The increased yield of products was evidently due to the synergistic effect of Ru/C combined with MgCl 2 .