Cascade Utilization of Biomass: Strategy for Conversion of Cellulose, Hemicellulose, and Lignin into Useful Chemicals

Efficient utilization of all three components of lignocellulose—cellulose, hemicellulose, and lignin—impels efficient utilization of carbon dioxide fixed by photosynthesis. Conversion of all three of these polymeric components of lignocellulosic biomass into the corresponding monomeric chemicals was investigated using reusable solid catalysts in water without organic solvents, acids, or bases. Cellulose and hemicellulose were first converted into sugar alcohols such as sorbitol and xylitol using a carbon-supported platinum catalyst (Pt/C), H 2, and bagasse as a reactant at 463 K for 16 h. The sugar alcohol yield was 64%. The solid residue from this process, which was mainly lignin and Pt/C, was recovered by simple filtration. Lignin in the solid residue was then converted into aromatic products at 673 K for 1 h. The yield of monomeric aromatics was 40%. After this process, only Pt/C catalyst was recovered as a solid residue, and it retained its activity for the conversion of all three components of lignocellulosic biomass into the corresponding monomeric chemicals throughout four runs. The two-step conversion of bagasse using Pt/C was thereby shown to be a powerful technique for converting the cellulose, hemicellulose, and lignin in lignocellulosic biomass into useful chemicals.