Efficient valorization of woody biomass using two-step oxidation toward multipurpose fractionation

Abstract

In recent years, efficient conversion of sustainable and renewable woody biomass to high value-added processable chemicals or materials has drawn a great attention. In this study, we investigated the potential of a two-step oxidation strategy for efficient fractionation of woody biomass to well-defined aromatic monomers and carbohydrate pulp. Firstly, pre-oxidation treatment was performed to convert the active CαOH groups of lignin fraction in woody biomass to stable CαO. Then the pre-oxidized woody biomass was cooked with oxygen in methanol for fractionation of woody biomass. As a result, the lignin fraction in woody biomass was solubilized and depolymerized into well-defined aromatic monomers (e.g. vanillin, methyl vanillate, syringaldehyde, and methyl syringate) with high yield of 29.4 %. Compared with oxygen cooking strategy, the aromatic monomers yield could be double with two-step oxidation. Simultaneously, most cellulose and hemicellulose fractions were remained as carbohydrate pulp with high delignification of 92.3 %, which mainly consist of 3.9 % lignin, 68.7 % glucan, and 18.3 % xylan. Overall, our strategy provides a possibility for the effective fractionation of entire woody biomass to value-added products.