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Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by-products of agricultural biomass in crop-producing filed, valorization of corn straw has attracted considerable attention. In this study, a two-step depolymerizing strategy of high-pressure CO 2 -H 2 O pretreatment and oxidation-hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high-pressure CO 2 -H 2 O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production., (© 2024 Wiley-VCH GmbH.)

Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by‐products of agricultural biomass in crop‐producing filed, valorization of corn straw has attracted considerable attention. In this study, a two‐step depolymerizing strategy of high‐pressure CO2−H2O pretreatment and oxidation‐hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high‐pressure CO2−H2O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production. [ABSTRACT FROM AUTHOR]

Corncob is one of the main by-products of agricultural biomass in corn-producing area. Here, the valorization of corncob polysaccharide components to produce furfural and glucose was studied. Firstly, corncob was treated by high-pressure CO2-H2O; the in situ formed-carbonic acid catalyzed the selective hydrolysis of hemicellulose component with xylo-oligosaccharide and xylan as the main products. The obtained liquid fraction was further upgraded to furfural with H2SO4 as catalyst. After reaction at 140 °C for 1 h, 7.0 g L−1 of furfural was given. The conversion of C5 sugar and the selectivity of furfural was 56% and 72%, respectively. Then, the cellulose component of the residual solid fraction was depolymerized by oxidation-hydrolysis method. The hydroxymethyl group on the cellulose unit was partially oxidized to carboxyl group, which catalyzed the following hydrolysis of the cellulose component to glucose. 17.2 g of glucose per 100 g oxidized solid fraction was given at 170 °C for 6 h with water as the solvent. Additionally, the oxidation-hydrolysis strategy was also performed for the hydrolysis of the industrial furfural residues. [ABSTRACT FROM AUTHOR]

Hydrolysis of cellulose to glucose is one of the most important processes for the conversion of biomass to fuels and chemicals. Besides cellulose, lignin is the third of the main components of native lignocellulose. It is essential to understand the role of lignin in the depolymerization process of cellulose using lignocellulose as raw material. Here, the role of lignin was studied by using a lignin dimer model with a β-O-4 linkage and an organsolv lignin as the additive, respectively, for depolymerization of cellulose via oxidation-hydrolysis method. The results showed that both lignin dimer model and organsolv lignin substantially promoted the oxidation of cellulose and increased the yield of glucose. 30.01% yield of glucose was given for microcrystalline cellulose in present of 10% organsolv lignin, compared to 22.64% glucose yield for pure microcrystalline cellulose. Additionally, the mechanism of the promotion effect of lignin on the oxidation of cellulose process was proposed. [Display omitted] • Lignin role in cellulose depolymerization via oxidation-hydrolysis was studied. • Lignin promoted the oxidation of cellulose and increased the yield of glucose. • In present of 10% lignin, glucose yield was improved from 22.6% to 30.0%. • Oxidation of hydromethyl to carboxyl group was improved via radical route. • Hydrogen bond reconstruction made attack of β-glycosidic bond by proton easier. [ABSTRACT FROM AUTHOR]