Effects of γ-Valerolactone/H₂O Solvent on the Degradation of pubescens for Its Fullest Utilization

Abstract

Solvent-thermal conversion of biomass was promising for obtaining value-added chemicals. However, little was known about the interactions between solvents and biomass in the process, which hindered the effective utilization of biomass. The effects of γ-valerolactone (GVL) and HO on enhancing pubescens degradation via the cleavage of inter- and intramolecular linkages were studied. At 160 °C, HO selectively promoted the cleavage of the intermolecular linkages by forming hydrogen bonds, making mainly contributions to hemicellulose dissolution, while GVL and HO promoted lignin dissolution by forming hydrogen bonds with -OCH group of lignin. HO promoted the cleavage of β-(1,4)-glycosidic bonds in hemicellulose derived oligomers to xylose, while the oxygen in the ring of GVL might interact with hydroxyl groups of xylose unit to enhance the dehydration of xylose to furfural, whereas GVL with HO promoted the depolymerization of lignin to oligomers mainly including β-O-4' and β-β' linkages connecting to G and S units.

New Understandings of the Relationship and Initial Formation Mechanism for Pseudo-lignin, Humins, and Acid-Induced Hydrothermal Carbon

“…Lignocellulosic biomass is regarded as a promising candidate to substitute for petroleum-based products such as fuels , and polymer materials because of its abundance and renewability. − However, the challenge still exists in the direct utilization of lignocellulose owing to its complicated physical structure formed among cellulose, hemicellulose, and lignin in the cell wall. Recently, the strategy to make full use of lignocellulose after components separation has drawn increased attention especially in the area of biorefinery. − During the transformational processes of each composition, it is unavoidable to form several products, such as pseudo-lignin (PL), humins, and hydrothermal carbon (HC).…”

A hemicellulose and lignin-first process for corn stover valorization catalyzed by aluminum sulfate in γ-butyrolactone/water co-solvent

“…Here, "hemicellulose and lignin-first" strategy is provided to achieve corn stover valorization and its goal is to first simultaneous fractionation of hemicellulose and lignin, while keeping as much cellulose as possible in solid residues that can be further used. According to previous research, 38,39 water tends to dissolve hemicellulose, while organic solvents have a higher affinity for lignin. As a result, three types of green solvents, EA, 2-MeTHF and GBL, were mixed with water to make co-solvents for corn stover transformation at 160 °C for 2 h, respectively (Fig.…”

“…After being treated with 25% GBL/H 2 O, the characteristic absorption peaks of lignin at 1038 cm −1 mainly assigned to aromatic C-H in-plane deformation of G unit in lignin showed a blue shift. 42 The absorption peak at 1267 cm −1 , which corresponds to the C-O stretching vibration of G unit in lignin, 39 showed a slight decrease. With the addition of Al 2 (SO 4 ) 3 in 25% GBL/H 2 O, the peak at 1038 cm −1 significantly shifted, and the peak at 1267 cm −1 was completely disappeared.…”

An integrated process for the valorization of corn stover promoted by NaCl in a GVL/H2O system

“…The characteristic peaks assigned to cellulose at 1427, 1372, 1316, 1163, 1104, 1056 and 897 cm −1 were almost unchanged. 31,35 Therefore, the simultaneous extraction of hemicellulose and lignin could be achieved by adjusting and controlling the amount of NaCl and the ratios of GVL/H 2 O. At the same time, most cellulose was kept intact in solid samples under these conditions.…”