Integrated Cascade Biorefinery Processes to Transform Woody Biomass Into Phenolic Monomers and Carbon Quantum Dots.

Xue Chen,Jiubin Zhu,Ling-Ping Xiao,Wenlu Song

doi:10.3389/fbioe.2021.803138

Abstract

A novel cascade biorefinery strategy toward phenolic monomers and carbon quantum dots (CQDs) is proposed here via coupling catalytic hydrogenolysis and hydrothermal treatment. Birch wood was first treated with catalytic hydrogenolysis to afford a high yield of monomeric phenols (44.6 wt%), in which 4-propanol guaiacol (10.2 wt%) and 4-propanol syringol (29.7 wt%) were identified as the two major phenolic products with 89% selectivity. An available carbohydrate pulp retaining 82.4% cellulose and 71.6% hemicellulose was also obtained simultaneously, which was further used for the synthesis of CQDs by a one-step hydrothermal process. The as-prepared CQDs exhibited excellent selectivity and detection limits for several heavy metal cations, especially for Fe3+ ions in an aqueous solution. Those cost-efficient CQDs showed great potential in fluorescent sensor in situ environmental analyses. These findings provide a promising path toward developing high-performance sensors on environmental monitoring and a new route for the high value-added utilization of lignocellulosic biomass.

Highlights

Lignocellulosic biomass, sustainable and high-energy content stored in the biosphere, is regarded as a promising feedstock for the production of sustainable materials and chemicals (Li et al, 2020)
A wide variety of heterogeneous metal catalysts were used for catalytic hydrogenolysis of lignocellulosic biomass
The direct reductive catalytic fractionation (RCF) of birch afforded the carbohydrate pulp remained as a solid residue with 82.4 wt% C6 and 71.6 wt% C5 retention according to the chemical composition analysis (Figure 1A; Supplementary Table S1), which makes it a promising candidate for the co-production of carbon quantum dots (CQDs)

Summary

Introduction

Lignocellulosic biomass, sustainable and high-energy content stored in the biosphere, is regarded as a promising feedstock for the production of sustainable materials and chemicals (Li et al, 2020). Lignin as the largest naturally occurring aromatic/phenolic compound accounts for 15–40% of lignocellulosic biomass (Ragauskas et al, 2014). The current lignocellulosic biorefinery focuses on carbohydrate (cellulose and hemicellulose) valorization, including sulfite, kraft, and organosolv pretreated processes. During those processes, stable C–C linkages would inevitably be formed in the separated lignin samples, which predominantly affect the depolymerization of lignin into monomeric phenols (Renders et al, 2017). The harnessing of lignin in a practical manner is still a major challenge

Methods

Results

Conclusion