Challenges and Perspective of Recent Biomass Pretreatment Solvents

Abstract

The increased demands on renewable and sustainable products require enhancing the current conversion efficiency and expanding the utilization of biomass from a single component (i.e., cellulose) to entire biomass components in the biorefinery concept. Pretreatment solvent plays a critical role in various biorefinery processes. Recent pretreatment solvents such as organic co-solvents, acid hydrotropes, ionic liquids and deep eutectic solvents showed effective biomass fractionation as well as preservation of high-quality cellulose and lignin under mild conditions. Despite these significant enhancements in biomass pretreatment solvent, there are still many challenges, such as feedstock variety, valorization of non-cellulose components, and eco-friendliness of the applied catalyst and solvent. These technical, economic and environmental obstacles should be considered in future biomass pretreatment solvents. In particular, the development of feedstock-agnostic solvent with high fractionation performance for high quality and quantity of all three major components (i.e., cellulose, hemicellulose, and lignin) together would be an ideal direction.

A comprehensive review on how ionic liquids enhance the pyrolysis of cellulose, lignin, and lignocellulose toward a circular economy

“…Solvents have been very useful in realizing this and positively affect product quality. Ethers and alcohols are common solvents used in PB pre‐treatment, but they must be consumed excessively, and their high volatility causes terrible environmental effects (Kim & Yoo, 2021). The optimal approach in this field is the use of green solvents.…”

Organosolv Lignin as a Green Sizing Agent for Thermoformed Pulp Products

“…Solvents are designed to reduce the reaction severity, correlated directly with the degradation and condensation of hemicellulose and lignin during the process. Sustainability and environmental impact of the solvent are important . Organosolv fractionation is described in the literature as a promising strategy for valorization of lignocellulosic biomass, which could facilitate the transition to improve utilization of renewable feedstocks…”

“…Sustainability and environmental impact of the solvent are important. 18 Organosolv fractionation is described in the literature as a promising strategy for valorization of lignocellulosic biomass, which could facilitate the transition to improve utilization of renewable feedstocks. 19 The concept of using fiber materials and polymers from the biomass is interesting since the material would be completely based on renewable resources.…”

“…Sustainability and environmental impact of the solvent are important. 18 Organosolv fractionation is described in the literature as a promising strategy for valorization of lignocellulosic biomass, which could facilitate the transition to improve utilization of renewable feedstocks. 19…”

How lignin sticks to cellulose—insights from atomic force microscopy enhanced by machine-learning analysis and molecular dynamics simulations

“…3 However, this complex structure [4][5][6] hinders the fractionation of biomass for isolation of its macro-molecular components and acts as a barrier for enzymes targeting depolymerization of the polysaccharides into monomeric sugars. Many efforts have been devoted to addressing biomass recalcitrance, including plant genetic engineering 7 and chemical approaches, 8,9 but with partial success. For instance, while thermochemical pre-treatments have been widely recognized as a way to enhance biomass digestibility, lignin redeposition on cellulose surfaces is a bottleneck for polysaccharides breakdown since it prevents enzymatic saccharification.…”