Optimization of Lignin Extraction from Pine Wood for Fast Pyrolysis by Using a γ-Valerolactone-Based Binary Solvent System

Abstract

Fast pyrolysis of lignin is a promising method to produce aromatic chemicals and fuels. Lignin structure and pyrolysis conditions determine the liquid yield and product selectivity. Extraction of pine wood using -valerolactone (GVL) mixed with water in the presence of diluted sulfuric acid obtains lignin (GVL-lignin) which shows different product yield and selectivity. The composition of the extraction medium influences the yield of GVL-lignin and affects its native structure. The GVLto-water ratio affects the lignin yield without significantly modifying the structure of the extracted lignin, whereas the sulfuric acid concentration affects both the extraction yield and the extracted Page 1 of 29 ACS Paragon Plus Environment ACS Sustainable Chemistry & Engineering 2 lignin structure. These structural changes influence the products distribution after fast pyrolysis, which generates phenols and alkoxy phenols as the main products in the liquid fraction. Lignin extracted with a mixture of 4/1 of GVL/H 2 O (w/w) with 0.075 M sulfuric acid solution produces the highest pyrolysis liquid yield. Pyrolysis of GVL-lignin at 750 °C generates the maximum liquid yield. The amount of phenols in fast pyrolysis products increases with increasing temperature and sulfuric acid concentration used in the GVL-lignin extraction. This indicates that the extraction conditions of GVL-lignin may be optimized to increase the selectivity in fast pyrolysis.

Acid-Catalyzed α-O-4 Aryl-Ether Cleavage Mechanisms in (Aqueous) γ-Valerolactone: Catalytic Depolymerization Reactions of Lignin Model Compound During Organosolv Pretreatment

“… 37 Approximately 65% of lignin was recovered under the reaction conditions: 180 °C, 4 h, 0.019 M, GVL/water 3:1. The result is comparable with the data reported in the literature; for instance, the yield of lignin recovered by Jampa et al was 41% (reaction conditions: 160 °C, 24 h, 0.22 M, GVL/water 4:1), 15 while nearly the same amount (40%) was isolated by Fang and Sixta (reaction conditions: 170 °C, 2 h, 0.05 M, GVL/water 9:1). 16 The comparison of the results suggests that the temperature and water amounts are the key parameters to improve the yield of lignin.…”

“… 9 , 12 The highest expected lignin removal from the pretreated substrates is 80–90%, 13 , 14 while the yields of the recovered lignin by precipitation are reported with a more modest ∼40%. 15 , 16 However, by employing a two-step lignin precipitation with vacuum distillation, a yield of more than 90% could be attained. 13 The chemistry of GVL pulping and the corresponding reaction pathway have not been fully investigated yet.…”

Improving fast pyrolysis of lignin using three additives with different modes of action

“…A vast number of studies on the fast pyrolysis of lignin concern analytical pyrolysis. [21][22][23][24] However, results from analytical pyrolysis cannot be directly translated to what is expected from larger scale pyrolysis units, given the longer hot-vapor residence time and vapor condensation present in the latter. 25 Up-scaling from analytical pyrolysis to large-scale pyrolysis of lignocellulosic biomass has been proved on a large scale.…”

Selectivity Control of C-O Bond Cleavage for Catalytic Biomass Valorization

“…Lignin is a three-dimensional amorphous and complex aromatic polymer mainly composed of phenylpropanoids (Delgado-Aguilar et al, 2016). The three main monomers in lignin have been identified as p-coumaric acid, coniferous alcohol, and mustard alcohol (Jampa et al, 2019). Different monomers are connected by various C-O (e.g., α-O-4, β-O-4 and 4-O-5) and C-C bonds (Figure 1) (Wu et al, 2021).…”