Improving Phenolic-Rich Bio-Oil Production via Deep Eutectic Solvent Pretreatment of Lignin
Penghui Li, Yuliang He, Shubin Wu, Wenjuan Wu
Abstract
Deep eutectic solvents (DES), as a potential eco-friendly solvent, have driven advances in sustainable biorefining technologies. Lignin pretreatment using DES has become an ideal option to enhance the advanced applications of lignin due to its adjustability and high solubility for lignin. Treatment of lignin using DES modification, especially alcohol-based DES such as ethylene glycol, has resulted in significant structural changes in regenerated lignin and demonstrated great potential for the production of phenolic compounds through rapid pyrolysis. To comprehensively analyze the characteristics of the regenerated lignin, we combined various analytical tools, including NMR, FTIR, XPS, TG, and EA, which are used for functional group and compositional analysis, to establish the structure–property relationship between lignin and alcohol-based DES. Further, we explored the high yield of phenolic compounds obtained from different regenerated lignins by pyrolysis by in situ IR, U-tube three-phase product analysis, and Py GC–MS. We analyzed the pyrolysis mechanism in depth in combination with theoretical calculations. This finding provides a new research direction for an in-depth study of the impact of alcohol-based DES systems on the structural adjustment of lignin for further pyrolysis.