Mechanism study of ternary deep eutectic solvents with protonic acid for lignin fractionation

This paper investigated the fractionation of lignin by ternary DES of different polyols using simulation calcu-lation. ChCl-EG-PTSA showed the highest degradability of lignin with the absolute value of total interaction energy of-8023.80 kJ/mol, and the total number of hydrogen bonds was 91.4. The highest degradability was observed for ChCl:EG: PTSA = 2:4:1. The results show that CL- plays a dominant role in lignin fractionation and readily forms hydrogen bonds with gamma-OH. The difference is that the polyol preferred to form hydrogen bonds with alpha-OH in lignin. The addition of PTSA provided protons to the original system. It formed a new 7C-7C stacking interaction with the lignin benzene ring, which destroyed the 7C-7C stacking interaction between the original lignin. And increased the interaction of DES on lignin from-39.73 kcal/mol to-58.15 kcal/mol based on DFT.