Depolymerization of technical lignin to valuable platform aromatics in lower alcohol without added catalyst and external hydrogen

Depolymerization of technical lignin to platform aromatic monomers can significantly increase the productivity and profitability of biorefinery. Establishing an efficient and economical way for technical lignin depolymer-ization is vital to make this process practical. Herein, we report the one-pot depolymerization of technical lignin into aromatic monomers without added catalyst and external H2 gas. Ethanol, as an inexpensive and recyclable solvent, was used to induce the technical lignin hydrogenolysis. The significant solubility and H-transfer ability of ethanol resulted in an exceptional hydrogenolysis efficiency of the beta-O-4 lignin linkages, giving an aromatic monomer yield of 20.62C% at 300 degrees C for 4 h, rival those from technical lignin disassembly with metal catalysts and added H2 gas. Over 14.70C% of the monomers could be identified, among which phenol, guaiacol, 4-ethyl phenol, 4-ethyl guaiacol, and syringol were obtained with prominent yields. The depolymerization procedure was thoroughly recognized with GC x GC-MS, GPC, MALDI-TOF-MS, HSQC NMR, and FT-ICR-MS analyses to provide an in-depth understanding of the molecular weight, functionality, and elemental composition evolutions of the technical lignin.

Automated summary

In this study, a one-pot depolymerization method of technical lignin into aromatic monomers without added catalyst and external H2 gas was reported. Ethanol was used as a solvent to induce the hydrogenolysis of technical lignin. The exceptional hydrogenolysis efficiency of the beta-O-4 lignin linkages was achieved, resulting in a yield of 20.62C% of aromatic monomers after 4 hours at 300 degrees C.