Microwave-assisted Depolymerization of Lignin with Metal Chloride in a Hydrochloric Acid and Formic Acid System

Rongge Zou, Yunfeng Zhao, Yunpu Wang, Dengle Duan, Liangliang Fan, Leilei Dai, Yuhuan Liu, Rongsheng Ruan

Research output: Contribution to journalArticlepeer-review


A microwave-assisted depolymerization method of lignin with various metal chloride catalysts (MgCl2, AlCl3, FeCl3, ZnCl2, and MnCl2) in a formic acid and hydrochloric acid system under mild conditions (160 °C for 30 min) was studied. The resulting bio-oil was identified by a gas chromatography-mass spectrometer, and the solid residue was analyzed by Fourier transform infrared spectroscopy (FT-IR). Furthermore, the molecular weight change of lignin after the reaction was measured by gel permeation chromatography. The MnCl2 catalyzed lignin to produce most aromatic monomers, including approximately 23.0% G-type, 11.9% S- type, and 14.8% H-type monomer compounds. Different metal chloride catalysts had different effects on the depolymerization of lignin, which were embodied in the type and content of the products. It was also worth noting that the catalytic effects of transition metal chlorides on lignin may have been related to each chloride’s cation radius.

Original languageEnglish (US)
Pages (from-to)3704-3719
Number of pages16
Issue number2
StatePublished - 2018

Bibliographical note

Funding Information:
This work was financially supported by the International Science and Technology Cooperation Program of China (2-14DFA61040) and the Program of the Natural Science Foundation of China (21466022).Thanks also goes to Sepax Technologies, Inc. for the use of their equipment.

Publisher Copyright:
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  • Hydrochloric and formic acid system
  • Metal chloride
  • Microwave-assisted
  • Organosolv lignin


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