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Extraction of Lignin with High β-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield
Published on: January 7, 2019
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Reductive Catalytic Depolymerization of Semi-industrial Wood-Based Lignin
Xiaojia Lu1,2, Lucas Lagerquist3, Kari Eränen1
1Laboratory of Industrial Chemistry and Reaction Engineering, Johan Gadolin Process Chemistry Centre, Åbo Akademi University, Henriksgatan 2, 20500 Turku, Finland.
Industrial & Engineering Chemistry Research
|December 9, 2021
Summary
Reductive catalytic depolymerization efficiently breaks down lignin into valuable aromatic compounds. This novel process optimizes conditions for high yields of monomers and dimers, supporting sustainable chemical production.
Area of Science:
- Biomass Valorization and Green Chemistry
- Catalysis and Chemical Engineering
Background:
- Lignin, a complex aromatic biopolymer, is a major component of lignocellulosic biomass and a potential source for valuable chemicals.
- Efficient depolymerization of lignin is crucial for its valorization and the development of sustainable chemical processes.
- Existing methods often face challenges in achieving high yields and product stability.
Purpose of the Study:
- To investigate the reductive catalytic depolymerization (RCD) of lignin using a novel semi-industrial process.
- To obtain aromatic mono-, di-, tri-, and tetramers from lignin for subsequent valorization.
- To optimize RCD process parameters for enhanced yield and product stability.
Main Methods:
- Characterization of lignin substrate and depolymerization products using High Pressure Size-Exclusion Chromatography (HPSEC), Gas Chromatography-Mass Spectrometry (GC-MS), GC-Flame Ionization Detector (FID), GC-FID/Thermal Conductivity Detector (TCD), and Nuclear Magnetic Resonance (NMR).
- Systematic study of RCD by varying parameters: lignin solubility, reaction time, hydrogen pressure, temperature, pH, catalyst type/loading, and solvent composition.
- Analysis of reaction mechanisms and their impact on product structures.
Main Results:
- Elevated temperature, a redox catalyst, and a hydrogen atmosphere were identified as essential for effective lignin depolymerization and product stability.
- The reaction medium significantly influences the RCD process outcomes.
- Achieved yields of mono- to tetramers reached 98%, with mono- to dimers exceeding 85% in liquid phase products.
- Reaction mechanisms affected aliphatic chains in monomers but largely preserved phenolic structures and methoxy groups.
Conclusions:
- The developed RCD process is effective for producing valuable aromatic monomers and oligomers from lignin.
- Process optimization using specific conditions (temperature, catalyst, hydrogen, solvent) is key to maximizing yields.
- This work contributes to the development of a sustainable, debottlenecked process for efficient wood fraction utilization, aligning with green engineering principles.
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