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Updated: May 23, 2025
10:18
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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Primary Processes of Depolymerization of Lignin Dispersed into Gas Phase
Marwan Y Rezk1, Mohamad Barekati-Goudarzi1, Divine Nde2
1Department of Biological and Agricultural Engineering, Louisiana State University and LSU AgCenter, Baton Rouge, Louisiana 70803, United States.
Energy & Fuels : an American Chemical Society Journal
|May 21, 2025
Summary
Hydrolytic lignin depolymerization in the gas phase is faster than previously thought, with environmentally persistent free radicals (EPFRs) playing a key role. These radicals may be biologically active in various combustion-related environments.
Area of Science:
- Chemical Engineering
- Environmental Science
- Materials Science
Background:
- Hydrolytic lignin (HL) depolymerization is crucial for biofuel production.
- Understanding intermediate formation, including environmentally persistent free radicals (EPFRs), is key.
- Gas-phase reactions may offer faster depolymerization pathways.
Purpose of the Study:
- To investigate the gas-phase depolymerization of hydrolytic lignin.
- To identify and characterize intermediate oligomers and EPFRs during lignin fragmentation.
- To evaluate the effect of a CuO/SiO2 catalyst on EPFR formation.
Main Methods:
- Lignin fragmentation in a continuous atomization (CA) fast flow reactor.
- Gas-phase reaction analysis.
- Spin trapping with electron paramagnetic resonance (EPR) spectroscopy for EPFR detection.
Main Results:
- Gas-phase HL fragmentation is significantly faster than reported liquid-phase rates.
- Phenolic compound formation is limited by slower rate constants.
- EPFRs were identified as hydroxyl radical generators, potentially biologically active.
- A 5% CuO/SiO2 catalyst showed an increasing trend in EPFR yield at higher concentrations.
Conclusions:
- Gas-phase depolymerization presents a more efficient route for lignin breakdown.
- EPFRs are significant intermediates in lignin fragmentation and may have environmental implications.
- Catalyst concentration influences EPFR formation, suggesting surface-mediated mechanisms.
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