Guidelines for Identifying the Structure of Heavy Phenolics in Lignin Depolymerization by using High-Resolution...

Area of Science:

• Biomass Conversion and Valorization
• Analytical Chemistry
• Polymer Science

Background:

• Efficient lignin conversion is crucial for reducing fossil fuel dependence.
• Understanding lignin depolymerization mechanisms is hindered by challenges in identifying high molecular weight products.
• Existing methods lack the capability for simultaneous molecular weight and structural analysis under operando conditions.

Purpose of the Study:

• To establish fundamental guidelines for analyzing lignin inter-unit linkages using tandem mass spectrometry (MS/MS).
• To identify major phenolic dimers and their linkages during lignin depolymerization.
• To achieve real-time monitoring of structural evolution during lignin depolymerization using in-situ MS/MS.

Main Methods:

• Application of tandem mass spectrometry (MS/MS) in both offline and in-situ modes.
• Establishment of MS/MS dissociation principles for key inter-unit linkages (β-O-4, 5-5, β-β, β-5, β-1).
• In-situ MS/MS analysis for real-time monitoring of structural changes.

Main Results:

• Fundamental MS/MS dissociation guidelines for typical inter-unit linkages were established.
• Major phenolic dimers were successfully identified, including their chemical formulas and linkage types.
• Real-time monitoring revealed distinct evolution pathways for isomers with the same chemical formula, highlighting common and obvious structural changes.

Conclusions:

• This study presents an advanced strategy for comprehensive analysis of lignin depolymerization.
• The developed MS/MS approach enables both static compositional analysis and dynamic structural evolution monitoring.
• The findings contribute to a deeper understanding of lignin breakdown mechanisms and facilitate efficient biomass conversion.