Selective C-O Bond Cleavage of Oxidized Lignin
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Solution Overview
Problem
Current methods for utilizing lignin as a bio-based chemical feedstock face challenges such as non-selective transformations, low-yield products, and the need for precious metal catalysts or harmful reagents, making it difficult to depolymerize lignin into value-added chemicals efficiently and selectively.
Innovation Solution
A method involving the oxidation of secondary benzylic alcohol groups and primary alcohol groups in lignin to corresponding ketones, followed by selective cleavage of C—O and C—C bonds in β-O-4 linkages using organic carboxylic acids or their salts, without the need for precious metal catalysts, to produce low molecular-weight aromatic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional oxidation methods are used to convert lignin to aromatic compounds, then aromatic products can be obtained, but the transformations are non-selective and yield is low
Solution Approach 1:
The patent applies preliminary oxidation to convert secondary benzylic alcohol groups and primary alcohol groups in lignin to corresponding ketones and aldehydes before cleavage. This preliminary transformation creates specific functional groups that enable subsequent selective C—O bond cleavage, thereby improving both selectivity and yield of aromatic compounds
Solution Approach 2:
The patent changes the chemical state parameters of lignin by oxidizing specific functional groups (secondary benzylic alcohols to ketones, primary alcohols to aldehydes) before cleavage. This parameter change enables selective C—O bond cleavage at the β-position of β-O-4 linkages, resolving the contradiction between selectivity and yield
2Productivity
If precious metal catalysts are used to improve catalytic activity, then reaction efficiency increases, but cost and environmental concerns increase
Solution Approach 1:
The patent replaces expensive precious metal catalysts with organic carboxylic acids (such as formic acid, acetic acid, propionic acid) and their salts, which are inexpensive, environmentally benign alternatives. These organic catalysts achieve effective C—O bond cleavage without the harmful effects associated with precious metals
Solution Approach 2:
The patent changes the catalyst type from precious metals to organic carboxylic acids and their salts, fundamentally altering the chemical parameters of the catalytic system. This substitution maintains reaction efficiency while eliminating environmental and economic drawbacks
3Productivity
If harmful reagents are used to achieve effective C—O bond cleavage, then depolymerization efficiency improves, but environmental and safety concerns worsen
Solution Approach 1:
The patent employs organic carboxylic acids (formic acid, acetic acid, propionic acid) and their salts as cleavage reagents, replacing harmful chemicals with environmentally friendly alternatives. These benign reagents achieve effective C—O bond cleavage of oxidized lignin while eliminating safety and environmental hazards
Solution Approach 2:
The patent converts potentially harmful strong oxidizing conditions into a beneficial two-step process: mild oxidation followed by controlled C—O cleavage using organic carboxylic acids. This transformation eliminates the need for harsh reagents while maintaining depolymerization efficiency
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables selective and efficient depolymerization of lignin, yielding high-value aromatic compounds with improved product selectivity and yield, reducing environmental and economic concerns associated with existing methods.
Implementation Method 1
oxidizing at least a portion of secondary benzylic alcohol groups and/or a portion of primary alcohol groups in the lignin or lignin sub-unit to corresponding ketones
Implementation Method 2
selectively cleaving C—O bonds and/or C—C in at least a portion of β-O-4 linkages in the lignin or lignin sub-unit
Data Source
AI summary
A method to cleave C—C and C—O bonds in β-O-4 linkages in lignin or lignin sub-units is described. The method includes oxidizing at least a portion of secondary benzylic alcohol groups in β-O-4 linkages in the lignin or lignin sub-unit to corresponding ketones and then leaving C—O or C—C bonds in the oxidized lignin or lignin sub-unit by reacting it with an organic carboxylic acid, a salt of an organic carboxylic acids, and/or an ester of an organic carboxylic acids. The method may utilize a metal or metal-containing reagent or proceed without the metal or metal-containing reagent.