Selective oxidative depolymerization of lignin into aromatic monomers using a palladium-doped polyoxometalate...

Area of Science:

• Catalysis
• Biomass Conversion
• Polymer Chemistry

Background:

• Lignin depolymerization is crucial for biomass valorization.
• Selective cleavage of β-O-4 linkages is hindered by Cα-OH group condensation.
• Existing methods for oxidative depolymerization are limited.

Purpose of the Study:

• To develop an efficient catalytic approach for lignin depolymerization.
• To suppress condensation side reactions during lignin conversion.
• To achieve high yields of aromatic monomers from lignin.

Main Methods:

• Synthesis of metal-doped polyoxometalate (POM) catalysts.
• Optimization of catalytic depolymerization conditions (temperature, oxygen pressure, time, catalyst ratio).
• Investigation using lignin model compounds and catalytic performance evaluation over multiple cycles.

Main Results:

• Pd/CsPMA exhibited optimal performance in lignin depolymerization.
• Achieved an aromatic monomer yield of 11.01 wt% under optimized conditions (180 min, 150 °C, 1 MPa O₂).
• Demonstrated catalyst stability over five consecutive cycles with no significant deactivation.

Conclusions:

• Polyoxometalate (POM)-based catalysts offer a promising route for lignin valorization.
• The Pd/CsPMA catalyst promotes selective oxidation of Cα-OH groups, mitigating condensation.
• This approach provides valuable insights into suppressing side reactions in biomass conversion.