Lignin-first depolymerization of native corn stover with an unsupported MoS₂ catalyst

Area of Science:

• Biomass Conversion
• Catalysis
• Green Chemistry

Background:

• Lignin-first biorefineries offer a sustainable pathway for producing phenolic chemicals from lignocellulosic biomass.
• Developing efficient and cost-effective catalysts is crucial for advancing these processes.

Purpose of the Study:

• To investigate the efficacy of an unsupported non-noble molybdenum disulfide (MoS2) catalyst for producing phenolic monomers from corn stover via a lignin-first approach.
• To optimize reaction conditions and understand the catalytic mechanism for enhanced lignin depolymerization.

Main Methods:

• Utilized corn stover as feedstock for a lignin-first biorefinery process.
• Employed an unsupported non-noble MoS2 catalyst for lignin depolymerization and phenolic monomer production.
• Characterized lignin degradation and phenolic product yields using Fourier-Transform Infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy.

Main Results:

• Achieved a significant enhancement in phenolic monomer yield from 6.65% to 18.47% using MoS2 at 250 °C.
• Degraded approximately 75% of lignin while preserving over 90% of glucan in the solid residues.
• Demonstrated catalyst reusability with a 14.30% phenolic monomer yield after five reaction cycles.
• Identified enhanced cleavage of β-O-4, γ-ester, and benzyl ether linkages in lignin.

Conclusions:

• The MoS2 catalyst is effective for the lignin-first production of phenolic monomers from corn stover, showing good stability and reusability.
• The study provides insights into the lignin depolymerization mechanism, highlighting the catalyst's role in cleaving key lignin linkages.
• This research contributes foundational knowledge for improving graminaceous plant lignin-first processes using non-noble metal catalysts.