Design and Validation of a High-Throughput Reductive Catalytic Fractionation Method

Area of Science:

• Biomass Conversion and Bioenergy
• Catalysis and Reaction Engineering
• Green Chemistry

Background:

• Reductive catalytic fractionation (RCF) is effective for lignin extraction and depolymerization.
• Traditional bench-scale RCF in batch reactors has low throughput (1-6 reactions/day), limiting research progress.
• High-pressure reactions require specialized equipment, posing scalability challenges.

Purpose of the Study:

• To develop a high-throughput RCF (HTP-RCF) method for increased experimental throughput.
• To screen solvent mixtures and catalyst loadings for hydrogen-free RCF.
• To establish efficient analytical methods for low-material loadings.

Main Methods:

• Developed a modular HTP-RCF system using 1 mL wells in Hastelloy reactor plates, enabling 240 reactions per experiment.
• Screened solvent mixtures (e.g., isopropanol/methanol) and catalyst loadings for poplar biomass.
• Implemented parallel filtration, washing, drying, and 1H NMR spectroscopy for sample analysis.

Main Results:

• Identified a 1:1 isopropanol/methanol solvent system yielding optimal monomer and 4-propyl substituted monomer selectivity.
• Validated HTP-RCF results with identical monomer yields in larger 75 mL batch reactors.
• Screened 50 switchgrass samples, revealing wide variations in monomer yields (21-36%), S/G ratios (0.41-0.93), and oil yields (40-75%).

Conclusions:

• The HTP-RCF system significantly enhances the throughput for screening lignin depolymerization conditions.
• The developed analytical pipeline efficiently processes low-material samples for rapid characterization.
• This approach accelerates the discovery of optimal catalysts and reaction conditions for biomass valorization.