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ARS Home » Northeast Area » Wyndmoor, Pennsylvania » Eastern Regional Research Center » Sustainable Biofuels and Co-products Research » Research » Publications at this Location » Publication #415618
Research Project: Chemical Conversion of Biomass into High Value Products

Location: Sustainable Biofuels and Co-products Research

Title: Microwave-assisted lignin depolymerization to phenolic monomers

Author
item Sharma, Brajendra - Bk
item KOHLI, KIRTIKA - University Of Illinois
item PRAJAPATI, RAVINDRA - University Of Illinois
item KATUWAL, SARMILA - University Of Illinois
item KIM, JAEMIN - University Of Illinois
item Mullen, Charles
item Strahan, Gary
item Biswas, Atanu

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 7/31/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The efficient valorization of biomass-derived wastes, lignin, is important for the economic viability of biorefineries. Lignin, which accounts for 15–30% of the available renewable carbon, can be processed to produce value-added phenolic chemicals. In this study, the microwave-assisted depolymerization of a Kraft lignin in a methanol/formic acid (FA) solvent to produce high-value-added phenolic monomers was investigated, in which methanol acts as a solvent and FA acts as an acid catalyst and an in-situ hydrogen donor. The highest lignin conversion of 78% was achieved at a temperature of 140°C and an FA-to-lignin mass ratio of 4 after a 20-minute reaction time. Acid-catalyzed cleavage of the linkages in lignin occurs in the presence of FA, which results in the formation of a liquid product. Further, the catalytic depolymerization of Kraft lignin with an added methanol/FA solvent system was conducted in the presence of mixed-metal oxides to maximize the liquid product yield and minimize the solid residue formation. Three different mixed metal oxide catalysts were prepared using hydrotalcite-structured materials, i.e., Mg3AlCO3, Mg3AlSO4, and Mg3AlCl. A mixed-metal oxide-Mg3AlCl catalyst with a particle size of 50 nm was found to be effective for Kraft lignin depolymerization. The effects of catalyst composition, catalyst amount, and reaction conditions on the lignin conversion and product yields were explored. The highest lignin conversion of 89 % (with 81% bio-oil yield) was obtained under optimized reaction conditions. The depolymerized liquid product contains mainly G-type phenolic monomers (~60%).