Characterization and Catalytic Transfer Hydrogenolysis of Deep Eutectic Solvent Extracted Sorghum Lignin to Phenolic Compounds
- Univ. of Kentucky, Lexington, KY (United States). Biosystems and Agricultural Engineering
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. of Biological Science. BioEnergy Science Center. Center for BioEnergy Innovation. Biosciences Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. of Biological Science. BioEnergy Science Center. Center for BioEnergy Innovation. Biosciences Division
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Joint Inst. of Biological Science. BioEnergy Science Center. Center for BioEnergy Innovation. Biosciences Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical and Biomolecular Engineering. Inst. of Agriculture. Dept. of Forestry, Wildlife, and Fisheries. Center for Renewable Carbon
Deep eutectic solvent (DES) is intrinsically cheaper than many ionic liquids (ILs) due to low precursor cost, simple synthesis, and improved recyclability. Meanwhile, DES can be as effective as ILs toward dissolving lignin from plant materials. However, the lignin depolymerization mechanism in DES, the structural and chemical properties of DES-extracted lignin (DES-EL), and the possible valorization pathways of DES-EL toward value-added products were not well understood. This paper aims to characterize the lignin streams from DES (1:2 choline chloride:lactic acid) treated sorghum and further upgrade the extracted lignin to phenolic compounds. As revealed by HSQC, 13C, and 31P NMR analysis, DES cleaved nearly all ether linkages in native lignin, resulting in significant size reduction. We further catalytically upgraded DES-EL to phenolic compounds via catalytic transfer hydrogenolysis in the presence of isopropyl alcohol. Among the three tested catalysts (Ru/C, Pd/C, and Pt/C), Ru/C proved the most effective in deconstructing DES-EL, with oil, char, and gas yields of 36.3, 46.4, 17.3 wt %, respectively. Major lignin monomeric products in the oil were phenol, 4-ethylphenol, 4-ethyl-2-methoxyphenol, 2-methoxy-4-propylphenol, and 4-hydroxy-benzenepropanoic acid. Finally, this study provides a mechanistic understanding of lignin depolymerization in DES and demonstrates a possible way to catalytic upgrading of DES-EL to low molecular weight phenolic compounds.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Kentucky, Lexington, KY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)
- Grant/Contract Number:
- AC05-00OR22725; 1355438; 1632854
- OSTI ID:
- 1463981
- Journal Information:
- ACS Sustainable Chemistry & Engineering, Vol. 6, Issue 8; ISSN 2168-0485
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Ru/hydroxyapatite as a dual-functional catalyst for efficient transfer hydrogenolytic cleavage of aromatic ether bonds without additional bases
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journal | January 2019 |
Thermochemical properties of lignin extracted from willow by deep eutectic solvents (DES)
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journal | May 2019 |
Fractionation and characterization of lignin streams from unique high-lignin content endocarp feedstocks
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journal | November 2018 |
Comparing a deep eutectic solvent (DES) to a hydrotrope for their ability to enhance the fractionation and enzymatic hydrolysis of willow and corn stover
|
journal | January 2019 |
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