Novel integrated biorefinery concepts for a carbon neutral bio-economy
The NIBCON project aims to identify and convert fibrous biobased materials, like lignin, into various new building blocks through biorefining technologies. These building blocks can then be used to replace non-renewable resources.
Project type: cSBO in MOT1 Biobased Chemistry
Approved on: 12/12/2019
Start date: 01/01/2020 (expected duration of 18 months)
PublicationsReductive catalytic fractionation of pine wood: elucidating and quantifying the molecular structures in the lignin oil
Chemical Science, 2020 – DOI: 10.1039/D0SC04182C
In-depth structural analysis of biorefined lignin is imperative to understand its physicochemical properties, essential for its efficient valorization to renewable materials and chemicals. Up to now, research on Reductive Catalytic Fractionation (RCF) of lignocellulose biomass, an emerging biorefinery technology, has strongly focused on the formation, separation and quantitative analysis of the abundant lignin-derived phenolic monomers. However, detailed structural information on the linkages in RCF lignin oligomers, constituting up to 50 wt% of RCF lignin, and their quantification, is currently lacking. This study discloses new detailed insights into the pine wood RCF lignin oil’s molecular structure through the combination of fractionation and systematic analysis, resulting in the first assignment of the major RCF-derived structural units in the 1H–13C HSQC NMR spectrum of the RCF oligomers. Specifically, β-5 γ-OH, β-5 ethyl, β-1 γ-OH, β-1 ethyl, β-β 2x γ-OH, β-β THF, and 5-5 inter-unit linkages were assigned unambiguously, resulting in the quantification of over 80% of the lignin inter-unit linkages and end-units. Detailed inspection of the native lignin inter-unit linkages and their conversion reveals the occurring hydrogenolysis chemistry and the unambiguous proof of absence of lignin fragment condensation during proper RCF processing. Overall, the study offers an advanced analytical toolbox for future RCF lignin conversion and lignin structural analysis research, and valuable insights for lignin oil valorization purposes.
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