Lignin is the most abundant natural resource of aromatics on earth. Due to the societal changes towards a bioeconomy where replacements of fossil-based aromatics by renewable ones is targeted, lignin is of high interest as a polymer precursor for different applications. About one third of the lignocellulosic biomass is constituted of lignin, and today technical lignin that are obtained from the kraft and sulfite pulping is mainly used as an energy source. One problem with technical lignin for material applications is the heterogeneity.<br/>Alcohol-based organosolv pulping is a well-known pulping process that has been tested in small scale plants. It has shown promising results with less heterogeneous lignin compared to kraft lignin. The process is also more green due to the solvent systems that are used. Ethanol, that is often used as the organic solvent in the solvent system, is a sustainable and green solvent that can be produced from biomass.<br/>The mechanisms involved in organosolv lignin extraction are still poorly understood and deeper structural studies are also of interest. Together, these can be central for designing and optimizing the process for production of more homogeneous lignins with attractive chemical and physical characteristics for use as polymer and monomer precursors. The adopted approach in the study is unique and performed in two steps. In the first step hemicellulose is extracted with water at sub-critical conditions. This is followed by an organosolv ethanol extraction with acid catalyst to extract native-like lignin by using both physical and chemical protection strategies. The extracted lignin’s was investigated in function of time, where time dependent changes was studied and connected to reaction mechanisms.<br/>Detailed NMR characterization for structure include both 1D and 2D techniques, while size exclusion chromatography was used to study the molar mass.

Integrated lignin biorefinery: Preserving the lignin structure through additive-free protection strategies

ACS Spring Meeting 2021

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