Natural product separation and valorization
The production of target compounds from plants as renewable resources gains more and more interest. On the one hand the application of fossil resources might be partially replaced and, on the other hand, some particular complex molecules are only accessible via isolation from the natural plant origin. The projects in this frame are concerned with investigating the potential of crystallization processes for isolation of a certain target compound from plant-based extracts. Subjects currently studied refer to separation and purification of pharmaceutically relevant substances from the related plant extract (e.g. Rutin) and the recovery and valorization of lignin with defined properties from lignocellulose within the biorefinery concept.
Lignin Valorization
Lignocellulosic biomass (LCB) is the most abundant terrestrial source of renewable carbon and can serve as a central feedstock for future biorefinery concepts. However, unlike cellulose and hemicellulose, lignin exhibits a complex, heterogeneous structure after LCB deconstruction, limiting its direct use in high-value applications. In particular, lignin's broad molecular weight distribution leads to its incorporation into low-value applications, such as a dispersant and additive in concrete mixtures. To address this, our research focuses on developing a scalable, molecular-weight-based fractionation strategy to produce lignin fractions with more uniform physicochemical properties. Increasing lignin homogeneity broadens its suitability for incorporation into advanced materials and value-added applications.
Therefore, a new process, designated LigniFrac, was designed and successfully demonstrated using beech wood lignin in acetone-water mixtures[1]. In contrast to typical anti-solvent addition precipitation fractionation, this method leverages the evaporation of the organic solvent to induce phase separation and precipitate the desired lignin fraction with a specific molecular weight. The integration of an in situ filtration step prevents lignin encrustation, ensuring stable operation and supporting the feasibility of scale-up. The robustness of the method is currently being validated by fractionating lignins from different feedstocks and pulping liquors.
References
[1] Ponnudurai, A., et al., (2024), Process for fractionating polymeric material, patent appl. filed EPO Nr. 24 207 411.0 from 18.10.24