Defence Z. Wang: "Native-like lignin for the development of lignin-focused biorefineries"

Promotores: Prof. dr. P. J. Deuss and Prof. dr. H.J. Heeres

Abstract: Searching for renewable alternatives for fossil carbon resources to produce chemicals, fuels and materials is essential for the development of a sustainable society. Lignin, a major component of lignocellulosic biomass, is an abundant renewable source of aromatics and is currently underutilized as it is often burned as an undesired side stream in the production of paper and bioethanol. This while lignin harbors great potential as source of high value aromatic chemicals and materials. Biorefineries focused on lignin are currently under development with aim of acquiring added value from lignin. However, the performance of these novel lignin-focused biorefineries are closely linked with the quality of extracted lignin in terms of the level of degradation. Thus, the degradation pathways of the native lignin contained in the plant material needs to be understood in detail in order to achieve higher value from lignin. Undegraded native-like lignin with an as close as possible structure to native lignin contained in the lignocellulosic plant material serves as a promising model lignin to support detailed studies on the structure and reactivity of native lignin, yielding key understanding for the development of new technologies for lignin-focused biorefineries. This thesis firstly gives a general introduction on the isolation of native-like lignin and its application. Then there are four experimental chapters. The first, describes the development of a reliable method for the isolation of native-like lignin in high yield. In the second native-like lignin isolated by the method was used as model lignin to study the influence of minor units and saccharides of lignin catalytic hydrogenolysis. The third, includes a detailed study on the effect of acidic deep eutectic solvents treatment on this native-like lignin. In the fourth chapter, the development of novel ionic liquids that can mediated selective alcohol incorporation in lignin which allow for the tuning of the lignin properties. Finally, perspectives on the use of native-like lignin on lignin-focused biorefineries are discussed. This thesis demonstrates the great potential that this type of lignin brings for understanding the effect of different biomass treatments on the native lignin structure.

Dissertation