Hardwood delignification – understanding chemistry and mass transport fundamentals

Why is this importants:

Fundamental mechanistic understanding of the sequence of chemical and physical processes governing kraft delignification is still largely missing, especially when it comes to the less studied and more diverse hardwood. In an effort to provide a complement to the knowledge established on softwood, this project aims at elucidating delignification mechanisms on the cell wall level of hardwood and – through a comparative approach – a deeper mechanistic understanding of kraft delignification in general.

Methods we use:

Delignification studies of the wood meal (mass transport limited to the cell wall) will be performed in a flow through reactor (see illustration) where the conditions can be well controlled and the extracted material continuously sampled. Broad initial studies on a range of hardwood species will elucidate main delignification characteristics of their cell wall. Selected species will then be further subjected to in-depth investigations where composition of the cooking chemicals will be varied in order to distinguish contribution of the chemical reactions versus mass transport to the overall process. Analytical work will rely on chromatography (IC, GPC) and spectroscopy methods (NMR) allowing for assessment of chemical composition, molecular weight distribution and the presence of critical covalent linkages (lignin)

Expected results and scientific impact:

The project will provide a complementary knowledge to the existing understanding of the softwood pulping and enable deeper general insight into characteristics of kraft delignification, which is a prerequisite for further development towards efficient and diversified forest based biorefineries.

Project partners:

Chalmers, Stora Enso, Södra, SCA, Billerud, Valmet, Holmen
Flow-through rector for delignification of wood meal (enabling assessment of the delignification on the cell wall level)




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