Hardwood delignification - understanding chemistry and mass transport fundamentals

Purpose and goal:

Kraft pulping (delignification) is the core of the absolutely dominant technology standing today for the primary separation of wood components and is seen as an embryo for tomorrow´s biorefineries with high requirements for resource efficiency. However, our understanding of sub-steps that mechanistically govern this process is not complete. The overall goal of this project is, thus, a better mechanistic understanding of hardwood kraft pulping as a complement to the general knowledge of this process, with a focus on chemical reactions and mass transport in the hardwood cell walls.

Expected results and effects:

With its strong focus on basic chemical and mass transport aspects involved in cell wall delignification, this project is expected to fill some essential knowledge gaps and open up for a more efficient process design, especially as the project is directly based on the pulp mill´s need to increase understanding of the course of delignification and link it to process improvements. The project will also contribute to an increased momentum in process engineering research and the supply of skills necessary for the industry´s transition to a circular bio-based economy.

Approach and implementation:

Delignification of wood flour (a material where mass transport is considered to be limited to the cell wall) in a flow-through reactor allowing fine-tuning of process conditions and direct removal of the extracted components will be the core of the work. Initially, a broad study of different hardwoods (birch, beech, aspen, alder, eucalyptus) will provide an orienting knowledge on how delignification behavior is affected by wood morphology and chemical composition.

Based on that, interaction of chemical reactions with mass transport will be studied in depth on selected hardwoods.