Study of lignin reactivity in ionic liquids

Résumé

Serious geopolitical implications arise from the fact that our society is heavily dependent on only a few energy resources such as petroleum. In addition, the ecological disadvantages have come into prominence as the use of fossil energy sources suffers a number of ill consequences for the environment, including the greenhouse gas emissions, air pollution, acid rain, etc... that are causing the climate change. Trying to stop the climate change renewable sources and technologies are investigated to replace fossil carbon. One of these technologies is the conversion of biomass to fuels and chemicals in the so-called ¿Integrated Biorefinery¿. Following the same trend of reducing the environmental impact, many researches are focused on ionic liquids (considered as a new generation of green solvents) as substitutive for organic solvents. The main objective of this thesis was the introduction of ionic liquids in the biorefinery industry, more concretely involving lignin reactivity. The aim was to replace organic solvents in all the process where lignin is involved. Ionic liquids were applied for lignin extraction from biomass, lignin purification and lignin depolymerisation to produce added value products.Lignin derived from two different sources, hardwood (apple tree pruning) and grass (miscanthus) was successfully extracted by ionosolv process using different ionic liquids as solvents. After extraction lignin depolymerisation was studied under different conditions. Depending on the source of lignin, ionosolv solvent and depolymerisation treatment, different behaviour was observed.