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December 18, 2015
Claire Monot, LGP2's Ph.D. student, defended her doctoral thesis : "Contribution to the study of lignin-carbohydrate complexes (LCCs) in wood. Study of the impact of the different steps of a sulfur-free biorefinery process on these LCCs".
This University Grenoble Alpes doctoral thesis was prepared under the supervision of Christine Chirat, Associate Professor (Grenoble INP-Pagora / LGP2).
The valorization of lignocellulosic biomass is nowadays a major issue due to the reduction of fossil resources. Separating each component to valorize them the best way possible is the goal of the pulp and paper biorefineries. The effluent of the mill, called the black liquor, is currently burnt to produce energy, but gasification would increase the energy efficiency. For this, a sulfur-free cooking of wood is necessary, as sulfur inhibits gasification.
Therefore this study first focused on the feasibility of cooking without sulfur, which is more difficult than a conventional kraft cooking containing sulfur. The work was done on softwood which is more difficult to delignify than hardwood. The wood was first pretreated with an autohydrolysis to remove hemicelluloses for further valorization.
The results were conclusive for the production of cellulose for textile applications. To explain the fact that the autohydrolysed wood was easier to delignify than the control wood with kraft and soda cooking, structural differences of wood components were looked for. Lignin did not show major differences whether the wood was prehydrolyzed or not, whereas the complexes between lignin and carbohydrates (LCCs) showed significant differences, which could explain the results obtained.