VALORIZATION OF SULFUR FREE BLACK LIQUOR THROUGH HYDROTHERMAL LIQUEFACTION

摘要

Numerous studies deal with the conversion of chemical pulp mills into wood-based biorefineries. Inrnparticular, the extraction of the hemicelluloses by an autohydrolysis allows the recovery of sugars for the chemicalrnindustry and the use of a soda cooking instead of a kraft cooking to produce cellulosic pulp. Lignin ends up in anrnaqueous effluent called black liquor, usually burned in a Thomlison boiler to recover the sodium and energy. In thisrnwork, conversion of black liquor through hydrothermal liquefaction will be compared to the Thomlinson recovery inrnterm of energy efficiency, sodium recovery and the production of phenolic compounds will be studied. Experimentsrnwere performed in a batch reactor between 250 and 310℃ and 5 and 120min using a sulfur free black liquor atrn19%WT. A viscous biocrude containing up to 59% of the carbon and 70% of the HHV of black liquor is produced.rnThe remaining aqueous phase contains 97% of initial Na and phenolic compounds (mainly catechol, guaiacol andrnsyringol). Medium molecular weight of organic molecules in the aqueous phase is divided by 6. Those resultsrndemonstrate hydrothermal liquefaction is efficient in term of energy and sodium recovery and chemical plateformrnmolecules were produced.