Process development for separation of lignin from OrganoCat lignocellulose fractionation using antisolvent precipitation

Abstract

For the sustainable production of chemicals, lignocellulosic biomass can be fractionated into cellulose, hemicellulose and lignin, which can be subsequently converted into valuable intermediates. In the OrganoCat pulping process, lignin is separated from other fractionation products by in situ extraction into the organic solvent 2-methyltetrahydrofuran. However, a suitable concept for the subsequent separation of lignin from this solvent has not yet been identified. In this work, a technically feasible process for the separation of lignin from 2-methyltetrahydrofuran solutions using antisolvent precipitation is developed and evaluated based on lignin precipitation yield, solvent recovery and energy efficiency. For the determination of suitable antisolvents, an experimental solvent screening is performed. The conceptual process design is accomplished on the basis of lignin solubility measurements and process simulations. High lignin precipitation yields are achieved using n-hexane and n-pentane. An efficient process for lignin separation by combining solvent evaporation and precipitation using n-pentane is presented. The proposed separation process leads to lignin which can be separated by filtration and is characterized by low energy consumption and effective antisolvent recovery.