Recovery of ionic liquid for re-use

摘要

Metsae Group is developing a process lor the conversion of carbohydrate-containing pulp (e.g. wood pulp) to regenerated carbohydrate-containing materials. The process is based on dissolving the pulp in an ionic liquid (hereinafter also "IL") and then regenerating the pulp-based materials e.g. in the form of filaments (the filament tows can then be cut to staple fibres). Before mixing with pulp the IL is typically in a solution comprising, at least, IL and water. When the pulp meets the IL/water solution, the water content can be high (i.e. the pulp usually also contains water). The water content in the said IL/water solution, before mixing with pulp, can be e.g. 20% (w/w). It can also be higher or lower. In the subsequent processing steps, after mixing pulp with IL/water solution, the water content of the mix decreases. Dissolution of the carbohydrates (e.g. cellulose and/or hemicellulose) takes place when the water content is low enough.