Lignin-based solvents and methods for their preparation

A process for converting biomass into furfural, the process comprising the steps of:

• (a) providing a pentosan-containing biomass material;
• (b) subjecting the pentosan-containing biomass material to an acid catalyzed digestion process in a digestion vessel at a temperature greater than about 100° C. for a period of time sufficient to produce a digested product stream comprising C5-carbohydrates and solids comprising cellulose;
• (c) separating the digested product stream into a liquid product stream and a solid product stream wherein:
• (i) the liquid product stream comprises carbohydrate compounds, of which at least 50 wt % of the carbohydrate compounds are C5-carbohydrate compounds, based on the weight of carbohydrate compounds in the liquid product stream,
• (ii) the solid product stream comprises solids comprising lignin and cellulose;
• (d) contacting the solid product stream with an organic solvent, thereby converting at least part of the lignin to a phenolic solvent, to produce solids and a solvent product stream comprising the phenolic solvent;
• (e) subjecting the C5-carbohydrate in the liquid product stream to a dehydration reaction in a reaction vessel at a temperature in the range of from about 100° C. to about 250° C. in the presence of an acid catalyst and a biphasic mixture comprising an aqueous phase and a water-immiscible organic phase, which comprises at least a portion of the phenolic solvent produced in step (d), for a period of time sufficient to produce furfural or a furan derivative;
• (f) retrieving from the reaction vessel a dehydration product stream comprising water, organic solvent and furfural, and separating the dehydration product stream into an aqueous recycle stream and an organic product stream comprising furfural;
• (g) recovering the furfural from the organic product stream by at least one separation process;
• and
• (h) recycling the organic product stream from step (g) back to the reaction vessel in step (e).