A process to produce furfural and acetic acid from pre-hydrolysis liquor of kraft based dissolving pulp process

Pre-hydrolysis Liquor (PHL) is an aqueous stream containing dissolved organics, produced in the pre-hydrolysis kraft (PHK)-based dissolving pulp production process. Hemicelluloses (6 wt.%) and acetic acid (1 wt.%) present in the PHL can be used or recovered as valuable products, instead of being used as fuel for recovery boiler operation. In this work, hemicelluloses in the PHL were concentrated about 3 times by membrane nano-filtration (NF), while simultaneously separating acetic acid in permeate. NF permeate was subjected to reverse osmosis (RO) to obtain concentrated acetic acid which was subsequently extracted with tertiary amines and polar organic diluents. The concentrated sugars/hemicelluloses in the NF concentrate were converted to furfural using monophase and biphase reactor systems. Overall, a sequential bio-refining process to recover organics from PHL was developed.