Process Development on the High-Yielding Reactive Extraction of Xylose with Boronic Acids

Previous studies have identified the reactive extraction of xylose from water to an organic phase by means of esterification with boronic acid (BA) on a laboratory scale as a promising step for producing furfural from lignocellulosic biomass. In this study, the extraction is investigated further, to lay out the foundations needed for development to an industrial process, and prove that it works with a real feedstock. Various parameters, such as temperature, interfacial area, and choice of solvent and BA, were evaluated. Experiments were carried out with both pure xylose and acid hydrolysate of bagasse. Our findings show that xylose can be extracted from acid hydrolysate with a high single-pass yield of 85 mol % and low losses of BA of 0.25% when using naphthalene BA at 90 °C. Furthermore, an extraction isotherm was constructed for the naphthalene BA-DowTherm A system, showing a high extraction yield of 85% per pass at various concentrations. This allowed for the preliminary design of a countercurrent extraction column, which needs 3 trays to recover 90% of the sugars from an acid bagasse hydrolysate at a solvent-to-feed ratio (S/F) of 1:1.