Obtaining xylitol by hydrolysis-hydrogenation of liquors derived from sugarcane bagasse

Abstract

This work presents the study of heterogeneous catalysis of sugarcane bagasse hydrothermal treatment spent liquors using a sulfonated resin. Besides, results were compared with those obtained by a conventional route using sulfuric acid as a homogeneous catalyst. Heterogeneous catalysis is suitable for the hydrolysis of sugarcane bagasse hydrothermal liquors under mild conditions (100 °C and 6 h). The obtained maximum xylose yield was 82% due to furfural formation, which causes a xylose selectivity drop. The hydrogenation of this xylose-rich liquor at 100 °C and 3 MPa of hydrogen pressure employing a supported Ni/γ-Al2O3 produced the total conversion of xylose with a selectivity towards xylitol of 100% by using a catalyst to xylose mass ratio of 0.5. Heterogeneous catalysis in a two-step route (hydrolysis and hydrogenation) constitutes an outstanding alternative to producing xylitol from sugarcane bagasse hydrothermal spent liquors since materials can be easily separated and reused in several reaction cycles.