HETEROGENEOUS CATALYTIC FRACTIONATION OF BIRCH-WOOD BIOMASS INTO MICROCRYSTALLINE CELLULOSE, XYLOSE AND ENTEROSORBENTS

Abstract

For the first time, it was proposed to fractionate the main components of birch wood into microcrystalline cellulose, xylose and enterosorbents by integrating heterogeneous catalytic processes of acid hydrolysis and peroxide delignification of wood biomass. The hydrolysis of wood hemicelluloses into xylose is carried out at a temperature of 150 °C in the presence of a solid acid catalyst Amberlyst® 15. Then the lignocellulosic product undergoes peroxide delignification in a "formic acid – water" medium in the presence of a solid TiO2 catalyst to obtain microcrystalline cellulose (MCC) and soluble lignin. Under the determined optimal conditions (100 °С, Н2О2 – 7.2 wt.%, НСООН – 37.8 wt.%, LWR 15, time 4 h), the yield of MCC reaches 64.5 wt.% and of organosolvent lignin 11.5 wt% from the weight of prehydrolyzed wood. By the treatment of organosolvent lignin with a solution of 0.4% NaHCO3 or hot water the enterosorbents were obtained, whose sorption capacity for methylene blue (97.7 mg/g) and gelatin (236.7 mg/g) is significantly higher than that of the commercial enterosorbent Polyphepan (44 mg/g and 115 mg/g, respectively). The products of catalytic fractionation of birch wood are characterized by physicochemical (FTIR, XRD, SEM, GC) and chemical methods.