Birch wood biorefinery into microcrystalline, microfibrillated, and nanocrystalline celluloses, xylose, and adsorbents

For the first time, it is proposed to combine the environmentally friendly heterogeneous catalytic processes of wood hemicelluloses hydrolysis and peroxide delignification of «hemicellulose-free» wood for the biorefinery of birch wood into microcrystalline, microfibrillated, and nanocrystalline celluloses, xylose, and sorbents. The use of the solid acid catalyst ZrO 2 /SO 4 2− for the hydrolysis of birch-wood hemicelluloses at a temperature of 150 °C makes it possible to obtain xylose with a yield of 72.5% from the weight of hemicelluloses. The optimal conditions for peroxide delignification of «hemicellulose-free» birch wood in a «formic acid–water» medium over TiO 2 catalyst, which ensure a high yield of microcrystalline cellulose (41.2% from weight of wood), were established. By sulfuric acid hydrolysis and ultrasonic treatment of microcrystalline cellulose, samples of microfibrillated and nanocrystalline celluloses were produced. Adsorbents with high sorption activity were obtained from organosolv lignin formed as a side product of peroxide delignification of birch lignocellulose. The birch biorefinery products were characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, gel permeation chromatography, 31 P nuclear magnetic resonance, dynamic light scattering, as well as chemical and elemental analysis.