Hydrolysis of Lignocellulosic Biomass in Hot-Compressed Water with Supercritical Carbon Dioxide

This study investigated the decomposition behavior of bamboo under hydrothermal and hydrolysis conditions with H₂O/CO₂ in a semicontinuous-flow reactor at 9.8 MPa. At 255 °C, with and without CO₂, xylan in bamboo completely decomposed into xylo-oligosaccharide (XOD). The yield of glucan degradation products with CO₂ was significantly higher compared with that under the hydrothermal reaction (25.7 vs 14.9 wt %, respectively). The reaction rate of glucan decomposition with CO₂ was slightly higher than the rate of hydrothermal reaction (k _H /k _H = 1.3). Increasing the fluid velocity of the hydrothermal reaction (3-10 mL/min) significantly accelerated the solubilization rate, but the ultimate yield of the soluble fraction was unchanged. The ultimate yield of the soluble fraction was slightly affected by physical effects. Hydrolysis with CO₂ under severe conditions exhibited effective degradation of glucan. The catalytic activity of the H₂O/CO₂ system under hydrolysis can be explained by the system's chemical effect.