Kinetic model analysis of dilute sulfuric acid-catalyzed hemicellulose hydrolysis in sweet sorghum bagasse for xylose production

Sweet sorghum is a high-yielding energy crop that leaves a large amount of lignocellulosic residues after the sugar fraction fermented to ethanol. Here, we developed a biphasic kinetic model for the dilute sulfuric acid-catalyzed hemicellulose hydrolysis of sweet sorghum bagasse at temperatures of 110–150 °C, and we then calculated the kinetic parameters for xylose production and furfural decomposition. The results indicated that elevated reaction temperatures promote the hydrolysis of hemicellulose and the degradation of xylose. The xylose yield increased in proportion to reaction time in the initial stages and then declined due to the degradation of xylose to furfural. The pre-exponential factors for the ‘easy-to-hydrolyze’ fraction, the ‘hard-to-hydrolyze’ fraction of hemicellulose and xylose degradation were 3.53 × 106, 1.80 × 105 and 0.62 min−1, respectively, and the activation energies were 60.7, 58.1 and 14.5 kJ/mol, respectively. The ideal hydrolysis condition for xylose production was 140 °C for 50 min, under which the xylose yield reached 60% of hemicellulose weight. This xylose can be used to form bioethanol and produce further downstream products.

► We developed a biphasic kinetic model for the dilute sulfuric acid-catalyzed hemicellulose hydrolysis of sweet sorghum bagasse.
► The ‘hard-to-hydrolyze’ fraction accounts for a large portion of hemicellulose.
► The ideal hydrolysis condition was 140 °C for 50 min, the xylose yield reached 60% of hemicellulose weight.