Kinetic Modeling of Xylooligosaccharides Production by Acid Hydrolysis of an Eucalyptus globulus Pulp Extract

The production of xylooligosaccharides (XOS) by acid hydrolysis using an alkaline extraction filtrate from the bleached kraf t pulp of Eucalyptus globulus is a rapid and effective process. The reaction kinetics knowledge is, however, extremely important to optimize the experimental conditions that maximize XOS production and limit the formation of xylose (unwanted product). In this work, a pseudo-homogeneous model of irreversible first-order reactions is proposed, considering the sequential degradation of fast-reacting xylan into high- and lowmolecular-weight oligomers, followed by their conversion to xylose. A kinetic parameter estimation based on the Arrhenius equation was performed, considering the temperature and acid concentration effects. The kinetic model presented good fittings to the experimental results (R-2 mostly between 0.97 and 0.99), proving its suitability to describe xylan hydrolysis over time. The mapping of XOS maximum yields as a function of pH, temperature, and time was also represented, allowing fast prediction for other operating conditions.