8-04: Kinetic characterization of hemicellulose hydrolysis of corn stover with dilute acid cycle spray flowthrough pretreatment

Abstract The kinetic characterization of hemicellulose hydrolysis of corn stover was investigated by a novel processing system based on the dilute sulfuric acid cycle spray-flowthrough (DCF) pre-treatment. The reactor proposed was highly effective in enhancing xylose sugar yields and cellulose digestibility and increasing the removal of lignin. Within the DCF system, the xylose sugar yields (>90%) could be achieved for corn stover pretreated with 2% dilute sulfuric acid at 95°C during the optimal reaction time, and the remaining solid residue exhibited enzymatic digestibility (>90%) with cellulase loading of 60 FPU/g cellulose that was due to the effective lignin removal in this process. A simplified kinetic model was developed for the reactor to describe its performance. The results indicate that the reaction rates of xylose formation and degradation are sensitive to flow rate, temperature and acid concentration. Moreover, the kinetic data of hemicellulose hydrolysis fit a first order reaction model and the experimental data with actual acid concentration after accounting for the neutralization effect of the substrates at different temperatures. Over 90% of the xylose monomer yield and below 5.5% of degradation product (furfural) yield were observed in this reactor. Kinetic constants for hemicellulose hydrolysis models in this pretreatment were analyzed by an Arrhenius-type equation, and the activation energy and the pre-exponential factor of xylose formation were 1.8×10¹⁴ min^-1, 112.5 kJ/mol, and 1.2×10⁸ min^-1, 78.9 kJ/mol for xylose degradation, respectively.