Modeling of countercurrent shrinking-bed reactor in dilute-acid total-hydrolysis of lignocellulosic biomass

A mathematical model was developed for a countercurrent shrinking-bed reactor to investigate its performance in dilute-acid pretreatment/hydrolysis of lignocellulosic biomass. The results indicate that bed shrinking provides a positive effect on both hemicellulose and cellulose hydrolysis resulting high yield and product concentration. The effect of bed shrinking is more profound on cellulose hydrolysis than on hemicellulose hydrolysis. With dilute sulfuric acid (0.08 wt%) and with optimal adjustment of other operating parameters, the model predicts that near quantitative recovery of hemicellulose sugars is feasible. It further predicts that 80–90% yield with 2–4 wt% product concentration is attainable from hydrolysis of hardwood cellulose. The model also indicates that acid concentration and temperatures acutely affect the reactor performance in cellulose hydrolysis. In contrast, hemicellulose hydrolysis is less sensitive to acid concentration and temperature allowing broader latitude in operating conditions.