Comparisons and Modeling Studies on Hydrolysis Reactors
Several researchers have attempted to compare different reactor configurations applied in the dilute acid hydrolysis by experimental and simulation methods. Torget and Kim have compared three reactor configurations, batch, percolation, and shrinking-bed percolation, using similar hydrolysis severities to begin addressing chemical, physical, and hypothesized boundary layer phenomenon governing rate-limiting steps of glucose release from two prehydrolyzed yellow poplar cellulosic substrates [31]. The characteristics of the logarithmic release of glucose as well as the logarithmic disappearance of cellulose as a linear function of time were found to be reactor dependent. Use of a percolation reactor was described where the initial hydrolysis rate constant for cellulose using 0.07% w/w sulfuric acid at 225°C is enhanced five-fold compared to a batch reactor. Additionally, when lower hydrolysis severities are used for hydrolyzing yellow poplar cellulose in batch mode, biphasic kinetics was observed. Furthermore, Torget and Kim demonstrated that near quantitative yields of glucose from cellulose can indeed be obtained using a bench-scale shrinking — bed percolation reactor in which an internal spring compresses the biomass as the reaction progresses [31].