Performance evaluation of a recycle-integrated process for the production and purification of monosaccharides from lignocellulosic biomass

Performance of a recycle-integrated process for producing monosaccharides from lignocellulosic biomass was investigated. The process combined continuous concentrated sulfuric acid hydrolysis of hemicellulose extract in a plug-flow reactor with single-column batchwise chromatographic fractionation of the resulting hydrolysates via sulfuric acid recycling. A pseudo-first order model with rate constants depending on proton and bisulfate concentrations was derived and successfully used to describe the hydrolysis kinetics. Sulfuric acid concentration was found to affect the process significantly. At a constant level of monosaccharide production rate, the hydrolysis reactor volume was found to decrease by 90% and the separation column volume increase by 76-130%, depending on the amount of monosaccharides in the feed, when sulfuric acid concentration was increased from 0.5 to 2.5 mol/L. However, at the same time, the difference between the equipment volumes decreased. The maximum monosaccharide productivity in the chromatographic separation decreased by 40%, and eluent consumption at the operating points giving these maxima increased by 33%, when the sulfuric acid concentration was increased from 0.5 to 2.5 mol/L. On the basis of the results, the studied process should be operated with 1.0-1.5 mol/L sulfuric acid.