KINETICS STUDY OF 2nd HYDROLYSIS IN CONCENTRATED H2SO4 HYDROLYSIS PROCESS BY 1H-NMR SPECTROSCOPY

摘要

Lignocellulosic biomass resources are abundant, renewable, and inexpensive energy sources. Those are mainly composed of cellulose, hemicellulose, and lignin; the contents vary according to plant species. To make this structure suitable for conversion in fermenting process, cellulose and hemicellulose must be hydrolyzed. When hydrolyzed, these lignocellulosic materials produce sugars (D-glucose, D-galactose, Dmanose, D-xylose, and L-arabinose) and several compounds derived from sugar and lignin degradation (furfural, hydroxymethylfurfural (HMF), acetic acid, syringic acid,p-hydroxybenzoic acid, vanillin, and other compounds). Those lignocellulosic hydrolyzates can be used as fermentation media to obtain xylitol, ethanol, and other useful products. However, the byproducts produced during hydrolysis negatively affect not only fermentation efficiency, but also quantitative analysis of reaction products and kinetic studies. In this study, authors tried to apply 1H-NMR spectroscopy for quantitative analysis of reaction products and its kinetics without hydrolyzates neutralization. As increasing the 2nd stage acid hydrolysis temperature from 100 to 110 or 120°C, significant amounts of xylose were converted to furfural or other condensation products.