Hydrolysis Kinetics of Woody Biomass: Surface Renewal

Woody biomass is known to be composed of three major components: cellulose, lignin and hemicellulose. Cellulose is the most stable natural polymer in woody biomass, a linear dehydration polymer of b-D-glucose. Glucose is the common sugar that has been the substrate in ethanol production and other fine chemicals since the early humanity. This is naturally the sugar of importance in a biorefinery. To get to the glucose or cellulose, one must deal with the other components of the woody biomass. Lignin is a macromolecular substance of phenopropane units. It has the highest energy density among all the components. Hemicellulose is heteropolymer of five and six carbon sugars with other residues such as acetyl. Hemicellulose is the easiest to degrade among the major woody biomass components. Hydrolysis of woody biomass produces Xylose, Galactose, Glucose, Mannose, Rhamnose and Arabinose, along with their oligomers. In this presentation, we show that the mechanism of woody biomass hydrolysis occurs from the solid surface, and the kinetics follow closely to the surface renewal model. The apparent order of reaction is zero. The kinetic model agrees quite well with hot-water extraction of woody biomass.