Thermochemical degradation polysaccharides

Carbohydrates would be the predominant raw materials for future biorefineries. The major polysaccharides found in nature are cellulose, hemicellulose and starch (see Chapter 1). These molecules would be mainly utilised after they are broken down to their respective monomers via enzymatic hydrolysis, thermochemical degradation or a combination of these two. Cellulose and hemicellulose, together with lignin, constitute the main structural components of biomass. Starch is the major constituent of cereal crops. This section would focus on the potential utilisation of carbohydrates and lignocellulosic biomass for chemical production. 

Krochta, J.M. Hudson, J.S. Tillin, S.J. "Kinetics of alkaline thermochemical degradation of polysaccharides to organic acids." In This Volume. 

Kinetics of Alkaline Thermochemical Degradation of Polysaccharides to Organic Acids... 

Starch and cellulose can both be thermochemically degraded in alkaline solution to water-soluble compounds of relatively low molecular weight. (A parallel study examines more completely the nature of these compounds (15).) Both starch and cellulose degradation processes can be described by second-order kinetics, with the hydroxide ion concentration determined by the stoichiometry of polysaccharide conversion to organic acids. The thermochemical degradation activation energy in alkaline solution for both starch and cellulose is 39,500 calories/mole. 

Increasing the yields of the desirable acids produced from the thermochemical, alkaline degradation of polysaccharides will require additional understanding of the reaction mechanisms and kinetics involved. Additional research should also proceed to determine the effect of other bases and supplementation of alkali catalysis by other catalytic materials. 

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