Decomposition of carbohydrates

As discussed above, the pyrolysis of biomass at high temperature (>1000 °C) results in the formation of synthesis gas, a valuable mixture of CO and H2. The decomposition of carbohydrate to synthesis gas is an endothermic reaction since the heating value of product is —125% of that of the feedstock (Reaction 1). The reaction becomes nearly thermo-neutral upon burning about 1/4 of the products. Since the thermodynamics favors the combustion of H2 over CO, the gasification reaction resemble the theoretical Reaction (2). Indeed numerous gasification processes feed 02 or air to drive the gasification reaction. 

Tomasik, P., Palasinski, M., and Wiejak, S. (1989a). The thermal decomposition of carbohydrates. Parts I. The decomposition of mono-, di-, and oligosaccharides. Adv. Carbohydr. Chem. Biochem. 47 203-278. 

The pyrolytic gasification of biomass has been interpreted to involve the decomposition of carbohydrates by depolymerization and dehydration followed by steam-carbon and steam-carbon fragment reactions. So the chemistries of coal and biomass gasification are quite similar in terms of the steam-carbon chemistry and are essentially identical after a certain point is reached in the gasification process. Note, however, that biomass is much more reactive than most coals. Biomass contains more volatile matter than coal, and the pyrolytic chars from biomass are more reactive than pyrolytic coal chars. 

THE THERMAL DECOMPOSITION OF CARBOHYDRATES. PART I. THE DECOMPOSITION OF MONO-, DI-,... 

However, the thermal decomposition of carbohydrates between 250 and 1000 has also been studied, and this aspect is of theoretical and practical interest. In this Chapter, the decomposition of saccharides by heat is discussed in two Sections, devoted respectively to caramelization of saccharides and their pyrolysis above 250°. 

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