Rapid Pyrolysis of Wood with Application to Gasification

Abstract

The process of polysaccharide depolymerization during acid hydrolysis was modelled using the stochastic approach of chemical kinetics. A Monte Carlo technique was used to simulate the rate of glucose generation in such a process. This procedure involves the preliminary determination of kinetic constants and activation energies for the conversion of model compounds. In the present case, the acid hydrolysis of glycosidic bonds in cellobiose, as well as the degradation of glucose produced, were performed at temperatures ranging from 90°C to 160°C. The kinetic constants so generated were introduced into expressions of bond rupture probabilities necessary for the Monte Carlo procedure to simulate the conversion of amylose and cellulose. Amylose, being a linear non-crystalline polysaccharide, its hydrolysis results were satisfactorily represented by the stochastic procedure. With cellulose, however, the situation is more complex. A more sophisticated model of the polymeric chain including crystalline, semi-amorphous, and amorphous zones had to be considered. This complicated model yielded rather satisfactory results, using the kinetic constants derived from the model compounds.