KINETIC INSPECTIONS OF PYROLYSIS OF WOOD USING NUMERICAL-INTEGRATION

The approximation method proposed by van Krevelen and others for estim ating the reaction order of a temperature-programmed process was recon sidered, and we point out a limitation of their method. By numerical i ntegration using a computer, the major characteristics of the reaction rate of the first-order reaction are clarified solving differential e quations and expanding the applicable range of the method. In each dif ferential curve during the pyrolysis of wood, a clear shoulder was obs erved in the pre-maximum stage. We make clear that the curve with a sh oulder is a composite curve of two first-order reactions and obtain ki netic parameters for each stage. Considerable differences existed amon g the kinetic parameters for untreated and treated woods, and woods of beech and larch, which may be based on the difference of inorganic an d organic compositions among them. The differential curve for bark has a complex shape with some jags. We distinguish between the main and a ccompanied reactions and obtain kinetic parameters for each reaction. The differential curve for cellulose shows a very simple and nearly sy mmetric shape, and activation energy E is different between the first and last parts divided at the maximum rate temperature. We propose a m ethod to obtain each kinetic value.