Pyrolysis of pine and beech wood under isothermal conditions: the conventional kinetic approach

Pyrolysis of pine and beech wood was investigated by isothermal thermogravimetry at five different temperatures (280, 290, 300, 310, and 320 A degrees C) in an atmosphere of flowing nitrogen. It was found that isothermal pyrolysis of pine and beech can be described by three-dimensional diffusion mechanisms with different reaction geometry (Jander type for pine and Ginstling-Brounstein type for beech). It was established that, for both systems, values of the apparent activation energy (E (a)) calculated in an extrapolated temperature range coincide with values calculated by use of the classical Arrhenius equation. It was found that different values of the kinetic data and diffusion geometry of the volatile products probably result from slight changes of the structure and chemical composition of the wood which occur during pyrolysis.