Reality in the Kinetic Modelling of Pyrolysis of Plant Fuels

This work investigated the physical nature of kinetic data for plant pyrolysis obtained by using global single component reaction model (GSCRM). The mass change and rate data of leaf and stem (twig) samples of 12 coniferous and broadleaf plant species were collected at a constant heating rate in an inert atmosphere. The kinetic data for pyrolysis of the plant samples were retrieved by using GSCRM, and then were compared with those obtained by the multi-component reaction model. It was found that the apparent activation energy for pyrolysis of leaf samples varies from 43 to 80 kJ mol−1, whereas that of the stems (twigs) ranges between 84 and 110 kJ mol−1. The activation energy determined for the decomposition of the hemicellulose, cellulose and lignin of the samples essentially fluctuates in narrow ranges. Further analysis revealed that the apparent activation energy obtained from GSCRM is essentially dominated by the cellulose content of the samples, which does not correspond to the energy barrier of any reactions occurring during plant pyrolysis. Nevertheless, GSCRM is still useful in the theoretical modeling of plant pyrolysis because of its practicability and reasonable accuracy exhibited.