Improvements of global models for the determination of the kinetic parameters associated to the thermal degradation of lignocellulosic materials under low heating rates

Abstract

The study presents improvements of global models, among which the Extended Independent Parallel Reaction (EIPR) model, which can be used for the determination of the kinetic parameters associated to the pyrolysis of a lignocellulosic material under low temperature ramps. The number of constituents of the lignocellulosic material and their proportions which are involved in the simulations are linked to characterizations of the material. A quartic objective function to be minimized is proposed to simulate in a more efficient way the slow pyrolysis of the material and which leads to a unique set of optimal values of the kinetic parameters. Three different materials are considered in the present study as examples: a T-shirt sample, Cameroonian palm nut fibers and Russian hydrolysis lignin. The good agreement between the experimental and simulated mass and mass rate curves validates the values of the kinetic parameters thus determined. These values are finally compared to that obtained when applying the differential isoconversional method (DIC) or the Distributed Activation Energy Model (DAEM).