Kinetic modeling of biomass components pyrolysis using a sequential and coupling method

Abstract

This study proposed a sequential and coupling method to determine the comprehensive kinetic models for pyrolysis of cellulose, hemicellulose and lignin. Isoconversional method was employed to find the correlation between activation energy and conversion rate. Cellulose pyrolysis could be interpreted by one-step global reaction model, while pyrolysis of hemicellulose and lignin could be divided into three stages and two stages, respectively, in which competitive parallel reactions occurred. Coats-Redfern method and Kissinger method were subsequently used to obtain the reaction model f(α). Particularly, a new mean reaction model f′(α) was introduced to deal with the complex competitive parallel reactions. It was proposed that pyrolysis of cellulose followed Avrami-Erofeev (m=2) nucleation model, while pyrolysis of hemicellulose and lignin could be described by reaction-order model. The other kinetic parameters and the contribution of each parallel reaction to devolatilization were further analyzed based on the modified distributed activation energy models. And the detailed kinetic models for pyrolysis of biomass components were finally obtained.