Comparison between two-step and single-step kinetic models for non-isothermal CO2 gasification of biomass char generated by fast pyrolysis

Kinetic analysis plays a critical role in the gasification process. The kinetics of CO2 gasification for various wood chars, which were prepared in a single particle reactor (SPR), were studied using a non-isothermal method in a thermogravimetric analyzer. To statistically derive significant conclusions, the data obtained from the gasifi-cation of fast pyrolyzed chars are used to compare the performance of the volumetric model (VM), grain model (GM), random pore model (RPM), integrated core model (ICM), and two-step (first step: VM; second step: ICM) parallel model. The obtained results show that most |DDTG| curves show one local minimum, representing at least one reaction step. When combined with the TG curves, the gasification process exhibits a distinct devo-latilization and char gasification component. ICM has a better performance compared to the other single-step models. The two-step model significantly improves over the single-step model due to the additional equation. The two-step model's average deviation DEV(X) is 0.95 %, which shows an 80 % improvement compared to ICM (DEV(X) = 4.64 %). The predicted activation energy (devolatilization: 54.8-76.2 kJ/mol; gasification: 185.7-247.5 kJ/mol) falls within a reasonable range, which is consistent with the findings reported in the literature.