Gasification mechanism and kinetics analysis of coke using distributed activation energy model (DAEM)

Highlights: • The gasification properties of four cokes were studied by the thermogravimetric analysis. • Component and structural analysis of four cokes were systematically tested. • Microcrystalline structure of carbon was an important factor affecting the gasification reactivity. • The single-step global model and distributed activation energy model were used to investigated kinetic characteristic. -- Abstract: This work studied the gasification reaction of four different metallurgical cokes (Coke-A, Coke-B, Coke-C, Coke-D) with CO₂ by the thermogravimetric analysis. The physical, chemical and structure features were also analyzed systematically. It is found that with increasing the heating rate, the conversion curves move to high temperature for all these four cokes, and the maximum gasification rate also increases. Meanwhile, at the same heating rate, the gasification reactivity of these four cokes is ordered as: Coke-D > Coke-C > Coke-B > Coke-A. According to the component and structural analysis, the gasification reactivity was mainly due to the microcrystalline structure of the carbon in the coke, and the gasification reactivity of coke increases when the content of amorphous carbon increases. Comparing with the single-step global model, the distributed activation energy model (DAEM) is more accurate to characterize the gasification kinetics for the studied cokes, and the activation energies are in the range of 159.8–254.1 kJ/mol.