Microcrystalline structure of a commercial coke prepared from a mixture of different coals

The microcrystalline structure, the chemical states of oxygen and the ash components of an industrial coke prepared from a mixture of different coals were investigated by XRD, HRTEM, XPS and SEM/EDS to reveal the microstructure of the coke. Results showed that the carbon matrix in the coke was composed of graphite microcrystallites and amorphous carbon. The graphite microcrystallites had an average lamellar size of 4 nm and stack thickness of 1.9 nm, and had a high orientation degree within an optical domain. The oxygen in the coke was mainly in C—O, COOH and CO groups. The presence of oxygen distorted the graphite microcrystallites, which increased the coke reactivity with CO₂ and decreased its strength after the reaction. The ash components in the coke were SiO₂ and Al-Si-metal alloy, with the latter having a spherical morphology due to its low melting point.