A High-Temperature Thermal Simulation Experiment for Coal Graphitization with the Addition of SiO₂

Abstract

The effect of SiO2 on coal graphitization was investigated by adding SiO2 as an additive to vitrinite in coal from the Gemudi mining area in Guizhou province (SW China) via a high-temperature heating treatment. The graphitization products of the samples were analyzed by X-ray diffraction (XRD), Raman spectroscopy, and high-resolution transmission electron microscopy (HRTEM), and the influence of the SiO2 additive on the process of coal graphitization was investigated. The results showed that, with the temperature increases, the graphitization degree of all samples was promoted, and the orderliness of the microcrystalline structure in the vitrinite increased. Compared with the samples without additives, the graphitization degree, graphite lamellae ductility, and stacking degree of the samples with SiO2 additives were higher, and the carbon layer spacing reached 0.3379 nm at 3000 °C, entering the graphite stage. The Raman spectra showed that the peak intensities of the defect structures (D1 and D2) in the samples with SiO2 were lower than those of the samples without additives, exhibiting fewer in-plane and interlayer defects in the samples with SiO2. The microstructures of the experimental samples were observed by HRTEM; at the same temperature, the carbon layer stacking degree of the samples with the SiO2 additives was higher than that of the samples without SiO2, and large graphite lamellae with smoother and clearer edges were observed.

Keywords

• coal
• high temperature
• SiO₂ additive
• coal-based graphite