Characterization of graphitic materials prepared from different rank Pennsylvania anthracites

In this work, two Pennsylvania anthracites were calcined (1420 °C) and then graphitized (3000 °C). The objective of this study was to evaluate the influence of anthracite rank on the microstructure of graphitization products, with PSOC1515 being semianthracite and DECS21 being anthracite. The as-received anthracites were studied using high-resolution transmission electron microscopy and surface area measurements. As-received anthracites and their graphitization products were characterized using X-ray diffraction, Raman spectroscopy and temperature programmed oxidation. Results showed that the higher rank anthracite graphitizes to a product with better-developed crystalline structure than the anthracite of lower rank, as was shown by a higher degree of graphitization, smaller Raman disorder parameter (ID/ I_D + I_G) and higher oxidation resistance for products obtained from DECS21. The degree of metamorphism determines the extent of development in the lamellar structure and, by extension, the quality of the graphitization product. The dominance of aluminum-rich minerals in these coals led to no evidence of in situ catalytic graphitization. Contrarily, demineralization of both anthracites prior to graphitization led to products with slightly better degrees of graphitization, indicating that the minerals inherent in these anthracites may physically inhibit the ordering of graphene sheets rather than act as a catalyst. The formation and subsequent decomposition of silicon carbide in native anthracites facilitated the enhancement of crystallite width.