| Abstract
| - Three Pennsylvania anthracites from the Penn State Coal Sample Bank and Data Base wereheat-treated to temperatures to 2900 °C. The products were characterized by X-ray diffraction.These anthracites clearly differ in the extent to which they transform to a graphitic structure byheat treatment at ambient pressure. Graphitizability, based on approach of interlayer spacingto the ideal value for graphite and development of crystallite height, is in the order DECS 21 >PSOC 1461 > PSOC 1468. By 2700 °C the interlayer spacing is largely established, sinceimprovements by increasing graphitization temperature to 2900 °C are small. The crystallitestacking continues to develop; significant changes are achieved at 2900 vs 2700 °C. The structuralchanges can be related to composition via two factors. In heat treatment to 2000 °C, the structuralordering may be impeded by a “locking” of aromatic sheets in place by cross-linkers, such asoxygen atoms. At the higher temperatures, i.e., 2700 and 2900 °C, the ease of rearrangement ofaromatic sheets, which is related to their size, is the dominant issue. The relative sizes of aromaticsheets can be approximated from the net hydrogen content of the anthracites. DECS-21, whichhas both the highest oxygen content and the highest net hydrogen value, shows the least orderafter heat treatment to 2000 °C, but the best structural development after reaction at 2700 or2900 °C.
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