Synthesis of pitch materials from hydrogenation of anthracite

A Pennsylvania anthracite was ground, carefully dried and hydrotreated into materials with properties resembling those of pitches. The hydrotreatment was carried out using two hydrogen donors, 9,10-dihydroanthracene (DHA) and 1,2,3,4-tetrahydronaphthalene (THN), and two catalysts, molybdenum hexacarbonyl (Mo(CO)6) and ammonium tetrathiomolybdate (ATTM). Due to the high reactivity at low temperatures, the degree of hydrogenation was probed in the temperature range 300, 350 and 400 °C. The optimum hydrogen donor, catalyst and hydrogenation temperature were 1,2,3,4-tetrahydronaphthalene, ammonium tetrathiomolybdate and 300 °C, respectively. This was reflected in an increase in the hydrogen-to-carbon atomic ratio (H/C) from 0.33 for the original anthracite to 0.42 for the pitch-like material from anthracite. Further, differential scanning calorimetry (DSC) showed that the anthracite-derived pitch material had a glass transition temperature (Tg) around 81.6 °C and softening point of 205.7 °C. This indicates that the softening behavior of the anthracite-derived pitch is similar to that of high-softening-point coal tar pitches. The anthracite-derived pitch material was evaluated by producing a small carbon body directly from the anthracite-derived pitch, and partial binding was observed.