Modification of Eureka Pitch (Part 1) Catalytic Hydrogenation with Ni-Mo/Al₂O₃ Catalyst

Catalytic hydrogenation of Eureka pitch was studied using a commercial nickel-molybdenum/alumina catalyst under hydrogen pressure of 100 kg/cm² at 320—400°C to modify the optical texture in the resultant coke particularly through the hydrogenation of its quinoline insoluble fraction (QI). QI in the pitch was catalytically hydrogenated into the quinoline-soluble fraction (QS) under the present conditions (Fig, 1), its content decreasing from 18 wt% to 3 wt% under the best conditions of moderate temperature when 1-methylnaphthalene and te-trahydrofluoranthene were used as solvent. The hydrogenated pitches produced a coke of needle-like texture (Fig. 3) with some decrease of coke yield by carbonization under atmospheric pressure (Table 3) in spite of some remaining QI in the pitch. From the material balance calculation (Fig. 2), we are inclined to believe that 52 wt%, at least, of QI in the starting pitch was converted to QS by the reaction at 380°C for 2h. Another 13wt% was deposited on the catalyst, the rest (35 wt% including experimental loss) remained, as QI, in the pitch. Microscopic examination of QI fraction in the pitch before and after the hydrogenation (Fig. 5) showed spherical shapes of its hydrogenation reaction. Such solubility may allow its direct interaction with the catalyst surface to be hydrogenated. Some of QI deposited on the catalyst surface showed a slightly deformed spherical shape in comparison with those in the original pitch, although major parts contributed respectively to fusion during the reaction. These observation supports the above mechanism. QS fraction in the pitch was slightly desulfurized and hydrogenated. Thus, their modifying activity in the co-carbonization have been improved for sure. Further, the needle-like texture may have developed after the hydrogenation. Elemental and IR analyses suggest that QI grains with more methyl and methylene groups were converted to QS by the hydrogenation, whereas QI of large condensed aromatic rings without substituents stayed QI, although its hydrogenation may surely have taken place to a certain extent.