Effect of hydrogenation on solubility of carbonized pitch.

概要

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The effect of hydrogenation of carbonized pitch on its solubility in quinoline was investigated in connection with structural changes of the pitch during carbonization. Naphtha-tar pitch (NTP) and acenaphthylene were carbonized at 673 and 703 K, respectively, for various periods of time. The pitches thus heat-treated were hydrogenated by BenKeser reaction and the amount of quinoline insolubles (QI) in the hydrogenated pitch was determined. An acenaphthylene pitch (ACP) heat-treated for 24 h was rendered completely soluble into quinoline by the hydrogenation, whereas a considerable amount of insolubles was left in the case of NTP treated for longer residence times than 8 h. This can be explained in terms of the difference in interaction among aromatic molecules constituting the QI components derived from NTP and ACP. ACPs doped with elemental sulfur left a significant quantity of QI after the hydrogenation. The addition of sulfur is considered to form crosslinking bonds between aromatic molecules through hydrogen abstraction by the sulfur. When QI separated from carbonized NTP was hydrogenated, the degree of conversion into quinoline solubles (QS) was low as compared with that for the whole sample of the same NTP. The presence of QS in the pitch plays a very important role for the hydrogenation.