The 1, 2, 3, 4 tetrahydroquinoline (THQ) has high solvency, high hydrogen donating capacity and high hydrogen shuttling capacity for coals and/or pitches.The THQ is used as a hydrogen donor solvent in the first stage process of coal liquefaction and/or of spinning pitch making for carbon fiber.
The advancement trends of the research and development in the solvolysis liquefaction of coal are reviewed.The solvolysis liquefaction process, that is the Honda and Yamada process, is a hybrid process containing the low-temperature thermal cracking of petroleum heavy residues and the liquefaction of coal by extractive chemical disintegration.For the more development of the solvolysis liquefaction, the importance of THQ is considered.As the first stage of coal liquefaction, the short contact time solvolysis and qualifying (SCT-SQ) process with THQ is proposed.And also the two stage liquefaction of coal, that is SCT-SQ as the first stage process, and the lightening and/or upgrading as the second stage process, is proposed.
In order to get the high performance pitch-based carbon fiber, it is necessary to control the transverse texture of pitch fiber by the pretreatment of raw pitch, the constitution and the spinability of spinning pitch, the spinning conditions and so on.It is obvious that the preordered larger transformation, the improvement of spinability and the thermal stability are required in the spinning pitch.For the pretreatment and/or modification such as hydrogenation and degradation of raw pitch, the importance of THQ is considered in the first stage of spinning pitch making.As the second stage of spinning pitch making, the separation of useless components and the controlled polycondensation of the isophase pitch made from raw pitch by the THQ treatment are necessary.
It is supposed that, although the polymerization degree may have some differences, the chemical structure and chemical constitution are similar to that in the products from coal and/or pitch, because the reaction mechanism is considered analogous in the first stage process of coal and/or pitch with THQ treatment.The difference in the coal liquefaction and the spinning pitch making occurs in the second stage process, since the former is in need of a controlled progressive reaction and the latter is in need of a controlled retrogressive reaction.
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