FEATURES OF COKE FORMATION DURING THE THERMAL-DEGRADATION OF PETROLEUM RESIDUES IN THE PRESENCE OF SUPPORTS OF DIFFERENT NATURE

An investigation has been made of the thermal degradation of tars in t he presence of contact coking coke, iron ore concentrate, and lignite, which are used to localize the process of asphaltene conversion to co ke on their surface. It has been shown that contact coking coke and ir on ore concentrate are inert supports which have no catalytic effect o n the degradation and condensation of high-molecular weight hydrocarbo ns and high-molecular weight compounds of crude oil, since the amount of degradation products formed and their composition hardly differ fro m the corresponding values obtained during the thermal degradation of tar without a support. The non-additivity of tar thermal degradation c arried out in the presence of lignite should be pointed out. It has be en shown that there is a significant change in the yield of the main c onversion products by comparison with thermal degradation in the absen ce of lignite. There is an increase in the yield of gasoline fraction and a considerable increase in the yield of 180-350 degrees C fraction , with a simultaneous reduction in the yield of 500-540 degrees C frac tion and vacuum residue with an ibp of 540 degrees C. With increase in the lignite content of the reaction system and in the time of thermal degradation, the degree of demetallization of the tar reaches 95%, wh ereas during the thermal degradation of tar in the presence of contact coking coke and iron ore concentrate it varies from 70 to 80%. (C) 19 97 Elsevier Science Ltd.