ANALYSIS OF HYDROCARBONS AND SULFUR-COMPOUNDS IN 2 FCC DECANT OILS AND THEIR CARBONIZATION PRODUCTS

Two decant oils (DO A and DO B) which produce coke with different opti cal textures were quantitatively analyzed before and at several stages of carbonization. The differences observed in mesophase development a nd sulfur incorporation in the semicokes were related to differences i n the molecular composition of the two decant oils, including hydrocar bons and sulfur compounds. The analysis of the GC-amenable fractions o f the decant oils showed that DO A contains an abundance of pyrene and substituted pyrenes, while DO B is dominated by high concentrations o f polymethylphenanthrenes. In general, DO B has a much higher proporti on of alkyl-substituted PAHs and a higher concentration of n-alkanes. The presence of more reactive hydrocarbons in DO B is considered to be responsible for the inferior texture development and rapid incorporat ion of sulfur in the semicoke. Extensive methylation/demethylation rea ctions appear to occur during the early stages of carbonization; the r ole of these reactions in mesophase development and sulfur incorporati on is addressed further in the companion papers (Energy Fuels 1997, 11 , 631, 637).