Conradson carbon residue coke formation

The separate effects of coke formation and metals deposition have been described in a study with two different residual oil feedstocks [18]. Their properties are listed in Table 1. They have a similar tendency to form coke (Conradson Carbon Residue) but much different contents of organometa11ic compounds (nickel and vanadium). 

Consequently, there are significant differences in FCC unit operation when residue is added to normal feed. Conversion falls and less gasoline is produced, as shown in Table 5.2, and the catalyst-to-oil ratio must rise as coke yields increase. The coke also has a different composition relative to that produced from normal feed not only because of the higher Conradson carbon levels and high-boiling compounds, which are absoibed by the catalyst particles, but also from the dehydrogenation activity of the metal impurities, which leads to polymerization reactions and contaminant coke formation. 

---