Page 85 - Fluid Catalytic Cracking Handbook

62 Fluid Catalytic Cracking Handbook

Table 2-6
Sulfur Content of Coke vs. Quantity of Residue in FCC Feed*

Pilot Plant Data, Riser Cracking for Maximum Liquid Recovery

Feed Sulfur, Sulfur in Coke
Feedstock Type Wt% Wt% of Feed

Gas Oil 0.7 3,5
Gas Oil + 10% of 1.0 13,8
West Texas Sour VTB
Gas Oil + 10% of 1.32 18.6
West Texas Sour VTB
*As the residue content of the feed is increased, there is a marked increase in the coke's
sulfur due to higher coke yield and a higher sulfur content of the coke precursors,
Source: Campagna [8]

Table 2-7
Sulfur Content of Coke vs. Hydrotreated* FCC Feed Quality

Pilot Plant Data, Riser Cracking for Maximum Liquid Recovery
Feedstock Hydrocarbon Type Sulfur in Coke,
Feedstock Source Sulfur, Wt% % Tri-aromatics* Wt% of Feed
Light Arabian HDS 0.21 7.3 28.1
Heavy Arabian HDS 0.37 17.6 48.2
Maya HDS 0.70 5.0 43.7

*In a hydrotreated feed, the more polyaromatic type sulfur compounds, the more sulfur ends
up in coke.
Source: Campagna [8]

(text continued from page 59)
Metals

Metals, such as nickel, vanadium, and sodium, are present in crude
oil. These metals are concentrated in the heavy boiling range of
atmospheric bottoms or vacuum residue, unless they are carried over
with the gas oil by entrainment.
These metals are catalysts themselves and promote undesirable
reactions, such as dehydrogenation and condensation. Dehydrogenation
means the removal of hydrogen; and condensation means polymerization,