shows, is that spent catalyst is less active but somewhat more selective than the
clean regenerated catalyst at constant conversion.
This makes recycling spent catalyst an option which increases the effective
catalyst/oil ratio and reduces the initial regenerated catalyst activity.
The PetroFCC utilizes many of the same technologies that are used in the
standard UOP FCC units. This includes both the Optimix nozzles and vortex
separator system. A second riser for recracking the naphtha is provided that
operates at higher temperature.
Fig. 30 PetroFCC process (UOP)
Table 21 Selectivity of
spent catalyst
Regenerated
Spent
Initial carbon
0.0
0.91
MAT conversion
64.5
55.0
Yields @ 70 wt% conversion
C 2 minus
2.0
2.1
Gasoline
49.3
50.0
Coke
2.9
1.6
Fluid Catalytic Cracking (FCC) in Petroleum Refining
303