Page 142 - Fluid Catalytic Cracking Handbook

FCC Catalysts 117

13. Issue the final report
a. Analyze benefits
b. Evaluate selection methodology

There is a redundancy of flexibility in the design of FCC catalysts.
Variation in the amount and type of zeolite, as well as the type of
active matrix, provide a great deal of catalyst options that the refiner
can employ to fit its needs. For smaller refiners, it may not be practical
to employ pilot plant facilities to evaluate different catalysts. In this
case, the above methodology can still be used with emphasis shifted
toward using the MAT data to compare the candidate catalysts. It is
important that MAT data are properly corrected for temperature,
"soaking time," and catalyst strippability effects.

For many years, cat cracker operators have used additive compounds
for enhancing cat cracker performance. The main benefits of these
additives (catalyst and feed additives) are to alter the FCC yields and
reduce the amount of pollutants emitted from the regenerator. The
additives discussed in this section are CO promoter, SO X reduction,
ZSM-5, and antimony.

CO Promoter

The CO promoter is added to most FCC units to assist in the
combustion of CO to CO 2 in the regenerator. The promoter is added
to accelerate the CO combustion in the dense phase and to minimize
the higher temperature excursions that occur as a result of afterburning
in the dilute phase. The promoter allows uniform burning of coke,
particularly if there is uneven distribution between spent catalyst and
combustion air.
Regenerators operating in full or partial combustion can utilize the
benefits of the CO promoter. The addition of the promoter tends to
increase the regenerator temperature and NOx emission. The metallurgy
of the regenerator internals should be checked for tolerance of the
higher temperature.
The active ingredients of the promoter are typically the platinum
group metals. The platinum, in the concentration of 300 ppm to 800