Page 123 - Fluid Catalytic Cracking Handbook

FCC Catalysts 9§

Acid leaching, chemical extraction, and chemical substitution are all
forms of dealumination that have become popular in recent years. The
main advantage of these processes over conventional dealumination
is the removal of the nonframework or occluded alumina from the
zeolite cage structure. A high level of occluded alumina residing in
the crystal is thought to have an undesirable impact on product
selectivities by yielding more light gas and LPG; however, this has
not been proven commercially.
In the manufacturing of USY catalyst, the zeolite, clay, and binder
are slurried together. If the binder is not active, an alumina component
having catalytic properties may also be added. The well-mixed slurry
solution is then fed to a spray dryer. The function of a spray dryer is
to form microspheres by evaporating the slurry solution, through the
use of atomizers, in the presence of hot air. The type of spray dryer
and the drying conditions determine the size and distribution of
catalyst particles.

Engelhard Process

Engelhard's "in-situ" FCC catalyst technology is mainly based on
growing zeolite within the kaolin-based particles as shown in Figure
3-9A. The aqueous solution of various kaolins is spray dried to form
microspheres. The microspheres are hardened in a high-temperature
(1,300°F/704°C) calcination process. The NaY zeolite is produced by
digestion of the microspheres, which contain metakaolin, and mullite
with caustic or sodium silicate. Simultaneously, an active matrix is
formed with the microspheres. The crystallized microspheres are
filtered and washed prior to ion exchange and any final treatment.

With each shipment of fresh catalyst, the catalyst suppliers typically
mail refiners an inspection report that contains data on the catalyst's
physical and chemical properties. This data is valuable and should be
monitored closely to ensure that the catalyst received meets the agreed
specifications. A number of refiners independently analyze random
samples of the fresh catalyst to confirm the reported properties. In
addition, quarterly review of the fresh catalyst properties with the
catalyst vendor will ensure that the control targets are being achieved.