Hydrocarbon Processing - December 2022 - 28

Catalysts
realized due to the loss in conversion.
As a result, there was no improvement
in bottoms upgrading compared to the
incumbent Catalyst A.
The benefit of both the improved
zeolite-Y technology and the more moderate
Z/M level Catalyst B can be seen in
FIG. 1. The FCC proprietary catalystb
imparted
more activity than the low-Z/M,
other catalyst, resulting in higher conversion
levels. While the conversion levels
were lower than the incumbent Catalyst
A, the impact of the improved porosity
and matrix technology are seen as the
bottoms upgrading noticeably improved
vs. the other two catalysts-shown by
the higher LCO and lower bottoms
yields. This trial provides an example
where the catalyst technology must be
balanced with optimization of other catalyst
parameters (in this case, Z/M) to
achieve bottoms upgrading goals.
Case Study 2. This case study involved
a European refinery whose main objectives
were to improve coke selectivity
and minimize bottoms product and
dry gas yields. The incumbent catalystc
(Catalyst C) was a moderate-to-low
Z/M catalyst designed to minimize
bottoms and maximize fuels without
increasing dry gas and coke. It is a precursor
to the authors' company's newer,
enhanced Catalyst Dd
, which improves
upon the incumbent catalyst to meet the
same objectives. The refinery commissioned
a catalyst evaluation and tested
various catalysts. A non-BASF catalyst
showed very favorable testing outcomes,
promising lower bottoms yields among
other benefits. The refinery decided to
change from the incumbent Catalyst C
and trial the other catalyst in the FCCU.
After a few months of the industrial
FIG. 1. Bottoms upgrading vs. conversion in Case Study 1's trials at a North American FCCU.
trial, the refinery-after having tracked
the chemical markers and the catalyst
turnover-decided that the performance
seen in the unit was not in alignment
with expectations based on testing.
Furthermore, the regenerator temperature
was higher due to delta coke, the
wet gas compressor was constrained due
to an increase in dry gas and slurry yields
were noticeably higher. The refinery decided
to change back to BASF Catalyst
C and perform a post audit to determine
the industrial yield shifts.
Ecat samples from the non-BASF
FIG. 2. Post-audit yield results from Case Study 2.
TABLE 2. Yield selectivities at iso-coke (8.5 wt%)
Yield, wt%
Hydrogen
Dry gas
Total LPG
Gasoline
LCO
Bottoms
Conversion
LCO/BOT
Non-BASF catalyst
0.61
3.2
20.4
39.1
15.6
13.3
71.2
1.2
28 DECEMBER 2022 | HydrocarbonProcessing.com
Catalyst Ee
0.56
3.3
21.1
41.3
14.7
11
74.3
1.3
catalyst's trial period and Catalyst C's
periods were chosen for post-audit
analysis. The ECAT metals levels between
the two time periods were comparable
(both samples had > 4,500 ppm
Ni + V), but nearly twice as much ZSM5
was used during Catalyst C's period;
therefore, the anlaysis was done on
LPG + gasoline to eliminate additive effects
on selectivity.
The post-audit results are shown in
FIG. 2. These results reveal large differences
in bottoms upgrading and
overall liquid yields between the two
catalyst trials. The non-BASF catalyst
resulted in lower LPG + gasoline and
LCO yields. Furthermore, the LCO/
bottoms ratio was worse with the other
catalyst, going from 1.3 wt%/wt to 1.1
wt%/wt. These changes were not captured
in pre-trial testing, went against

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