Hydrocarbon Processing - December 2022 - 36

Catalysts
catalyst performance claims, resulting in
the other bidders coming out ahead in the
catalyst evaluation. However, how did the
refiner know the vendor did not offer decent
catalysts without pilot plant testing?
While the estimates might be suspicious,
the catalyst R&D and actual performance
might actually prove accurate.
Another example of how vendors may
" manipulate " kinetic models is an accidental
internal email in a catalyst company
that discusses how to alter the original
TABLE 1. An example of feed properties from a real bid tender for a hydrocracking
catalyst package with the corresponding data sources
Property
Specific gravity at 15°C
Sulfur, wt%
Nitrogen, ppm wt%
CCR, wt%
Heptane insoluble
(C7
), wt%
Distillation (SIMDIST)
IBP, °C
T5, °C
T10, °C
T30, °C
T50, °C
T70, °C
T90, °C
T95, °C
FBP, °C
Recovery at cracked
temperature, %
Metal, mg/kg
Ni
V
Na
Fe
Al
Si
As
Hg, ng/g
Total aromatics, %m/m
Mono
Di
Tri
Tetra+
AAS by ICP or IP 501/03
HT SIMDIST or
ASTM D1160
Historical data-Current cycle average
274.7 Historical data-Current cycle average
349.4 Historical data-Current cycle average
374.4 Historical data-Current cycle average
423.1 Historical data-Current cycle average
455.9 Historical data-Current cycle average
494 Historical data-Current cycle average
545.7 Historical data-Current cycle average
565.4 Historical data-Current cycle average
605 Historical data-Current cycle average
100 Historical data-Current cycle average
0.4 Historical data-Worst case
AAS by ICP or IP 501/03 0.07 Historical data-Worst case
AAS by ICP or IP 501/03 0.42 Historical data-Worst case
AAS by ICP or IP 501/03 0.22 Historical data-Worst case
AAS by ICP or IP 501/03 0.23 Historical data-Worst case
AAS by ICP or IP 501/03 0.68 Historical data-Worst case
0.02 Historical data-Worst case
Historical data-Worst case
UOP 946-96 (ICP-HG)
UOP 398-000
SMS 2783
2
15.3 Historical data-Worst case
Historical data-Worst case
4.18
3.39 Historical data-Worst case
4.08 Historical data-Worst case
3.65 Historical data-Worst case
TABLE 2. A list of metals commercially used in hydrocracking catalyst manufacturing
and their attributes
Metal
Co-Mo
Ni-Mo
Ni-W
Pd/Pt
Active form
Sulfided
Sulfided
Sulfided
Reduced
Hydrogenation strength Note
-
-
Base
+
36 DECEMBER 2022 | HydrocarbonProcessing.com
Rarely seen
Less popular
Most popular
Typically used in the 2nd stage,
requires low-sulfur environment
Test method
ASTM D4052
ASTM D4294
ASTM D4629
ASTM D4530
VGO Data source
0.9012 Historical data-Current cycle average
0.42 Historical data-Current cycle average
1500 Design data
1.35 Design data
Design data
0.1
pretreating temperature to make it believable
during a hydrocracking catalyst bidding.
This catalyst vendor later realized
that the refinery contact was mistakenly
included in the internal communication,
although that contact never mentioned it.
These real stories are perfect examples
of how refiners should always challenge
the data presented in vendors' proposals
and how paper-based evaluations can be
highly subjective.
Inherent flaws in paper-based catalyst
evaluations exist and should be avoided,
even when selecting naphtha hydrotreating
catalysts. The authors have seen a
naphtha hydrotreating unit that chronically
suffered from off-specification product
due to sulfur recombination reactions
as a result of lower-than-expected catalyst
activity (e.g., the reactor temperature
exceeded the olefin saturation equilibrium).
In another example, a kerosene
hydrotreater with more than 150% of gas
plus overhead liquid products-compared
to the design (and catalyst specification)
and at much lower reactor temperatures
than the design-overloaded
the top section of the stripper column.
The myth of hydrocracking catalyst
selection. It is vital to test hydrocracking
catalysts to reduce the risks of selecting
a suboptimal hydrocracking catalyst
package. As this major conversion unit is
a significant profit center, a slight performance
gap can easily cause multi-milliondollar
losses. Nonetheless, the risk level
associated with hydrocracking catalyst
selection is not necessarily higher than
other refining catalysts, as discussed in
the following sections.
Clear distinctions exist between good
and average/poor hydrocracking catalysts.
As demonstrated in FIG. 2, catalyst Package
C is clearly the best by both paper-based
and pilot plant-based evaluation. While
Package E seems a relatively weak second-best
on paper, it performed well and
almost won in the pilot plant testing-
a $10 MM/cycle benefit gap, although
seemingly significant, is considered relatively
close in hydrocracking. According
to the authors' survey, many refiners agree
that the catalyst vendors that designed
catalyst Packages C and E are technically
fine based on past operating experiences.
Conversely, catalyst Packages A, B
and D are inferior on both paper and pilot
plant testing. The only difference is
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