Hydrocarbon Processing - December 2022 - 29

Catalysts
unit objectives and were detrimental to
unit profitability.
Case Study 3. The final case study of
tailoring catalyst technology and design
to meet the bottoms upgrading objectives
of an FCCU was at an Asian refinery.
The refinery wanted to increase FCC
profitability by improving bottoms upgrading,
while maintaining high conversion
and coke selectivity despite sporadic
metals poisoning episodes and maintaining
Ecat metals levels greater than 7,500
ppm of Ni + V. The unit was often limited
in bottoms upgrading ability due to
reaching regenerator temperature limits.
Using an activity model fine-tuned
to the FCCU's operation, a catalyst was
proposed (BASF Catalyst Ee
) to maximize
conversion in a heavy resid environment.
The objective for this catalyst
was to offer improvements to the incumbent
catalyst through enhanced pore architecture
and metals passivation. Catalyst
E was evaluated-along with other
candidates-through pilot plant testing,
modeling and sensitivity studies and was
eventually selected for trial.
TABLE 2 details the post-audit results
using both catalysts at iso-coke conditions.
BASF Catalyst E demonstrated
improved coke selectivity by showing
significantly higher conversion at isocoke
levels. As a result, LPG and gasoline
yields were also higher. Additionally,
the hydrogen yield of Catalyst E was
lower despite the higher conversion, a
result of the strong metals passivation
of the catalyst. Finally, LCO/BOT and
overall bottoms yield were both improved,
demonstrating that this catalyst
was the right fit for optimizing bottoms
upgrading in this unit.
FIG. 3 shows two cross plots from
the post-audit study of this catalyst
trial. The strong coke selectivity and
improved bottoms upgrading provided
by Catalyst E can further be seen in
this analysis. Catalyst E demonstrated
slightly higher conversion yet consistently
lower coke make. Similarly, Catalyst
E was also able to crack significantly
more bottoms at comparable coke levels.
Once again, despite being a different
technology than the catalysts seen in the
previous two trials, consideration of the
specific requirements of this unit led to
an improvement in bottoms upgrading
through catalyst selection.
Takeaway. As one of the least valuable
FCC products, the need to minimize bottoms
is expected to increase as pressure
on refiners to get the most out of every
barrel of feed intensifies. The three trials
detailed in this article illustrate that
understanding the needs and constraints
of each unit is critical to maximizing bottoms
upgrading through FCC catalyst selection,
as the strategy for the appropriate
catalyst technology used in each trial
is different. Three different catalysts were
used across the three trials. Despite the
three catalysts being different, bottoms
upgrading was improved significantly in
each case because close collaboration between
the refinery and the FCC catalyst
supplier ensured that the catalyst provided
met the precise needs of the unit and
delivered maximum profitability.
NOTES
a BASF's NaphthaMax® catalyst
b BASF's Luminate® catalyst
c BASF's Aegis® catalyst
d BASF's Altrium® catalyst
e BASF's Fortress® NXT catalyst
FIG. 3. Selected yield plots from Case Study 3's post-audit study.
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Hydrocarbon Processing | DECEMBER 2022 29
Hydrocarbon Processing - December 2022

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