The Catalyst Review January 2025 - 13

Experimental Abstracts
Special Focus-Catalysts: The Distinct Operational Advantages of Aluminasupported
Catalysts for Hydrocracker Pretreat and Hydrotreating applications
Hydroprocessing units in
refineries use hydrogen
and specialized catalysts
under
extreme
conditions
to convert crude
oil into clean transportation
fuels. These catalytic
systems, composed of
base
metals
supported
Figure 1. An illustration of alumina-supported catalysts loaded in a reactor (left), catalyst extrudates (top
middle), and microscopic close-ups of alumina structures showing the high porosity resulting in high
accessibility to the active sites within the extrudates (right).
on alumina or silica, effectively
remove impurities
like sulfur, nitrogen,
and metals from fossil
crude oil. The process
is crucial for producing
high-quality,
environmentally
compliant fuels using hydrotreating and hydrocracker pretreatment techniques. Their performance
and ability to meet product specifications depend on various critical factors, including the feed's
physical and chemical properties, operating conditions, and catalyst selection. These units play a crucial role in producing
clean, high-quality fuel products by addressing contaminants and improving overall fuel characteristics.
Alumina-supported catalysts are the preferred choice for hydroprocessing applications. It is well understood that
the physical strength of this catalyst system originates from an alumina support providing desirable textural properties
(i.e., surface area, pore volume, optimal average pore diameter, pore size distribution) to ensure fast reactant
diffusion and accessibility to the highly dispersed active metal sites inside the catalyst extrudates (Figure 1).
Combining these textural properties with the desired microstructure, attrition resistance, and phase
compositions of the alumina provides strength, hardness, inertness, and chemical and hydrothermal
stability to the catalyst support and the final catalyst. The authors discuss in depth how these characteristics
of alumina-supported catalysts enhance the performance of hydroprocessing units.
The choice of catalysts can significantly
impact a unit's profitability;
therefore, catalyst
options should be investigated
broadly from an operational
standpoint
to determine the
Figure 2. Transmission electron micriscioy (TEM) images of the basal plane of catalytic active NiMoS
sites showing the important edge promotion effect of the NiMoS active sites (green slabs) found in
alumina9supported catalysts which allows full utilization of the active metals (right two).
best fit with the unit. A holistic
comparison, including catalyst
activity, H2 consumption,
temperature control, pressure
drop limitation, yields, turnaround
concerns, cycle objectives, operational feasibility, process constraints, and catalyst price, needs to be considered
to determine the optimal catalyst system for the unit. As a result, top-tier NiMoS alumina-supported catalysts (Figure 2)
have been found to possess distinct operational advantages for hydrocracker pretreat and conventional hydroprocessing
applications where high hydrogenation and stable volume swell throughout the cycle are desired. Singh R, Maldonado
X.E.R, and Johansson F B, (2024, July) Hydrocarbon Processing, http://admin.hydrocarbonprocessing.com/magazine/2024/july-2024
The
Catalyst Review
January 2025
13
The Catalyst Review January 2025

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