Chemical Engineering May 2021 - 16

ogy could also help conserve energy
as less energy-intensive steps are required.
Currently,
the researchers point out,
most C2C processes combine technologically
mature units (high-severity
fluid catalytic cracking (FCC) units
and naphtha crackers) to maximize
the production of ethylene, propylene
and aromatics. " Although economically
attractive, this approach still requires
the use of oil pre-treatment
processes [hydrotreating], energyintensive
distillation units for separating
different fractions and the primary
products of FCC, and the use of other
energy-intensive units, such as steam
crackers, " the team writes in a recent
study in Nature Catalysis.
The multi-zone configuration of
the reactor allows for in-situ catalyst
stripping and regeneration, the
KAUST team says, where catalyst
particles undergo cycles of deactivation,
stripping and regeneration in
separate zones of the same fluidizedbed
vessel (Figure 3). Meanwhile, the
incorporation of silicon carbide (SiC)
into the catalyst improves its physical,
mechanical and heat-transport
properties. As a result, this reactorcatalyst
combination has shown stable
conversion of untreated Arabian
Light crude oil into light olefins with
per-pass yields of over 30 wt.% with
a minimum production of dry gas,
the researchers say.
The untreated crude oil is fed into
the reactor at the middle of the vessel,
which has the cracking zone at
the top section and the stripping
zone and catalyst regeneration at
the bottom, Gascon explains. " Different
reaction zones in the reactor
vessel can be fine-tuned to achieve
different environments and residence
times with continuous operation of
the catalyst, " he says.
" Carrying out cracking and stripping
in the same reactor obviates the
need for several units in the process, "
Gascon says, and " you can utilize the
energy from coke burning to run the
cracking reaction, while maintaining
the activity of the catalyst. "
The KAUST team is currently building
a mini-pilot plant (capable of processing
10 L of crude oil per day) in
order to conduct material and energy
balances and economic analyses for
16
the process, as well as evaluating its
performance on other types of crude.
New alkylation technologies
Alkylate, formed by the reaction of
light olefins (such as butylene) with
isobutane, is the most sought-after
blendstock for gasoline because
of its high research octane number
(RON) values and low (or no) sulfur
content. Two new technologies
launched this year can improve alkylation
operations at refineries.
In April 2021, Chevron Corp. (San
Ramon, Calif.; www.chevron.com)
and Honeywell announced the commissioning
and startup of the world's
first commercial-scale IsoAlky process
unit at Chevron's Salt Lake City
refinery. IsoAlky technology utilizes
ionic liquids to produce alkylate, and
is designed to offer a cost-effective
and safer alternative to conventional
liquid-acid systems. Using a nonaqueous
liquid salt, or ionic liquid as
a catalyst (rather than hydrofluoric
or sulfuric acid), the new process
requires only standard personal protective
equipment and produces a
valuable high-octane blending component.
IsoAlky technology was
pioneered by Chevron USA Inc. and
licensed to Honeywell UOP to offer
the technology to the wider entire industry.
Bryan
Glover, president and CEO
of Honeywell UOP says " Ionic liquids
have strong acid properties
that enable them to produce alkylate
without the volatility of conventional
acids, allowing for simpler handling
procedures. " He adds that the newly
commercialized technology canpromote
cleaner-burning fuels at a lower
cost while simplifying complex handling
requirements. "
IsoAlky can be used in new refineries,
as well as existing facilities
undergoing capital expansion or retrofits.
The technology has wider and
improved feed flexibility
relative to
conventional alkylation technologies,
Glover says, and the ionic-liquid catalyst
material is regenerated onsite,
eliminating the need to transport it
offsite for regeneration and polymer
byproduct handling.
In another alkylation-related development,
Lummus
Technology
(Houston;
www.lummustechnology.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM MAY 2021
com) recently announced the startup
of its first C5 CDAlky unit at Valero
Energy Corp.'s (San Antonio, Tex.;
www.valero.com) St. Charles Refinery
in Norco, La. C5 CDAlky is a new
version of the company's CDAlky
technology, a low-temperature sulfuric
acid alkylation process.
The St. Charles installation is the
first C5 CDAlky alkylation unit in the
world, and Lummus' first CDAlky
unit in the U.S. Lummus developed
this new version of the alkylation
platform to process low-value C5
feedstock at its pilot plant facility in
Pasadena, Texas. A depentanizer
column is used to recover C5 olefins
from light cat naphtha and to
remove impurities from feedstocks.
The CDAlky unit converts C5 olefins
into a superior alkylate product with
minimum acid consumption. The
capacity of the new C5 CDAlky alkylation
complex is 17,000 bbl/d of
alkylate product.
The C5 CDAlky version employs
the same core technology as the
original technology, but couples the
CDAlky with a CDHydro depentanizer,
a specific pretreatment system
for fractionating and hydrogenating
C5 impurities, such as cyclopentene
and pentadienes.
" In the past, refiners would need
a depentanizer plus a hydrogenation
step to deal with the C5 stream,
but through process intensification
the CDHydro uses the principles of
catalytic distillation to separate the
C5 feedstock and to remove impurities
in the same unit, " explains Todd
Vogt, head of refining at Lummus.
" With this system, refiners can
take the C5 stream and turn it into
high-value gasoline blendstock, "
adds Jackeline Medina, Lummus
technology manager for alkylation
technologies (Lummus was previously
owned by McDermott International,
but was recently spun off as a
standalone company).
n
Scott Jenkins
Editor's note: For additional information on
the petroleum refining segment, including a
new process configuration for the production of
premium gasoline from naphtha, and projects for manufacturing
sustainable aviation fuels, visit www.chemengonline.com
for an extended version of this article.
http://www.valero.com http://www.chevron.com http://www.chemen http://www.gonline.com http://www.lummustechnology http://WWW.CHEMENGONLINE.COM
Chemical Engineering May 2021

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