The Catalyst Review April 2024 - 6

SPECIAL FEATURE
Crude Oil to Chemicals
Part II: Synergy of Olefins, Steam Crackers & Chemicals
By Marcio Wagner da Silva
Part I in the March edition detailed the synergy of steam cracking and FCC technologies.
Light Paraffin Dehydrogenation Technologies
Another alternative to improve the yield of light olefins in the refining hardware is to apply paraffin dehydrogenation technologies. Light
paraffin is normally commercialized as LPG or gasoline and presents reduced added value when compared with light olefins.
Dehydrogenation process involves the removal of hydrogen from paraffinic the molecule and consequently hydrogen production, according
to the reaction (1):
The dehydrogenation reactions have
strongly endothermic characteristics,
and the reactions conditions include
high temperatures (close to 600°C) and
mild operating pressures (close to 5
bar). The catalyst normally applied in the
dehydrogenation reactions are based on
platinum carried on alumina (other active
metals can be applied).
Figure 7 shows a schematic process flow
diagram for a typical dehydrogenation
process unit.
The main processes that can produce
streams rich in light paraffin are physical
separation processes, such as LPG
from atmospheric distillation and units
dedicated to separate gases from crude
oil.
R2CH-CHR2
↔ R2C=CR2
+ H2
(1)
Figure 7. Process flow diagram for a typical light paraffin dehydrogenation process unit.
Source: Author.
The feed stream is mixed with the recycle stream before to entering the reactor, the products are separated in fractionating
columns and the produced hydrogen is sent to purification units (normally PSA units) and, posteriorly sent to consumers units as
hydrotreating and hydrocracking, according to refining scheme adopted by the refiner. Light compounds are directed to the refinery
or petrochemical complex fuel gas pool, after adequate treatment while the olefinic stream is directed to petrochemical intermediates
consumer market.
During the dehydrogenation process, there is a strong tendency to coke deposition on the catalyst surface and is carried out
periodically regeneration of the catalytic bed through controlled combustion of the produced coke. Some process arrangements
present two reactors in parallel, aimed to optimize the processing unit operational availability, in these cases while a reactor is in
production the other is in the regeneration step.
Due to the growing market and high added value of light olefins, great technology developers have dedicated their efforts to develop
paraffin dehydrogenation technologies. The UOP Company developed and commercialized the OLEFLEX™, capable to produce
olefins from paraffin dehydrogenation with a continuous catalyst regeneration process. Despite the higher initial investment, this
technology can minimize the unavailability period to regenerate the catalyst. Figure 8 presents a basic process flow diagram for
the OLEFLEX™ technology by UOP Company. Another paraffin dehydrogenation technology from UOP Company is the PACOL™
process.
6
The Catalyst Review
April 2024

The Catalyst Review April 2024

Table of Contents for the Digital Edition of The Catalyst Review April 2024