Hydrocarbon Processing - January 2022 - 35

Biofuels, Alternative/Renewable Fuels
HDT renewable diesel
C16
-C18 n-paraffins
Poor cold flow properties
High selectivity to multi-branched
isomerization is key to enabling
deep delta cloud while maintaining
yield of dielsel
Delta cloud point or conversion
FIG. 2. The proprietary dewaxing catalysta
can help promote multi-branch isomerization.
in the diesel boiling range. The higher
the cloud point improvement, the more
important it is to selectively isomerize vs.
crack to maintain diesel yield.
The author's company's proprietary
dewaxing catalysta
is formulated to meet
diesel cold flow specifications, even at
deep delta cloud, while maintaining high
liquid yields through its selectivity to
multi-branch isomerization.7
Increasing interest in the production
of jet fuel-or sustainable aviation fuel
(SAF)-has the potential to shift the design
and operation of renewable fuel processes.
For co-production of diesel and jet
fuel, this may require changes to the product
separation equipment and operating
severity, thereby introducing additional
capital and operating expenses.
Renewable feedstocks typically have a
narrow boiling range; therefore, the operating
conditions need to drive molecules
from the diesel boiling range to the jet
fuel boiling range. The goal is to make
this transition with the highest jet fuel and
diesel total yield, while avoiding the production
of naphtha and light ends. The
proprietary dewaxing catalysta
manage this balance (FIG. 2).
can help
Takeaway. Production of renewable diesel
includes technical challenges (including
the removal of contaminants, corrosion
concerns and metallurgy selection,
as well as the management of high heat
release and hydrogen consumption) beyond
those of conventional processing,
thus preventing catalyst activity inhibition
and providing deep dewaxing, while
maintaining high liquid yields. The design
of the process configuration and operation
of the unit are critical for the mitigation
and management of these factors. The
author's company's proprietary renewable
3
diesel processb
features a two-stage unit
design that uses the proprietary dewaxing
catalysta
and processes a range of renewable
feedstocks to produce high yields of
renewable diesel, with the flexibility to also
produce nominal volumes of jet fuel. The
use of two stages enables separate control
of the hydrotreating and dewaxing chemistries,
thus allowing refiners to better adjust
to changing objectives compared to singlestage
processes. The author's company's
expertise as both an owner and operator of
hydroprocessing units allows it to address
all the key challenges noted in this article
in the design and operation of the proprietary
renewable diesel process and to deliver
a high-performance technology that
meets renewable product objectives.
NOTES
a
b
ExxonMobil's Bio-Isomerization Dewaxing
(BIDW™) catalyst
ExxonMobil Renewable Diesel (EMRD™) process
LITERATURE CITED
1
U.S. Energy Information Administration (EIA),
" Renewable Diesel is a Biomass-Based Diesel Fuel, "
August 18, 2020, online: https://www.eia.gov/energyexplained/biofuels/biodiesel-in-depth.php
2
Zhang,
B., J. Wu, C. Yang, Q. Qiu, Q. Yan, R. Li, B.
Wang, J. Wu and Y. Ding, " Recent Developments in
Commercial Processes for Refining Bio-Feedstocks
to Renewable Diesel, " Bioenergy Research, July 2018.
Sharma, Y. C., M. Yadav and S. N. Upadhyay, " Latest
Advances in Degumming Feedstock Oils for LargeScale
Biodiesel Production " Biofpr, October 2018.
Complete literature cited available online at
www.HydrocarbonProcessing.com.
SARA GREEN is a Customer
Solutions Advisor at ExxonMobil
Catalyst and Licensing. She has
worked at ExxonMobil for 7 yr and
specializes in hydroprocessing and
dewaxing technologies of fuels and
lubricants. Dr. Green has held roles in
research and development and manufacturing support,
and has been involved with several major capital
projects. She earned a BS degree in general engineering
from Smith College and a PhD in chemical engineering
from the University of Massachusetts Amherst.
Hydrocarbon Processing | JANUARY 2022 35
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Single branch
isomerization
at low dCP
Other catalysts
promote cracking
reactions at high dCP
The proprietary dewaxing
catalysta
promotes
multi branch isomerization
at high dCP
Yield loss due
to cracking
Diesel yield, wt%
HPI
MARKET
DATA
2022
HydrocarbonProcessing.com

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Hydrocarbon Processing - January 2022

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