The bright future for PAOs - Ever increasing fuel efficiency requirements, environmental regulations and resulting performance demands are being ...
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COVER STORY
The bright future for PAOs
Ever increasing fuel efficiency requirements,
environmental regulations and resulting performance demands
are being met by PAO manufacturers.
By Jeanna Van Rensselar
Senior Feature Writer
There is no doubt that the demand for polyalphaolefin (PAO) base stock is increasing
KEY CONCEPTS
and has been for decades. What’s different in recent years is the introduction of high
PAO developers are making viscosity metallocene PAOs (mPAOs) that mitigate the few shortcomings of PAOs.
significant investments to meet the
current and projected demand. Three major suppliers of PAO base Petroleum Institute has designated them
stock are ExxonMobil Chemical Co., as Group IV. And they have many benefits
PAO developers also are rolling out new INEOS and Chevron Phillips Chemical. over Group I, II and III base stocks.
technologies for new requirements. Other suppliers include LANXESS and PAOs provide superior lubrication
Naco (China). performance over wider operating and
Although the COVID-19 pandemic
PAOs are 100% synthetic, nearly 100% temperature ranges than mineral-based
created a few interruptions, the long-term
pure, nonpolar polymers that are created by oils, are usually less volatile and have good
projection for PAOs is strong.
polymerizing alphaolefins. The American lubricity in metal-to-metal applications.
28 • FEBRUARY 2021 TRIBOLOGY & LUBRICATION TECHNOLOGY WWW.STLE.ORG
low. They can yield longer drain intervals enabling precision properties for discrete
because of reduced volatility and better end-products and their applications.
oxidation, thermal, molecular and additive When compared with conventional
package stability. Group IV base stock, the general benefits
STLE Vice President Dr. Ken Hope, of mPAOs include:
global PAO technical services manager, • Improved shear stability for product
Chevron Phillips Chemical, says, “PAOs durability and long drain intervals.
are well known for their excellent low- • Improved Brookf ield viscosity 2
temperature viscometrics, oxidative sta- and lower pour point improve low-
bility, Noack volatility,1 low pour points, temperature viscosity and, thus, cold-
thermal conductivity and also food-grade start performance.
properties. The reduction in the coefficient • A higher VI for excellent performance
of friction and the low Noack volatility have across a wide range of temperatures.
become very important for low-viscosity • Better air release and foam properties.
lubricants targeting energy efficiency
Metallocene high-viscosity PAO is
advantages. However, there are many
produced by major suppliers. Applica-
different types of base oils and reasons
tions for mPAOs include auto, truck and
for each. The plethora of lubricant appli-
stationary engine oils, multigrade gear
cations across the globe requires a signif-
oils, wind turbine lubricants, compressor
icant array of specific base oil properties.”
lubricants and greases.
According to STLE Fellow Jack
Zakarian, formerly with Chevron Lubri- PAOs are 100% synthetic,
cants and now a consultant for JAZTech nearly 100% pure, nonpolar
Consulting, LLC, the breakthroughs in
polymers that are created by
PAOs involve the manufacturing pro-
cess, which has led to better performance.
polymerizing alphaolefins.
“There were two recent advances: one “All of the major producers use the
involves high viscosity (mPAO) and the metallocene process,” Zakarian explains.
other involves ultra-low viscosity PAO “The migration is slow because of the time
(low-viscosity, low-volatility, LVLV),” he and cost involved to reformulate and reap-
says. “This is PAO that has the ability prove products. Given the performance ad-
to self-assemble under high pressures, vantage, I would say that the metallocene
thereby reducing fluid friction. This new process is preferred.”
PAO has lower volatility compared to con- “There are many benefits for the
ventional PAO, which is a big advantage in mPAO products over traditional high-
engine oil formulations.” viscosity PAOs,” Hope says. “Most nota-
Hope adds, “The mPAO-based technol- ble are the low pour point, very high VI
ogy represents a considerable change in and excellent low-temperature viscos-
technology away from the traditional high ities. Other important features include
viscosity polymerization that has been the reduction in the ability to generate
used since the 1980s.” and stabilize a foam, oxidative stability,
air release and shear stability.”
Greases with PAO base oils are less prone Metallocene PAO Zakarian observes, “The market has
to water washout and creep. For the last decade or so, there had been been slow to take advantage of metal-
They also exhibit excellent oxidation growing demand for PAO base stocks with locene products. The reason is the time
resistance—no points on the hydrocarbon extended drain intervals, better tempera- and cost involved to reformulate current
chains that tend toward oxidation. PAOs ture performance, increased durability in products. However, over time, I expect that
have higher viscosity indexes (VIs) and re- the most severe conditions and—most nearly everyone will migrate to the better
quire fewer viscosity improving additives importantly—improved energy efficiency. performing product.”
(which also reduces shearing). The answer was mPAO technology. It ExxonMobil agrees that market
Because PAOs do not contain waxes involves the use of metallocene oligomer- acceptance of metallocene high-viscosity
that readily form crystalline structures, ization catalysts that yield products with products will continue in both conven-
they have better cold flow properties— higher kinematic viscosity and a much tional and metallocene products and is
keeping the pour point exceptionally narrower molecular weight distribution— committed to both platforms.
WWW.STLE.ORG TRIBOLOGY & LUBRICATION TECHNOLOGY FEBRUARY 2021 • 29
COVER STORY
The demand for PAOs strong due to superior performance attri- Lanigan adds, “In terms of technology,
PAO demand has grown in recent years. butes in many applications.” formulators will need new base stocks in
Hope explains, “Several factors have Zakarian observes that the increased order to meet future fuel economy targets.”
contributed to this growth, including the demand for PAO is coming at the expense The next-generation LVLV PAOs offer
need for better performing engine oils that of other base oils—although there has been much lower viscosity, lower volatility and
lead to lower CO2 emissions and higher a modest upsurge in both Group III and higher oxidation resistance versus con-
performing lubricants for industrial equip- Group IV demand in recent years. “The ventional low-viscosity PAOs and versus
ment. This leads to lower maintenance demand for Group III and Group IV is driv- Groups III products. Lanigan continues,
costs and improved efficiency.” en by fuel economy and emission reduc- “These ‘step out’ LVLV PAO products can
Kerrie-Anne Lanigan, vice president, tion mandates,” he explains. “In addition to help formulators meet the challenging re-
synthetics, ExxonMobil Chemical Co., reducing friction and having a wide oper- quirements in future engine, transmission,
says, “PAO demand is influenced by the ating temperature range, Groups III and IV axle and gear oils (see Figure 1).”
health of the macro economy and the also give excellent oxidation stability, which
state of the global transportation mar- allows for longer drain intervals.” PAO demand is driven in
ket. In 2019, PAO demand was impacted Lanigan agrees that demand is driven large part by environmental
somewhat by a global economic slowdown in large part by environmental concerns
and low-viscosity PAO, in particular, also and regulations. “Longer term, we expect
concerns and regulations.
How PAO developers are
Low Viscosity Base Stocks – NOACK vs CCS at -35 C meeting the demand
There has been a significant amount of re-
cent and future production expansion an-
nounced by the major suppliers for both lin-
ear alphaolefin (LAO) and PAO (see LAO base
stock on page 32). “This is very good news for
lubricant marketers who, at times, were
tightly constrained on PAO availability,”
Zakarian says. “If all of the announced
projects are built, there actually could be
a surplus of PAO on the market.”
Chris Hausler, global business manag-
er, PAO, Chevron Phillips Chemical, says,
“We do believe that the growth is sustain-
able as a result of investments that have
been made in recent years to increase PAO
supply capacity, and it is our belief that the
industry will continue to invest to keep
pace with demand.”
Figure 1. Low-viscosity base stock comparison. Figure courtesy of ExxonMobil. He continues, “The industry has add-
ed additional feedstock and PAO capacity
to support increasing demand. We de-
was affected somewhat by Group III and that increasingly stringent regulations bottlenecked one of our PAO production
Group III+ products.3 Obviously in 2020, will continue to aggressively drive facilities a few years ago to increase our
PAO demand has been impacted due to the the industry toward improved energy production capacity and provide security
COVID-19 pandemic.” efficiency, fuel economy and reduced of supply to our customers.”
Lanigan continues, “COVID-19 brings emissions, and this, in turn, will contin-
a high level of uncertainty, which makes ue to drive demand growth for synthetic Into the future
near-term demand projections very chal- PAO base stocks,” she says. We believe Zakarian is convinced that PAO is the gold
lenging. Whether demand effects due to that PAO demand growth will persist, but standard for a hydrocarbon base oil. “The
COVID-19 are temporary or longer lasting to deliver the needed improvements in comparison to Group III is very dependent
is an open question. Additionally, while energy efficiency, fuel economy, emissions on what performance properties you need
Group III+ has continued to increase pen- and durability, formulators need support to meet,” he says. “For many products,
etration in some low-viscosity applications, to overcome the challenges posed by Group III will pass specifications, and it is
overall PAO demand continues to remain next-generation lubricant requirements.” preferred because of lower cost. If you
30 • FEBRUARY 2021 TRIBOLOGY & LUBRICATION TECHNOLOGY WWW.STLE.ORG
COVER STORY
Hausler also expects that the market
for PAOs will remain strong. “We do expect
this trend to continue as countries around
the world look for sustainable solutions
that help to reduce CO2 emissions and
manufacturers look to optimize efficiency
of their equipment and reduce mainte-
nance costs,” he says. “We believe PAOs
are a valuable group of products that can
provide environmental and sustainability
benefits, equipment efficiency improve-
ments and cost savings when formulated
into finished lubricants.”
Hope concludes, “As technical require-
ments continue to become more difficult
to achieve, formulators will continue to be
challenged to meet those with new and ex-
isting technologies. We feel PAOs offer con-
siderable advantages and can help meet
these emerging challenges. We continue
to find new applications due to changes in
our societal needs, and PAOs continue to
contribute to lubricant solutions.”
Jeanna Van Rensselar heads her own
communication/public relations firm,
Smart PR Communications, in Naperville,
Ill. You can reach her at jeanna@
smartprcommunications.com.
REFERENCES
New vehicle technology will have a mostly positive effect on the PAO market. 1. The Noack Volatility Test indicates lubricant
evaporation loss in high-temperature
operating environments.
cannot pass specifications, then PAO she says. “In the future, we see potential
becomes the obvious choice. The biggest demand upside in new EV applications 2. Brookfield viscosity measures fluid viscosity
at given shear rates.
advantage for PAO will occur in SAE 0W such as heat transfer fluids and multipur-
3. Premium Group III base stocks with VI
motor oils that have very low viscosity, pose fluids. However, we’re also monitor-
levels in excess of 130 are occasionally
such as 0W-8, 0W-12 and 0W-16.” ing the rate and pace of vehicle electrifi- marketed as Group III+, which is not
ExxonMobil is optimistic about the cation and its impact on the conventional recognized as an official category by the
future of PAOs. “The global trends favoring internal combustion engine (ICE) fleet.” American Petroleum Institute.
reduced emissions, improved fuel/energy
efficiency and durability will become in-
creasingly important as new regulations
continue to be announced and become
more stringent,” Lanigan says. Lanigan
LAO base stock
also feels confident the world will need
unique step-out base stocks like the next- Linear alphaolefins (LAOs) are synthetic hydrocarbon liquids produced by the polym-
generation LVLV PAO base stocks. erization of ethylene, H2C=CH2. As the name implies, LAOs have a linear structure
Lanigan also believes new vehicle with a double bond (olefin) at the end of the chain. This makes them more biode-
technology will have a mostly positive gradable than other olefins. LAOs are remarkably varied. They can be customized
effect on the PAO market. “When thinking to individual specifications—making them attractive for new chemical development.
about future trends, it is important to con- They are highly pure and used in applications that include high-performing engine/
sider the effect that vehicle electrification industrial oils, specialty chemicals, waxes, surfactants and plastic packaging.
might have on automotive lubricants,”
32 • FEBRUARY 2021 TRIBOLOGY & LUBRICATION TECHNOLOGY WWW.STLE.ORGYou can also read
