A Brief History of Lubricants

It may seem prosaic, but lubricants in various states of evolution date back to 1400 BCE, according to Hantzer. At that time, they were simple animal fats, and their use was prompted by the invention of the wheel around 3300 BCE.

It was not until the 1850s that crude oil was used for the first time, leading to the birth of modern refining in the 1860s. Fast forward to 1936, which saw the first use of catalytic oil cracking. Then, in the 1950s, hydrotreating was used.

Refining technology has come a long way, and its role in maximizing cost efficiencies continues to push research boundaries. According to Hantzer, the late 1990s saw landmark industry developments, including Exxons own mineral solvent dewaxing (MSDW) process, which is now in its third iteration. In 1999, an Exxon partner company developed a process known as raffinate hydroconversion (RHC).

It was a process added to a solvent plant, so you have solvent extraction and RHC to increase viscosity index and then do solvent dewaxing. This was how Exxon produced a Group II+ which is now an API classification. Hantzer also acknowledged the wax isomerization another process, (MWI), created in 2003 that produced a base oil with a viscosity index of 40 to 55.

In line with other industry forecasts, Hantzer predicts lubricant demand will grow at a modest 1 percent per year through 2022 with European and North American markets flat or even declining and Asia-Pacific continuing to witness the strongest growth. Engine oils account for the vast proportion of lubricant demand, and the automotive sector consumes just over one-half of all lubricant volumes.

Hantzer said engine oil specifications in the automotive market are more harmonized than before, including API/ILSAC, ATIEL and original equipment manufacturer specifications, but there is undoubtedly a rapid pace of change. That is largely because of more demanding performance requirements, including fuel economy and emissions reduction targets that can be met only by higher viscosity index base stocks. Increasingly, specifications are being designed with base stock quality limits in mind.

Hantzer said that despite the dominance of the automotive market, other lubricant categories account for a large portion of total sales and are sometimes overlooked. People often forget about the other half of the lubricant market – process oil, marine and industrial – but those sectors are not harmonized, and there is a wide range of viscosities.

Multiple Production Pathways

Depending on the process chosen, several options are available following the solvent extraction process that determine the type and quality of base stock produced. Coming out of the solvent plant, you have two streams: the extract from the solvent extraction and the raffinate, Hantzer explained.

Raffinate can be solvent dewaxed as well as hydrofinished to improve sulfated ash, phosphorus and sulfur content, leading to an API Group I base oil, Hantzer said. Similarly, raffinate can be taken through hydroconversion, followed by solvent dewaxing and hydrofinishing to produce Group II & II+ base oils. To produce Group II & III base oils, catalytic dewaxing and hydrofinishing replace solvent dewaxiing.

Raffinate conversion technology allows the solvent dewaxing process to be retained and also improves base oil quality. A further step would be to replace solvent dewaxing with catalytic dewaxing. Ultimately, the solvent dewaxing process can be interchanged with a hydrocracker followed by catalytic dewaxing and vacuum distillation to produce Group II and III base oils.

Whether it is Group II and III will be determined by whether the hydrocracker is a fuel or lube hydrocracker, explained Hantzer. A lube hydrocracker will produce more unconverted oil but also a lower viscosity index, typically a Group II. Conversely, a fuel hydrocracker will have a higher conversion rate, 70 to 80 percent, and will yield Group II+ and III base oils. You can change viscosity index by changing the hydrocracker, Hantzer said.

Modern base stock technology, particularly for Group II and III, uses hydroprocessing. To adjust viscosity, the process uses vacuum distillation to produce vacuum gas oil through the hydrocracker, followed by dewaxing and hydrofinishing. Each stage of the process removes impurities and improves viscosity index. Catalytic dewaxing will improve cold pour properties while maintaining a higher viscosity index, and hydrofinishing will improve color, reduce aromatics and produce more stable base oil with better oxidation capabilities. Hantzer said the deasphalted oil
can also go into the hydrocracker. You can still produce high quality base oils even if your unconverted
oil is not such high quality.

Making the Right Investment

Economics are a major aspect of deciding what technology to use, and understanding what exactly is required takes careful thought, said Hantzer. Issues include whether the strategy is a regional or export-led plan as well as specific company needs. The plans should be flexible enough to adapt to changes in market or industry dynamics.

One size does not fit all, he warned. Investment costs include equipment size and the amount of catalyst and precious metals that will be consumed. Forecast start-of-run (SOR) activity and yields are important, but so are a long-lasting catalyst and preventing yield does from degrading, Hantzer added. In other words, you should be looking for low aging and a robust catalyst that is able to withstand refinery upsets.

Understanding that markets differ requires a solution tailored to the refiners business. As an example, Hantzer cited the difference in product mix between Europe and the Middle East. In the Middle East, the commercial vehicle market is about 42 percent where in Europe it is around 20 percent. Equally, other issues such as a regions performance categories and viscosity grade mix are important factors.

The Middle East has an advantage in that it is in close proximity to base stock supplies and is well placed from a logistical and distribution perspective. According to Hantzer, industry trends do not always align with individual company needs.

Improved Catalysts

Mobil Selective Dewaxing
(MSDW) was introduced in 1997. The second generation of the process had higher activity; so, the temperature required to produce the same pour point was much lower. In addition, the process improved base oil yield. The third generation, launched in 2006, improved activity further while maintaining the same selectivity as the second generation.

Increasing activity by reducing the start-of-run temperature is important but not at the cost of reduced yield, said Hantzer. ExxonMobil is working on the fourth and fifth generation of the process, but refiners can already capture the gain in activity in several areas.

You can reduce your equipment size and lower your start-of-run temperature, Hanzer noted. Lowering SOR temperature extends catalyst life and provides feed flexibility. In recent tests with a MSDW licensee catalyst, activity improvements showed a low aging rate over a 10-year cycle on the same catalyst fill. In addition, high selectivity
was maintained over the duration of the catalyst cycle with no yield degradation. Also, the licensee increased the unconverted oil feed rate by about 20 percent over the same catalyst cycle.

Putting these advances together allows refiners to maximize base stock production with each catalyst volume. In the current (third) generation, tangible improvements have been made in SOR temperature, low catalyst aging and increased feed rates.

Robust technology and the high activity that follows also reduce capital investment by permitting smaller reactors, lower catalyst volume and lower precious metal requirements. Hantzer estimated that a 1 percent change in yield can have a significant impact on revenues, particularly when refining margins are low and could be worth as much as U.S. $7.8 million for a Group III plant, based on recent spot prices. What is important is that yields are maintained throughout the period, and you will want to save money wherever you can get it whether it is smaller reactor, more yield or lower temperature, which saves energy, he concluded.

Hantzer claimed that 65 to 70 percent of all Group II and III base oil is produced using a MSDW catalyst. We currently have 30 licensees and 23 MSDW plants operating worldwide with the exception of South America. ExxonMobil Research and Engineering has entered an alliance with Honeywells UOP that offers lube and advanced fuels hydroprocessing and engineering capabilities to companies in the refining sector.

Looking to the Future

Overall capacity growth and growth in hydroprocessing methods will be seen mainly in Group II and III light and medium neutral stocks, said Hantzer. He claimed that hydroprocessing not only improves quality but also permits the manufacture of base oil from a broader range of crudes previously deemed unsuitable for lubricant production.

At a time when base oil oversupply coincides with lower organic growth in the overall lubricant market, refiners will increasingly focus on plant economics. And a big part of that will be the role technology plays in driving profits. Irrespective of its source, using catalyst technology can reduce capital expenditure and reduce operating costs. It also provides intrinsic flexibility because of a wide operating range to safeguard against plant disruptions, maximizing plant uptime without the need to reload the catalyst.

Whatever decision is made needs to take into account how widely the technology has been used and the experience the company has in designing the process. It is perhaps no surprise that MSDW accounts for a major share of the market. What is clear is that lower crude prices could be around for some time, and further improvements will underpin the quest for better performance and profitability being demanded by refiners.