Singapore all-catalytic lube plant perfoms well

July 19, 1999
The performance of Mobil Corp.'s first all-catalytic lube basestock plant, built in 1997 in Jurong, Singapore, has been successful.

The performance of Mobil Corp.`s first all-catalytic lube basestock plant, built in 1997 in Jurong, Singapore, has been successful.

Construction for the plant project was efficient, and the plant is a reliable source of Group II base oils in the Pacific Rim. Plant operations have demonstrated new proprietary technology for lube hydro cracking and MSDW isomerization dewaxing.

Efforts are under way to further extend the capabilities of this world-scale plant to produce Group III light neutrals and high grade white oils.

Continuous improvement of Mobil`s proprietary MSDW isomerization dewaxing catalyst has led to a next-generation catalyst denoted MSDW-2, which provides significantly enhanced yields and viscosity indices (VIs) over previous technology.

The performance advantages of MSDW-2 have led Mobil`s Jurong refinery to elect an early replacement of its current MSDW-1 catalyst with MSDW-2 at the first opportunity in the year 2000.

The enhanced activity of MSDW-2 has shown potential for isomerization dewaxing of high viscosity feedstocks, such as hydroprocessed de asphalted oils. This makes it possible to produce a full range lube slate, including bright stocks, with a single dewaxing catalyst.

Jurong lube plant

Mobil started up its world-scale, all-catalytic lube base oil plant at the Jurong, Singapore, refinery in 1997. This grassroots plant has become a significant basestock source for both Mobil and third parties in the growing Asia Pacific region.

The lube base oil plant is integrated within the 300,000 b/d Jurong refinery and aromatics complex. It uses Mobil technology to produce 8,000+ b/d of Group II light and heavy neutrals, designated J150 and J500, respectively.

The driving forces for the lube project included the shortfall in Asia Pacific regional basestock supply in the early and mid-1990s, coupled with the outlook for continued lube-demand growth throughout the Pacific Rim. Heavy neutral was chosen as the main design stock since the shortfall was expected to be concentrated in that grade.1

Jurong was selected as the site for the new lube capacity because of the strategic location of Singapore, good refinery infrastructure, and synergies with existing process units in the plant. Mobil selected the all-catalytic route to lubes because it has low capital and manufacturing costs relative to conventional solvent-based plants.

The feedstock flexibility advantage of all-catalytic lube processing was particularly important for Jurong where crude selection greatly varies depending on the crude market. Production of lubes from 30 different types of lubes/condensates per year is typical. Sources range among the Persian Gulf, West Africa, and Southeast Asia.

The construction schedule of the lube plant was fast-paced. Engineering started in mid-1995 and was followed by construction kick-off in April 1996. The plant was mechanically complete just more than a year from the start of construction. On-specification base stock was sent to tankage in June 1997, 1 month ahead of an already aggressive schedule.

The project received several industry accolades. Benchmarking by Independent Project Analysis Inc. ranked the Jurong project in the top quartile for the global refining industry in terms of indices for capital cost, execution schedule, cycle time, and safety.

The safety record of the project was exemplary with no lost-time injuries in almost 5 million man-hours of construction and commissioning. For this safety performance, Mobil earned the Business Roundtable`s Construction Industry Safety Excellence Award.

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The plant comprises two major components, both developed by Mobil Technology Co.: the lube hydrocracking complex (LHDC) followed by Mobil selective dewaxing (MSDW) complex (Fig. 1).

The main function of the LHDC is to convert undesirable aromatic molecules into higher viscosity index (VI) compounds with improved oxidation characteristics. This is accomplished over a hydrocracking catalyst in the presence of high pressure hydrogen.

Useful byproducts of hydrocracking are naphtha, kerosine, and distillate. Kerosine and distillate have excellent fuel properties.

The waxy hydrocracked bottoms are then processed in the MSDW isomerization-dewaxing unit to convert linear, high pour point molecules to low pour point, high VI branched species. This dramatically lowers the pour point of the base oil to enhance performance characteristics.

The MSDW catalyst (denoted MSDW-1) is a Mobil proprietary zeolite formulation, and the Jurong unit was the first commercial application of this technology.

Commercial performance

The start-up and operation of the new lube plant have been excellent. After establishing LHDC operation at target settings during the June 1997 start-up, on-specification base oil was produced from the MSDW complex within 24 hr of streaming. No off-spec base oil tanks were generated over the course of the start-up.

The smooth start-up was the culmination of meticulous planning, execution, and teamwork by the Jurong refinery, the project task force, and Mobil Technology Co.

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LHDC catalyst aging has been very stable since start-up (Fig. 2), even on a widely varying diet of crudes. The current cycle is projected to last 3-4 years.

Controlling the LHDC for making on-spec waxy hydrocrackate has been simple. Only minor reactor-temperature adjustments have been needed to maintain constant quality for a widely varying crude slate.

The unit is principally controlled for VI of the waxy hydrocrackate. The robust activity of the MSDW-1 isomerization dewaxing catalyst in the subsequent unit allows for flexibility of nitrogen and sulfur contaminant levels of the hydro crackate.

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Like the LHDC catalyst, the MSDW-1 catalyst aging has also been stable since start-up (Fig. 3). The current cycle is projected to last 3-4 years.

MSDW-1 catalyst aging has shown good performance despite variation of the waxy hydrocrackate feed. The feed has varied in contaminant level and wax load as a result of crude-slate changes.

Controlling the MSDW for making on-specification base oil has been smooth, with only minor reactor-temperature adjustments needed to meet the pour point.

Expansion to light neutral

After the Jurong plant came on stream in 1997, shifts in the Asian base stock market demanded light neutral in addition to heavy neutral stocks.

In response to the light neutral demand, a very successful fast track program was undertaken between the Jurong Refinery and Mobil Technology Co. to develop schemes for the manufacture of Group II light neutral at the plant. A light neutral (J150) was added to the production slate as of January 1998, following successful refinery-demonstration runs and product-quality evaluations.

Mobil has also demonstrated Group III light neutral production at Jurong during a successful test run in 1998. Product testing is currently under way, and other Group III viscosity grades are under consideration.

In keeping with objectives to further extend the flexibility of the lube base oil plant, Jurong will soon be producing medicinal and technical grade white oils.

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Typical properties of the Group II light and heavy neutral and Group III light neutral test-run base oil produced at Jurong are shown in Table 1.

Base oils have been produced at a consistently high quality, characterized by low levels of aromatics, nitrogen, and sulfur. Jurong stocks exceed the performance of solvent-refined base oils in volatility, air release, and demulsibility. Extensive testing has demonstrated that Jurong stocks can be substituted for solvent-processed base oils in a wide variety of product lines.

Finished lube products formulated with Jurong base oils have shown excellent performance in engine, industrial, and marine oils. These finished products have exhibited better oxidation stability and low temperature viscometrics than products formulated with solvent-refined stocks.

The high quality of Jurong stocks has made the refinery a key source of supply within Asia and the subcontinent, both for the Mobil lube system and for third party base oil sales.

Next generation catalyst

Mobil has commercialized 10 proprietary zeolites and produced over 50 types of finished catalysts to date in manufacturing plants in the U.S. and Japan. Its proprietary catalysts have been used for petrochemical processing to produce ethylbenzene, cumene, and paraxylene.

In refining, Mobil has introduced four distinct lube and fuels processes-MSDW, MLDW, MDDW and MIDW2-8-which has been used in a total of 45 commercial units worldwide in the past 20 years.

As reported by Helton, et al.,9 Mobil recently developed a next-generation catalyst denoted MSDW-2 that significantly improves lube yields and VIs compared to MSDW-1 for a wide viscosity range of hydroprocessed stocks. The superior performance of MSDW-2 results from higher paraffin-isomerization selectivity combined with lower nonselective cracking activity.

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Mobil fast-tracked the development and commercialization of this new catalyst. With this catalyst, Mobil expects higher yield gains and VIs for Jurong feeds (Fig. 4). Based on the successful scale-up of catalyst commercialization and the substantial performance advantages on typical Jurong feeds, the refinery has made plans to replace its current MSDW-1 fill with MSDW-2 in 2000.

Although, as presented in Fig. 2, MSDW-1 aging performance at Jurong has been outstanding with several more years of useful life projected, the compelling yield and VI advantages of MSDW-2 have led the refinery to elect an early catalyst change-out.

The higher yield of MSDW-2 offers the potential for additional light and heavy basestock production at a constant dewaxer-feed rate. Alternatively, the higher dewaxing yield can be used to reduce feedstock requirement at fixed basestock production. The higher VI from MSDW-2 can be used as a step toward higher VI quality if that is an objective, or hydrocracker severity can be reduced to maintain current VI, thus lowering crude requirement.

MSDW-2 activity improvements

Another objective of Mobil`s program for continuous improvement of MSDW catalyst has been to increase activity while maintaining high isomerization selectivity. This will improve dewaxing performance on the highest viscosity feedstocks, such as hydroprocessed deasphalted oils.

Very high viscosity grades can be difficult for isomerization dewaxing catalysts to process when they have high levels of nitrogen and sulfur heteroatom poisons. Results from earlier generations of MSDW catalyst suggested processing be limited to feedstocks with viscosity less than 15 cSt at 100° C. for this reason.2

Others have proposed two different dewaxing catalysts be used to process a full viscosity range feed slate: an isomerization dewaxing catalyst for light viscosity grades and a more nitrogen and sulfur tolerant catalyst such as ZSM-5 for heavy grades.10

Recent efforts by Mobil to improve the activity of MSDW-2 catalyst, however, have made it possible to produce a full viscosity-range lube slate, including bright stocks, with a single dewaxing catalyst.

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In a 6-month MSDW-2 pilot plant run, Mobil demonstrated excellent long-term dewaxing activity for making bright stocks from four hydrocracked deasphalted oils (HDC DAO). The four test feedstocks (inspections given in Table 2) were derived from two commercially prepared deasphalted oils (DAO A and B) that were each hydro cracked in the laboratory at two severity levels.

MSDW-2 reactor temperature stabilized well within normal operating temperature range with no apparent aging, even with the most highly contaminated feed (Feed Number 4) after 6 months of on stream time.

Contaminant levels of the HDC DAOs used in this study were very aggressive for isomerization dewaxing catalysts. The enhanced robustness of MSDW-2 at these high contamination levels reduces the requirements on the "clean up" function of the hydrocracking step, allowing lower severity hydro cracking with accompanying higher yields of waxy bottoms and the preservation of viscosity.

As noted in Table 2, a bright stock bottoms fraction was recovered via distillation of the MSDW pilot plant effluent, and viscosities of 20-40 cSt at 100° C. were obtained on these fractions. Product quality testing on the bright stocks is in progress.

References

  1. Baker, C.L., Hall, G.R., and Tan, C.T., "Refining and Product Quality Benefits for New Hydroprocessed Lube Base Stocks in Singapore," presented at 3rd Annual Lubes & Fuels Asia Conference, Singapore, Jan. 19-22, 1997.
  2. Dougherty, R.C., McGuiness, M.P., Rogers, T.W. and Smith, F.A., "Advances in Catalytic Lube Dewaxing," presented at IIP International Symposium on Products and Application of Basestocks, New Delhi, India, Nov. 23-25, 1994.
  3. Smith, K.W., Starr, W.C., and Chen, N.Y., "New process dewaxes lube basestocks," OGJ, May 26, 1980.
  4. Ramage, M.P., Graziani, K.R. and Katzer, J.R., "Science and Application of Catalytic Lube Oil Dewaxing," presented at Japan Petroleum Institute, Tokyo, Japan, Oct. 27, 1986.
  5. Wise, J.J., Katzer, J.R., and Chen, N.Y., "Catalytic Dewaxing in Petroleum Processing," presented at ACS National Meeting, Apr. 13, 1986.
  6. Ireland, H.R., Redini, C., Raff, A.S. and Fava, L., "Distillate Dewaxing in Operation," Hydrocarbon Processing, May 1979.
  7. Pappal, D.A., Tracy, W.J., and Weinstabl, D., "MAKFining Mobil Isomerization Dewaxing (MIDW), Pathway to Enhanced Diesel Fuel," European Refining Technology Conference, Berlin, Germany, November 1998.
  8. Angevine, P.J., Buyan, F.M., Pappal, D.A., and Partridge, R.D., "Mobil Isomerization Dewaxing (MIDW), a New Flexible Dewaxing Process," European Refining Technology Conference, London, England, October 1996.
  9. Helton, T.E., Degnan, T.F., Mazzone, D.N., McGuiness, M.P., Hilbert, T.L., and Dougherty, R.C., "Catalytic hydroprocessing: a good alternative to solvent processing," OGJ, July 20, 1998.
  10. Miller, S.J., U.S. Patent 5,833,837.

The Authors

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Robert G. Wuest is a skill leader in conventional and catalytic lube processing for Mobil Technology Co. He has spent much of his 24 years in the petroleum industry working for Mobil in the lube processing area as well as petrochemicals.
Wuest holds a BS in chemical engineering from Cornell University, an MS in chemical engineering from the University of Pennsylvania, and an MBA from Drexel University.
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Robert J. Anthes is a senior associate in the catalytic lubes area for Mobil Technology Co. He has worked in a variety of areas during his 17 years with Mobil including lube processing, petrochemicals, refinery optimization and phosphate minerals.
Anthes holds a BS in chemical engineering from New Jersey Institute of Technology.
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Robert T. Hanlon is a senior associate in catalytic lubes for Mobil Technology Co. He has spent much of his 12 years with Mobil advancing projects in lube processing research and development.
Hanlon holds a BS in chemical engineering from Bucknell University and an MS and ScD in chemical engineering from Massachusetts Institute of Technology.
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S.M. Jacob is a licensing executive with Mobil Technology Co. He has more than 32 years of experience in the petroleum industry and has held various management positions within Mobil.
Jacob holds a PhD in chemical engineering from Northwestern University.
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Leslie Loke is a process-engineering superintendent in Mobil`s Singapore Refinery. He has 19 years` experience in petroleum refining.
Loke received a BS in chemical engineering from Leeds University and an MS in chemical engineering from Manchester University.
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Chin Tung Tan is the technical and planning manager of Mobil`s Singapore refinery. He has 28 years` experience in petroleum refining.
Tan holds a BS in chemical engineering from University College, London, an MS in chemical engineering from Imperial College, London, and an MBA from Temple University.