Technology Origin and Development
Chevron's lube hydroprocessing experience extends back to 1984, when the company was the first to combine catalytic dewaxing with hydrocracking and hydrofinishing in their Richmond Lube Oil Plant (RLOP) in California, employing catalysts to crack n-paraffins in the conventional catalytic dewaxing process. During subsequent years, Chevron developed a selective wax isomerization catalyst, which culminated in its commercialization at RLOP in 1993, marking the beginning of the ISODEWAXING catalytic dewaxing technology. When Chevron Lummus Global was formed, the technology became part of CLG's premium base oil technology portfolio.
Technology Summary and Chemistry
Fundamental Innovation: ISODEWAXING® technology transformed catalytic dewaxing by changing the fundamental approach to wax molecules. Rather than removing wax (as solvent dewaxing does) or cracking wax molecules to light hydrocarbons (as conventional catalytic dewaxing does), ISODEWAXING catalytically isomerizes the molecular structure of the wax into isoparaffins (Fig. 1).
Figure 1 - Chemistry of catalytic dewaxing inside molecular sieving zeolites
Selective cracking takes place inside the pores of the catalyst.
n-Alkanes can enter the pores, but bulky iso-alkanes cannot.
Zeolite structure shown on the right hand side.
Catalysts: ISODEWAXING catalysts are zeolite and alumina-based systems with SiO₂/Al₂O₃ ratios ranging from 3.4 to 60. The active metals—Pt (0.5 to 1.5%), Ni, Co, Fe, and Zn, or combinations thereof—are introduced via inorganic precursors (chloride, nitrate) or organometallic precursors (carbonyl, acetylacetonate).
Chemical Transformation: The ISODEWAXING reactor isomerizes normal paraffins (waxes) to high viscosity index isoparaffins and lowers the pour point. Other paraffins are cracked to highly saturated light products, such as high smoke point jet fuel and high cetane index diesel. These isoparaffins exhibit high VI, low pour points, and excellent resistance to oxidation.
Key Advantage: Because ISODEWAXING preserves the base oil's paraffinicity rather than removing or cracking it, the technology can produce higher product VI and/or higher yields than other dewaxing processes (conventional catalytic dewaxing, solvent dewaxing).
Process Description
Feed Preparation and Heating:
Waxy neutral oil feed from a hydrocracker/hydrotreater process step, together with treat gas, is preheated (via furnace) and fed to the ISODEWAXING reactor. The ISODEWAXING / ISOFINISHING unit operates with a dedicated high-pressure recycle gas loop. When ISODEWAXING is integrated with an upstream hydrocracker/hydrotreater in a combined unit, the ISODEWAXING section maintains its own separate recycle gas system independent from the hydrocracker's recycle gas loop.
ISODEWAXING Reactor:
The preheated feed enters the fixed-bed ISODEWAXING reactor where catalytic isomerization occurs. The reactor operates under hydrogen pressure with:
- Reaction type: Catalytic isomerization of n-paraffins to isoparaffins + mild hydrocracking
- Hydrogen: High-pressure recycle gas loop with make-up hydrogen
- Product characteristics: High VI isoparaffins with reduced pour point
Reactor Conditions:
- Hydrogen Pressure (P) Operating Range:
ISODEWAXING units can be designed to operate across a flexible hydrogen pressure range depending on feedstock characteristics, integration requirements, and target product specifications. Operating pressure categories include low pressure (<1000 psi / <70 kg/cm²), moderate pressure (1000-2000 psi / 70-141 kg/cm²), and high pressure (>2000 psi / >141 kg/cm²).
- Temperature (T): 250 to 350°C (482 to 662°F)
- Weight Hourly Space Velocity (WHSV): up to 3 hr⁻¹
- Once-through processing: No recycling of unconverted wax required
Product Separation:
The effluent from the ISODEWAXING reactor is sent to the separation system, which includes hot/cold separation (H/D), fractionation (F), product recovery (R), and additional separation equipment (X). This separates:
- Light products (jet fuel, diesel)
- Dewaxed base oil product
- Recycle hydrogen
Integration with ISOFINISHING:
When integrated, the effluent from the ISODEWAXING reactor is then sent to the ISOFINISHING reactor where the product undergoes deep hydrofinishing via aromatics saturation to provide a highly stable finished neutral oil product after atmospheric and vacuum distillation. ISOFINISHING technology uses noble-metal catalysts to produce higher-quality base oils at lower temperatures.
Performance and Yields
Feedstock Flexibility:
ISODEWAXING technology is capable of processing a wide range of petroleum and renewable streams to produce Group II, II+, III, and III+ base oils, process oils, and white oils. Commercial and pilot plant experience has been demonstrated with vacuum gas oils (VGO) of complete boiling range, blends of VGO/hydrocracker gas oil (HCGO), deasphalted oil (DAO) from solvent deasphalting units operating at low, medium, and high DAO yields, blends of VGO/DAO/HCGO, raffinate streams from solvent extraction of complete boiling range, blends of VGO/DAO/extracts, Fischer-Tropsch wax, slack wax, hard wax (fully refined paraffin wax), renewable feedstocks, and recycled lubricant oils.
Yield Comparison (per 10,000 BPD hydrocracker feed):
| Technology |
Hydrocracker Waxy Base Oil Yield |
Dewaxer Feed Rate (BPD) |
Dewaxer Yield % |
Base Oil Yields (BPD) |
| Catalytic dewaxing |
52% |
5,200 |
81% |
4,200 |
| Solvent dewaxing |
63% |
6,300 |
84% |
5,300 |
| ISODEWAXING |
75% |
7,500 |
94% |
7,050 |
Key Performance Metrics:
- Space Velocity: higher than conventional hydrofinishing, allowing smaller reactor and lower investment
- Dewaxer yield: 94% (vs. 84% for solvent dewaxing, 81% for catalytic dewaxing)
- Overall base oil yield: 67% higher than catalytic dewaxing, 33% higher than solvent dewaxing
- Hydrocracker severity: Using ISODEWAXING catalyst allows refiners to lower processing severity in the hydrocracker and substantially increase yields
Product Quality Range:
- Viscosity Index: 95 to 140 and higher
- Pour point: Low (-9 to -15°C) to ultra-low (<-40°C)
- Slack wax processing: Once-through process where 140 VI base oils can be made from slack wax without recycling unconverted wax
- Product quality: Almost water-white oils with ultra-low aromatics, high color stability, high oxidation and thermal stability
Commercial Deployment and Market Experience
- First Commercial Unit: Richmond Lube Oil Plant (RLOP), California, USA - 1993
- As of 2002: Ten ISODEWAXING units in commercial operation with total capacity exceeding 100,000 BPD (100 MBPD). Eight additional ISODEWAXING units with additional capacity in excess of 60,000 BPD were in various stages of engineering and construction
- As of 2011: Over two-thirds of the world's Group II and Group III base oils are produced using ISODEWAXING technology due to the high purity of the base oil
References
- Abbas A.S., University of Bagdad (2009 estimated). Isodewaxing & Isofining Technologies. SCRIBD
- Chevron Lummus Global. ISODEWAXING
- Outhwaite A. & Rosenbaum, J. (2011). Base oils – An evolving landscape. Lubrisense White Paper, 11-11. Axel Christiernsson AB
- Eser S. FSC 432: Petroleum Refining — Catalytic Dewaxing. Penn State University.
- Mostyn T., Hydrocarbon Engineering (August 22, 2019). Chevron Lummus Global awarded hydroprocessing technology contract
- Bhattacharya, S., Chevron Lummus Global (May 5, 2023). The Evolution of Base Oil Hydroprocessing. Paper presented at the 27th ICIS World Base Oils and Lubricants Conference
- CB&I (2012). ISODEWAXING & ISOFINISHING brochure. Retrieved via Yumpu
