Technology

The Neste NEXPAO™ technology is a process for producing high-quality polyalphaolefin (PAO) synthetic base oils from 1-decene feedstock. The original PAO process of Neste in commercial operation at Neste's Beringen facility (1991-2011) used catalytic distillation with solid acid catalysts. The advanced NEXPAO technology (2021-present) described in this article features Neste's innovative cone reactor design with BF₃/alcohol homogeneous catalysts combined with advanced catalyst recovery systems, and is currently being implemented at CSPC China's 50,000 tpy facility.

Process Description

Feed Preparation and Storage

• Primary feed: 1-Decene (C₁₀H₂₀), minimum 98% purity
• Impurity limits: <100 ppm total impurities including peroxides, oxygen, sulfur, nitrogen compounds, acetylenic compounds
• Storage: Ambient temperature with nitrogen blanket to prevent oxidation and polymerization
• Feed treatment: Molecular sieve drying and trace contaminant removal before reactor feed

Oligomerization Section

Cone Reactor Design:

The centerpiece of NEXPAO technology is Neste's patented cone reactor featuring:

• Unique geometry: Cross-sectional area decreases from top (large diameter) to bottom (small diameter)
• Self-mixing: Cone shape eliminates need for external mixing equipment through natural circulation
• Materials: Stainless steel construction for BF₃ compatibility
• Volume: Sized for 5-40 minute residence time at design capacity
• Cooling system: External heat exchangers with thermal oil circulation
• Capacity flexibility: Operates efficiently at 60-100% capacity with constant residence time
• Temperature control: Extensive external cooling loop maintains isothermal conditions
• Recycle pump: High-capacity circulation pump (180-300 m³/h)

Operating Conditions:

• Temperature: 30°C (optimized for maximum conversion rate and selectivity)
• Pressure: Moderate pressure (40-60 psig estimated)
• Residence time: 5-40 minutes total, with 90-95% recycle providing optimal contact time
• Conversion: >95% 1-decene conversion per pass through reactor system

Catalyst System:

• Primary catalyst: Boron trifluoride (BF₃) gas
• Co-catalyst: n-Butanol (preferred) forming liquid BF₃/alcohol complex
• Catalyst loading: 1 mol-% BF₃/n-butanol complex relative to fresh feed
• Mechanism: Cationic oligomerization producing statistical distribution of dimers, trimers, tetramers, pentamers

Product Distribution:

• Dimers (C₂₀): 15-25%
• Trimers (C₃₀): 40-50% (markedly peaked for PAO 4 optimization)
• Tetramers (C₄₀): 25-35%
• Pentamers+ (C₅₀+): 5-15%

Catalyst Recovery Section

Flash Separation:

• Flash separator: Low-pressure vessel designed for BF₃ vapor handling
• Flash conditions: 0.1-2 psia to vaporize BF₃ from product stream
• BF₃ recovery: Up to 80% recovery efficiency at optimal conditions
• Temperature: Ambient to 50°C to maintain BF₃ vapor pressure

Catalyst Recycling:

• Vapor treatment: Counter-current absorption column using fresh n-butanol
• Catalyst reformation: Reformed BF₃/alcohol complex recycled to reactor
• Economic benefit: 39-47% improvement in catalyst efficiency vs once-through operation
• Purge stream: Small purge to prevent accumulation of catalyst deactivators

Unreacted Monomer Recovery:

• Separation: Flash overhead contains unreacted 1-decene
• Recycle: High-purity 1-decene recycled to reactor feed
• Efficiency: >99% monomer recovery minimizing feedstock losses

Product Separation and Hydrogenation

Primary Fractionation:

• Feed: Crude oligomer product from catalyst recovery
• Separation: Distillation into two fractions based on viscosity
  • Light fraction: ≤5 cSt (primarily PAO 2 + PAO 4)
  • Heavy fraction: >5 cSt (primarily PAO 6 + PAO 8)

Hydrogenation Units

• Reactor design: Fixed-bed reactors with downflow operation
• Catalyst loading: 50-100 m³ catalyst per reactor
• Pressure rating: Designed for 10 MPa operating pressure
• Temperature control: Multi-zone heating with inter-bed cooling

Neste's advanced approach uses separate hydrogenation for each fraction:

• Light Fraction Hydrogenation:
  • Temperature: 130-200°C
  • Pressure: 3-5 MPa H₂
  • Catalyst: Nickel on alumina support (extruded pellets)
  • LHSV: 2-8 h⁻¹
  • Objective: Saturate double bonds while minimizing thermal stress
     
• Heavy Fraction Hydrogenation:
  • Temperature: 150-250°C
  • Pressure: 4-6 MPa H₂
  • Catalyst: Noble metal (Pd/Pt) on support for lower temperature operation
  • LHSV: 0.5-3 h⁻¹
  • Benefits: Reduced thermal degradation of higher molecular weight oligomers

Final Product Fractionation

Product Separation:

• Distillation columns: Multi-stage atmospheric and vacuum distillation columns with structured packing
• Product cuts: Precise molecular weight separation
• Blending: Fine-tuning of viscosity grades through controlled blending

Final Product Specifications:

Utilities Systems

• Thermal oil system: 8,000 kW total heating capacity (modernized to electric heating)
• Cooling water: Closed-loop system with cooling towers
• Nitrogen system: For tank blanketing and process purging
• Hydrogen supply: On-battery storage with vaporization system
• Emissions control: Thermal oxidizer (3,000 kW) for process emissions

Process Block Flow Summary

Stream Flows:

• Feed: 1-Decene → Purification → Cone Reactor
• Catalyst: BF₃ + n-Butanol → Complex Formation → Reactor → Recovery → Recycle (80% recovery)
• Recycle: 90-95% reactor outlet → External cooling → Back to reactor
• Product: Crude PAO → Primary separation → Dual hydrogenation → Final fractionation → PAO grades

Key Equipment:

1. Cone Reactor: Unique geometry, no external mixing, 30°C operation
2. Flash Separator: BF₃ recovery at 0.1-2 psia
3. Dual Hydrogenation: Separate light (≤5 cSt) and heavy (>5 cSt) fraction processing
4. Multi-stage Distillation: Precise molecular weight separation

Operating Conditions:

• Oligomerization: 30°C, 5-40 min residence time, 90-95% recycle
• Hydrogenation: 130-250°C, 3-6 MPa H₂ pressure
• Product Quality: VI 127-142, Pour points -65°C to -54°C

Access this diagram here

Process Performance

Conversion and Yields

• 1-Decene conversion: >95% per pass, >99.5% overall with recycle
• Selectivity to desired oligomers: >85% (dimers through pentamers)
• Catalyst consumption: 0.5-1.0 kg BF₃ per tonne PAO product (with recovery)
• Energy consumption: 0.8-1.2 GJ per tonne PAO product

Product Quality Advantages

• Ultra-high viscosity index: Superior temperature-viscosity characteristics
• Exceptional low-temperature performance: Pour points as low as -65°C
• Low volatility: Excellent NOACK evaporation loss values
• Thermal stability: Enhanced through complete hydrogenation (bromine number <1)
• Oxidative stability: Excellent additive response and long service life

Operational Reliability

• Plant availability: >95% based on 20-year Beringen operational history
• Campaign length: >12 months between major turnarounds
• Catalyst life: 2-4 years for hydrogenation catalysts
• Environmental compliance: Zero serious incidents in commercial operation

Commercial Validation

• Original Neste's PAO technology: 20-year commercial operation (60,000 tpy Beringen plant)
• Technology transfer success: Seamless transition to Chevron Phillips Chemical
• Newest NEXPAO technology: Active liensing to CSPC China for 50,000 tpy project demonstrates continued viability

References

1. Wahlström, J., Vikman, K. (2025). Process for producing poly-α-olefins. World Intellectual Property Organization Patent WO 2025/012514 A1. Filed July 4, 2024.
2. Wahlström, J. (2022). Process and apparatus for producing poly-alpha-olefins. Finnish Patent and Registration Office Patent FI 129793 B. Filed June 15, 2021.
3. Neste Oil Oyj (2015). Process for the manufacture of olefin oligomers. European Patent Office Patent EP 2029701 B2. Filed June 14, 2007.
4. Directie Omgeving - Vlaanderen (2022). Omgevingsvergunning - Chevron Phillips Chemical International NV, Industrieweg 152, 3583 Beringen. Available at: https://gpbv.omgeving.vlaanderen.be/api/view/vergunningsbesluiten/bestand?uniekeSleutel=0a29148f-3e36-4f15-acee-4eb252cc6fc1 (accessed September 30, 2025).
5. Neste Corporation (2022). Neste's NEXPAO technology to be implemented at CNOOC and Shell Petrochemical Co. Ltd.'s Huizhou production site in China. Press release, October 18, 2022. Available at: https://neste.com/news/nestes-nexpao-technology-to-be-implemented-at-cnooc-and-shell-petrochemical-co-ltd-s-huizhou-production-site-in-china
6. Neste Oil Corporation (2011). Sale of Neste Oil's PAO plant in Belgium approved. Press release, November 30, 2011. Available at: https://www.neste.com/news/sale-of-neste-oils-pao-plant-in-belgium-approved
7. Chevron Phillips Chemical Company (2011). Chevron Phillips Chemical Completes Acquisition of Neste PAO Plant in Belgium. Press release, November 29, 2011. Available at: https://www.cpchem.com/media-events/news/news-release/chevron-phillips-chemical-completes-acquisition-neste-pao-plant
8. Neste Corporation (1997). Annual Report 1996. Aalto University Library Archives. Available at: https://web.lib.aalto.fi/fi/old/yrityspalvelin/pdf/1996/eneste.pdf
9. Neste Oil Corporation (2011). Annual Report 2010. Available at: https://www.annualreports.com/HostedData/AnnualReportArchive/n/neste_2010.pdf
10. Neste Oil Corporation (2012). Annual Report 2011. Available at: https://www.neste.com/files/pdf/499378.pdf
11. Neste Corporation (2024). NEXPAO™ - Technology for Top Quality Synthetic Base Oil. Technical brochure. Available at: https://www.neste.com/files/pdf/1YTugklXUq04UTukfIQfMd-nexpao.pdf
12. Neste Corporation (2024). Technology for Superior Quality Synthetic Base Oils. Available at: https://www.neste.com/products-and-innovation/process-technology-licensing/process-technologies/synthetic-base-oils
13. Environment and Climate Change Canada (2018). Draft screening assessment - Base oils. Available at: https://www.canada.ca/content/dam/eccc/documents/pdf/pded/base-oils/Draft-screening-assessment-base-oils1.pdf
14. Patents Assigned to Neste Oyj (2025). Justia Patents Database. Available at: https://patents.justia.com/assignee/neste-oyj (accessed October 1, 2025).
15. Greyb Research (2025). Neste Patents Key Insights & Stats. Available at: https://insights.greyb.com/neste-patents/ (accessed March 9, 2025).
16. Ray, S., Rao, P.V.C., Choudary, N.V. (2012). Poly-α-olefin-based synthetic lubricants: a short review on various synthetic routes. Lubrication Science, 24(1), 23-44. DOI: 10.1002/ls.166
17. Base Oil News (2022). CSPC to use Neste's NEXPAO technology at Huizhou petrochemical complex. October 18, 2022. Available at: https://www.baseoilnews.com/news/neste-nexpao-cspc-china-oct2022-pressrelease
18. Fuels & Lubes International (2022). China's CSPC to produce PAO using Neste's NEXPAO technology. October 20, 2022. Available at: https://www.fuelsandlubes.com/chinas-cspc-to-produce-pao-using-nestes-nexpao-technology/
19. Neste Corporation (2024). Annual Report 2024 - Sustainability Data Package. Available at: https://www.neste.com/files/pdf/5yIgJVXOGNA9KZQDKnQg72-Neste_Annual_Report_2024_Sustainability_Data_Package.pdf
20. Neste Corporation (2024). Licensed Process Technologies. Available at: https://www.neste.com/products-and-innovation/process-technology-licensing/process-technologies
21. Chevron Phillips Chemical Company (2022). Chevron Phillips Chemical to expand low viscosity PAO unit in Belgium to address growing worldwide demand. Press release, June 7, 2022. Available at: https://www.cpchem.com/media-events/news/featured-story/chevron-phillips-chemical-expand-low-viscosity-pao-unit-belgium
22. Neste Engineering Solutions (2024). NEX Process Technologies Portfolio. Available at: https://www.neste.com/files/pdf/c20b46bd3648e55f51d330f6e624ab61-nexoctane.pdf
23. Neste Corporation (2024). Cost-Effective Selective Diolefin Hydrogenation - NEXSELECT. Technical brochure. Available at: https://www.neste.com/files/pdf/1toY8CDn8I50TTuBdi2SQE-nexselect.pdf
24. Neste Corporation (2023). Annual Report 2023 - Sustainability. Available at: https://www.neste.com/files/pdf/3SiB5xKRfcL3dDDJvA73aD-Neste_Sustainability_2023.pdf
25. Neste Corporation (2017). Listing Prospectus 2017. Available at: https://www.neste.com/files/pdf/cNg5CjcYrgOa02616ae4Q-neste_-_listing_prospectus_2017.pdf