Technology

Axens’ Alkyfining^® process is the licensed, turnkey solution for treating C₄ cuts—especially butadiene-rich (BD-rich) streams—from steam crackers, FCC units or dehydrogenation units. It converts 1,3-butadiene into mono-olefins (butenes) and removes acetylenes (vinyl/ethyl acetylene) in a single, multi-stage fixed-bed hydrogenation unit, achieving >99.5% butadiene conversion, <1 ppm residual acetylenes and <2% butene loss under mild conditions (1–4 bar, 40–80 °C).

1. Technology Scope & Integration

Alkyfining^® encompasses:

• Full Process License & Design: PFDs, P&IDs, equipment specifications, control logic
• Proprietary Reactors & Separation: Multi-stage fixed-bed reactors with interstage cooling; gas/liquid separators for H₂ recycle
• SeLene™ Catalyst Selection: Customized grades (LD 265, LD 269, LD 271, LD 277) matched to feed composition and target olefin profile
• Technical Services: Start-up, operator training, troubleshooting
• Integration: Upstream of alkylation, MTBE/ETBE or polymerization units

2. Reaction Chemistry & Catalysts

Key reactions:

• Butadiene Monohydrogenation: 
  
  CH₂=CH–CH=CH₂ + H₂ → 2 CH₂=CH–CH₂–CH₃ 
   
• Alkynes Removal:
  
  RC≡CH + H₂ → RCH=CH₂ 

SeLene™ catalyst grades for Alkyfining^®:

• LD 265: General butadiene saturation
• LD 269: Butadiene → butenes + 1-butene isomerization to 2-butenes
• LD 271: Maximizes 1-butene yield, suppresses isomerization
• LD 277: Specialist for vinyl acetylene removal

3. Process Flow and Operation

4. Operating Conditions & Performance

5. Commercial Experience

• Market Leader: ~75% share in alkylation feed pretreatment; >90 units licensed since the 1970s.
• Key Deployments:
  • S-Oil RUCP (South Korea): Integrated C₄ complex including Alkyfining^®
  • Borouge 4 (UAE): C₄ BD-rich hydrogenation upstream of Pygas hydrogenation
  • Global Refineries: Dozens of alkylation blocks worldwide
• Feed Types: C₄ cuts from FCC, steam crackers, dehydrogenation units, variable butadiene content (5–80%).

References

1. Feb 2022 - Commercial Bulletin – Alkyfining^® - Axens
2. Olefins Selective Hydrogenation - Axens
3. Jean-Paul Boitiaux, Patrick Sarrazin, Selective hydrogenation of diolefins in steam cracking petrol on catalysts based on a support metal in which an organic compound has been incorporated prior to loading into the reactor, United States Patent US5417844A, Patent filed Nov 128, 1992, IFP Energies Nouvelles IFPEN
4. T. Redjala et al.. Bimetallic Au-Pd and Ag-Pd Clusters Synthesised by γ or Electron Beam Radiolysis and Study of the Reactivity/Structure Relationships in the Selective Hydrogenation of Buta-1,3-Diene. Oil & Gas Science and Technology - Revue d'IFP Energies nouvelles, 2006, 61 (6), pp.789-797. DOI: 10.2516/ogst:2006019.
5. Jack, June 19, 2018 - Upgrading Steam Cracker C4 Cuts Process by Axens - Oil & Gas PRocess Engineering
6. Edgar Jordan, Charlotte Fritsch and Joachim Haertlé, hte GmbH, Q2 2024 - Flexible downscaling of MAPD removal from C₃/C₄ olefin streams - Digital Refining
7. Jul 16, 2015 - PR - Axens to supply technologies for S-OIL’s residue upgrading capacity expansion project - Axens
8. Jan 13, 2020 - PR - Axens is awarded a licensing contract for Borouge 4 project in UAE - Axens