Technology

Name

Axens Alkyfining

Owner

/ Axens SA

Brand

Alkyfining®

Process

Hydrogenation

Type

Selective Hydrogenation

Available

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

Step	Function	Highlights
Feed Conditioning	Pre-heat, filtration	Removes particulates; raises to reaction temperature
Selective Hydrogenation Reactor	Fixed-bed, liquid-phase	Multi-stage beds with interstage cooling; H₂ reacts with diolefins and acetylenes over SeLene™ catalyst
Gas/Liquid Separation & Recycle	Flash separation	Unreacted H₂ recovered and recycled; hydrocarbons proceed to polishing
Final Polishing (Optional)	Guard bed or stripper	Ensures <10 ppm residual diolefins/acetylene

4. Operating Conditions & Performance

Parameter	Range	Target
Temperature	40–80 °C	50–60 °C
Pressure	1–4 bar	~2 bar
H₂/Feed ratio	1–5 mol/mol	2–3 mol/mol
LHSV	1–10 h⁻¹	2–5 h⁻¹
Butadiene conversion	—	>99.5%
Acetylene removal	—	>99.9% (<1 ppm)
Butene loss	—	<2%

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%).