Key takeaways
- Light naphtha (roughly C5 to C6) is mainly used as steam cracker feed to make ethylene and propylene.
- Heavy naphtha (roughly C7 to C10) is mainly fed to catalytic reformers to produce high-octane gasoline components and aromatics.
- PIONA composition, distillation range, density and sulfur are the core specification parameters.
Naphtha is a light liquid hydrocarbon fraction obtained from crude oil distillation and from natural gas condensate. It sits between LPG and kerosene in the boiling range. Although it is often traded simply as "naphtha", its value depends heavily on composition, because different processing units want very different molecules.
Light, heavy and full-range naphtha
| Light naphtha | Heavy naphtha | |
|---|---|---|
| Carbon range | about C5 to C6 | about C7 to C10 |
| Boiling range | about 30 to 90 °C | about 90 to 200 °C |
| Density at 15 °C | about 0.64 to 0.70 kg/l | about 0.72 to 0.78 kg/l |
| Main use | Steam cracker feed | Catalytic reformer feed |
| Valued for | High paraffin content | High naphthenes + aromatics (N+A) |
Full-range naphtha covers both cuts and is common in trade. In Asia, petrochemical-grade naphtha is often traded as open-spec naphtha (OSN), with a minimum paraffin content.
Why composition matters: PIONA
Naphtha is analysed by PIONA, which measures five hydrocarbon groups:
- Paraffins (normal alkanes)
- Iso-paraffins (branched alkanes)
- Olefins
- Naphthenes (cycloalkanes)
- Aromatics
For steam crackers
Steam crackers produce the most ethylene from paraffinic feed. A higher paraffin content, especially normal paraffins, means better olefin yields and less heavy by-product. Olefins and aromatics in the feed reduce yields and increase coking.
For catalytic reformers
Reformers convert naphthenes into aromatics and boost octane. Feed with a high N+A content gives higher reformate yield and octane, which is why heavy naphtha with more naphthenes is more valuable to refiners.
Key specification parameters
- Density at 15 °C
- Distillation (initial and final boiling points, ASTM D86)
- PIONA, total paraffins and N+A content
- Total sulfur, which matters for catalysts and product quality
- Reid vapour pressure (RVP) for storage and handling
- Olefins, oxygenates and metals such as lead, arsenic and mercury, which can poison catalysts
- Colour (Saybolt) and appearance
Contaminants like mercury and arsenic may appear in naphtha from some condensate sources. Steam cracker operators often set very low limits because these elements damage downstream equipment and catalysts.
Other uses of naphtha
- Gasoline blending component
- Feedstock for hydrogen and ammonia production in some regions
- Solvents and special boiling point spirits
- Diluent for heavy crude oil transport
Shipping and safety
Naphtha is shipped in product tankers (MR, LR1 and LR2 sizes) and stored in floating-roof tanks. It is a highly flammable liquid with a low flash point and high volatility, so vapour control, grounding and fire protection are essential. Benzene content in some naphthas adds health precautions for personnel.
Buying naphtha
Before buying, match the naphtha type to the unit it will feed: light, paraffinic naphtha for crackers or heavier, naphthenic naphtha for reformers. Agree PIONA limits and contaminant limits in the contract, and use independent load-port inspection.
Aban Chemical supplies light and heavy naphtha for petrochemical and refining customers. See our naphtha product page, read about delivery terms, or request a quote.
