# Naphtha
**Naphtha** (petroleum naphtha) is a generic term for refined, partly refined, or unrefined liquid petroleum fractions that distill below 240 °C (465 °F), making it the volatile fraction of crude oil; it is used as a solvent and, above all, as a precursor to gasoline and to petrochemicals such as ethylene and aromatics[1](https://www.sciencedirect.com/topics/engineering/naphtha). Under standard distillation conditions, not less than 10% by volume of the material should distill below 75 °C (167 °F) and not less than 95% by volume below 240 °C (465 °F), although individual grades have narrower boiling ranges within this window[1](https://www.sciencedirect.com/topics/engineering/naphtha). In energy statistics the [International Energy Agency](https://www.edgepedia.org/international-energy-agency) defines naphtha as hydrocarbons in the 30 °C to 210 °C distillation range, or part of that range, most commonly destined as feedstock for the petrochemical industry[2](https://www.iea.org/articles/oil-market-report-glossary).
| Key fact | Detail |
|---|---|
| Definition | Generic term for refined, partly refined, or unrefined petroleum fractions distilling below 240 °C (465 °F)[1](https://www.sciencedirect.com/topics/engineering/naphtha) |
| Share of crude | 15–30% of crude oil by weight; hydrocarbons with 5–12 carbon atoms, plus sulfur and small quantities of nitrogen[1](https://www.sciencedirect.com/topics/engineering/naphtha) |
| Boiling cuts | Light naphtha 30–90 °C (C5–C6); heavy naphtha 90–200 °C; medium naphtha below 150 °C (mainly C7–C9)[1](https://www.sciencedirect.com/topics/engineering/naphtha) |
| Straight-run composition | Medium straight-run naphtha: 40–70 wt% paraffins, 20–50 wt% naphthenes, 5–20 wt% aromatics, 0–2 wt% olefins[1](https://www.sciencedirect.com/topics/engineering/naphtha) |
| Main uses | Steam cracking to olefins (ethylene, propylene); catalytic reforming to high-octane reformate and BTX aromatics; solvent uses[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf) • [4](https://www.eia.gov/energyexplained/oil-and-petroleum-products/refining-crude-oil-the-refining-process.php) |
| BTX source | Catalytic reforming of naphtha gives rise to about 65% of the benzene, toluene, and xylenes used in the chemical industry[5](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf) |
| Hazards | Flammable liquid (flash point −40 to −86 °F for rubber solvent grade); OSHA PEL 500 ppm (2,000 mg/m³) 8-hour TWA[6](https://www.cdc.gov/niosh/npg/npgd0492.html) |
## Origin in the refinery
Naphtha is a light fraction of the crude oil distillation process[4](https://www.eia.gov/energyexplained/oil-and-petroleum-products/refining-crude-oil-the-refining-process.php). In an atmospheric distillation column, crude oil is separated into fractions by boiling point, with light fractions condensing near the top[4](https://www.eia.gov/energyexplained/oil-and-petroleum-products/refining-crude-oil-the-refining-process.php). Straight-run naphtha is the crude naphtha derived directly from this column[1](https://www.sciencedirect.com/topics/engineering/naphtha). The fraction boiling between 30 °C and 90 °C, containing the C5 and C6 hydrocarbons, is light naphtha; heavy naphtha boils between 90 °C and 200 °C, and the part of the heavy cut boiling below 150 °C, containing mainly C7–C9 hydrocarbons, is called medium naphtha[1](https://www.sciencedirect.com/topics/engineering/naphtha).
Naphtha is also produced as a secondary product when heavier fractions are converted. Gas oil from atmospheric or vacuum distillation yields naphtha in catalytic cracking and hydrocracking units, and residuum yields naphtha in coking and hydrocracking[1](https://www.sciencedirect.com/topics/engineering/naphtha). In coking, residual material from the distillation tower is heated until it breaks down into oil, gasoline, and naphtha, leaving behind an almost pure carbon residue called coke[7](https://www.epa.gov/sites/production/files/documents/AppendixA_Overview_of_Petroleum_Ref.pdf).
**Composition varies widely.** It depends on the crude oil source, the boiling range, and whether the naphtha comes directly from distillation or from catalytic or thermal cracking of heavier fractions[1](https://www.sciencedirect.com/topics/engineering/naphtha). The molecules are mostly paraffins (alkanes, CnH2n+2), naphthenes (cycloalkanes, CnH2n), and aromatics (CnH2n−6, which carry high octane numbers)[1](https://www.sciencedirect.com/topics/engineering/naphtha). Straight-run medium naphtha typically contains 40–70 wt% paraffins, 20–50 wt% naphthenes, 5–20 wt% aromatics, and only 0–2 wt% olefins, whereas naphtha from fluid catalytic cracking, coking, or visbreaking may include 30–50 wt% olefins[1](https://www.sciencedirect.com/topics/engineering/naphtha). The number of possible hydrocarbon isomers in this boiling range is so large that complete speciation of individual constituents is impossible; analytical methods identify hydrocarbon types as chemical groups instead[1](https://www.sciencedirect.com/topics/engineering/naphtha).
## Route to gasoline: catalytic reforming
Reforming uses heat, moderate pressure, and catalysts to turn naphtha, a light and relatively low-value fraction, into high-octane gasoline components[4](https://www.eia.gov/energyexplained/oil-and-petroleum-products/refining-crude-oil-the-refining-process.php). The process uses heavy naphtha, the second lightest liquid stream from an atmospheric distillation column[8](https://www.eia.gov/todayinenergy/detail.php?id=10731). Before reforming, practically all naphtha fed to catalytic reforming units is hydrotreated to remove arsenic, sulfur, and nitrogen that would damage the catalyst[7](https://www.epa.gov/sites/production/files/documents/AppendixA_Overview_of_Petroleum_Ref.pdf).
Inside the reformer, a catalyst and heat restructure low-octane naphtha into higher-octane molecules, turning straight-chain hydrocarbons into cyclic compounds while removing hydrogen[8](https://www.eia.gov/todayinenergy/detail.php?id=10731). The product, reformate, is a high-octane gasoline blending component; because it contains significant amounts of benzene, toluene, and xylene, it is also an important petrochemical feedstock, and the hydrogen byproduct is recycled within the refinery or sold[8](https://www.eia.gov/todayinenergy/detail.php?id=10731). [Catalytic reforming](https://www.edgepedia.org/catalytic-reforming) of naphtha gives rise to about 65% of the benzene, toluene, and xylenes (BTX) used in the chemical industry[5](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf).
## Route to petrochemicals: steam cracking
In steam cracking, naphtha feedstock is fed into a furnace and undergoes pyrolysis, a thermal cracking of petroleum hydrocarbons with steam[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf). The feed is pre-heated and diluted with steam, then heated to its cracking temperature; steam dilution lowers the hydrocarbon partial pressure, enhancing olefin yield, and steam also reacts with coke deposits to limit coking[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf). Naphtha cracking yields the full range of basic petrochemicals, including ethylene, propylene, C4 olefins, and aromatics, whereas ethane feed produces only ethylene[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf) • [5](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf). Conventional ethylene synthesis through naphtha cracking uses energy equivalent to the release of 0.76 tons of CO₂ per ton of ethylene produced[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf).
**Feedstock choice differs by region.** In Europe, ethylene is mainly produced by cracking naphtha[9](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A32024M11247), with naphtha and ethane the primary feedstocks and LPG about 25% of the feed and gaining importance[3](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf). In North America, abundant shale gas made ethane a cheaper olefin feedstock than naphtha, and demand for naphtha into petrochemicals declined accordingly in the United States[5](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf). Naphtha remains attractive for trade because, as a liquid, it moves between regions far more cheaply than gases such as ethane[5](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf).
## Other uses and handling
Beyond fuels and petrochemicals, naphtha fractions serve as solvents, cleaning fluids, and paint and varnish ingredients[10](https://www.sciencedirect.com/topics/earth-and-planetary-sciences/oil-refinery). In energy statistics, naphtha is counted among petrochemical feedstocks, products derived from refined or partially refined petroleum used principally to manufacture chemicals, synthetic rubber, and plastics[11](https://www.eia.gov/tools/glossary/index.php?id=Petrochemical+feedstocks). A fuel in the heavy naphtha boiling range, meeting Military Specification MIL-T-5624L (Grade JP-4), is known as naphtha-type jet fuel, used primarily in military turbojet and turboprop engines[12](https://www.eia.gov/tools/glossary/index.php?id=naphtha).
As a workplace material, petroleum distillates (naphtha) are colorless liquids with a gasoline- or kerosene-like odor, mixtures of paraffins from C5 to C13 that may contain a small amount of aromatics[6](https://www.cdc.gov/niosh/npg/npgd0492.html). The rubber-solvent grade has a flash point of −40 to −86 °F, explosive limits of 1.1% to 5.9% in air, and is incompatible with strong oxidizers[6](https://www.cdc.gov/niosh/npg/npgd0492.html). The OSHA permissible exposure limit is 500 ppm (2,000 mg/m³) as an 8-hour time-weighted average, and the NIOSH recommended limit is 350 mg/m³, with a 15-minute ceiling of 1,800 mg/m³[6](https://www.cdc.gov/niosh/npg/npgd0492.html). Exposure routes are inhalation, ingestion, and skin or eye contact, with symptoms including eye, nose, and throat irritation, dizziness, drowsiness, headache, nausea, dry cracked skin, and chemical pneumonitis if aspirated[6](https://www.cdc.gov/niosh/npg/npgd0492.html).
## References
1. [Naphtha – an overview, ScienceDirect Topics](https://www.sciencedirect.com/topics/engineering/naphtha)
2. [Oil Market Report Glossary, International Energy Agency](https://www.iea.org/articles/oil-market-report-glossary)
3. [Industrial Innovation, Part 1 (ethylene production via naphtha steam cracking), European Commission](https://climate.ec.europa.eu/system/files/2019-03/industrial_innovation_part_1_en.pdf)
4. [Refining crude oil – the refining process, U.S. Energy Information Administration](https://www.eia.gov/energyexplained/oil-and-petroleum-products/refining-crude-oil-the-refining-process.php)
5. [Petrochemical Outlook: Challenges and Opportunities (Executive Report), OPEC/Nexant via European Commission](https://energy.ec.europa.eu/document/download/a0b3d572-a300-4307-a35f-b43b2fef9f21_en?filename=opec_petrochemical_outlook_-_nexant_executive_report.pdf)
6. [NIOSH Pocket Guide to Chemical Hazards – Petroleum distillates (naphtha), CDC](https://www.cdc.gov/niosh/npg/npgd0492.html)
7. [DEIS Appendix A – Overview of Petroleum Refining, U.S. EPA](https://www.epa.gov/sites/production/files/documents/AppendixA_Overview_of_Petroleum_Ref.pdf)
8. [Catalytic reforming boosts octane for gasoline blending, U.S. Energy Information Administration](https://www.eia.gov/todayinenergy/detail.php?id=10731)
9. [EUR-Lex merger decision CELEX 32024M11247](https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX%3A32024M11247)
10. [Oil Refinery – an overview, ScienceDirect Topics](https://www.sciencedirect.com/topics/earth-and-planetary-sciences/oil-refinery)
11. [EIA Glossary – Petrochemical feedstocks](https://www.eia.gov/tools/glossary/index.php?id=Petrochemical+feedstocks)
12. [EIA Glossary – Naphtha](https://www.eia.gov/tools/glossary/index.php?id=naphtha)
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*Topic: Encyclopedia › Technology and the built world › Energy technology › Oil industry › Drilling, refining, and products*
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