Petroleum

Petroleum (from Greek petra – rock and oleum – oil), crude oil, sometimes colloquially called black gold, is a thick, dark brown or greenish liquid. A widely believed myth is that the oil itself is flammable, however it is actually the gas that evaporates from the oil that is flammable. Petroleum exists in the upper strata of some areas of the Earth's crust. Another name is naphtha, from Persian naft or nafátá (to flow). It consists of a complex mixture of various hydrocarbons, largely of the alkane series, but may vary much in appearance, composition, and purity. It is an important "primary energy" source (IEA Key World Energy Statistics). Petroleum is also the raw material for many chemical products, including solvents, fertilizers, pesticides, and plastics.

Composition

In refining, the component chemicals of petroleum are separated by fractional distillation, which is a separation based on relative boiling points (or equivalently relative volatility). The different products (in order of boiling points) include light gases (e.g. methane, ethane, propane), gasoline, jet fuel, kerosene, diesel, gasoil, paraffin wax, and asphalt. Subtler techniques, such as gas chromatography, HPLC, and GC-MS, can separate some fractions of petroleum into individual compounds; these are analytical chemistry methods used mainly in quality control in refineries.

Related Topics:
Refining - Fractional distillation - Boiling points - Volatility - Ethane - Propane - Gasoline - Jet fuel - Kerosene - Diesel - Gasoil - Paraffin wax - Asphalt - Gas chromatography - HPLC - GC-MS - Analytical chemistry - Quality control - Refineries

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Strictly speaking, petroleum consists of hydrocarbons (compounds of hydrogen and carbon) and non-hydrocarbon fractions, which might also include nitrogen, sulfur, oxygen, or traces of metals such as vanadium or nickel, such elements often constituting less than 1% of the whole.

Related Topics:
Hydrogen - Nitrogen - Sulfur - Oxygen - Metal - Vanadium - Nickel - Element

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The four lightest alkanes — CH4 (methane), C2H6 (ethane), C3H8

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(propane) and C4H10 (butane) — are all gases, boiling at -161.6 °C, -88.6 °C, -42 °C, and -0.5 °C, respectively (-258.9°, -127.5°, -43.6°, and +31.1° F).

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The chains in the C5-7 range are all light, easily vaporized, clear naphthas. They are used as solvents, dry cleaning fluids, and other quick-drying products. The chains from C6H14 through C12H26 are blended together and used for gasoline. Kerosene is made up of chains in the C10 to C15 range, followed by diesel fuel/heating oil (C10 to C20) and heavier fuel oils as the ones used in ship engines. These petroleum compounds are all liquid at room temperature.

Related Topics:
Naphthas - Solvent - Dry cleaning - Kerosene - Diesel fuel - Heating oil - Fuel oil - Ship - Engine - Room temperature

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Lubricating oils and semi-solid greases (including Vaseline®) range from C16 up to C20.

Related Topics:
Lubricating oils - Grease - Vaseline

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Chains above C20 form solids, starting with paraffin wax, then tar and asphaltic bitumen.

Related Topics:
Paraffin - Tar - Asphaltic - Bitumen

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Boiling ranges of petroleum atmospheric pressure distillation fractions in degrees Celsius:

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• petrol ether: 40 - 70 °C (used as solvent)
• light petrol: 60 - 100 °C (automobile fuel)
• heavy petrol: 100 - 150 °C (automobile fuel)
• light kerosene: 120 - 150 °C (household solvent and fuel)
• kerosene: 150 - 300 °C (jet engine fuel)
• gasoil: 250 - 350 °C (diesel fuel/ heating)
• lubrication oil: > 300 °C (engine oil)
• remaining fractions: tar, asphalt, residual fuel