Naphtha

Not to be confused with Naphthalene.

White gas, exemplified by Coleman Camp Fuel, is a common naphtha-based fuel used in many lanterns and torches

Naphtha (/ˈnæpθə/ or /ˈnæfθə/), Petroleum naphtha, Coleman fuel is a colorless, flammable, aliphatic or aromatic liquid hydrocarbon mixture ${\ce {C5 , C10}}$ distilled from petroleum or coal tar, especially as used in solvents or petrol. is an intermediate hydrocarbon liquid stream derived from the refining of crude oil.

It is most usually desulfurized and then catalytically reformed, which re-arranges or re-structures the hydrocarbon molecules in the naphtha as well as breaking some of the molecules into smaller molecules to produce a high-octane component of gasoline (or petrol).

Mixtures labelled naphtha have been produced from natural gas condensates, petroleum distillates, and the distillation of coal tar and peat, shale deposits, tar sands and the destructive distillation of wood.

In different industries and regions naphtha may also be crude oil or refined products such as kerosene. Mineral spirits, also historically known as "naptha", are not the same chemical.

There are hundreds of different petroleum crude oil sources worldwide and each crude oil has its own unique composition or assay. There are also hundreds of petroleum refineries worldwide and each of them is designed to process either a specific crude oil or specific types of crude oils. Naphtha is a general term as each refinery produces its own naphthas with their own unique initial and final boiling points and other physical and compositional characteristics.

Coleman fuel is a mixture of cyclohexane, nonane, octane, heptane, and pentane. It is used primarily for fueling lanterns and camp stoves.

Etymology

White gas, exemplified by Coleman Camp Fuel, is a common naphtha-based fuel used in many lanterns and torches

The word naphtha is from Latin and Ancient Greek (νάφθα), derived from Middle Persian naft ("wet", "naphtha"), from Old Persian 𐎴𐎳𐎫 (naft). In Ancient Greek, it was used to refer to any sort of petroleum or pitch. In antiquity the term entered Semitic languages as well: it appears in Arabic as نَفْط nafṭ ("petroleum"), in Syriac as ܢܰܦܬܳܐ naftā, and in Hebrew as נֵפְט neft.

In the Song of the Three Children the Greek word νάφθα designates one of the materials used to stoke the fiery furnace. The translation of Charles Brenton renders this as "rosin".

The book of II Maccabees tells how a "thick water" was put on a sacrifice at the time of Nehemiah and when the sun shone it caught fire. It adds that "those around Nehemiah termed this 'Nephthar', which means Purification, but it is called Nephthaei by the many [literally hoi polloi]."

Naphtha is the root of the word naphthalene. The second syllable of "naphtha" can also be recognised in phthalate.

It also enters the word napalm, a contraction of the "na" of naphthenic acid and "palm" of palmitic acid, originally made from a mixture of naphthenic acid combined with aluminium and magnesium salts of palmitic acid.

In older usage, "naphtha" simply meant crude oil, but this usage is now obsolete in English. It was also used for mineral spirits (also known as "Stoddard Solvent"), originally the main active ingredient in Fels Naptha laundry soap. The Ukrainian and Belarusian word нафта (lit. nafta), Lithuanian, Latvian and Estonian "nafta", the Russian word нефть (lit. neft') and the Persian naft (نفت) mean "crude oil". Also, in Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Italy, Serbia, Slovenia, nafta (нафта in Cyrillic) is colloquially used to indicate diesel fuel and crude oil. In the Czech Republic and Slovakia, nafta was historically used for both diesel fuel and crude oil, but its use for crude oil is now obsolete and it generally indicates diesel fuel. In Bulgarian, nafta means diesel fuel, while neft, as well as petrol (петрол in Cyrillic), means crude oil. Nafta is also used in everyday parlance in Argentina, Paraguay and Uruguay to refer to gasoline/petrol. In Poland, the word nafta means kerosene,, as in lampa naftowa "paraffin lamp"; crude oil and (colloquially) diesel fuel are called ropa "pus". In Flemish, the word naft is used colloquially for gasoline.

There is a conjecture that the Greek word naphtha came from the Indo-Iranian god name Apam Napat, which occurs in Vedic and in Avestic; the name means "grandson of (the) waters", and the Vedas describe him as fire emerging from water, perhaps inspired by a burning seepage of natural gas.

Types

The table below lists some typical virgin heavy naphthas, available for catalytic reforming, derived from various crude oils. It can be seen that they differ significantly in their content of paraffins, naphthenes and aromatics:

Typical heavy naphthas

Crude oil name $\Rightarrow$Location $\Rightarrow$	Barrow Island Australia	Mutineer-Exeter Australia	CPC Blend Kazakhstan	Draugen North Sea
Initial boiling point, °C	149	140	149	150
Final boiling point, °C	204	190	204	180
Paraffins, liquid volume %	46	62	57	38
Naphthenes, liquid volume %	42	32	27	45
Aromatics, liquid volume %	12	6	16	17

Health and safety

The material safety data sheets (MSDSs) from various naphtha vendors are also indicative of the non-specific nature of the product and reflect the considerations due for a flammable mixture of hydrocarbons: flammability, carcinogenicity, skin and airway irritation, etc.

Humans can be exposed to naphtha in the workplace by breathing it in, swallowing it, skin contact, and eye contact. The US Occupational Safety and Health Administration (OSHA) has set the permissible exposure limit for naphtha exposure in the workplace as 100 ppm (400 mg/m³) over an 8-hour workday. The US National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 100 ppm (400 mg/m³) over an 8-hour workday. At levels of 1000 ppm, 10% of the lower explosive limit, naphtha is immediately dangerous to life and health.

The major source of petroleum naphtha in a petroleum refinery

The first unit operation in a petroleum refinery is the crude oil distillation unit. The overhead liquid distillate from that unit is called virgin or straight-run naphtha and that distillate is the largest source of naphtha in most petroleum refineries. The naphtha is a mixture of many different hydrocarbon compounds. It has an initial boiling point (IBP) of about 35 °C and a final boiling point (FBP) of about 200 °C, and it contains paraffins, naphthenes (cyclic paraffins) and aromatic hydrocarbons ranging from those containing 4 carbon atoms to those containing about 10 or 11 carbon atoms.

The virgin naphtha is often further distilled into two streams:

• a virgin light naphtha with an IBP of about 30 °C and a FBP of about 145 °C containing most (but not all) of the hydrocarbons with 6 or less carbon atoms
• a virgin heavy naphtha containing most (but not all) of the hydrocarbons with more than 6 carbon atoms. The heavy naphtha has an IBP of about 140 °C and a FBP of about 205 °C.

The virgin heavy naphtha is usually processed in a catalytic reformer, because the light naphtha has molecules with six or fewer carbon atoms—which, when reformed, tend to crack into butane and lower molecular weight hydrocarbons that are not useful as high-octane gasoline blending components. Also, the molecules with six carbon atoms tend to form aromatics, which is undesirable because the environmental regulations of a number of countries limit the amount of aromatics (most particularly benzene) in gasoline.

Cracked naphthas

Some refinery naphthas also contain some olefinic hydrocarbons, such as naphthas derived from the fluid catalytic cracking, visbreakers and coking processes used in many refineries. Those olefin-containing naphthas are often referred to as cracked naphthas.

In some (but not all) petroleum refineries, the cracked naphthas are desulfurized and catalytically reformed (as are the virgin naphthas) to produce additional high-octane gasoline components.

Other uses

Some petroleum refineries also produce small amounts of specialty naphthas for use as solvents, cleaning fluids, paint and varnish diluents, asphalt diluents, rubber industry solvents, dry-cleaning, cigarette lighters,recyclig products and portable camping stove and lantern fuels. Those specialty naphthas are subjected to various purification processes.

Sometimes the specialty naphthas are called petroleum ether, petroleum spirits, mineral spirits, paraffin, benzine, hexanes, ligroin, white oil or white gas, painters naphtha, refined solvent naphtha and Varnish makers' & painters' naphtha (VM&P) . The best way to determine the boiling range and other compositional characteristics of any of the specialty naphthas is to read the Safety Data Sheet (SDS) for the specific naphtha of interest.

On a much larger scale, petroleum naphtha is also used in the petrochemicals industry as feedstock to steam reformers and steam crackers for the production of hydrogen (which may be and is converted into ammonia for fertilizers), ethylene and other olefins. Natural gas is also used as feedstock to steam reformers and steam crackers.

Safety

People can be exposed to petroleum naphtha in the workplace by breathing it, swallowing it, skin contact, and eye contact. The Occupational Safety and Health Administration (OSHA) set the legal limit (permissible exposure limit) for petroleum naphtha exposure in the workplace as 500 ppm (2000 mg/m³) over an 8-hour workday. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 350 mg/m³ over an 8-hour workday and 1800 mg/m³ over 15 minutes. At levels of 1100 ppm, 10% of the lower explosive limit, petroleum naphtha is immediately dangerous to life and health.

See also

• Crude oil
• Fluid catalytic cracking
• Hydrocarbon
• Keroselene
• Naphtha launch
• Oil refinery
• Petroleum distillation
• Tar