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Naphtha (/ˈnæfθə/, recorded as less common or nonstandard[1] in all dictionaries:/ˈnæpθə/) is a flammable liquid hydrocarbon mixture. Generally, it is a fraction of crude oil, but it can also be produced fromnatural-gas condensates,petroleum distillates, and thefractional distillation ofcoal tar andpeat. In some industries and regions, the namenaphtha refers tocrude oil or refined petroleum products such askerosene ordiesel fuel.
Naphtha is also known as Shellite in Australia.[2]
The wordnaphtha comes fromLatin throughAncient Greek (νάφθα), derived fromMiddle Persiannaft ("wet", "naphtha"),[3][4] the latter meaning of which was an assimilation from theAkkadian𒉌𒆳𒊏napṭu (seeSemitic relatives such asArabicنَفْطnafṭ ["petroleum"],Syriacܢܰܦܬܳܐnaftā, andHebrewנֵפְטneft, meaning petroleum).[5]
The book ofII Maccabees (2nd cent. BC) tells how a "thick water" was put on a sacrifice at the time ofNehemiah 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."[6] This same substance is mentioned in theMishnah as one of the generally permitted oils for lamps onShabbat, althoughRabbi Tarfon permits onlyolive oil (Mishnah Shabbat 2).
In Ancient Greek, it was used to refer to any sort ofpetroleum orpitch. The Greek wordνάφθα designates one of the materials used to stoke the fiery furnace in theSong of the Three Children (possibly 1st or 2nd cent. BC). The translation of Charles Brenton renders this as "rosin".
The naphtha of antiquity is explained to be a "highly flammable lightfraction of petroleum, an extremely volatile, strong-smelling, gaseous liquid, common in oil deposits of the Near East"; it was a chief ingredient in incendiary devices described by Latin authors of the Roman period.[7]
Since the 19th century,solvent naphtha has denoted a product (xylene ortrimethylbenzenes) derived byfractional distillation from petroleum;[8] thesemineral spirits, also known as "Stoddard Solvent", were originally the main active ingredient inFels Naptha laundry soap.[9] The naphtha in Fels Naptha was later removed as a cancer risk.[10]
The usage of the term "naphtha" during this time typically implies petroleum naphtha, a colorless liquid with a similar odor to gasoline. However, "coal tar naphtha", a reddish brown liquid that is a mixture of hydrocarbons (toluene, xylene, andcumene, etc.), could also be intended in some contexts.[11]
In older usage,[when?] "naphtha" simply meantcrude oil, but this usage is now obsolete in English. There are a number ofcognates to the word in different modern languages, typically signifying "petroleum" or "crude oil".
TheUkrainian andBelarusian wordнафта (nafta),Lithuanian,Latvian andEstonian "nafta" and thePersiannaft (نفت) mean "crude oil". The Russian wordнефть (neft') means "crude oil", but нафта (nafta) is a synonym ofligroin. Also, inAlbania,Bosnia and Herzegovina,Bulgaria,Croatia,Finland,Italy,Serbia,Slovenia,Macedonianafta (нафта in Cyrillic) is colloquially used to indicatediesel fuel andcrude oil. In theCzech Republic andSlovakia,nafta was historically used for both diesel fuel and crude oil, but its use for crude oil is now obsolete[12] and it generally indicates diesel fuel. InBulgarian,nafta means diesel fuel, whileneft, as well aspetrol (петрол in Cyrillic), means crude oil.Nafta is also used in everyday parlance in Argentina, Paraguay and Uruguay to refer to gasoline/petrol.[13] In Poland, the wordnafta meanskerosene,[14] and colloquially crude oil (technical name for crude oil isropa naftowa, also colloquially used for diesel fuel asropa). InFlemish, the wordnaft(e) is used colloquially for gasoline.[15]
Various qualifiers have been added to the term "naphtha" by different sources in an effort to make it more specific:
One source[16] distinguishes by boiling point:
Light naphtha is the fraction boiling between 30 °C and 90 °C and consists of molecules with 5–6 carbon atoms.Heavy naphtha boils between 90 °C and 200 °C and consists of molecules with 6–12 carbon atoms.
Another source[17] which differentiateslight andheavy comments on the hydrocarbon structure, but offers a less precise dividing line:
Light [is] a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from five to six carbon atoms per molecule.Heavy [is] a mixture consisting mainly of straight-chained and cyclic aliphatic hydrocarbons having from seven to nine carbon atoms per molecule.
Both of these are useful definitions, but they are incompatible with one another and the latter does not provide for mixes containing both six and seven carbon atoms per molecule. These terms are also sufficiently broad that they are not widely useful.
"Petroleum naphtha", which contains both heavy and light naphtha, typically constitutes 15-30% of crude oil by weight.[18]
Naphtha is used to diluteheavy crude oil to reduce its viscosity and enable/facilitate transport; undiluted heavy crude cannot normally be transported by pipeline, and may also be difficult to pump ontooil tankers. Other common dilutants includenatural-gas condensate andlight crude. However, naphtha is a particularly efficient dilutant and can be recycled from diluted heavy crude after transport and processing.[19][20][21] The importance of oil dilutants has increased as global production of lighter crude oils has fallen and shifted to exploitation of heavier reserves.[20]
Light naphtha is used as a fuel in some commercial applications. One notable example is wick-based cigarette lighters, such as theZippo, which draw "lighter fluid"—naphtha—into a wick from a reservoir to be ignited using the flint and wheel.
It is also a fuel for camping stoves and oil lanterns, known as "white gas", where naphtha's low boiling point makes it easy to ignite. Naphtha is sometimes preferred over kerosene because it clogs fuel lines less. The outdoor equipment manufacturerMSR published a list of trade names and translations to help outdoor enthusiasts obtain the correct products in various countries.[22]
Naphtha was also historically used as a fuel in somesmall launch boats where steam technology was impractical; most were built to circumvent safety laws relating to traditional steam launches.[23]
As an internal combustion engine fuel, petroleum naphtha has seen very little use and suffers from lower efficiency and lowoctane ratings, typically 40 to 70RON. It can be used to run unmodified diesel engines, though it has a longer ignition-delay than diesel. Naphtha tends to be noisy in combustion due to the high pressure rise rate. There is a possibility of using naphtha as a low-octane base fuel in an octane-on-demand concept, with the engine drawing a high-octane mix only when needed. Naptha benefits from lesser emissions in refinement: fuel energy losses from "well-to-tank" are 13%; lower than the 22% losses for petroleum.[18]
Naphtha is a crucial component in the production ofplastics.[24]
Thesafety data sheets (SDSs) from various naphtha vendors indicate various hazards such as flammable mixture ofhydrocarbons:flammability,carcinogenicity, skin andairway irritation, etc.[25][2][26][27]
Humans can be exposed to naphtha in the workplace by inhalation, ingestion, dermal contact, and eye contact. TheUSOccupational Safety and Health Administration (OSHA) has set thepermissible exposure limit for naphtha in the workplace as 100 ppm (400 mg/m3) over an 8-hour workday. TheUSNational Institute for Occupational Safety and Health (NIOSH) has set arecommended exposure limit (REL) of 100 ppm (400 mg/m3) over an 8-hour workday. At levels of 1000 ppm, which equates to 10 times the lower exposure limit, naphtha isimmediately dangerous to life and health.[28]
