A mixture of hydrocarbons obtained either from coal tar or from petroleum. It has a boiling range of about 100180°C. Naphtha from coal tar is mainly aromatic, containing much toluene, while that from petroleum is mainly aliphatic.
Naphtha (not to be confused with Naphthalene) is a group of various volatile flammable liquid hydrocarbon mixtures used primarily as feedstocks in refineries for the reforming process and in the petrochemical industry for the production of olefins in steam crackers.
Production of naphtha in refineries and uses
Naphtha is obtained from petroleum refineries as a small percentage (around 4%) of the distillation of crude oil. The generic name naphtha describes a range of different refinery cuts used in the different applications. To further complicate the matter similar naphtha types are often referred to by different names.
The different naphthas are distinguished by:
density (kg/m3 or specific gravity) PONA or PIONA analysis, which measures (usually in volume percent but can also be in weight percent): Paraffin content (volume percent) Isoparaffin content (only in a PIONA analysis) Olefins content (volume percent) Naphthenes content (volume percent) Aromatics content (volume percent)Paraffinic naphthas
Generally speaking, less dense ("lighter") naphthas will have a higher paraffin content. The main application for these naphthas is as a feedstock in the petrochemical production of olefins. This is also the reason they are sometimes referred to as "light distillate feedstock" or LDF (these naphtha types can also be called "straight run gasoline"/SRG or "light virgin naphtha"/LVN).
When used as feedstock in petrochemical steam crackers, the naphtha is heated in the presence of water vapour and the absence of oxygen or air until the hydrocarbon molecules fall apart.
Heavy naphthas
The "heavier" or rather denser types are usually richer in naphthenes and aromatics and therefore also referred to as N&A's. These can also be used in the petrochemical industry but more often are used as a feedstock for refinery catalytic reformers where they convert the lower octane naphtha to a higher octane product called reformate. Alternative names for these types are Straight Run Benzene (SRB) or Heavy Virgin Naphtha (HVN).
Other applications / descriptions
Naphthas are also used in other applications such as
(as an unprocessed component - in contrast to reforming above) in the production of petrol/motor gasoline. historically, as a probable ingredient in Greek fire (together with grease, oil, sulfur, and naturally occurring saltpeter from the desert)Examples
Shellite (Australia), also known as white gas (North America), white spirit or Coleman fuel, is a water white liquid with a hydrocarbon odour. Naphtha may also have been derived from the name of the Vedic Hindu and Avestic god Apam Napat, a form of Agni, or fire god.
Naphtha is the root of the words naphthalene and napalm from which it is derived by mixing under controlled conditions with aluminium salts of palmitic acid (a type of soap).
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