Naphtha: Encyclopedia II - Naphtha - Production of naphtha in refineries and uses

Naphtha - Production of naphtha in refineries and uses

Naphtha is obtained from petroleum refineries as a portion of the distillation (also referred to as a cut). It is an intermediate between the lighter gasoline and the heavier benzine. Naphtha has a specific gravity of about 0.7. 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)

Naphtha - Paraffinic naphthas

Generally speaking "lighter" or rather less dense naphthas will have a higher paraffin content, these are therefore also referred to as paraffinic naphtha. The main application these naphthas are used for are 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 (as described above a variety of names exist and these 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. The primary products of the cracking process are olefins (ethylene / ethene, propylene / propene and butadiene) and aromatics (benzene and toluene). These are used as feedstocks for derivative units that produce plastics (polyethylene and polypropylene for example), synthetic fiber precursors (acrylonitrile), industrial chemicals (glycols for instance).

Naphtha - 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 - reformate. Alternative names for these types are straight run benzene/SRB or heavy virgin naphtha/HVN.

Naphtha - 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.
• as industrial solvents and cleaning fluids
• as an ingredient in shoe polish
• as an ingredient in some lighter fluids for wick type lighters such as Zippo lighters.
• as an adulterant to petrol

Adapted from the Wikipedia article "Production of naphtha in refineries and uses", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki