Diesel engine.
Diesel cycle

Endothermic engine

What is gasoline?

What is gasoline?

Gasoline (or essence and gasoline popularly) is a mixture of hydrocarbons derived from petroleum used as fuel in internal combustion engines. It has a very high calorific value of about 46 MJ / kg.

Gasoline is flammable liquid, colorless, not so dense as water (specific gravity: 0.70 to 0.75). Gasoline obtained from petroleum distillation, between 60 ° and 200 ° C, or by cracking of heavy fractions.

From a chemical point of view, gasoline is a mixture of alkanes, cycloalkanes and aromatic compounds from 4 to 10 carbon atoms and at times of alkenes. Gasoline is mainly used as a fuel in internal combustion engines. For this reason, the fuel must have a high antiknock power, which is measured by the octane (octane).

This antiknock power can be improved by varying the chemical composition, procedures for refining (cracking, reforming, isomerization, etc.) and adding anti-knock (tetraetilplom). It is also used as a solvent in many applications, and volatility is obtained by variation of the desired end point distillation.

Components of gasoline

It can be considered composed of a mixture of octane and hidrucarburs Nona. Usually considered naphtha fraction of the oil that its boiling point is approximately between 28 and 175 ° C (threshold varies depending on the business needs of the refinery). At the same time, this product is subdivided into light naphtha (up to 100 ° C) and heavy naphtha (the rest). The light naphtha is one of the components of gasoline, with octane levels of around 70 heavy naphtha has enough quality to be used for this purpose, and destiny is transformation through catalytic reforming, chemical process which is also obtained by hydrogen, while increasing the octane of the gasoline.

Besides reformed naphtha and light naphtha, other components that are used in the formulation of a commercial gasoline are FCC naphtha, light naphtha isomeritzada, desbenzenitzada pyrolysis gasoline, butane, butenes, MTBE, ETBE , ethanol and alkylate. The formulas of each refinery usually different (even belonging to the same company), depending on process units and their disposal depending summer or winter.

The naphtha is obtained by a process called fluid catalytic cracking (FCC gasoline sometimes called FCC) of heavy diesel. If you're not fine can be up to 1000 ppm of sulfur. It has around 40% to 20% aromatics and olefins. Its octane (MON / RON) is around 80/93.

The light naphtha isomeritzada (isomers) obtained from the distillation of light naphtha through a process that uses solid catalysts based on platinum / aluminum or zeolitic. It is a component free of sulfur, benzene, aromatics and olefins, with octane (MON / RON) around 87/89.

Gasoline pòlisis desbenzenitzada obtained as by-product of the manufacture of ethylene from naphtha light. It is composed by approximately 50% aromatics (toluene and Chilean) and 50% of olefins (isobutene, Hexen). It has around 200 ppm sulfur. Benzene usually containing originally purified and sold as petrochemical feedstock. Its octane (MON / RON) is around 85/105

The alkylate obtained from isobutane and butenes, through a process using acid catalysts (either sulfuric acid or hydrofluoric acid). Nor is sulfur, benzene, aromatics or olefins. Its octane (MON / RON) are around 94/95.

Manufacture of petrol

Gasoline is derived from crude oil and is obtained in a refinery. Usually obtained from the distillation of gasoline, which is lighter fraction liquid petroleum gas (except gas). NAFTA also obtained from the conversion of heavy petroleum fractions (vacuum gas oil) in process units called FCC (fluidized catalytic cracking) or hidrocracatge.

Must be met a series of specifications required for the engine to work well and other types of environment, both regulated by law in most countries. The specification is the most characteristic octane, indicating its tendency to detonate.

There are different types of commercial gasolines classified according to their octane. The gasoline sold in Europe (2004) has a minimum of 85 MON and RON least 95.

History of petrol

The first combustion engines of automobiles, called Otto engines have been developed in the last quarter of the 19th century in Germany. The fuel was relatively volatile hydrocarbon obtained from coal gas. With a boiling point of about 85 ° C (octane boil about 40 ° C higher), which was very suitable for first carburetors (evaporators). The development of a carburetor "filter" allowed the use of less volatile fuels.

We tried other improvements in engine efficiency with high compression ratios, but the first attempts were blocked by detonation (premature explosion of fuel). In the 1920s, anti-knock compounds were introduced by Thomas Midgley and Boyd specifically tetraetilplom (TEL). This innovation began a series of improvements in fuel efficiency which coincided with the development of large-scale oil refining to provide more products in the boiling range of gasoline.

In the 1950s oil refineries began to focus on high-octane fuel, and then added to gasoline detergents to clean the jets in the carburetor. The 1970s witnessed greater attention to the environmental consequences of burning gasoline. These considerations led to the phasing out of TEL and its substitution by other anti-knock compound. Later, it introduced low-sulfur gasoline, partly to preserve the catalysts in modern exhaust systems.

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Last review: November 17, 2016