Ethanol
The ethanol , or ethanol , is a alcohol, having the following semi-developed structure:
-
CH-CH-OH
The ethanol is usually indicated by the abbreviation EtOH .
It is a colorless, miscible liquid with water in all proportions.
It is called often simply “alcohol”, because the ethanol is the alcohol which finds in all the alcoholic drinks. In the European Pharmacopeia, ethanol indicates the absolute ethanol , i.e. pure to 100%, whereas alcohol pH. Eur. indicates ethanol satisfying a certain quantity with water. Its synonyms are spirit of wine, alcohol grain. The Alcoolisme is drink the excessive consumption containing of ethanol and its fatal consequences make a historical plague of it.
Historically, the ethanol was produced by Fermentation direct of Sucre S natural: the production of Wine or Bière fermented is attested in the Babylonian empire as of 3000 av. J. - C. first pure obtainings are probably due to the alchemists Perse S which developed the art of the Distillation with 8th and 9th century century of the Christian era.
One also industrially manufactures it by hydration of the ethylene.
The ethanol is used as intermediary of synthesis in chemical industry and like solvent. It is also one disinfecting.
In North America and especially in Brazil, some gasoline S available to the pump can comprise up to ethanol 20% and bear the name of ethanol blend .
In France, the government officially launched at the end of 2006 E85, a mixture of 85% of ethanol and 15% of gasoline like Agrocarburant. It should be available in several hundreds of stations of service from here the end of the year 2007.
Industrial production of ethanol
By direct catalytic hydration of ethylene
The synthesis of ethanol by hydration of ethylene rests on the following reaction:
The variation of Enthalpie related to this reaction is ΔH = − 43,4 kJ · mol −1 . To obtain an output with satisfactory balance (usually ranging between 7% and 22%), this reaction requires to be catalyzed. The majority of catalysts described in the technical literature present an acid character. One will quote in particular the phosphoric Acid and the acid silicotungstic. These catalysts generally impregnate a porous support.
The finished product of the hydration of ethylene is a mixture containing between 10% and 25% of ethanol in weight. Successive distillations will be thus necessary to obtain a mixture more concentrated. With final, the optimal conditions for the realization of this reaction of hydration depend largely on catalyst used, of the characteristics of the engine and qualities of the starting product.
By indirect hydration of ethylene
The production of ethanol per indirect hydration of ethylene utilizes a more complex reactional mechanism with two great stages: a whole of reactions of esterification then of Hydrolysis. This process consumes great quantities of Acid sulphuric and requires in entry a gas mixture of good quality.
Production of ethanol starting from the biomass
In this case, one speaks about Bioéthanol. The majority of bioéthanol produces today comes from the treatment of the sugar plants (Beet, Cane with sugar,…) or of the cereals (Corn, Corn,…).Other dies exist however, in particular the production of bioéthanol (known as cellulose bioéthanol) starting from vegetation wastes (sawdust, corn straw,…). The most elaborate process in this field is currently that developed by the Canadian company Iogen Corporation.
Price of the ground
In 2007, it was revealed that the consumption of ethanol in Brazil radically made increase the price of the ground and the production costs of corn, milk, sugar and the meat. Ethanol producers as Archer Daniels Midland caused criticisms of researchers who fear possible a Famine because of a probable rise in the price of food and Monoculture of the ground, which obliges with the producers to import essential food.
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