Formation of Ethanol

Formation of Ethanol.

Ethanol is a straight chain alcohol (C2H5OH); it is a volatile, colourless liquid that has a strong characteristic odour. Ethanol is commonly used as a psychoactive drug in alcoholic beverages. It has a numeral uses such as an antiseptic, feedstock and fuel.

Ethanol is notable as a renewable energy, derived by several means from the fermentation of sugar or hydration of ethylene; ethanol is being developed as an alternative to petrol to fuel cars.

In present time, in several countries, ethanol is blended with motor fuels as an additive, to increase the octane rating of the fuel. This reduces ground-level ozone formation by lowering volatile organic compound and hydrocarbon emissions, decreasing carcinogenic benzene, particular matter emissions from the combustion of petrol, resulting in fuel burning more cleaning.

As aforementioned, ethanol is made by two ways; hydration of ethylene and by the fermentation of sugars or cellulous.

Fermentation

Ethanol is the most common biologically produced alcohol. It is formed from the action of microorganisms and enzymes through the fermentation of sugars or starches, or cellulous, which is a more difficult process than the usage of sugars.

The most widely know process of the formation of ethanol by the means of fermentation begins with carbohydrates; mainly monosaccharides and disaccharides such as glucose, fructose and sucrose. The carbohydrates are converted to cellular energy thereby producing ethanol in the ...

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As aforementioned, ethanol is made by two ways; hydration of ethylene and by the fermentation of sugars or cellulous.

Fermentation

The reaction is catalysed by an enzyme in the yeast called zymase. At temperatures below 25°C, the reaction is slow, whereas at temperatures above 37°C, the enzyme denatures. Therefore, in relation to yield of the ethanol, the reaction is done at a strict temperature of 37°C. The fermentation is carried out non-aseptically in the absence of air for about 1-3 days where it would be distilled.

Another method of forming ethanol from fermentation is by using cellulosic materials. There is a higher yield of ethanol from this process in comparison to the fermentation of sugars

Lingocellulosic materials such as hardwood and softwood residue is used - the process consist of hydrolysis on pretreated cellulosic materials, using enzymes to break complex cellulose into simple sugars such as glucose. This is followed by the fermentation of the sugars and finally distilled.

Cellulosic material can also be fermentated by gasification. This transforms the raw material into gaseous carbon dioxide and carbon dioxide. These gases can be converted to ethanol by the fermentation or chemical cataylsis.

Hydration of Ethylene

Ethanol for use as an industrial feedstock is made by the hydration of ethylene. Excess water is reacted with the ethylene in the presence of a catalyst (most commonly phosphoric acid) and under high pressure and a temperature of 300°C.

(g) + (g) → CH3CH2OH(l).