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Ethanol..The Meaner, Greener, Cleaner, Energy Source!

How Ethanol is Made

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The two most popular ways to produce ethanol are:

  1. Ethylene hydration
  2. Fermenting sugars using yeast

 

Ethylene hydration is represented by the chemical equation H2C=CH2 + H2O → CH3CH2OH. To explain this chemical reaction of hydrating ethylene better, the molecule ethylene (H2C=CH2) is hydrated (water added to it) to form CH3CH2OH (ethanol). This is the modernized way which is most popular. The method used in the 30s was more complicated, using sulffuric acid to react with the ethylene to prduce ethyl sulfate. The ethyl sulfate was then hydrated to form ethanol and sulffuric acid. The folloing chemical equations show how this was done.

H2C=CH2 + H2SO4 → CH3CH2OSO3H

CH3CH2OSO3H + H2O → CH3CH2OH + H2SO4

 

Fermentation is another way to produce ethanol. Fermentation is when species of yeast are breaking down sugars to obtain the required energy the body needs under anaerobic conditions. When the process is done, the yeasts gain the energy it needs and releases ethanol and carbon dioxide as waste products. The most basic way to represent this is C6H12O6 → 2 CH3CH2OH + 2 CO2. A glucose (sugar) molecule is broken apart to form carbon dioxide and ATP.

 

Both of these methods are only a start to producing pure ethanol. In fermentation the products approximate maximum ethanol content is 14%. Any higher and it destroys the enzyme zymase and fermentation stops. In order to get pure ethanol a distillation process is required but this process doesn’t quite get 100% pure ethanol. Its max is 96% ethanol and 4% water. In order to get rid of the small portion of water a dehydration agent is used.