11.6.6

Manufacture of Ethanol: Fermentation & Hydration

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Manufacture of Ethanol: Fermentation & Catalytic Hydration

Ethanol is made by fermentation of glucose and catalytic hydration of ethene using yeast and acid catalysts.

Fermentation overview

Fermentation overview

  • Fermentation produces ethanol using aqueous glucose.
    • Yeast acts as a catalyst during fermentation.
    • Temperature is kept between 25°C and 35°C.
    • Oxygen is absent during this process.
  • The process was discovered before 1850 and is traditional in brewing.
Fermentation process details

Fermentation process details

  • Glucose breaks down into ethanol and carbon dioxide.
    • The reaction is: C6H12O6 → 2C2H5OH + 2CO2.
  • Yeast enzymes speed up fermentation.
  • Fermentation stops if the temperature rises above 35°C.
  • Ethanol yield is limited to about 15% due to yeast sensitivity.
Catalytic hydration overview

Catalytic hydration overview

  • Ethanol also forms by adding steam to ethene.
  • Steam and ethene react at 300°C.
  • Pressure is high, about 6000 kPa (60 atm).
  • An acid catalyst, like phosphoric acid, speeds the reaction.
    • This method started in the early 20th century for industrial ethanol.
Catalytic hydration process details

Catalytic hydration process details

  • Ethene (C2H4) and steam (H2O) form ethanol (C2H5OH).
    • Reaction: C2H4 + H2O → C2H5OH.
  • Acid catalyst helps break and form chemical bonds faster.
  • The process allows large-scale ethanol manufacturing.
  • It uses ethene from cracking hydrocarbons.
Comparing both methods

Comparing both methods

  • Fermentation uses renewable glucose, is slower, and produces less pure ethanol.
  • Catalytic hydration uses ethene, allowing continuous production at high purity.
    • Fermentation of ethanol is important in food and drink.
    • Catalytic hydration of ethanol is useful for fuel and industry.
  • Both methods are key to the organic chemistry topic of alcohol manufacture.
Jump to other topics
1

States of Matter

2

Atoms, Elements & Compounds

3

Stoichometry

4

Electrochemistry

5

Chemical Energetics

6

Chemical Reactions

7

Acids, Bases & Salts

8

The Periodic Table

9

Metals

10

Chemistry of the Environment

11

Organic Chemistry

11.1

Formulae, Functional Groups & Terminology

11.2

Naming Organic Compounds

11.3

Fuels

11.4

Alkanes

11.5

Alkenes

11.6

Alcohols

11.7

Carboxylic Acids

11.8

Polymers

12

Experimental Techniques & Chemical Analysis

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