Lesson 11 - Ethanol Learning Objectives: Describe the two methods for producing ethanol. Describe the advantages and disadvantages of each method.

Ethanol is an important industrial product Organic Chemicals Cosmetics Drugs Inks Detergents Bioethanol fuel

General Formula Alcohols are NOT hydrocarbons. They have the extra group –OH. Example: Ethanol = C2H5OH

Making Ethanol from Crude Oil Ethene is produced from cracking crude oil. Ethene can then be reacted with steam, using a catalyst, to produce ethanol. Cracking Can you think of why this is called hydration? Hydration

Fermentation Ethanol can also be made from the fermentation of carbohydrates (from plants). Carbohydrates are broken down into sugars and then converted into ethanol by enzyme action by yeast. Sugar cane and sugar beet

Fermentation C6H12O6  2C2H5OH + 2CO2 yeast C6H12O6  2C2H5OH + 2CO2 Glucose  Ethanol + Carbon Dioxide Yeast are microorganisms. They feed on sugar and in the absence of oxygen release energy through anaerobic respiration. This produces ethanol and carbon dioxide as waste.

Distillation

Ethanol as Biofuel Biofuel = fuel made from plant material (renewable) Being researched as an alternative to petrol so that we are no longer so reliant on crude oil, which is a non-renewable resource.

Carbon Neutral The combustion of ethanol produces the same amount of carbon dioxide as the plant absorbed while living, so ethanol is said to be a carbon neutral fuel. This is seen as a positive because CO2 is a greenhouse gas associated with global warming. However, this does not take into account other energy costs such as transportation or processing.

Hydration of Ethene vs. Fermentation Advantages Disadvantages Advantages Disadvantages

Hydration of Ethene vs. Fermentation Advantages No waste products Produces ethanol continuously Disadvantages Uses crude oil which is non-renewable Requires a lot of energy for high heat and high pressure Advantages Renewable (uses plants) Uses less energy, lower temperatures Disadvantages Slow, batch process, have to start a new batch once yeast die Produces CO2 as waste