3.8.3

Cracking

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Cracking

Cracking is the process of converting alkanes into alkenes and shorter alkanes. We crack alkanes because the shorter chain alkanes are more valuable (they are used as fuel).

Illustrative background for Thermal crackingIllustrative background for Thermal cracking ?? "content

Thermal cracking

  • Thermal cracking uses harsh conditions like high temperature and high pressure.
  • It breaks the alkanes into a high percentage of alkenes and comparatively few alkanes.
  • Thermal cracking is done at about 1,000oC and 70 atm pressure.
Illustrative background for Catalytic crackingIllustrative background for Catalytic cracking ?? "content

Catalytic cracking

  • Using a catalyst allows you to lower the temperatures and pressures needed for the reaction. This reduces costs and makes the reaction faster.
  • Catalytic cracking is done at 450oC and only just above atmospheric pressure.
  • The catalyst we use is called a zeolite. This is an ionic compound containing aluminium, silicon, and oxygen.
  • You tend to get molecules containing benzene rings and short hydrocarbons.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

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