Fractional Distillation: This involves the heating of crude oil, and separating the various mixtures in the basis of their boiling points.

Octane Number

The Octane Number of a fuel is a measure of the tendency of the fuel to resist knocking.

  • Heptane = 0
  • 2,2,4 Trimethylpentane = 100
  • Shorter the alkane chain, higher the octane number.
  • More branched the chain, higher the octane number.
  • Cyclic compounds have higher octane numbers than straight chain compounds.

Increasing the Octane Number

  • Isomerisation – Changing straight chain alkanes into their isomers.
  • Catalytic Cracking is the breaking down of long-chain hydrocarbon molecules into short chain molecules for which there is greater demand.
  • Adding oxegenates involves the adding of compounds containing oxygen in their molecules.