Fractional Distillation

• Why is fractional distillation used for crude oil?

  The hydrocarbons in crude oil have different boiling points,so we use fractional distillation to separate the useful hydrocarbons into fractions,which contains hydrocarbons with similar number of carbon atoms.
• Stages of Fractional Distillation


  1. Evaporation

  2. Condensation

  3. Collection
• Evaporation

  Heat crude oil to evaporate it and the crude oil vapour is put into the fractioning column from the bottom and rises upwards
• Condensation

  1. Temperature is highest at the the bottom of the fractioning column so long chain hydrocarbons condense at the bottom and are collected as liquids

  2. Short chain hydrocarbons have lower boiling points so they pass up the column and condense at lower temperatures at the top
• Collection


  1. Fractions are collected and used to create end products

  2. Fuels like petrol and diesel are a common end product used for cars

  3. The petrochemical industry can use some fractions as feedstock materials to make solvents/detergents/lubricants/polymers
• What is feedstock?

  Chemical used to make other chemicals