Fractional distillation of petroleum

Ever stopped and thought how useful petroleum is in our daily lives? And how it gets from it's natural state, deep underground, to the familiar fuels and chemicals we use it for?

Petroleum is a mixture of hydrocarbons, which occurs naturally in geological formations beneath the surface of the earth. It is a non-renewable resource. It is separated out into its useful components by the process of fractional distillation. 

The process of fractional distillation can be demonstrated as an experiment in the school laboratory too. Here's how fractional distillation works and how it can be shown in class.

What is fractional distillation of petroleum?

Petroleum can be separated into various types of fuel, by a process called refining, using fractional distillation.

Petrol, Diesel and Kerosene are all products (or fractions) of the process of refining Petroleum.

On an industrial scale, the different fractions of Petroleum are separated out by fractional distillation. The Petroleum is heated up, and the gas produced enters the fractionating column. The column is very hot at the bottom and gets cooler as the gas travels up the column, this allows different fuels to drain out at different temperatures up the column, with the exception of Bitumen, which is used to surface roads, this stays liquid and is drained off at the bottom of the column.

The fuels are drained off depending on the length of the hydrocarbon chain they are made up of.

The longer the hydrocarbon chain, the higher the boiling point and the earlier on they drain from the column:

how a fractionating column works

How can I demonstrate fractional distillation to my class? 

We can replicate the fractional distillation of Petroleum in the school laboratory, by using specialist glassware and a synthetic Crude Oil Substitute made up to a recipe suggested by CLEAPSS.

The recipe can be found on the CLEAPSS website: 

  • Put the synthetic crude oil in the flask and attach the fractionating column and condenser as shown above.
  • Gradually heat the flask. The different hydrocarbons in the mixture will have different boiling points, and will start to evaporate at different temperatures.
  • Once the first liquid has been collected, change the collection beaker or test tube and raise the temperature to collect the next fraction.

fractional distillation experiment lab equipment

Learn more about fractional distillation experiments

The Philip Harris specialist team are here to help with any technical questions you have about this experiment, or any other support you need. Call them on 0345 120 4521 or e-mail 

Check out our Twitter and Facebook for more experiment ideas to inspire the most inquisitive of scientific minds.

What equipment do I need for a fractional distillation experiment? 

Quickfit Round bottom flask (100ml 14/23)

Quickfit Adaptor Expansion (14/23 24/29)

Quickfit Fractionating Column (24/29)

Quickfit Still head (14/23)

Quickfit Thermometer Pocket (14/23)

Quickfit Reduction Adaptor (24/29 14/23)

Quickfit Liebig Condenser (14/23)

Quickfit Receiver Adaptor (14/223)

Crude Oil Substitute

Heating Mantle:

Bunsen Burner



Red Rubber Tubing