Why do we refine crude oil? Refining Crude oil Learning Objectives: Why do we refine crude oil? How do we do it? What do we get from it

Local oil refinery

What happens at an oil refinery? Fractional Distillation Boiling the crude oil at different temperatures so that the different fractions evaporate and can be collected separately. The heavier the fraction the higher the boiling point Cracking – Increasing the proportion of the useful smaller hydrocarbons by breaking C-C bonds holding together longer chain molecules.

Knocking greatly reduces the performance of engines What happens contd Reforming Turning light gasoline and naphtha from single chain to hydrocarbons to highly branched and aromatic hydrocarbons. This is done to stop their pre-ignition in combustion engines (known as knocking) Knocking greatly reduces the performance of engines

Crude oil A soup of different chemicals

What it comprises (a barrel) This varies from different oil fields. Not all crude oils are the same. Light or sweet crude is the best because it has the largest amount of petrol/gasoline. US, North Sea and Libyan known for their high quality.

Chemical description of components Note fractions different for different crude oils

Parts of a refinery

Fractionating column

Cracking

How cracking fits in

Plenary questions Octane is an important hydrocarbon Which fraction of crude oil would it be found in? What would be its likely use? From what length carbon chains could it be produced by cracking?

Complete this fractionating column by adding the uses of the different fractions.