Distillation is the separation of a mixture into its components by using their differences in points. Boiling point is the at which a substance boils. This is also the temperature at which it [freezes/melts/condenses/sublimes]. During condensation, a substance changes from to . Long-chained hydrocarbons condense at [higher/lower] temperatures than short-chained hydrocarbons.

A distillation column has different temperatures throughout its height. At the bottom it is very [cold/hot]. It gets cooler and cooler [higher up/lower down]. The hydrocarbon mixture formed by the Fischer Tropsch process is heated to over 350°C, making all its components vaporise, that is, turn to . This hot mixture is fed into the bottom of the column.

Even though the temperature at the bottom of the column is hot, it is not hot enough to keep the [shortest/longest]-chained hydrocarbons in the gaseous phase. They and sink to the bottom. These hydrocarbons have more than 20 carbon atoms per molecule. They are then led off. They may be used, for example in wax, or they may be sent back to the to be split into shorter chains.

The [shorter/longer] hydrocarbons, still in the gaseous phase, rise. As they do so they come to cooler parts of the distillation column. At about 200°C, condenses, and is led off. Diesel is made of a mixture of hydrocarbons having from 12 to 18 carbon atoms per molecule. It is used in some vehicles. At about 120°C, kerosene condenses. Kerosene is used as fuel. Kerosene is a mixture of hydrocarbons having 9 to 14 carbon atoms per molecule. At 40°C, , also called gasoline, condenses. It is made of a mixture of hydrocarbons having from 5 to 10 carbon atoms per molecule. This is used to power many vehicles. At 20°C liquid petroleum gas (LPG) condenses. LPG is often sold in gas bottles and might be used in gas heaters or stoves. It contains very [short/long] hydrocarbon chains which have only 3 or 4 carbon atoms per molecule. Even smaller molecules, consisting of only 1 or 2 carbon atoms per molecule, form fuel gas. This exits at the top of the distillation column, still in the gaseous phase.

So by cooling the heated hydrocarbon mixture to different , it is separated into its components as each component at a different temperature, and therefore a different , in the distillation column. A similar process is used in the separation of crude oil into its components. The temperatures used and products formed would, however, differ slightly from those given here.