Definition and purpose of distillation

Summary

Distillation (also called classical distillation) is the process of separating the components of a liquid mixture by selectively boiling the mixture and then condensing the resulting vapors in a still. Because different components have different relative volatilities, the vapor composition differs from the liquid composition, enabling separation and collection of higher-purity fractions. Distillation can be performed across a wide range of pressures and is used for mixtures whose components span a broad range of volatility differences. The purpose of distillation is to obtain convenient, time-tested, high-purity separations in a continuous or batch manner. In industry, distillation is treated as a physical unit operation (not a chemical reaction), and it is used for applications such as producing alcoholic beverages, desalinating water, stabilizing crude oil, refining petroleum into fuels and chemical feedstocks, and separating industrial gases like oxygen, nitrogen, and argon. Although effective, distillation can have a large environmental footprint because phase-change separation requires substantial energy inputs.

Key Points

• 1

  Distillation separates mixture components by selective boiling and condensation of vapors based on differences in relative volatility.

• 2

  Its main purpose is to produce high-purity fractions for laboratory and industrial uses, typically as a physical (non-reactive) unit operation.

• 3

  Common applications include alcohol production, desalination, crude oil stabilization, petroleum refining, and cryogenic separation of air into industrial gases.