Destructive Distillation vs. Fractional Distillation — What's the Difference?

Destructive distillation occurs in the absence of air and breaks down the material into several smaller volatile compounds. This process often results in a solid residue and an array of gaseous, liquid, or solid distillates. Fractional distillation, on the other hand, involves the separation of a mixture into its individual components by heating to specific boiling points where each component vaporizes and is collected separately.

In destructive distillation, complex organic substances such as coal, wood, or oil shale are transformed into simpler substances like gases, liquids, and a carbonaceous residue. With fractional distillation, each component of a homogeneous mixture is isolated without chemically altering any of the substances, often used to refine crude oil into its components like gasoline, kerosene, and diesel.

The equipment used for destructive distillation must withstand high temperatures and prevent the entry of air to avoid combustion. For fractional distillation, a fractionating column is essential to achieve the required separation of components, making use of the different boiling points to separate the mixture into fractions that condense at various levels within the column.

The purpose of destructive distillation is to decompose a substance to obtain useful by-products, while maintaining an oxygen-free environment to prevent burning. Fractional distillation aims to purify a substance or separate a mixture based on the volatility of its components, often carried out under atmospheric or reduced pressure.

Destructive distillation is characterized by chemical changes in the starting material, such as the breakdown of long hydrocarbon chains into simpler substances. Fractional distillation is a physical process, where the composition of the starting material remains unchanged, but its components are isolated based on boiling point differences.