What Is Fractional Distillation?

Fractional distillation is a method of separating several mixtures with different boiling points. During the process, no new material is formed, but the original material is separated. Fractionation is the process of heating a certain mixture and cooling and separating it into a relatively pure single substance according to the different boiling points of the components in the mixture.

Fractional distillation and

Fractionation is performed with a fractionation column. After the fractionated solvent is boiled in a distillation flask, the vapor is evaporated from the round-bottomed flask into the fractionation column, and partially condensed into a liquid in the fractionation column. Because this liquid contains a lot of low-boiling components, its boiling point is lower than that of the liquid in the distillation flask. When another part of the vapor in the distillation flask rises to the fractionation column, it will exchange heat with these already condensed liquids to make it boil again, and the rising vapor itself is partially condensed, so a new one is generated. Liquid-vapor equilibrium results in an increase in low-boiling components in the vapor. When this new vapor rises in the fractionation column, it is condensed into a liquid, and then it is boiled by heat exchange with another rising vapor. As the rising vapor continually condenses and evaporates in the fractionation column, each condensation and evaporation causes the low-boiling components in the vapor to continuously increase. Therefore, during the rising process of the vapor in the fractionation column, similar to the simple distillation after repeated many times, the low-boiling components in the vapor are gradually increased.

It can be seen that the fractionation column is the key device in the fractionation process. If an appropriate fractionation column is selected, the vapors that can come out from the top of the fractionation column and the liquid obtained after condensation may be pure low-boiling components or Low boiling points account for the main component of the effluent. ^[2]