The first snapshot shows the compositions in the still of methanol, 1-propanol, and 1-hexanol in red, blue, and green, respectively. It is clear that methanol in the still is being depleted. By contrast, the 1-propanol composition increases. At the end of the operation, only 1-hexanol and 1-propanol are present.

The second snapshot shows the composition in the distillate. The lighter component (methanol) distills first (see red curve). The solute is the highest-boiling chemical species and remains in the apparatus, as indicated by the green curve.

If you decrease the reflux ratio (see the third snapshot), the distillation operation is conducted faster and the solvent swap is more rapidly achieved. You can also vary the number of stages of the column and observe that the lower the number of stages, the sloppier the separation. Finally, it is possible to see how the still's volume and the molar flow rate of the stream of 1-propanol vary with time. As an extension of the present calculation, one can find: (1) the required time to replace 99.9% of methanol with 1-propanol; and (2) the volume of 1-propanol needed to swap 99.9% of the original solvent.