Process for the separation of mixtures of aromatic hydrocarbons into single components

In a process for the separation of an aromatic hydrocarbon mixture into its single components through passage of the mixtures in the vapor phase on an adsorption bed formed of a potassium-exchanged Y zeolite, the latter being previously saturated by desorbent vapor, said aromatic hydrocarbon mixture containing either at least two xylenes or at least two xylene and ethyl benzene, the improvement comprising employing isopropylbenzene as the desorbent keeping the zeolite material bed at a temperature between 152.5.degree. C. and 250.degree. C., including treating the zeolite bed during the desorption phase with a feed of isopropylbenzene in the vapor phase which separates fractions of the pure components except for the presence of the desorbent and fractions formed of mixtures of two or more of said components in presence of the desorbent, the amount of desorbent required to effect said separation being less than the amount of toluene required to give the same separation.