A process for producing paraxylene is provided. The process includes separating a first mixture of C8 aromatic hydrocarbons in a simulated moving bed apparatus using a desorbent to produce (i) an extract comprising ≧50.0 wt % of the paraxylene in the first mixture; (ii) a desorbent-rich raffinate comprising ≧75 wt % of the desorbent withdrawn, and (iii) an desorbent-lean raffinate comprising ≦25 wt % of the desorbent withdrawn in the desorbent-rich and desorbent-lean raffinates. The desorbent-lean raffinate can then, without an intervening separation step, be passed to a refinery process or a vapor phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-lean raffinate. The desorbent-rich raffinate can be passed to a liquid phase isomerization reaction to produce an effluent comprising paraxylene in a greater concentration than the desorbent-rich raffinate.