Paraxylene separation process

A process for producing paraxylene, the process comprising:

• (a) providing a first mixture comprising ≧5.0 wt % of aromatic C8 isomers, said C8 isomers comprising paraxylene, metaxylene, orthoxylene, and ethylbenzene, to a first separation stage to produce a C8 aromatics stream and a C9+ hydrocarbon stream;
• (b) separating the C8 aromatics stream in a second separation stage comprising a simulated moving bed apparatus comprising use of a desorbent to produce a paraxylene-rich extract, a desorbent-rich raffinate, and a desorbent-lean raffinate,
• wherein the paraxylene-rich extract comprises ≧50.0 wt % of the paraxylene in the first mixture,
• wherein the desorbent-rich raffinate comprises metaxylene, orthoxylene, ethylbenzene, and ≧75 wt % of the desorbent withdrawn in the desorbent-rich raffinate and the desorbent-lean raffinate, and
• wherein the desorbent-lean raffinate comprises metaxylene, orthoxylene, ethylbenzene, and ≦25 wt % of the desorbent withdrawn in the desorbent-rich raffinate and the desorbent-lean raffinate;
• (c) passing, without an intervening separation step, at least a portion of the desorbent-lean raffinate to a vapor phase isomerization reaction to produce a first reaction effluent having a higher paraxylene concentration than the desorbent-lean raffinate;
• (d) passing at least a portion of the desorbent-rich raffinate to liquid phase isomerization reaction to produce a second reaction effluent having a higher paraxylene concentration than the desorbent-rich raffinate;
• and
• (e) recycling at least a portion of the first reaction effluent from step (c) and the second reaction effluent from step (d) to the first separation stage of step (a) or the second separation stage of step (b).