Process for Separating Para-Xylene from a Mixture of C8 and C9 Aromatic Hydrocarbons

A process for separating para-xylene from a feed stream comprising para-xylene, at least one other C8 aromatic, and a C9 aromatic, the process comprising:

• (a) contacting an adsorbent comprising a zeolite with the feed stream and a first desorbent stream in an adsorptive separation zone to produce an extract stream and a raffinate stream, the zeolite selected from the group of zeolites consisting of Y zeolites and X zeolites, the first desorbent stream comprising para-diethylbenzene, the extract stream comprising para-xylene, para-diethylbenzene, and the C9 aromatic, and the raffinate stream comprising para-diethylbenzene, the at least one other C8 aromatic, and the C9 aromatic;
• (b) passing the extract stream to an extract distillation zone to produce a para-xylene product stream, and a second desorbent stream comprising para-diethylbenzene and the C9 aromatic;
• (c) passing the raffinate stream to a raffinate distillation zone to produce a raffinate product stream comprising the at least one other C8 aromatic, and a third desorbent stream comprising para-diethylbenzene and the C9 aromatic;
• (d) passing at least a portion of at least one of the second desorbent stream and the third desorbent stream to a desorbent distillation zone to produce a fourth desorbent stream comprising para-diethylbenzene, and a C9 aromatic product stream comprising the C9 aromatic;
• and
• (e) recycling at least a portion of the fourth desorbent stream to step (a) as at least a portion of the first desorbent stream.