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  UOP PAREX PROCESS

The UOP Parex* process is an innovative adsorptive separation method for the recovery of para-xylene from mixed xylenes. The term mixed xylenes refers to a mixture of C8 aromatic isomers

that includes ethylbenzene para-xylene meta-xylene and ortho-xylene. These isomers boil so

closely to!ether that separatin! them by conventional distillation is not practical. The Parex process provides an efficient means of recoverin! para-xylene by usin! a solid zeolitic adsorbent

that is selective for para-xylene. Unli"e conventional chromato!raphy the Parex process

simulates the countercurrent flo# of a li$uid feed over a solid bed of adsorbent. %eed and products enter and leave the adsorbent bed continuously at nearly constant compositions. This

techni$ue is sometimes referred to as simulated  moving-bed &'() separation

  INTEGRATED UOP AROMATICS COMPLEX.

 +n a modern aromatics complex the Parex unit is located do#nstream of the xylene column and

is inte!rated #ith a UOP +somar* unit. The feed to the xylene column consists of the C8,

aromatics product from the CC* Platformin!* unit to!ether #ith the xylenes produced in the

Tatoray unit. The C8 fraction from the overhead of the xylene column is fed to the Parex unit

#here hi!h-purity para-xylene is recovered in the extract. The Parex raffinate is then sent to the+somar unit #here the other C8 aromatic isomers are converted to additional para-xylene and

recycled to the xylene column. UOP Parex units are desi!ned to recover more than / #t 0 of the para-xylene from the feed in

a sin!le pass at a product purity of . #t 0 or better. The Parex desi!n is ener!y-efficient

mechanically simple and hi!hly reliable. On-stream factors for Parex units typically exceed 1 percent.