Xylene Isomerization Process by UOP LLC

Application: The UOP Isomar process isomerizes C8 aromatics to mixed xylenes, to maximize the recovery of paraxylene in a UOP aromatics complex. Depending on the type of catalyst used, ethylbenzene (EB) is also converted into xylenes or benzene.

Xylene Isomerization Process by UOP LLC

The Isomar process re-establishes an equilibrium distribution of xylene isomers, essentially creating additional paraxylene from the remaining ortho- and meta-xylenes. The feed typically contains less than 1 wt% of paraxylene and is first combined with hydrogen-rich recycle gas and makeup gas. The combined feed is then preheated by an exchanger (1) with reactor effluent, heated in a fired heater (2) and raised to the reactor operating temperature. The hot feed vapor is then sent to the reactor (3), where it is passed radially through a fixed-bed catalyst.

The reactor effluent is cooled by exchanger with the combined feed and then sent to the product separator (4). Hydrogen-rich gas is taken off the top of the product separator and recycled back to the reactor. Liquid from the bottom of the products separator is charged to the deheptanizer column (5). The C7– overhead from the deheptanizer is cooled and separated into gas and liquid products. The gas is exported to the fuel gas system and the liquid is sent to a debutanizer column or a stripper. The C8+ fraction from the bottom of the deheptanizer is recycled back to a xylene column.

There are two broad categories of xylene isomerization catalysts: EB isomerization catalysts, which convert ethylbenzene into additional xylenes; and EB dealkylation catalysts, which convert ethylbenzene to valuable benzene coproduct. The selection of the isomerization catalyst depends on the configuration of the UOP aromatics complex, the composition of the feedstocks and the desired product slate.

Licensor: UOP LLC, A Honeywell Company


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