Uop Lcc

Gary C Anderson

Anil Rajaram Oroskar

Hermann A Zinnen

James A Johnson

Roberto E Prada

In the process flow scheme for chromatographically separating para-xylene from C.sub.8 isomers containing substantial amounts of C.sub.9 aromatic hydrocarbon impurities with BaX or KY zeolite adsorbent and heavy desorbents, e.g., tetralin and diethyltoluene, a bottoms stream from the extract fractionation column containing desorbent is recycled to the separation unit and a sidecut stream, containing C.sub.9 aromatic hydrocarbon impurities and a minor amount of the desorbent from the raffinate stream, is directed to the raffinate fractionation column, thereby removing C.sub.9 aromatic hydrocarbons from the desorbent before recycling the desorbent to the separation unit, and preventing C.sub.9 aromatics from building up in the desorbent input. A fractionator for the extract column bottoms stream is eliminated, lowering capital costs, and energy requirements for the raffinate column are reduced.

Process for separating para-xylene from a C.sub.8 and C.sub.9 aromatic

In the process flow scheme for chromatographically separating paraxylene from C.sub.8 isomers containing substantial amounts of C.sub.9 aromatic hydrocarbon impurities with an X or Y zeolite adsorbent and heavy desorbents, e.g., tetralin and derivatives thereof and diethyltoluene, a drag stream is split from the extract fractionation column bottoms stream, containing desorbent and C.sub.9 aromatic hydrocarbon impurities for recycling to the separation unit, and is directed to the raffinate fractionation column, where C.sub.9 aromatic hydrocarbons are removed to prevent C.sub.9 aromatic hydrocarbons from building up in the desorbent input to the separation unit. A fractionator for the extract column stream is eliminated, lowering capital costs.

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Clarendon Hills, IL, United States of America

Gary C Anderson