Production of xylene isomer by phases of adsorption and isomerization of 8 carbon aromatic cut involves using isomerization catalyst containing EUO type zeolite

摘要

Production of the xylene isomer is maximized by the combination of an adsorption stage followed by an isomerization phase. Production of a xylene isomer from a charge comprising 8 carbon (C) aromatics comprises: (a) continuous contact in a simulated mobile bed adsorption zone of a charge containing the xylene isomer and ethylbenzene with a zeolite adsorbent bed in the presence of a desorption solvent and in conditions such as to obtain a primary fraction(containing solvent and rich in the required isomer) and a secondary fraction depleted in the isomer but comprising most of the other isomers and solvent; (b) distillation of the primary fraction to separate solvent from required isomer; (c) distillation of the secondary fraction to recover solvent and most of the other isomers;and (d) isomerization of the fraction containing the other isomers from (c) in the presence of H2 in an isomerization zone with recovery of an isomerate which is partly recycled to (a) after distillation. The process (d) is executed in the presence of a catalyst comprising a EUO zeolite and a group VIII element.