Texaco Inc.

William Smolin

John H Estes

Para-xylene may be recovered as raffinate by contacting a C-8 aromatic hydrocarbon mixture, in the presence of toluene desorbent, with a synthetic crystalline lithium aluminosilicate zeolite HP (formed by ion exchange from a sodium aluminosilicate zeolite HP having a lattice constant of 25.02-25.10 .ANG.)--preferably in the presence of a pyridine.

Zeolite adsorbent for separation of para-xylene

Para-xylene may be separated as extract product by contacting charge C-8 aromatic hydrocarbon mixture with a synthetic crystalline barium or barium/potassium aluminosilicate zeolite HP, formed by ion exchange from a sodium aluminosilicate zeolite HP having a lattice constant of 25.02-25.10 .ANG. and a ratio of silicon atoms to aluminum atoms of less than 1.0.

Adsorbent for separation of para-xylene

Para-xylene may be recovered as raffinate by contacting a C-8 aromatic hydrocarbon mixture, in the presence of toluene desorbent, with a synthetic crystalline sodium aluminosilicate zeolite HP, containing pyridine in amount of at least about 3.3 wt. % of said zeolite, having a lattice constant of 25.02-25.10.ANG..

Para-xylene may be separated as front-end product in high purity by contacting charge C-8 aromatic hydrocarbon mixture with NaX-type or LiX-type zeolite in the presence of a pyridine.

Pyridine-modified Na X-type or Li X-type adsorbent characterized by its

An adsorbent may be tested at ambient temperature to determine its selectivity for one component of a charge liquid composition with respect to a reference component of the charge composition by equilbration at ambient temperature in the presence of an essentially inert liquid charge; the results determined at e.g. room temperature of e.g. 70.degree. F. are found to permit separation of xylenes at elevated temperatures of typically 340.degree. F.

Method of determining, as a property of an adsorbent, the selectivity

Para-xylene may be separated as front-end product in high purity by contacting charge C-8 aromatic hydrocarbon mixture with certain NaY-type zeolites in the presence of a pyridine.

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Fishkill, NY, United States of America

William Smolin