# US 8,273,935 B2 · Selective aromatics isomerization process

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- Number: US 8,273,935 B2
- Document ID: US8273935B2
- Status: Granted
- Kind: B2
- Application number: 13/116,762
- Filed: 2011-05-26
- Published: 2011-09-22
- Granted: 2012-09-25
- Earliest claimed: 2008-11-19
- Assignees: Uop LLC
- Inventors: James E Rekoske; Patrick C Whitchurch; Robert B Larson
- Web page: https://patentgrep.com/patent/US8273935B2

## CPC

- C07C 5/2754: {with metals}
- C07C 5/2791: {with metals}
- C07C 2521/08: Silica
- C07C 2523/40: of the platinum group metals
- C07C 2523/42: Platinum
- C07C 2523/44: Palladium
- C07C 2523/46: Ruthenium, rhodium, osmium or iridium
- C07C 2529/83: Aluminophosphates (APO compounds)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

This invention is drawn to a process for isomerizing a non-equilibrium mixture of xylenes and ethylbenzene using a catalyst comprising a zeolite having specific particle-size characteristics, a platinum-group metal and a silica binder. A relatively minimal amount of hydrogen is supplied to the process on a once-through basis, resulting in low saturation of aromatics while achieving effective xylene isomerization with reduced processing costs.

## Claims

### Claim 1

A process for the isomerization of a non-equilibrium C8-aromatic feedstock comprising contacting the feedstock with a catalyst comprising an MFI zeolitic aluminosilicate having a median particle size between 1.2 to 1.7 microns, a platinum-group metal component, and an aluminum phosphate binder in an isomerization zone at isomerization conditions comprising a temperature of from about 320° C. to 500° C., a pressure of less than about 500 kPa, and a mass hourly space velocity of from about 5 to 50 hr−1 in the presence of a critical added amount of hydrogen on a once-through basis in a molar ratio relative to the feedstock of from about 0.05 to 0.1 to obtain an isomerized product comprising a higher proportion of para-xylene than in the feedstock.

### Claim 2 (depends on 1)

The process of claim 1 wherein the platinum-group metal component consists essentially of from about 200 to about 800 mass-ppm platinum on an elemental basis.

### Claim 3 (depends on 2)

The process of claim 2 wherein the catalyst consists essentially of from about 10 to 99 mass-% of an MFI zeolitic aluminosilicate having a pore diameter of from 5 to 8 angstroms, from about 200 to 800 mass-ppm on an elemental basis of a platinum-group metal component, and the balance of said binder and has a 4.6 ton water capacity between 3 to 5 mass-%.