# US 2018/0022669 A1 · Process for Xylenes Isomerization

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- Number: US 2018/0022669 A1
- Document ID: US20180022669A1
- Status: Published application
- Kind: A1
- Application number: 15/722,961
- Filed: 2017-10-02
- Published: 2018-01-25
- Earliest claimed: 2015-12-15
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: ExxonMobil Chemical Patents Inc.
- Inventors: Brian M. Weiss; Darryl D. Lacy; Scott J. Weigel
- Web page: https://patentgrep.com/patent/US20180022669A1

## CPC

- C07C 5/2737: {with crystalline alumino-silicates, e.g. molecular sieves}
- B01J 29/7046: {MTT-type, e.g. ZSM-23, KZ-1, ISI-4 or EU-13}
- B01J 35/613: {10-100 m2/g}
- C07C 4/18: Catalytic processes
- C07C 2529/40: of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
- C07C 2529/70: of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65
- Y02P 20/52: using catalysts, e.g. selective catalysts
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A process for the isomerization of a para-xylene depleted, meta-xylene rich stream under at least partially liquid phase conditions using ZSM-23 with an external surface area of at least 75 m2/g (indicating a small crystallite size), and a SiO2/Al2O3 ratio between 15 and 75 that produces a higher than equilibrium amount of para-xylene, i.e., more than about 24 wt % of para-xylene, based on the total amount of xylenes.

## Claims

### Claim 1

A process for producing para-xylene comprising contacting a feed stream comprising meta-xylene with a catalyst comprising ZSM-23 having a SiO2/Al2O3 ratio between 15 and 75 and an external surface area of at least 75 m2/g under at least partially liquid phase conditions effective to produce a first isomerized stream comprising para-xylene having a para-xylene content of more than 24 wt %, based on the total amount of xylenes in the first isomerized stream.

### Claim 2 (depends on 1)

The process of claim 1, wherein the catalyst comprises ZSM-23 having SiO2/Al2O3 ratio between 15 and 50 and an external surface area of at least 90 m2/g.

### Claim 3 (depends on 1)

The process of claim 1, wherein the catalyst is self-bound.

### Claim 4 (depends on 1)

The process of claim 1, wherein the feed stream consists essentially of meta-xylene.

### Claim 5 (depends on 1)

The process of claim 1, wherein the liquid phase conditions comprise a temperature from 400° F. (204° C.) to 1,000° F. (538° C.), a pressure of from 0 to 1,000 psig, a weight hourly space velocity (WHSV) of from 0.5 to 100 hr−1.

### Claim 6 (depends on 5)

The process of claim 5, wherein the liquid phase conditions comprise a temperature from 482° F. (250° C.) to 572° F. (300° C.), a pressure from 350 psig (2.41 MPa) to 500 psig (3.45 MPa), and a weight hourly space velocity (WHSV) from 0.5 to 10 hr−1.

### Claim 7 (depends on 1)

The process of claim 1, wherein said feed stream comprising meta-xylene is produced by:
(a) providing a C8 aromatic hydrocarbon mixture comprising para-xylene, ortho-xylene and meta-xylene to an ortho-xylene splitter;
(b) recovering a first stream comprising para-xylene and meta-xylene and a second stream comprising ortho-xylene; and
(c) recovering para-xylene from the first stream comprising para-xylene and meta-xylene in a para-xylene recovery unit.

### Claim 8 (depends on 7)

The process of claim 7, wherein the para-xylene recovery unit comprises an adsorptive separation unit or a crystallization unit.

### Claim 9 (depends on 7)

The process of claim 7, wherein the second stream comprising ortho-xylene is contacted with a catalyst comprising ZSM-5 having an alpha value of at least 300 under at least partially liquid phase conditions effective to produce a second isomerized stream and the second isomerized stream is recycled back to the ortho-xylene splitter.

### Claim 10 (depends on 7)

The process of claim 7, wherein at least a portion of the first isomerized stream is recycled back to the para-xylene recovery unit.