# US 8,541,639 B2 · Process for producing para-xylene

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- Number: US 8,541,639 B2
- Document ID: US8541639B2
- Status: Granted
- Kind: B2
- Application number: 13/594,286
- Filed: 2012-08-24
- Published: 2012-12-27
- Granted: 2013-09-24
- Earliest claimed: 2008-12-15
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: John Di-Yi Ou; John R. Porter
- Inventors: John Di-Yi Ou; John R. Porter
- Web page: https://patentgrep.com/patent/US8541639B2

## CPC

- C07C 5/2729: {Changing the branching point of an open chain or the point of substitution on a ring}
- C07C 5/22: by isomerisation (with simultaneous hydrogenation C07C5/13; with simultaneous dehydrogenation C07C5/373)
- C07C 5/222: {with crystalline alumino-silicates, e.g. molecular sieves}
- C07C 7/12: by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
- C07C 7/14: by crystallisation; Purification or separation of the crystals
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS

## Abstract

A process for producing a PX-rich product, the process comprising: (a) providing a PX-depleted stream; (b) isomerizing at least a portion of the PX-depleted stream to produce an isomerized stream having a PX concentration greater than the PX-depleted stream and a benzene concentration of less than 1,000 ppm and a C9+ hydrocarbons concentration of less than 5,000 ppm; and (c) separating the isomerized stream by selective adsorption.

## Claims

### Claim 1

In a PX-production process where a C8 hydrocarbon rich stream is separated into a PX-rich stream and a PX-depleted stream by fractional crystallization, and where the PX-depleted stream is subsequently isomerized to increase the concentration of PX in the PX-depleted stream for subsequent separation by selective adsorption, the improvement comprising isomerizing said PX-depleted stream in the liquid phase to produce a stream having a higher PX concentration than the PX-depleted stream, a benzene concentration of less than 300 ppm, and a C9+ hydrocarbon concentration of less than 3,000 ppm.

### Claim 2 (depends on 1)

The process of claim 1, wherein said selective adsorption produces a PX-rich stream and a PX-depleted stream.

### Claim 3 (depends on 1)

The process of claim 1, wherein at least a portion of said isomerized stream is treated to remove said C9+ hydrocarbon prior to said selective adsorption.

### Claim 4 (depends on 1)

The process of claim 1, wherein at least a portion of said isomerized stream is treated to remove said benzene prior to said selective adsorption.