# US 8,569,559 B2 · Paraxylene production process and apparatus

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- Number: US 8,569,559 B2
- Document ID: US8569559B2
- Status: Granted
- Kind: B2
- Application number: 13/108,410
- Filed: 2011-05-16
- Published: 2011-12-29
- Granted: 2013-10-29
- Earliest claimed: 2010-06-25
- Assignees: ExxonMobil Chemical Patents Inc.
- Applicants: John Di-Yi Ou
- Inventors: John Di-Yi Ou
- Web page: https://patentgrep.com/patent/US8569559B2

## CPC

- B01D 3/009: {in combination with chemical reactions}
- B01J 35/45: Nanoparticles
- C07C 5/2737: {with crystalline alumino-silicates, e.g. molecular sieves}
- C07C 7/04: by distillation
- 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 7/144: using membranes, e.g. selective permeation
- B01J 29/40: of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J 35/613: {10-100 m2/g}
- B01J 2219/00006: Large-scale industrial plants
- C07C 2529/40: of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11
- Y02P 20/52: using catalysts, e.g. selective catalysts
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The invention concerns a process for the production of paraxylene and an apparatus suitable for said process. The process separates the overhead from a xylenes re-run into a xylene-rich stream and a xylene-lean stream. The xylene-lean stream is isomerized under conditions such that the xylenes are in the liquid phase.

## Claims

### Claim 1

A process for the production of paraxylene comprising:
(i) providing a first feedstream, containing xylenes including paraxylene (PX) and non-xylenes, to a xylenes separator to produce a xylenes-rich second stream characterized by an increased concentration of xylenes, relative to said first feedstream, and a xylenes-lean third stream characterized by a decreased concentration of xylenes, relative to said first feedstream;
(ii) passing said second stream to a first paraxylene separation step whereby paraxylene is separated from orthoxylene (OX) and metaxylene (MX) to produce a fourth stream characterized by an increased concentration of paraxylene, relative to said second stream, and a fifth stream characterized by a decreased concentration of paraxylene, relative to said second stream;
(iii) passing said fourth stream to a second paraxylene separation step whereby paraxylene is separated from orthoxylene, and metaxylene, to produce a sixth stream characterized by an increased concentration of paraxylene relative to the concentration of paraxylene in said fourth stream, and a seventh stream characterized by a decreased concentration of paraxylene relative to the concentration of paraxylene in said fourth stream;
(iv) passing said fifth stream to a liquid phase isomerization step whereby orthoxylene and metaxylene are isomerized to produce an eighth stream characterized by an increased concentration of paraxylene, relative to the concentration of paraxylene in said fifth stream;
(v) passing at least a portion of said eighth stream to said xylenes separator (step (i));
(vi) passing said seventh stream to a vapor phase isomerization step whereby orthoxylene and metaxylene are isomerized to produce a ninth stream characterized by an increased concentration of paraxylene relative to the concentration of paraxylene in said seventh stream;
(vii) passing said ninth stream to said xylenes separator (step (i)) wherein said first paraxylene separation step (step ii) is selected from at least one of adsorptive separation, crystallization separation, and membrane separation.

### Claim 2 (depends on 1)

The process of claim 1, wherein ethylbenzene is separated with paraxylene into said fourth stream.

### Claim 3 (depends on 1)

The process of claim 1, wherein ethylbenzene is separated with metaxylene and orthoxylene into said fifth stream.

### Claim 4 (depends on 1)

The process of claim 1, wherein said first paraxylene separation step is a vapor phase separation.

### Claim 5 (depends on 1)

The process of claim 1, wherein said first paraxylene separation step in (ii) is a liquid phase separation.

### Claim 6 (depends on 1)

The process of claim 1, wherein said liquid phase isomerization step (iv) includes a step of contacting said fifth stream with a catalyst comprising ZSM-5 characterized by one or more of the following characteristics:
the ZSM-5 is in the proton form (HZSM-5);
the ZSM-5 has a crystal size of less than 0.1 microns;
the ZSM-5 has a mesoporous surface area (MSA) greater than 45 m2/g;
the ZSM-5 has a zeolite surface area (ZSA) to mesoporous surface area (MSA) ratio of less than 9;
the ZSM-5 has a silica to alumina weight ratio in the range of 20 to 50.

### Claim 7 (depends on 6)

The process of claim 6, wherein said ZSM-5 is characterized by at least two of said characteristics.

### Claim 8 (depends on 6)

The process of claim 6, wherein said ZSM-5 is characterized by at least three of said characteristics.

### Claim 9 (depends on 6)

The process of claim 6, wherein said ZSM-5 is characterized by at least four of said characteristics.

### Claim 10 (depends on 6)

The process of claim 6, wherein said ZSM-5 is characterized by all five of said characteristics.

### Claim 11 (depends on 1)

The process of claim 1, wherein step (vi), the ninth stream is further characterized by a decrease in the concentration of ethylbenzene relative to the concentration of ethylbenzene in said seventh stream.