# US 12,215,079 B2 · Method for separating mixed xylene

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- Number: US 12,215,079 B2
- Document ID: US12215079B2
- Status: Granted
- Kind: B2
- Application number: 17/999,200
- Filed: 2021-02-03
- Published: 2023-08-17
- Granted: 2025-02-04
- Earliest claimed: 2021-02-03
- Assignees: Zhejiang University
- Applicants: Zhejiang University
- Inventors: Zongbi Bao; Liangying Li; Qilong Ren; Lidong Guo; Qiwei Yang; Zhiguo Zhang; Yiwen Yang
- Web page: https://patentgrep.com/patent/US12215079B2

## CPC

- B01D 15/1821: {Simulated moving beds}
- B01D 15/185: {characterised by the components to be separated}
- B01D 53/02: by adsorption, e.g. preparative gas chromatography {(solid sorbent compositions B01J20/00, preparation of inorganic compounds or elements C01)}
- B01J 20/226: {Coordination polymers, e.g. metal-organic frameworks [MOF], zeolitic imidazolate frameworks [ZIF] (preparation of metal complexes containing carboxylic acid moieties C07C51/418; MOF's per se C07F)}
- B01J 20/28057: {Surface area, e.g. B.E.T specific surface area}
- B01J 20/28061: {being in the range 100-500 m2/g}
- B01J 20/28078: {Pore diameter}
- B01J 20/2808: {being less than 2 nm, i.e. micropores or nanopores}
- B01J 20/3433: {of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425}
- B01J 20/3483: {by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling}
- C07C 7/12: by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
- B01D 2253/204: Metal organic frameworks (MOF's)
- B01D 2256/24: Hydrocarbons
- B01D 2257/7027: Aromatic hydrocarbons
- B01D 2259/40088: by heating
- B01J 2220/56: Use in the form of a bed
- C07C 2601/16: the ring being unsaturated
- 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

## Abstract

A method for separating mixed xylene includes steps that the mixed xylene is subjected to adsorption separation by means of an adsorbent having a metal organic framework material, so that one or more of xylene isomers are separated out. An organic ligand in the metal organic framework material is 2,5-dihydroxy-1,4-benzoquinone. Xylene isomers can be effectively separated using this method.

## Claims

### Claim 1

A method for separating mixed xylenes, comprising subjecting the mixed xylenes to adsorptive separation by an adsorbent containing a metal-organic framework material to separate one or more xylene isomers from the mixed xylenes,
wherein the metal-organic framework material comprises metal ions and an organic ligand, and wherein the organic ligand comprises 2,5-dihydroxy-1,4-benzoquinone.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the metal ions are selected from transition metal ions and alkaline earth metal ions; the mixed xylenes are in gaseous state or liquid state, and comprise two or more compounds selected from ethylbenzene, ortho-xylene, meta-xylene, and para-xylene; and the xylene isomers are one or more compounds selected from ortho-xylene, meta-xylene, and para-xylene.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the metal ions comprise one or more selected from zinc ions, manganese ions, cobalt ions, magnesium ions, vanadium ions, zirconium ions, calcium ions, molybdenum ions, chromium ions, iron ions, nickel ions, copper ions, tin ions, niobium ions, titanium ions, and scandium ions.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the metal-organic framework material has a pore size of 4 Å or more, and has a specific surface area of 300 m2/g-2000 m2/g.

### Claim 5 (depends on 4)

The method according to claim 4, wherein the metal-organic framework material has a pore size of 4 Å-15 Å.

### Claim 6 (depends on 4)

The method according to claim 4, wherein the metal-organic framework material has a pore size of 4 Å-10 Å.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed at a temperature of −5° C.-300° C.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed at a temperature of 25° C.-250° C.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed at a temperature of 30° C.-150° C.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed at a pressure of 0.01 MPa-10 MPa.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed at a pressure of 0.1 MPa-6 MPa.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed using a fixed bed, the adsorbent being packed in an adsorption column of the fixed bed.

### Claim 13 (depends on 12)

The method according to claim 12, wherein the adsorptive separation comprises the following steps:
(1) passing a mixed xylenes vapor formed by the mixed xylenes and a carrier gas through the adsorption column of the fixed bed, so that a strongly adsorbed xylene isomer in the mixed xylenes is adsorbed on the adsorbent and a weakly adsorbed xylene isomer in the mixed xylenes passes through the adsorption column, thereby obtaining the weakly adsorbed xylene isomer; and
(2) desorbing the strongly adsorbed xylene isomer from the adsorbent to obtain the strongly adsorbed xylene isomer.

### Claim 14 (depends on 1)

The method according to claim 1, wherein the adsorptive separation is performed using a simulated moving bed, the adsorbent being packed in adsorption zone beds of the simulated moving bed.

### Claim 15 (depends on 14)

The method according to claim 14, wherein the adsorptive separation comprises the following step:
(3) passing the mixed xylenes in liquid state through the liquid phase simulated moving bed for adsorptive separation, and withdrawing para-xylene, ortho-xylene, and/or meta-xylene from different beds.

### Claim 16 (depends on 13)

The method according to claim 13, wherein the mixed xylenes vapor passes through the adsorption column of the fixed bed at a flow rate of 40-200 mL/min/g adsorbent; and the simulated moving bed has 4-32 adsorbent beds and the ratio of the adsorption zone beds to the desorption zone beds is 1.0-1.5.

### Claim 17 (depends on 1)

The method according to claim 1, further comprising regenerating the adsorbent after the adsorptive separation is completed, wherein the regenerating comprises heating the adsorbent to a temperature of 50° C.-300° C. under vacuum or inert atmosphere and keeping the adsorbent at the temperature for 20-120 hours.