# US 10,767,027 B1 · Magnetically-recoverable catalysts for depolymerization

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- Number: US 10,767,027 B1
- Document ID: US10767027B1
- Status: Granted
- Kind: B1
- Application number: 16/656,245
- Filed: 2019-10-17
- Granted: 2020-09-08
- Earliest claimed: 2018-10-23
- Assignees: National Technology & Engineering Solutions of Sandia, LLC; The Regents of the University of California
- Applicants: National Technology & Engineering Solutions of Sandia, LLC; The Regents of the University of California
- Inventors: Jian Sun; Blake A. Simmons; Seema Singh
- Web page: https://patentgrep.com/patent/US10767027B1

## CPC

- C08J 11/28: by treatment with organic compounds containing nitrogen, sulfur or phosphorus
- B01J 23/745: Iron
- B01J 31/1691: {Coordination polymers, e.g. metal-organic frameworks [MOF] (preparation of metal complexes containing carboxylic acid moieties C07C51/418; MOF's per se C07F)}
- B01J 31/28: of the platinum group metals, iron group metals or copper
- B01J 35/33: Electric or magnetic properties
- B01J 35/45: Nanoparticles
- C08J 11/16: by treatment with inorganic material (C08J11/14 takes precedence)
- C08J 11/24: containing hydroxyl groups
- B01J 2231/005: General concepts, e.g. reviews, relating to methods of using catalyst systems, the concept being defined by a common method or theory, e.g. microwave heating or multiple stereoselectivity
- B01J 2531/002: Materials
- B01J 2531/0205: Bi- or polynuclear complexes, i.e. comprising two or more metal coordination centres, without metal-metal bonds, e.g. Cp(Lx)Zr-imidazole-Zr(Lx)Cp
- B01J 2531/26: Zinc
- C08J 2367/02: Polyesters derived from dicarboxylic acids and dihydroxy compounds; (C08J2367/06 takes precedence)
- Y02W 30/62: Plastics recycling; Rubber recycling
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates, in part, to methods for depolymerizing a polymer, in which the method includes use of a magnetic catalyst. The magnetic catalyst can include, e.g., a ore-shell particle, such as a particle having a magnetic core and a shell including a metal-organic framework.

## Claims

### Claim 1

A method for depolymerizing a polymer, the method comprising:
providing the polymer and a reactant in the presence of a magnetic catalyst, wherein the magnetic catalyst comprises a magnetic core and a shell comprising a metal-organic framework;
incubating the polymer and the magnetic catalyst at an elevated temperature, thereby forming a monomer within a reaction mixture; and
applying a magnetic field, thereby separating the magnetic catalyst from the monomer and the reactant, if any.

### Claim 2 (depends on 1)

The method of claim 1, wherein the polymer comprises poly(ethylene terephthalate) (PET), poly (ethylene terephthalate)-glycol (PETG), poly(trimethylene terephthalate) (PTT), poly(propylene terephthalate) (PPT), poly(butylene terephthalate) (PBT), poly(cyclohexylene terephthalate), poly(cyclohexylenedimethylene terephthalate) (PCT), or a copolymer thereof.

### Claim 3 (depends on 1)

The method of claim 1, wherein the reactant comprises an alcohol or a diol.

### Claim 4 (depends on 1)

The method of claim 1, wherein a ratio of the reactant to the polymer is of from about 1:1 (w/w) to about 4:1 (w/w).

### Claim 5 (depends on 1)

The method of claim 1, wherein the magnetic core comprises an iron oxide.

### Claim 6 (depends on 5)

The method of claim 5, wherein the magnetic core comprises an anionic surface.

### Claim 7 (depends on 1)

The method of claim 1, wherein the magnetic core comprises an iron oxide particle, a mixed metal oxide particle, a metal-decorated iron oxide particle, reduced metal particle, or a metal alloy particle.

### Claim 8 (depends on 7)

The method of claim 7, wherein the metal-organic framework comprises a zeolitic imidazolate framework.

### Claim 9 (depends on 1)

The method of claim 1, wherein the magnetic catalyst comprises a core-shell nanoparticle or a core-shell microparticle.

### Claim 10 (depends on 1)

The method of claim 1, wherein the magnetic core comprises a nanoparticle.

### Claim 11 (depends on 1)

The method of claim 1, wherein a ratio of the magnetic catalyst to the polymer is of from about 1:10 (w/w) to about 1:80 (w/w).

### Claim 12 (depends on 1)

The method of claim 1, wherein the magnetic catalyst is present in an amount of from about 0.5 wt. % to about 10 wt. %.

### Claim 13 (depends on 1)

The method of claim 1, wherein the elevated temperature is of from about 150° C. to about 250° C.

### Claim 14 (depends on 13)

The method of claim 13, wherein the incubating step is conducted for a period of from about 1 hour to about 6 hours.

### Claim 15 (depends on 1)

The method of claim 1, wherein a magnetic flux density of the magnetic field is of from about 100 Gs to about 20,000 Gs.

### Claim 16 (depends on 1)

The method of claim 1, wherein the monomer comprises a terephthalate, a hydroxyalkyl terephthalate, or a bis(hydroxyalkyl) terephthalate.

### Claim 17 (depends on 1)

The method of claim 1, further comprising, prior to the applying step:
adding a solvent to the reaction mixture.

### Claim 18 (depends on 17)

The method of claim 17, wherein the solvent comprises an aqueous solvent.

### Claim 19

A method for depolymerizing a polymer, the method comprising:
providing a first polymer and a reactant in the presence of a magnetic catalyst, wherein the magnetic catalyst comprises a magnetic core and a shell comprising a metal-organic framework;
incubating the first polymer and the magnetic catalyst at an elevated temperature, thereby forming a first monomer within a reaction mixture;
applying a magnetic field, thereby separating the magnetic catalyst from the first monomer and the reactant, if any; and
reusing the magnetic catalyst to depolymerize a second polymer, wherein the first polymer and the second polymer is the same or different.

### Claim 20

A method for depolymerizing a polymer, the method comprising:
providing a first polymer and a reactant in the presence of a magnetic catalyst, wherein the magnetic catalyst comprises a magnetic core and a shell comprising a metal-organic framework;
incubating the first polymer and the magnetic catalyst at an elevated temperature, thereby forming a first monomer within a reaction mixture;
adding a solvent to the reaction mixture;
applying a magnetic field, thereby separating the magnetic catalyst from the first monomer and the reactant, if any; and
reusing the magnetic catalyst to depolymerize a second polymer, wherein the first polymer and the second polymer is the same or different.