Magnetically-recoverable catalysts for depolymerization
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.
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.
2. 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.
3. The method of claim 1 , wherein the reactant comprises an alcohol or a diol.
4. 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).
5. The method of claim 1 , wherein the magnetic core comprises an iron oxide.
6. The method of claim 5 , wherein the magnetic core comprises an anionic surface.
7. 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.
8. The method of claim 7 , wherein the metal-organic framework comprises a zeolitic imidazolate framework.
9. The method of claim 1 , wherein the magnetic catalyst comprises a core-shell nanoparticle or a core-shell microparticle.
10. The method of claim 1 , wherein the magnetic core comprises a nanoparticle.
11. 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).
12. The method of claim 1 , wherein the magnetic catalyst is present in an amount of from about 0.5 wt. % to about 10 wt. %.
13. The method of claim 1 , wherein the elevated temperature is of from about 150° C. to about 250° C.
14. The method of claim 13 , wherein the incubating step is conducted for a period of from about 1 hour to about 6 hours.
15. 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.
16. The method of claim 1 , wherein the monomer comprises a terephthalate, a hydroxyalkyl terephthalate, or a bis(hydroxyalkyl) terephthalate.
17. The method of claim 1 , further comprising, prior to the applying step:
adding a solvent to the reaction mixture.
18. The method of claim 17 , wherein the solvent comprises an aqueous solvent.
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.
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.