WO2024146827A1 - Catalysts for polyethylene terephthalate degradation - Google Patents
Catalysts for polyethylene terephthalate degradationInfo
- Publication number
- WO2024146827A1 WO2024146827A1 PCT/EP2023/087315 EP2023087315W WO2024146827A1 WO 2024146827 A1 WO2024146827 A1 WO 2024146827A1 EP 2023087315 W EP2023087315 W EP 2023087315W WO 2024146827 A1 WO2024146827 A1 WO 2024146827A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pet
- ppm
- textile
- source
- process according
- Prior art date
Links
- -1 polyethylene terephthalate Polymers 0.000 title claims abstract description 35
- 239000003054 catalyst Substances 0.000 title description 72
- 229920000139 polyethylene terephthalate Polymers 0.000 title description 6
- 239000005020 polyethylene terephthalate Substances 0.000 title description 6
- 230000015556 catabolic process Effects 0.000 title description 4
- 238000006731 degradation reaction Methods 0.000 title description 4
- QPKOBORKPHRBPS-UHFFFAOYSA-N bis(2-hydroxyethyl) terephthalate Chemical compound OCCOC(=O)C1=CC=C(C(=O)OCCO)C=C1 QPKOBORKPHRBPS-UHFFFAOYSA-N 0.000 claims abstract description 96
- 238000000034 method Methods 0.000 claims abstract description 95
- 239000004753 textile Substances 0.000 claims abstract description 76
- 229920000742 Cotton Polymers 0.000 claims abstract description 74
- 230000008569 process Effects 0.000 claims abstract description 74
- 239000004744 fabric Substances 0.000 claims abstract description 54
- 150000001875 compounds Chemical class 0.000 claims abstract description 49
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 144
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 72
- 239000001569 carbon dioxide Substances 0.000 claims description 71
- 150000001412 amines Chemical class 0.000 claims description 57
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 44
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 38
- 239000000463 material Substances 0.000 claims description 38
- 229910052751 metal Inorganic materials 0.000 claims description 24
- 239000002184 metal Substances 0.000 claims description 24
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical group [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 23
- 239000001099 ammonium carbonate Substances 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 19
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 18
- 239000000126 substance Substances 0.000 claims description 17
- VHYFNPMBLIVWCW-UHFFFAOYSA-N 4-Dimethylaminopyridine Chemical compound CN(C)C1=CC=NC=C1 VHYFNPMBLIVWCW-UHFFFAOYSA-N 0.000 claims description 16
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 15
- 229910021529 ammonia Inorganic materials 0.000 claims description 13
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 11
- 229920000297 Rayon Polymers 0.000 claims description 10
- 229910052739 hydrogen Inorganic materials 0.000 claims description 10
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 10
- RWRDLPDLKQPQOW-UHFFFAOYSA-N Pyrrolidine Chemical compound C1CCNC1 RWRDLPDLKQPQOW-UHFFFAOYSA-N 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 9
- RAXXELZNTBOGNW-UHFFFAOYSA-N imidazole Natural products C1=CNC=N1 RAXXELZNTBOGNW-UHFFFAOYSA-N 0.000 claims description 9
- KKEYFWRCBNTPAC-UHFFFAOYSA-L terephthalate(2-) Chemical compound [O-]C(=O)C1=CC=C(C([O-])=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-L 0.000 claims description 9
- 125000000484 butyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 8
- 125000001495 ethyl group Chemical group [H]C([H])([H])C([H])([H])* 0.000 claims description 8
- 125000000959 isobutyl group Chemical group [H]C([H])([H])C([H])(C([H])([H])[H])C([H])([H])* 0.000 claims description 8
- 125000001449 isopropyl group Chemical group [H]C([H])([H])C([H])(*)C([H])([H])[H] 0.000 claims description 8
- 150000002739 metals Chemical class 0.000 claims description 8
- 125000001436 propyl group Chemical group [H]C([*])([H])C([H])([H])C([H])([H])[H] 0.000 claims description 8
- 150000003839 salts Chemical class 0.000 claims description 7
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 6
- GLUUGHFHXGJENI-UHFFFAOYSA-N Piperazine Chemical compound C1CNCCN1 GLUUGHFHXGJENI-UHFFFAOYSA-N 0.000 claims description 6
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 6
- KWIUHFFTVRNATP-UHFFFAOYSA-N glycine betaine Chemical compound C[N+](C)(C)CC([O-])=O KWIUHFFTVRNATP-UHFFFAOYSA-N 0.000 claims description 6
- 239000004814 polyurethane Substances 0.000 claims description 6
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 5
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 5
- 235000012501 ammonium carbonate Nutrition 0.000 claims description 5
- 229920002635 polyurethane Polymers 0.000 claims description 5
- ICSNLGPSRYBMBD-UHFFFAOYSA-N 2-aminopyridine Chemical compound NC1=CC=CC=N1 ICSNLGPSRYBMBD-UHFFFAOYSA-N 0.000 claims description 4
- DHMQDGOQFOQNFH-UHFFFAOYSA-N Glycine Chemical compound NCC(O)=O DHMQDGOQFOQNFH-UHFFFAOYSA-N 0.000 claims description 4
- OAKJQQAXSVQMHS-UHFFFAOYSA-N Hydrazine Chemical compound NN OAKJQQAXSVQMHS-UHFFFAOYSA-N 0.000 claims description 4
- YNAVUWVOSKDBBP-UHFFFAOYSA-N Morpholine Chemical compound C1COCCN1 YNAVUWVOSKDBBP-UHFFFAOYSA-N 0.000 claims description 4
- LOUPRKONTZGTKE-WZBLMQSHSA-N Quinine Chemical compound C([C@H]([C@H](C1)C=C)C2)C[N@@]1[C@@H]2[C@H](O)C1=CC=NC2=CC=C(OC)C=C21 LOUPRKONTZGTKE-WZBLMQSHSA-N 0.000 claims description 4
- PXIPVTKHYLBLMZ-UHFFFAOYSA-N Sodium azide Chemical compound [Na+].[N-]=[N+]=[N-] PXIPVTKHYLBLMZ-UHFFFAOYSA-N 0.000 claims description 4
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 claims description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 3
- 229920000433 Lyocell Polymers 0.000 claims description 3
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 3
- 239000004202 carbamide Substances 0.000 claims description 3
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 claims description 3
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 3
- QVCUKHQDEZNNOC-UHFFFAOYSA-N 1,2-diazabicyclo[2.2.2]octane Chemical compound C1CC2CCN1NC2 QVCUKHQDEZNNOC-UHFFFAOYSA-N 0.000 claims description 2
- DCXYFEDJOCDNAF-UHFFFAOYSA-N Asparagine Natural products OC(=O)C(N)CC(N)=O DCXYFEDJOCDNAF-UHFFFAOYSA-N 0.000 claims description 2
- 235000001258 Cinchona calisaya Nutrition 0.000 claims description 2
- 239000004471 Glycine Substances 0.000 claims description 2
- DCXYFEDJOCDNAF-REOHCLBHSA-N L-asparagine Chemical compound OC(=O)[C@@H](N)CC(N)=O DCXYFEDJOCDNAF-REOHCLBHSA-N 0.000 claims description 2
- KDXKERNSBIXSRK-YFKPBYRVSA-N L-lysine Chemical compound NCCCC[C@H](N)C(O)=O KDXKERNSBIXSRK-YFKPBYRVSA-N 0.000 claims description 2
- 239000004472 Lysine Substances 0.000 claims description 2
- KDXKERNSBIXSRK-UHFFFAOYSA-N Lysine Natural products NCCCCC(N)C(O)=O KDXKERNSBIXSRK-UHFFFAOYSA-N 0.000 claims description 2
- 229920000877 Melamine resin Polymers 0.000 claims description 2
- 229960001230 asparagine Drugs 0.000 claims description 2
- 235000009582 asparagine Nutrition 0.000 claims description 2
- XYOVOXDWRFGKEX-UHFFFAOYSA-N azepine Chemical compound N1C=CC=CC=C1 XYOVOXDWRFGKEX-UHFFFAOYSA-N 0.000 claims description 2
- LOUPRKONTZGTKE-UHFFFAOYSA-N cinchonine Natural products C1C(C(C2)C=C)CCN2C1C(O)C1=CC=NC2=CC=C(OC)C=C21 LOUPRKONTZGTKE-UHFFFAOYSA-N 0.000 claims description 2
- 239000012973 diazabicyclooctane Substances 0.000 claims description 2
- 239000004312 hexamethylene tetramine Substances 0.000 claims description 2
- 235000010299 hexamethylene tetramine Nutrition 0.000 claims description 2
- 235000018977 lysine Nutrition 0.000 claims description 2
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 2
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 claims description 2
- 229960000948 quinine Drugs 0.000 claims description 2
- SBYHFKPVCBCYGV-UHFFFAOYSA-N quinuclidine Chemical compound C1CC2CCN1CC2 SBYHFKPVCBCYGV-UHFFFAOYSA-N 0.000 claims description 2
- IMNIMPAHZVJRPE-UHFFFAOYSA-N triethylenediamine Chemical compound C1CN2CCN1CC2 IMNIMPAHZVJRPE-UHFFFAOYSA-N 0.000 claims description 2
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 claims 1
- 229920000642 polymer Polymers 0.000 abstract description 19
- 239000000178 monomer Substances 0.000 abstract description 14
- 239000002699 waste material Substances 0.000 abstract description 12
- 229920003023 plastic Polymers 0.000 abstract description 11
- 239000004033 plastic Substances 0.000 abstract description 11
- 238000004064 recycling Methods 0.000 abstract description 11
- 229920000728 polyester Polymers 0.000 abstract description 10
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- XOJVVFBFDXDTEG-UHFFFAOYSA-N Norphytane Natural products CC(C)CCCC(C)CCCC(C)CCCC(C)C XOJVVFBFDXDTEG-UHFFFAOYSA-N 0.000 abstract description 4
- 230000001131 transforming effect Effects 0.000 abstract description 2
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 107
- 238000006243 chemical reaction Methods 0.000 description 80
- 230000034659 glycolysis Effects 0.000 description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 33
- 229910001868 water Inorganic materials 0.000 description 30
- 239000000047 product Substances 0.000 description 28
- 239000000758 substrate Substances 0.000 description 26
- 230000003197 catalytic effect Effects 0.000 description 25
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 21
- 239000002585 base Substances 0.000 description 21
- 238000005809 transesterification reaction Methods 0.000 description 18
- 238000006555 catalytic reaction Methods 0.000 description 14
- 239000011541 reaction mixture Substances 0.000 description 14
- LKUDPHPHKOZXCD-UHFFFAOYSA-N 1,3,5-trimethoxybenzene Chemical compound COC1=CC(OC)=CC(OC)=C1 LKUDPHPHKOZXCD-UHFFFAOYSA-N 0.000 description 12
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 12
- 239000007858 starting material Substances 0.000 description 12
- PSHKMPUSSFXUIA-UHFFFAOYSA-N n,n-dimethylpyridin-2-amine Chemical compound CN(C)C1=CC=CC=N1 PSHKMPUSSFXUIA-UHFFFAOYSA-N 0.000 description 10
- GETQZCLCWQTVFV-UHFFFAOYSA-N trimethylamine Chemical compound CN(C)C GETQZCLCWQTVFV-UHFFFAOYSA-N 0.000 description 10
- 235000013361 beverage Nutrition 0.000 description 9
- 238000001914 filtration Methods 0.000 description 9
- 240000001624 Espostoa lanata Species 0.000 description 8
- 235000009161 Espostoa lanata Nutrition 0.000 description 8
- 238000005481 NMR spectroscopy Methods 0.000 description 8
- 239000012535 impurity Substances 0.000 description 7
- 239000000376 reactant Substances 0.000 description 7
- 238000001228 spectrum Methods 0.000 description 7
- 238000002425 crystallisation Methods 0.000 description 6
- 230000008025 crystallization Effects 0.000 description 6
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 6
- 238000011084 recovery Methods 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- 239000002904 solvent Substances 0.000 description 6
- 238000002411 thermogravimetry Methods 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 5
- 229910007339 Zn(OAc)2 Inorganic materials 0.000 description 5
- 230000008901 benefit Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 238000000921 elemental analysis Methods 0.000 description 5
- 125000004494 ethyl ester group Chemical group 0.000 description 5
- 239000000706 filtrate Substances 0.000 description 5
- 239000012299 nitrogen atmosphere Substances 0.000 description 5
- 239000012041 precatalyst Substances 0.000 description 5
- 239000002243 precursor Substances 0.000 description 5
- DJWUNCQRNNEAKC-UHFFFAOYSA-L zinc acetate Chemical compound [Zn+2].CC([O-])=O.CC([O-])=O DJWUNCQRNNEAKC-UHFFFAOYSA-L 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 239000004743 Polypropylene Substances 0.000 description 4
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 4
- 238000011109 contamination Methods 0.000 description 4
- DQYBDCGIPTYXML-UHFFFAOYSA-N ethoxyethane;hydrate Chemical compound O.CCOCC DQYBDCGIPTYXML-UHFFFAOYSA-N 0.000 description 4
- 238000005457 optimization Methods 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 230000035484 reaction time Effects 0.000 description 4
- 238000012216 screening Methods 0.000 description 4
- 239000011701 zinc Substances 0.000 description 4
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 3
- 239000005977 Ethylene Substances 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- UEEJHVSXFDXPFK-UHFFFAOYSA-N N-dimethylaminoethanol Chemical compound CN(C)CCO UEEJHVSXFDXPFK-UHFFFAOYSA-N 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 3
- 239000004793 Polystyrene Substances 0.000 description 3
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 description 3
- 238000013459 approach Methods 0.000 description 3
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 3
- 230000009977 dual effect Effects 0.000 description 3
- 150000002148 esters Chemical class 0.000 description 3
- 229910001385 heavy metal Inorganic materials 0.000 description 3
- 238000004128 high performance liquid chromatography Methods 0.000 description 3
- 238000002329 infrared spectrum Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 125000004492 methyl ester group Chemical group 0.000 description 3
- 230000000269 nucleophilic effect Effects 0.000 description 3
- 238000000879 optical micrograph Methods 0.000 description 3
- 229920002647 polyamide Polymers 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 238000012667 polymer degradation Methods 0.000 description 3
- 230000008092 positive effect Effects 0.000 description 3
- 238000000746 purification Methods 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- 239000004246 zinc acetate Substances 0.000 description 3
- 238000004566 IR spectroscopy Methods 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 239000002879 Lewis base Substances 0.000 description 2
- 229920000459 Nitrile rubber Polymers 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 239000004676 acrylonitrile butadiene styrene Substances 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- JQVDAXLFBXTEQA-UHFFFAOYSA-N dibutylamine Chemical compound CCCCNCCCC JQVDAXLFBXTEQA-UHFFFAOYSA-N 0.000 description 2
- 230000035622 drinking Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 150000007529 inorganic bases Chemical class 0.000 description 2
- 150000007527 lewis bases Chemical class 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 229920001223 polyethylene glycol Chemical class 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 239000004800 polyvinyl chloride Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 150000003384 small molecules Chemical class 0.000 description 2
- 241000894007 species Species 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
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- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 2
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 1
- 238000005160 1H NMR spectroscopy Methods 0.000 description 1
- 244000025254 Cannabis sativa Species 0.000 description 1
- 235000012766 Cannabis sativa ssp. sativa var. sativa Nutrition 0.000 description 1
- 235000012765 Cannabis sativa ssp. sativa var. spontanea Nutrition 0.000 description 1
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 1
- 238000006000 Knoevenagel condensation reaction Methods 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 229920002334 Spandex Polymers 0.000 description 1
- XECAHXYUAAWDEL-UHFFFAOYSA-N acrylonitrile butadiene styrene Chemical compound C=CC=C.C=CC#N.C=CC1=CC=CC=C1 XECAHXYUAAWDEL-UHFFFAOYSA-N 0.000 description 1
- 229920000122 acrylonitrile butadiene styrene Polymers 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 230000009435 amidation Effects 0.000 description 1
- 238000007112 amidation reaction Methods 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- IMNFDUFMRHMDMM-UHFFFAOYSA-N anhydrous n-heptane Natural products CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000005815 base catalysis Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 235000009120 camo Nutrition 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 235000005607 chanvre indien Nutrition 0.000 description 1
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- 238000000354 decomposition reaction Methods 0.000 description 1
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- 230000001627 detrimental effect Effects 0.000 description 1
- 150000004985 diamines Chemical class 0.000 description 1
- ONIHPYYWNBVMID-UHFFFAOYSA-N diethyl benzene-1,4-dicarboxylate Chemical compound CCOC(=O)C1=CC=C(C(=O)OCC)C=C1 ONIHPYYWNBVMID-UHFFFAOYSA-N 0.000 description 1
- 150000002009 diols Chemical group 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 125000004185 ester group Chemical group 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
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- 239000005431 greenhouse gas Substances 0.000 description 1
- 239000011487 hemp Substances 0.000 description 1
- 239000008241 heterogeneous mixture Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000003317 industrial substance Substances 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 229960004592 isopropanol Drugs 0.000 description 1
- 239000010985 leather Substances 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 238000010907 mechanical stirring Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000001404 mediated effect Effects 0.000 description 1
- 238000006140 methanolysis reaction Methods 0.000 description 1
- QPJVMBTYPHYUOC-UHFFFAOYSA-N methyl benzoate Chemical compound COC(=O)C1=CC=CC=C1 QPJVMBTYPHYUOC-UHFFFAOYSA-N 0.000 description 1
- 238000000386 microscopy Methods 0.000 description 1
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Abstract
The present invention has been made within the field of plastic/polymer recycling and relates to a process for transforming e.g. end-of-use/waste PET polymer (a very common polyester) into a commonly used and pure monomer compound (e.g. BHET), which can re-enter the production of "pristine" PET, i.e. PET with similar or the same quality as non-recycled PET. Furthermore, the present invention can be used to recover both BHET and textile e.g. cotton from PET/textile blended fabric.
Description
CATALYSTS FOR POLYETHYLENE TEREPHTHALATE DEGRADATION
Technical field of the invention
The present invention has been made within the field of chemistry, more specifically plastic/polymer recycling and relates to a process for transforming e.g. end-of-use polyethylene terephthalate (PET) polymer into a commonly used monomer compound such as bis(hydroxyethyl)terephthalate (BHET), which can re-enter the production of pristine PET, i.e. PET with similar or equal quality as non-recycled PET. Furthermore, the present invention can be used to recover both BHET and textile, such as cotton, from blended fabrics.
Background of the invention
Synthetic polymers are amongst the greatest polluting concerns preventing sustainable growth of human society. Worldwide polymer production (ca. 348 million metric tons world production in 2017) has grown exponentially throughout the years. Polyethylene terephthalate (PET) is one of the most produced polymers - approximately 70 million metric tons per year and it is expected to grow more than 4% annually. PET-based polymers are mainly used in beverage bottles, while a third of the produced PET is blended with cotton-based fibers and viscose to produce fabrics for the textile industry. Consequently, recycling of these composite materials including beverage bottle wastes becomes an urgent societal issue. Chemical upcycling - also referred to as chemical recycling, monomer production and chemical decomposition - of plastic wastes has been an attractive option to produce higher-value products while avoiding additional greenhouse gas emission and negative environmental impact from energy recovery in waste incinerators.
Catalytic glycolysis and transesterification of PET bottles is an atom-economic approach affording the useful intermediate BHET (bis(hydroxyethyl)- terephthalate), which can be recycled as a precursor for producing PET via polymerization. Lewis acidic metals have been employed commercially in these reactions as a catalyst at high reaction temperatures (160 - 220 °C) to overcome the high reaction barrier and to accelerate solubilization of PET (Figure 1A). Metal- catalyzed PET glycolysis can be exemplified with the catalysts Zn(OAc)2, Ti(IV)
phosphate, and Mn(OAc)2 which show satisfactory performance (see for example: M.Ghaemy et al., Polymer Degradation and Stability, Volume 90, Issue 3, December 2005, Pages 570-576). Although these catalytic systems exhibit high efficiency, only a few protocols can be implemented in generating high purity BHET due to the metal contamination, thus, requiring tedious purification steps of crystallization of BHET, reducing compatibility of produced BHET in repolymerization to PET.
Contamination with heavy metals is a significant issue in polymerization of BHET obtained from the above methods in terms of yield and appearance of the PET polymers. Metal contamination of e.g. cotton in depolymerization of PET in mixed PET-cotton fabrics is also an issue for these methods. Organocatalysis may present a solution to such problems, and has been studied in this regard.
For example, WO 2015/056377 discloses a process for converting PET to BHET using various organic amine bases, such as for example trimethylamine (TEA), ethylene glycol at 220 °C and 20 psi pressure (Example 3, page 21). No source of CO2 is applied. High ratios of BHET to PET oligomers are reported in the depolymerization product. This method however has the disadvantage of using more toxic and costly amine catalysts, and harsher conditions including pressure and/or temperature) to obtain the yields reported.
Hence, an improved method of converting PET back to its monomer component BHET or useful derivatives thereof would be advantageous, and in particular a more high-yielding, environmentally friendly and facile method for producing BHET monomers from PET, and for separating PET from other textiles in blended fabrics would be advantageous.
Summary of the invention
Thus, an object of the present invention is to provide a method for producing BHET monomer or derivatives thereof from end-of-use/waste PET material, with the aim of providing a monomer that may produce recycled PET of similar quality as non-recycled PET.
In particular, it is an object of the present invention to provide a method that solves the above mentioned problems of the prior art with metal contaminants and undesired pigmentation of BHET from depolymerized PET and the resulting recycled PET material, while avoiding the use of toxic bases and high pressure and/or temperature.
Thus, a first aspect of the present invention is a process for chemical depolymerisation of poly(ethylene)terephthalate (PET) comprising the steps of: a) providing a material comprising PET; b) mixing the material comprising PET from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating the mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
Another aspect of the present invention is a process for separating poly(ethylene)terephthalate (PET) and a textile from a blended fabric comprising PET and textile, said process comprising the steps of:
a) providing a blended fabric comprising textile and PET; b) mixing the blended fabric from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating said mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
and textile; e) separating the compound of formula (II) and textile of said product of step d); wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
The present inventors have surprisingly found that these processes provides for BHET derivatives in high yields from the starting PET material, and is tolerant to the presence of many other materials in the reaction mixture, while allowing for easy separation of the product from the catalyst and solvents used.
Brief description of the figures
Figure 1 shows (A) an overview depiction of prior art chemical recycling of PET via glycolysis using metal catalysts, and (B) the CO2 and NHs-catalyzed chemical recycling of drinking bottles and textile wastes used in the present invention.
Figure 2A shows NP HCOs-catalytic transesterification of ethyl esters 1 to ethylene glycol esters 3 using ethylene glycol 2a, as compared to the same reaction with no catalyst. Yields in black are the NP HCOs-catalytic transesterification, while yields in parentheses are without catalyst. bMethyl benzoate was used as a starting material. Reactions performed at 150 °C with 25 mol% catalyst. NH4HCO3 Catalysed yields are shown to be significantly better than with no catalyst.
Figure 2B shows NP HCOs-catalytic transesterification of ethyl esters la to esters 3a-k using ethylene glycol and PEG derivatives 2a-k. NMR yields of the product is shown in percentages unless otherwise indicated. The results illustrates the substrate flexibility in terms of the compound of formula (I).
Figure 3A shows an exemplary reaction scheme for the catalytic depolymerisation of PET and recovery of cotton.
Figure 3B shows the reaction progress for ethylene glycolysis of PET polyester (75%) in the presence of cotton with* and without® catalyst (NH4HCO3) at 180 °C and 190 0 respectively. The catalysed reaction proceeds very well even at 180 °C- 190 °C, while the un-catalysed reaction provides below 50% yield after 6 h.
Figure 4A shows chemical recycling of PET/textile blended fabrics on a large scale from garments and furniture material. Glycolysis is performed with fabrics having 47-100% PET, showing optical images and yield percentages of recovered cotton/textile materials and BHET. Reactions show excellent recovery of textile and good yields of BHET.
Figure 4B shows Solid-state 13C NMR analysis of the recovered cotton from a reaction with NH4HCO3 (fourth panel from the top), without NH4HCO3 (third panel from the top), commercial cotton ball (second panel from the top) and the
starting material (first panel from the top). It is seen that the spectrum for recovered cotton is similar to that of commercial cotton balls.
Figure 4C shows optical microscope images of recovered cotton from reaction with NH4HCO3 (right panel) and recovered cotton from reaction with Zn2+ (left panel) at at 20 times, 40 times and 80 times magnification. The superior quality of cotton recovered from the method of the present invention is clearly visible.
Figure 4D shows optical microscope images of a commercial cotton ball (top, left panel), the starting material (top, right panel), recovered cotton from reaction without (bottom, left panel) and with NH4HCO3 (bottom, right panel). Improved removal of PET fibres is visible for the reaction of the present invention.
Figure 5A shows thermal-gravimetric analysis (TGA) results from chemical recycling of cotton from PET/cotton blended fabrics. TGA measurements with commercial cotton ball (solid line, *), residue after catalytic reaction with (solid line, K) and without (solid line, #) NH4HCO3, and starting material cloth (solid line, ^); In dashed lines: the corresponding DTG spectra. It is clear that the recovered cotton of catalysed reactions provides spectra similar to a commercial cotton ball, while textile from un-catalysed reaction is more similar to starting material.
Figure 5B shows infra-red spectroscopy of recovered cotton after depolymerisation of blended fabrics using NH4HCO3 (*), commercial cotton (M), starting material (75% polyester, 25% cotton) (#) and residual after a reaction without the NH4HCO3 catalyst
It is shown that the IR spectrum of recovered cotton from the catalysed reaction is close to the spectrum for commercial cotton.
Figure 6 shows the result of catalysed reaction on a mixture of a PET/cotton blended fabric and separately a number of other plastics/polymers. The reaction provides excellent yields of recovered cotton and BHET, while remaining plastics are not degraded and can be removed by filtration.
Figure 7A shows the BHET yields from glycolysis of PET using bases, such as Zinc Acetate (Zn(OAc)2), Sodium Hydroxide (NaOH), Triethylamine (TEA), and Ammonium Bicarbonate (NH4HCO3).
Figure 7B shows recovered substrates from glycolysis of PET using bases, such as Zinc Acetate (Zn(OAc)2), Sodium Hydroxide (NaOH), Triethylamine (TEA), and Ammonium Bicarbonate (NH4HCO3).
The present invention will now be described in more detail in the following.
Detailed description of the invention
Definitions
Prior to discussing the present invention in further details, the following terms and conventions will first be defined:
Depolymerisa tion
In the present context depolymerisation is the process of producing monomer units or precursors/derivatives thereof, from the polymer formed when these monomers are polymerised. As polymers are insoluble in most solvents depolymerisation happens partly in a heterogeneous mixture between polymer and reactants/solvent, which becomes more homogenous as the polymer is converted to oligomers and eventually single small molecules.
Poly( ethylene)terephthalate
In the present context polyethylene terephthalate, commonly abbreviated PET or PETE, is a polymer with a repeating unit of formula (a):
PET is the most common polymer of the polyester family. PET is a clear, strong, and lightweight plastic that is widely used for packaging foods and beverages. The
basic building blocks of PET are ethylene glycol (HO-CH2CH2-OH) and terephthalic acid, which are combined to form the repeating unit of the polymer chain.
Mixing
In the present context mixing is the basic process of bringing starting materials, reactants, catalyst and any other materials into contact with each other while agitating the mixture, typically by mechanical stirring, although other types of agitation may be used. The mixture subject to mixing may in the broadest sense be a solid mixture, a suspension of solids in liquids, or a solution. In the present context the mixture obtained will often be a suspension of PET in a solvent with reactants either dissolved or also in suspension. As depolymerization occurs, the PET will slowly dissolve as oligomers and eventually monomers.
Material comprising PET
In the present context the material comprising PET may essentially be any material with any amount of PET comprised. As the present method may both be used to isolate non-PET material from PET or PET monomer precursors (or both). The invention is relevant for material comprising small amounts of PET (such as some blended fabrics, or waste with some fraction of PET) and virtually pure PET starting material (such as isolated end-of-use PET from e.g. municipal waste).
Source of carbon dioxide
CO2 is a catalyst of the process of the present invention. Thus, in the present context, a source of carbon dioxide (CO2) is any such source, that can provide CO2 molecules under the reaction conditions of the present process. The source of CO2 may be CO2 as such, but preferably, the source is an easy to use solid or liquid pre-catalyst chemical, which releases CO2 under the reaction conditions. The source of CO2 may at the same time the source of other reactants, such as amine. Ammonium bicarbonate salt (NH4HCO3) is an example of a combined source of amine (NH3) and CO2.
Source of amine
Amine is a catalyst of the process of the present invention. Thus, in the present context, a source of amine is any such source, that can provide suitable amine molecules (such as NH3) under the reaction conditions of the present process. The
source of amine may be the amine as such, but preferably, the source is an easy to use solid or liquid pre-catalyst chemical, which releases the amine under the reaction conditions. Ammonia derivatives are also suitable sources of amine. The source of amine may at the same time the source of other reactants, such as CO2. Ammonium bicarbonate salt (NH4HCO3) is an example of a combined source of amine (NH3) and CO2.
Amine
In the present context, the amine is any amine capable of catalyzing the depolymerization reaction (transesterification) of the present invention. Nucleophilic and/or basic amines are preferred to catalyze the process.
Bis(hydroxyethyl)terephthalate ( BHET)
Bis(hydroxyethyl)terephthalate, abbreviated as BHET is an important industrial chemical, which is used as a precursor monomer of PET, but also has other applications. Bis(hydroxyethyl)terephthalate is a compound of formula (b):
Textile
In the present context textile is any textile that may be combined with polyester fabric such as PET fabrics. Common textiles in this category includes cotton and viscose. Textile may also comprise other materials that are compatible or do not interfere with the process of the present invention. The textiles are often polymers, which are either natural (cotton, hemp) or synthetic (other polyesters, polyurethane, viscose, and others).
Blended fabric
In the present context a blended fabric is a fabric comprising two or more fabrics types, i.e. PET and one or more textiles as defined above. Other materials may also be comprised (e.g. leather, rubber, metal (zippers, buttons), as long as they are not detrimental to the process of the present invention.
The present inventors have witnessed that CO2 can be an active, highly accessible, inexpensive, traceless and safe catalyst for organic transformation. Also, without being bound to theory, the presence of nucleophilic amines under transamidation conditions suggested the role of amines and CO2 in the activation of carbonyl functional groups: a nucleophilic and basic amine together with Lewis- and Brondsted acidic CO2 (in the form of carbonic acid) thus mediating dual catalysis. Therefore, the inventors report their investigation on transesterification of esters, PET bottles, PET-cotton blended fabrics to illustrate the advantage of catalytic CO2 together with amine as an additional base catalyst (Figure IB).
Thus, a first aspect of the present invention is a process for chemical depolymerisation of poly(ethylene)terephthalate (PET) comprising the steps of: a) providing a material comprising PET; b) mixing the material comprising PET from step a) with a source of carbon dioxide, a source of amine or nitrogen, and a compound of formula (I):
c) heating the mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
PET-based polymers are mainly used in beverage bottles, while a third of the produced PET is blended with cotton-based fibers and viscose to produce fabrics for the textile industry. Thus, in an embodiment the material comprising PET of step a) is selected from the group consisting of plastic bottles, plastic packaging, and a textile comprising PET, preferably plastic bottles or a textile comprising PET.
Although the present process is useful for any amount of PET in the material comprising PET, for producing BHET, it is advantage that the starting material has a high PET content. Therefore, in one embodiment, the material comprising PET comprises at least 30% of PET, such as at least 40% of PET, such as at least 60% of PET, such as at least 80% of PET, such as at least 90% of PET, such as at least 95% of PET, most preferably at least 99% of PET.
Carbon dioxide and amine are the catalysts of the present process. Without being bound to theory, both these catalysts interact with the ester groups of the PET polymer and nucleophiles (alcohols and amines), to activate these for transesterifaction or amidation with the compound of formula (I).
In an embodiment, the source of amine or nitrogen is selected from the group consisting of pyridine, ammonium, ammonia, imidazole, hydrazine, morpholine, 4- dimethylaminopyridine (DMAP), piperazine, ethanolamine (MEA), ethylenediamine (EDA), triethylamine (TEA), /V-butylamine, di-/V-butylamine, pyrrolidine, triazabicyclodecene (TBD), quinine, /V-Me-morpholine, and trimethylglycine (TMG), glycine, lysine, hexamethylenetetramine, asparagine, sodium azide, melamine, l,4-diazabicyclo[2.2.2]octane (DABCO), urea, 2,3,4,6,7,8,9,10- Octahydropyrimido[l,2-a]azepine (DBU), potassium cyanide, sodium cyanide, 2- aminopyridine, and quinuclidine, or any combination thereof.
In a preferred embodiment, the source of amine is selected from the group consisting of pyridine, ammonium, ammonia, imidazole, 4-dimethylaminopyridine (DMAP), piperazine, /V-butylamine, pyrrolidine, and trimethylglycine (TMG), or any combination thereof.
In one embodiment, the source of amine is selected from the group consisting of ammonium, ammonia and 4-dimethylaminopyridine (DMAP), preferably ammonium.
Using a source of carbon dioxide is important for the optimal performance of the present invention. The source of carbon dioxide may preferably be in the form of a solid pre-catalyst, and in one embodiment the source of carbon dioxide is selected from the group consisting of carbonate, bicarbonate and carbon dioxide, preferably bicarbonate.
In a preferred embodiment, the source of carbon dioxide and the source of amine is combined in a single source of carbon dioxide and amine. Said single source of carbon dioxide and amine may be selected from the group consisting of ammonium bicarbonate or ammonium carbonate, preferably ammonium bicarbonate. Both ammonium carbonate and ammonium bicarbonate are tested in example 2 and are both effective.
The present inventors employed ammonium bicarbonate salt (NH4HCO3) as an inexpensive pre-catalyst (10-25 mol% loading), which can easily decompose to CO2, ammonia, and water at above 36 °C (eq. 1).
36°C NH4HCO3 co2 + NH3 + H2O eq. 1
These reaction conditions offer practical and mild conditions for all tested wastes and recycled to generate high purity BHET, while selectively preserving cotton fabrics in the case of textile wastes.
Sub-stoichiometric amount of catalyst is sufficient to effectively provide good yields in the present process, and thus the single source of carbon dioxide and amine may be added in catalytic amounts as compared to PET, such as in the
range of 5-40 mol%, preferably 10-40 mol%, more preferably 15-30 mol%, most preferably 20-30 mol%.
The compound of formula (1) may be a polyethylene glycol (n = 2-10, X = O, R = OH), and may also be a hydroxyethyl amine [n = 1, X = O, R = NfR1^], or a diamine [n = 1, X = NR2, R = NfR1^]. In a preferred embodiment, the compound of formula (I) is ethylene glycol (n = 1, X = O, R = OH). Ethylene glycol is added in excess and may also function as solvent and/or suspending agent for PET and other reactants. Ethylene glycol may be added in 5-40 mol equivalents to the PET, preferably 10-30, more preferably 15-30, most preferably 20-30 mol equivalents to the PET.
In yet another embodiment, the amine (stemming from the source of amine) is NH3. AS with carbon dioxide, ammonia becomes gaseous, facilitating easy removal from products, whereas using a metal-based catalyst such as ZnC result in metal impurity of the final product.
In an embodiment, the process is performed with less than 20 wt% of water, such as less than 15 wt% of water, preferably less than 10 wt% of water, more preferred less than 5 wt% of water, most preferred less than 1 wt% of water relative to the total reaction.
In another embodiment, the process is performed essentially without water.
In the glycolysis of PET-based beverage bottles, a wide range of different temperatures are applicable, and may vary according to reactants used and other parameters such as the time of heating. Thus, in an embodiment, the temperature of step c) is within the range of 150°C to 200°C, preferably 160°C to 200°C, more preferably 170°C to 200°C, most preferably 180°C to 200°C. Since, cellulose of cotton, which can be a constitute of the blended fabrics comprising PET, begins to degrade at 200°C, an embodiment of the present invention relates to that the temperature of step c) does not exceed 200°C. In an embodiment, the reaction mixture is kept at the temperature of step c) for at least three hours, such as within the range of 3-24 hours, preferably at least 4 hours, more preferably at least 5 hours, most preferably at least 6 hours. In another
embodiment, the reaction mixture is agitated, such as stirred, during at least step c).
The compounds of formula (II) may be varied between the most common PET precursor BHET, but also to PEGylated derivatives and amine/amide derivatives in accordance with formula (II) which may have other applications.
In one embodiment, R1 is H or methyl, preferably H, and in another embodiment, R2 is H or methyl, preferably H. In another embodiment, X is O and/or R is OH. In yet another embodiment, n is 1-8, such as 1-6, 1-4, 1-3, 1-2, preferably 1. In the most preferred embodiment, the compound of formula (II) is bis(hydroxyethyl)- terephthalate (BHET).
High yields of the compound of formula (II) may be achieved in the process of the present invention. Thus, in an embodiment, the yield of the compound of formula (II) is at least 60% as compared to PET, preferably at least 70%, more preferably at least 80%, most preferably at least 90% as compared to PET.
Using metal salts as a catalyst results in metal impurities in the final product, whereas the same impurities are not observed for the process of the present invention. Thus, in an embodiment, the product comprising the compound of formula (II) comprises trace metals or salts thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm, such as preferably 10 ppm.
After catalysis according to the present depolymerization process, CO2 can easily be evaporated, while the amine catalyst is also easily removable using various approaches. As the method leaves no traces as a catalyst and works well below 200 °C, the present inventors envisioned that am ine/CC -cata lyzed glycolysis of PET could be a practical and scalable approach, particularly as the method is selective for depolymerization of PET from blended fabrics with e.g. cotton. Cotton-based materials pose a significant challenge in chemical recycling due to the labile glycosidic bonds.
Thus, another aspect of the present invention is a process for separating poly(ethylene)terephthalate (PET) and a textile from a blended fabric comprising PET and textile, said process comprising the steps of: a) providing a blended fabric comprising textile and PET; b) mixing the blended fabric from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating said mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
and textile; e) separating the compound of formula (II) and textile of said product of step d); wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
Blended fabrics may be sourced from several industries including the clothing and furniture industries. Thus, in an embodiment, the blended fabric is selected from the group consisting of garments, furniture covers, carpets and curtains. The blended fabric comprising PET can contain varies other textiles. Hence, in an embodiment, the textile of step a) is selected from the group consisting of cotton,
viscose, lyocell, polyurethane or a mixture thereof. The present process is able to depolymerize PET while keeping cotton fibres intact, and thus a preferred textile is cotton. In another embodiment, the ratio between the textile and PET is in the range of 10: 1 to 1: 10, such as 3: 1 to 1: 3, 2: 1 to 1:2, preferably 3: 1 to 1: 1, most preferably 2: 1 to 1: 1. The present process is highly selective and other components may be present apart from textile and PET. That said, separation of BHET and textile is generally easier in the absence of further components, and thus in one embodiment, the blended fabric consists of PET and textile, i.e. essentially without the presence of further components.
Since the cellulose fibres of cotton, which can be a constituent of the blended fabrics comprising PET, begins to degrade at 200°C, an embodiment of the present invention relates to, that the temperature of step c) does not exceed 200°C.
The optimised yields of textile in the process of the invention are good due to the relatively mild reaction conditions. Thus, in a preferred embodiment, the textile yield is at least 60%, preferably at least 70%, more preferably at least 80%, most preferably at least 90%. Another advantage of the present process is the lack of metal catalyst, which may often reside in the textile and PET after the process. Therefore, the product comprising the compound of formula (II) and/or the textile may preferably comprises trace metals or salts thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm such as preferably 10 ppm.
There are a number of ways known to the skilled person to separate the textile and the compound of formula (II) according to the present process. These processes may be adjusted and optimised also according to whether further components are present, and the physical characteristics of the compound of formular (II). Often the compound of formula (II) will be dissolved in the solvent used (e.g. the compound of formula (I)) and therefore filtration is possible.
Hence, in an embodiment, the compound of formula (II) and the textile are separated using filtration, preferably hot filtration.
The textile may be further purified a number of ways known to the skilled individual or adapted therefrom. In an embodiment, the textile is further purified by washing with a composition selected from water, organic solvent, surfactants, and any mixture thereof. More specifically, the cotton residual obtained through the process of the present invention was washed with water, ethanol, and diethyl ether. Hence, in an embodiment, the textile is washed with water, ethanol and diethyl ether. The compounds of formula (II) may be further isolated and purified using standard methods for small molecules, such as e.g. BHET, which may be crystallized. Thus, in an embodiment, the compound of formula (II) is further purified using a method selected from the group consisting of crystallization and column chromatography, preferably crystallization. In yet another embodiment, the blended fabric is added to the reaction as part of a composition also comprising further polymers.
It should be noted that embodiments and features described in the context of one of the aspects of the present invention also apply to the other aspects of the invention. In particular, the embodiments described for the first aspect relating to a process for chemical depolymerisation of PET also apply mutatis mutandis to the aspect related to separating (PET) and a textile from a blended fabric.
All patent and non-patent references cited in the present application, are hereby incorporated by reference in their entirety.
The invention will now be described in further details in the following non-limiting examples.
EXAMPLES
Example 1 - NFhHCOs-catalyzed transesterification reactions with ethylene glycol and derivatives thereof
Aim of study
The aim of this study was to establish a metal-free transesterification protocol by investigating the compound yields obtained by different transesterification reactions using ethylene glycol (Figure 2A) and derivatives thereof (Figure 2B). The reactions were catalysed by NH4HCO3 or performed without a catalyst under N2 atmosphere to investigate whether NH4HCO3 was a suitable catalyst for the transesterification reactions.
Materials and methods
A vial (8 ml) equipped with a magnet was charged with ester (1.0 mmol), alcohol (10.0 mmol, 10 equiv.) and ammonium bicarbonate (12-25 mol%). The vial was stirred at 130-150 °C and conversion was detected by analyzing aliquot samples NMR spectroscopy. After full conversion, the reaction mixture was directly subjected to silica gel chromatography to isolate the desired product.
Results
Ethylene glycolysis was tested with model substrates (methyl- and ethylesters, 1) to confirm the applicability of the process in depolymerization (Figure 2A).
Catalytic amounts of NH4HCO3 (12-25 mol%) enabled a transesterification reaction of methyl- or ethylesters (1) with ethylene glycol (2a, 10 equiv.) under mild reaction conditions (80-150 °C) affording the desired glycolysis products (3). The tested transesterification substrates were not reactive in the absence of the catalyst (percentages in grey in figure 2A); only trace amounts of products were observed under nitrogen atmosphere (up to 28 % conversion detected
NMR spectroscopic analysis of reaction mixtures). Under catalytic conditions, good to high yields ranging from 19% to 91% (percentages in black in figure 2A) of ethylene glycol esters were obtained regardless of the electronic properties of the substrates. Diethyl terephthalate, Im, employed as a model substrate for PET depolymerization, and the catalytic conditions afforded a reasonable isolate yield (57%) of BHET (3m) at 80°C while producing a mono-substituted product (36%) (3m'), implying approximately quantitative conversion of substrate Im (full conversion
NMR analysis). Encouraged by this result, the inventors further
investigated whether the NH4HCO3 catalyst where applicable in the transesterification of other ethylene glycol derivatives namely oligo(ethylene glycol) 2a-2k, which can produce thermoresponsive polymers (Figure 2B). With higher catalyst loading at an elevated temperature (25 mol%, 150 °C), the methodology afforded the selective mono-esterification products with moderate isolated yields (up to 55% isolated yield (2c)). 2-(Dimethylamino)ethan-l-ol (2h) afford moderate yield of the transesterification product. On the contrary, monomethyl ether equivalents (2e-2g) showed no substantially lower conversion, manifesting the importance of the diol functional group in the catalytic transesterification reaction: polarity, hydrogen bonding donor ability, dipole moments are important in the activation of carbonyls.
Conclusion
The transesterification of methyl- and ethylesters with ethylene glycol was more effective when NI- HCOs was used as a catalyst i.e. the compound yield of the different model substrates were higher (19-91%) as compared to the compound yield without a catalyst under N2 atmosphere (<l-28%). In addition, transesterification could be performed using derivatives of ethylene glycol specifically oligo(ethylene glycol) and 2-(Dimethylamino)ethan-l-ol.
Example 2 - Optimization of reaction conditions for glycolysis of PET- based beverage bottles
Aim of study
After establishing a metal-free transesterification protocol, the inventors turned their attention to PET substrates to generate monomer BHET. Further optimization of glycolysis was necessary to provide practical reaction conditions to access high purity BHET. It is important to note that minor metal impurities derived from catalysts and pre-treatment processes impose lower quality of recycled PET thus lowering the value of the whole recycling process. The aim of this study was therefore to optimize the reaction conditions for glycolysis of PET beverage bottles by changing the equivalents of ethylene glycol and CO2, the catalyst used, and the reaction temperature.
Materials and methods
A vial (8 ml, or 250 ml_ round bottom flask when the reaction is scaled up) equipped with a magnet was charged with PET substrate (2.0 mmol), ethylene glycol (25 equiv.) and a catalyst. The vial was stirred at 150 - 200 °C for 6-24 h. The XH NMR-yields were detected with aliquot samples in DMSO-cfe with 1,3,5- trimethoxybenzene as an internal standard. To determine conversion and yields of BEHT, reaction mixture was filtered to remove oligomers, unreacted and remaining PET substrate. To the filtrate, water was added to precipitation out BHET at 4 °C. The crystalline BHET was washed with cold water and diethyl ether to remove excess ethylene glycol, and dried to determine the isolated yield of BHET.
Results
The inventors conducted an intensive optimization of reaction conditions with drinking bottles as depolymerization substrate for glycolysis with various catalytic systems with and without the use of CO2 (Table 1). The inventors first confirmed that no background glycolysis was performed without catalysts (150-200 °C, table 1; entry 1). The use of CO2 in catalytic amounts (15 -30 mol%) and as a reaction atmosphere (1 atm) showed no effects without a catalyst (table 1; entry 2). The addition of the catalyst DMAP (30 mol%) afforded a higher yield of BHET (44%, table 1; entry 4) than when DMAP was employed without CO2 (24%, table 1; entry 3). This set of experiments confirmed the positive effect of CO2 in depolymerization of PET using DMAP as a catalyst (30 mol%).
Table 1:
aYield of BHET was determined by 1H NMR spectroscopy in DMSO-de with 1,3,5- trimethoxybenzene as an internal standard. b Reaction time was extended to 24 h.
The inventors further optimized the equivalent of ethylene glycol (EG) used in the reaction; a BHET yield of 40% was obtained with 10 equivalents of EG ( table 1; entry 5). Next, the inventors further optimized the conditions aiming for a higher conversion to BHET, assuming the recovery of EG is trivial due to the high boiling point of EG. When the inventors replaced the DMAP/CO2 combination with NH4HCO3, higher yields were obtained with 10-25 equivalents of EG (table 1; entries 6 and 7). This optimization led to an 84% yield of BHET highlighting the exclusive selectivity towards the monomer at 180 °C after 6 hours of reaction time. This reaction was further tested in a larger scale (50 mmol, 9.6 grams of waste PET bottles, table 1; entry 8) affording high selectivity and isolated yield of high purity BHET (>70% yield, up to 99.8% HPLC purity) without any sophisticated purification since all catalytically active species were evaporated. The advantage of this protocol is that the BHET product was crystalized from the filtrate after hot filtration by adding cold deionized water (6%, V/V). Considering that vacuum distillation was required after methanolysis of PET, this method showcased advantages in terms of energy economy of CO2- catalyzed catalytic glycolysis. Once again, the same reaction in the absence of the catalyst showed negligible conversion (7% by XH NMR spectroscopic analysis of the reaction mixture), highlighting the utility of CO2 and ammonia in catalytic glycolysis. Ammonium bicarbonate (NH4HCO3) has been utilized as a catalyst in a Knoevenagel condensation, which would decompose at the high reaction temperatures to generate NH3 and CO2 in situ to act as acid and base catalysts (see eq. 1 above).
Since, metal catalyst have previously been used in PET glycolysis, representative Zn-based Lewis acidic catalysts were tested herein. Zn(OAc)2 (table 1; entries 10 and 11) showed low to good yields of BHET, however, elemental analysis of the isolated BHET showed significant metal impurity (data not shown), presumably due to the residual zinc. The effect of ammonium carbonate (NH^COs (table 1; entry 12) was comparable to that of the ammonium bicarbonate catalyst, affording good yields of BHET (87% yield, table 1; entry 12), while strong inorganic bases (KOH, NazCOs, and NaOH) led to the contamination of BHET with the hydrolysis product, terephthalic acid, TPA (data not shown).
The reactions were repeated at a larger scale (2-50 g PET) with a fixed equivalence of ethylene glycol (25 equiv.) at 180 °C for 6 h (unless otherwise indicated) using the catalysts listed in table 2. Isolated yields were also determined for BHET.
Table 2:
a Reaction conditions: PET bottle substrate (0.2-50 g); a catalyst and ethylene glycol were added with a magnetic stirring bar, and the via! was heated for 6 h; Conversion (%) = (Woiigomers+BHEr/WpETbotties)X100, 1/1/ = weight. The reaction mixture was diluted with water to precipitate oligomers and BHET, which was crystalized to determine the yield of isolated BHET. b Reaction time extended to 24 h.
There was no background glycolysis in the absence of catalysts, even at prolonged reaction times (up to 24 h, at 150-200 °C). The use of CO2 in catalytic amounts (15-30 mol%) and as a reaction atmosphere (1 atm) showed no effects (Table 2; Entry 1). Well-known Zn-based Lewis acidic catalysts for glycolysis, e.g., Zn(OAc)2 and ZnC (Table 2; Entries 2 and 3), showed low to good conversion to BHET - 44% and 75%, respectively. However, an elemental analysis of the isolated BHET using the same purification sequence (hot filtration and crystallization) often showed various degrees of metal impurity (data not shown), presumably because of the residual zinc ions. The employment of orga nocatalyst DMAP (30 mol%) under N2 conditions afforded 63% conversion and 46% isolated yield of BHET (Table 2; Entry 4). The addition of catalytic amounts of CO2 (30 mol%) resulted in higher conversion and yield of BHET (Table 2; Entry 5) than when DMAP was used alone, confirming the positive effect of CO2 in glycolysis.
The catalytic NH4HCO3 showed an activity comparable to that of metal catalysts (Table 2; Entries 6 and 7), achieving a >50% isolated yield of BHET from a single crystallization step. A hot filtration, followed by a single crystallization operation with cold DI water (6%, V/V), afforded BHET in high purity (up to 99.8% HPLC purity), since all catalytic species and glycol could easily be removed (data not shown). The effect of ammonia as a sole catalyst (in water and methanol), without CO2, was inferior to that of NH4HCO3 (Table 2; Entry 8) confirming dual catalysis with CO2 and ammonia is critical to achieve optimal performance in catalytic glycolysis. Under optimized conditions, a larger scale (260 mmol, 50 grams of waste PET bottle substrate), quantitative conversion of PET with 51% selectivity toward BHET in 64% isolated yield was achieved (Table 2; Entry 9). It should be noted here that, under the tested catalytic conditions, there was no formation of cyclic carbonate or urea from the catalytic species and ethylene glycol.
Conclusion
Dual catalysis with ammonia or ammonium and CO2 is critical to achieve an optimal performance in catalytic glycolysis of PET-based beverage bottles. The ZnC catalyst was also effective in the depolymerisation of PET, however, a significant metal impurity was observed by elemental analysis of the isolated BHET, presumably due to the residual zinc. Hence, a source of ammonium or ammonia and carbon dioxide are very effective catalysts for depolymerisation of PET yielding high percentages of "pristine" PET, i.e. PET with similar or the same quality as non-recycled PET.
Example 3 - Glycolysis of PET in blended fabrics
Aim of study
After successfully applying the method in chemical recycling of PET waste bottles (example 2), the inventors attempted to test the reaction conditions for blended fabrics. The aim of this study was therefore to investigate different reaction conditions for depolymerisation of PET in blended fabrics and the concomitant recovery of cotton in a PET:cotton blended fabric.
Materials and methods
A vial (40 ml) equipped with a crossed magnet was charged with textile substrate (2.0 g of polyester), ethylene glycol (25 equiv., 15.8 mL) and ammonium bicarbonate (25 mol%). The vial was stirred at 160 - 190 °C for 6-24 h. The control experiments were performed without ammonium bicarbonate but under a N2 atmosphere. The XH NMR-yields were detected by analyzing aliquot samples in DMSO-cfe with 1,3,5-trimethoxybenzene as an internal standard. The reaction mixture was filtered while still hot to remove solid residues and insoluble oligomers, and then washed with 5 mL of water. The combined filtrate was cooled down to 4 °C, to crystalize BHET. The purity of BHET was confirmed by HPLC (conditions: column: Kromasil 5-AmyCoat (4.6 x 250 mm), iso- propanol/n- heptane (60/40, v/v), 0.5 mL/min, 8.9 MPa, detector A: 220 nm, detector B: 254 nm.)
Results
The inventors identified NH5HCO3 as an optimal catalyst affording high XH NMR yields of BHET from blended fabric (62% polyester, 33% viscose, 5% elastane
wt% based on the tag of the merchandise) and quantitative yields of recovered cotton (Figure 3A). Time-dependent yields of BHET was plotted over 6 h of a reaction illustrating the positive effect of catalysis (Figure 3B). In the absence of the catalyst and under a N2 atmosphere, lower conversion to BHET was recorded. Higher reaction temperatures (at 190 °C, full circles) showed higher yields of BHET under catalytic and non-catalytic conditions as compared to lower temperatures (at 180°C), while the reaction with the catalyst (25 mol%) was far superior achieving a higher yield of BHET as compared to the reaction without the catalyst (Figure 3B).
Next, recovery of cotton from PET/cotton blended fabric was investigated. The labile nature of glycosidic bonds of cotton materials should be taken into consideration when selective PET depolymerization is a desired process in parallel. To avoid acid and base-mediated hydrolysis of cotton materials, it is important to mediate the depolymerization under mild and neutral conditions to afford recycled cotton for textile industry and others. The inventors analyzed reaction mixtures under catalytic conditions to inspect polymer degradation degrees over time. Also the recovered cotton residues were analyzed by optical microscope, thermal gravimetric analysis (TGA), infrared spectroscopy, solid-state NMR spectroscopy and elemental analysis. During large-scale glycolysis of PET/cotton blended fabrics both BHET and cotton were recovered (Figure 4A). For the glycolysis of a T-shirt containing 75% PET with a 71% conversion, a yield of 47% BHET and 92% cotton and viscose were recovered. For the glycolysis of a sofa cover (213 g of textile with 47% polyester and 53% cotton), a yield of 62% BHET and 94% cotton was recovered. The residues recovered from the reaction without catalyst showed identical signals compared to the starting material, which is in accordance with the NMR yield detected by XH NMR spectroscopy (Figure 4B). On the other hand, the residual sample obtained from the reaction mixture with the catalyst displayed similar signals compared to a commercial cotton ball without signals detected from 130 to 163 ppm (aromatic signals and carbonyls from PET) indicating the full degradation of PET while displaying 13C signals responsible for cotton (Figure 4B). It is clear from the optical microscope images of figure 4C that cotton recovered using the NH4HCO3 catalyst is more comparable to the images of the substrate than when the cotton is recovered with Zn2+ glycolysis i.e. the recovered cotton of the present invention is more "pristine" than the cotton recovered using Zn2+ glycolysis (Figure 4C). Considering the further utilization of cotton and BHET, the
inventors confirmed traceless NH4HCO3 showcased more practical application in large scale, when compared to heavy metal catalysis, for example ZnC , due to the catalyst vestigial, which was detected by the elemental analysis of the recovered cotton and BHET (data not shown). In addition, the inventors noticed that the selective depolymerisation was realized using NH4HCO3, while heavy metal catalysts would cause cotton degradation. Microscopy at 80 times revealed that residual recovered after reaction with catalyst showed only cotton fiber similar to that of commercial cotton ball (Figure 4D).
According to the thermal gravimetric analysis, identical one-step mass losses were detected with the commercial cotton ball (solid line, *) and the residue isolated after catalytic reaction (solid line, M), suggesting the selective degradation of polyester from the textile (Figure 5A). Reasonably, similar two-step mass losses were observed for the starting material (solid line,
and the residue recovered after glycolysis without the catalyst NH4HCO3 (solid line, #). The corresponding DTG spectrums are shown in dash lines. The first mass loss (25% to 30% respectively) could be assigned to the decomposition of cotton (15% viscose and 10% cotton). The infra-red spectrum of recovered cotton (*) is close to the spectrum for commercial cotton (M), whereas the IR spectrum for residual recovered without the NH3HCO3 catalyst
resembles the spectrum of the starting material (#) (Figure 5B).
Conclusion
The process of the present invention can be used to effectively recover BHET and cotton from PET/cotton blended fabrics, with no trace metals in the products and high yields.
Example 4 - Depolymerisation of PET in blended fabrics with additional components present in the material comprising PET
Aim of study
To determine the selectivity of the reaction towards PET in the presence of various other components, and to see whether BHET and textile can be isolated from the resulting mixture.
Materials and methods
Trash mimicking glycolysis with 42.7 g of blended fabric (PET:cotton = 75:25 wt% based on the tag of the merchandise) and ethylene glycol (25 equiv.) were performed by following the procedure described in Example 3 with the following components further added to the reaction mixture: polypropylene, lego, polyyurethane, polystyrene, acrylonitrile butadiene rubber (NBR), acrylonitrile butadiene styrene (ABS), hair, polyamide (PA), polyethylene (PE), styrene-ethylene-butylene-styrene (SEBS), polyoxomethylene (POM), polyvinylchloride (PVC), polypropylene (PP), polystyrene (PS), and polyurethane (PU).
Results
The inventors mixed several plastic materials (PVC, PP, PE, polyamide, PS, ABS, POM, and SEBS, PU) to mimic realistic, daily use, plastic waste, and demonstrate the selective glycolysis of PET (Fig. 7). Under standard reaction conditions, we obtained a 23% yield of BHET after recrystallization, and of 75 % of recovered cotton, while the other plastic materials were collected with some deformation, but without clear signs of chemical depolymerization. The formation of precatalyst NH4HCO3 during the course of the reaction was confirmed, and the catalyst recovered by simple sublimation.
Conclusion
The process of the present invention can be used selectively in the presence of several other types of waste and chemicals, and textile and BHET can be isolated.
Example 5 - Depolymerization of PET by applying different base catalysts Aim of study
The aim of this study was to investigate whether other base catalysts or other sources of amines could be used to depolymerize PET in PET-based beverage bottles.
Materials and methods
Vials (8 ml) equipped with a magnet were charged with PET substrate (1.0 mmol), ethylene glycol (25 equiv.), a base additive and CO2. The vials were either sealed with N2 or vacuum sealed after which CO2 was added to some vials (see table 3
for more details). The vials were stirred at 180 °C for 6 h. The XH NMR-yields were detected with aliquot samples in DMSO-cfe with 1,3,5-trimethoxybenzene as an internal standard. To determine conversion and yields of BHET, reaction mixture was filtered to remove oligomers, unreacted and remaining PET substrate. To the filtrate, water was added to precipitation out BHET at 4 °C. The crystalline BHET was washed with cold water and diethyl ether to remove excess ethylene glycol, and dried to determine the isolated yield of BHET.
Results An examination of various organic and inorganic bases revealed that the conversion of PET to BHET is related to the pKa values of the base catalysts (Table 3). Maximum conversion was achieved with weak bases (approx. pKa = 6) in the presence of 25 mol% of CO2.
These results suggest that the glycolysis reaction mechanism follows a general base catalysis, highlighting the crucial role of catalytic CO2 in reactions involving weak bases, especially ammonia— derived from NH4HCO3 through thermal decomposition. These results also indicates that several different sources of amine could be used to depolymerize PET as described in the present invention.
Table 3:
aNMR-yields detected in DMS0-d6 with 1,3,5-trimethoxybenzene as an internal standard.
Conclusion This example demonstrates that several different sources of amine could be used in combination with carbon dioxide to depolymerize PET.
Example 6 - Base Screening of different Lewis bases for glycolysis of PET- Blended Textiles
Aim of study
The aim of this study was to investigate whether other base catalysts or other sources of amines could be used to depolymerize PET in PET-blended textiles.
Materials and methods
Two vials (40 ml) were equipped with crossed magnets and were charged with PET-blended textile (1 g) with a ratio of 65% PET and 35% Cotton, ethylene glycol (25 equiv., 6.65 ml_) and various bases (25 mol%). The first vial was sealed with N2 and the other was vacuum sealed after which 25 mol% of CO2 was added, and the vials were stirred at 180 °C for 6 h.
The reaction mixture was filtered while still hot to remove solid residues and insoluble oligomers, as well as to separate the remaining fabric. This was then washed with an appropriate amount of water to remove any remaining product and ethylene glycol. The recovered substrate after filtering was left to dry overnight to remove any residual ethylene glycol. The combined filtrate was cooled down in ice to crystallize BHET. The crystallized BHET was collected by performing another filtration. Both the BHET and recovered substrate were weighed to get the yields.
Results
From the results observed in the base screening of PET bottles in example 5, the bases showing the best BHET yields were chosen to be used in the screening for PET-Blended textiles. Some under N2, some under 25 mol% CO2, and some under both. Various criteria were considered such as high yields of BHET, color of recovered substrate, and condition of recovered substrate (Table 4). Some yields of the recovered substrate were found to be above 100% but this is either due to the fact that all of the ethylene glycols had not evaporated or that all of the PET present in the textile was not converted.
Bases like sodium hydroxide and sodium cyanide decolored the fabric to a high extent which is not favorable. The best yields of BHET (66%) and color of recovered substrate was noticed with di-n-butylamine. The reaction with zinc chloride showed the overall best yield of BHET with 78% but it degraded the
cotton to such an extent that only white flakes were recovered. The reaction with NH4HCO3 showed a yield of 27%. The relatively low yield compared with what was observed in example 3 can be explained by the fact that this reaction was only run for 6 hours. In previous work, yields of 70% were observed when the reaction was run overnight, with good quality of recovered substrate. Exemplary pictures of the BHET yields and recovered substrates are shown in figure 7A and 7B, respectively, for the bases zinc acetate, sodium hydroxide, triethylamine, and ammonium bicarbonate. Table 4: Base Screening of different Lewis bases for glycolysis of PET-blended Textile.
Conclusion
This example demonstrates that several different sources of amine could be used in combination with carbon dioxide to depolymerize PET and recover BHET and textile in PET-blended textiles.
Example 7 - Glycolysis of PET Bottles with the presence of water
Aim of study
The aim of this study was to investigate the resistance of the glycolysis reaction to water.
Materials and methods
To 4 vials (8 ml_) equipped with magnets, 1 mmol of PET was added along with 25 equivalents of ethylene glycol, and 25 mol% of the catalyst. Next, 1, 5, or 10 wt% of H2O was added to separate vials and the reaction was conducted at 180 °C for 6 hours. The XH NMR-yields were detected by analyzing aliquot samples in DMSO- d6 with 1,3,5-trimethoxybenzene as an internal standard.
Results
To test the resistance of the reaction to the presence of water, the reaction was conducted by adding different wt% of H2O to it. It is clear from Table 5 that the reaction works best with little to no water. There is a drastic shift in the yields with the addition of more water, but the yields are still moderately good with the addition of up to 10 wt% of water.
Table 5: Glycolysis of PET Bottles with presence of varying wt% of water
Conclusion
This example demonstrates that glycolysis of PET bottles according to the present invention can be performed in the presence of water, preferably below 10 wt% of water.
References
• M.Ghaemy et al., Polymer Degradation and Stability, Volume 90, Issue 3, December 2005, Pages 570-576
• WO 2015/056377
Items
1. A process for chemical depolymerisation of poly(ethylene)terephthalate (PET) comprising the steps of: a) providing a material comprising PET; b) mixing the material comprising PET from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating the mixture obtained in step b) to a temperature in the range of 130°C to 220°C;
d) obtaining a product comprising a compound of formula (II):
wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
2. The process according to item 1, wherein the source of amine is selected from the group consisting of ammonium, ammonia and 4-dimethylaminopyridine (DMAP), preferably ammonium.
3. The process according to any one of the preceding items, wherein the source of carbon dioxide is selected from the group consisting of carbonate, bicarbonate and carbon dioxide, preferably bicarbonate.
4. The process according to any one of the preceding items, wherein the source of carbon dioxide and the source of amine is combined in a single source of carbon dioxide and amine.
5. The process according to any one of the preceding items, wherein the single source of carbon dioxide and amine is ammonium bicarbonate or ammonium carbonate, preferably ammonium bicarbonate.
6. The process according to any one of the preceding items, wherein the temperature of step c) is within the range of 150°C to 200°C, preferably 160°C to 200°C, more preferably 170°C to 200°C, most preferably 180°C to 200°C.
7. The process according to any one of the preceding items, wherein X is O.
8. The process according to any one of the preceding items, wherein R is OH.
9. The process according to any one of the preceding items, wherein n is 1-8, such as 1-6, 1-4, 1-3, 1-2, preferably 1.
10. The process according to any one of the preceding items, wherein the compound of formula (II) is bis(hydroxyethyl)terephthalate (BHET).
11. The process according to any one of the preceding items, wherein the product comprising the compound of formula (II) comprises trace metals or salts thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm, such as preferably 10 ppm.
12. A process for separating poly(ethylene)terephthalate (PET) and a textile from a blended fabric comprising PET and textile, said process comprising the steps of: a) providing a blended fabric comprising textile and PET; b) mixing the blended fabric from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating said mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
and textile;
e) separating the compound of formula (II) and textile of said product of step d); wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
13. The process according to item 12, wherein the textile of step a) is selected from the group consisting of cotton, viscose, lyocell, polyurethane or a mixture thereof, preferably cotton.
14. The process according to any one of items 12-13, wherein the ratio between the textile and PET is in the range of 10: 1 to 1: 10, such as 3: 1 to 1: 3, 2: 1 to 1:2, preferably 3: 1 to 1: 1, most preferably 2: 1 to 1: 1.
15. The process according to any one of items 12-14, wherein the product comprising the compound of formula (II) and the textile comprises trace metals or salts thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm such as preferably 10 ppm.
Claims
1. A process for chemical depolymerisation of poly(ethylene)terephthalate (PET) comprising the steps of: a) providing a material comprising PET; b) mixing the material comprising PET from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating the mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10, and the source of amine is selected from the group consisting of pyridine, ammonium, ammonia, imidazole, hydrazine, morpholine, 4-dimethylaminopyridine (DMAP), piperazine, ethanolamine (MEA), ethylenediamine (EDA), triethylamine (TEA), N- butylamine, di-/V-butylamine, pyrrolidine, triazabicyclodecene (TBD), quinine, N- Me-morpholine, trimethylglycine (TMG), glycine, lysine, hexamethylenetetramine, asparagine, sodium azide, melamine, l,4-diazabicyclo[2.2.2]octane (DABCO), urea, 2,3,4,6,7,8,9,10-Octahydropyrimido[l,2-a]azepine (DBU), potassium
cyanide, sodium cyanide, 2-aminopyridine, and quinuclidine, or any combination thereof.
2. The process according to claim 1, wherein the source of amine is selected from the group consisting of ammonium, ammonia and 4-dimethylaminopyridine (DMAP), preferably ammonium.
3. The process according to any one of the preceding claims, wherein the source of carbon dioxide is selected from the group consisting of carbonate, bicarbonate and carbon dioxide, preferably bicarbonate.
4. The process according to any one of the preceding claims, wherein the source of carbon dioxide and the source of amine is combined in a single source of carbon dioxide and amine.
5. The process according to any one of the preceding claims, wherein the single source of carbon dioxide and amine is ammonium bicarbonate, ammonium carbonate, or ethylenediamine CO2 adduct, preferably ammonium bicarbonate.
6. The process according to any one of the preceding claims, wherein the temperature of step c) is within the range of 150°C to 200°C, preferably 160°C to 200°C, more preferably 170°C to 200°C, most preferably 180°C to 200°C.
7. The process according to any one of the preceding claims, wherein X is O.
8. The process according to any one of the preceding claims, wherein R is OH.
9. The process according to any one of the preceding claims, wherein n is 1-8, such as 1-6, 1-4, 1-3, 1-2, preferably 1.
10. The process according to any one of the preceding claims, wherein the compound of formula (II) is bis(hydroxyethyl)terephthalate (BHET).
11. The process according to any one of the preceding claims, wherein the product comprising the compound of formula (II) comprises trace metals or salts
thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm, such as preferably 10 ppm.
12. A process for separating poly(ethylene)terephthalate (PET) and a textile from a blended fabric comprising PET and textile, said process comprising the steps of: a) providing a blended fabric comprising textile and PET; b) mixing the blended fabric from step a) with a source of carbon dioxide, a source of amine, and a compound of formula (I):
c) heating said mixture obtained in step b) to a temperature in the range of 130°C to 220°C; d) obtaining a product comprising a compound of formula (II):
and textile; e) separating the compound of formula (II) and textile of said product of step d); wherein
R is selected from the group consisting of OH and N(RX)2,
X is selected from the group consisting of O and NR2,
R1 and R2 are independently selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, and isobutyl, n is any integer in the range of 1-10.
13. The process according to claim 12, wherein the textile of step a) is selected from the group consisting of cotton, viscose, lyocell, polyurethane or a mixture thereof, preferably cotton.
14. The process according to any one of claims 12-13, wherein the ratio between the textile and PET is in the range of 10: 1 to 1: 10, such as 3: 1 to 1: 3, 2: 1 to 1:2, preferably 3: 1 to 1: 1, most preferably 2: 1 to 1: 1.
15. The process according to any one of claims 12-14, wherein the product comprising the compound of formula (II) and the textile comprises trace metals or salts thereof in an amount of less than 1000 ppm, such as 500 ppm, 200 ppm, 100 ppm, such as 80 ppm, 50 ppm, 30 ppm such as preferably 10 ppm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP23150108.1 | 2023-01-03 | ||
| EP23178670.8 | 2023-06-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO2024146827A1 true WO2024146827A1 (en) | 2024-07-11 |
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