BR112021018708B1 - POLYETHYLENE TEREPHTHALATE (PET) DEPOLYMERIZATION PROCESS - Google Patents

Abstract

POLYETHYLENE TEREPHTHALATE (PET) DEPOLYMERIZATION PROCESS. The present disclosure relates to the formation of dimethyl terephthalate (DMT) and monoethylene glycol (MEG). The present invention also relates to the depolymerization of polyethylene terephthalate (PET) and the recovery of dimethyl terephthalate (DMT) and monoethylene glycol (MEG) using sodium methoxide as a catalyst.

Description

CROSS-REFERENCE

[0001]This application claims the benefit of Provisional Application Serial No. US 62/821,270 filed on March 20, 2019, which is incorporated herein by reference in its entirety.

FIELD OF INVENTION

[0002]The present disclosure relates to the formation of dimethyl terephthalate (DMT) and monoethylene glycol (MEG) from polyethylene terephthalate (PET).

FUNDAMENTALS OF THE INVENTION

[0003]The polyethylene terephthalate (PET) bottle resin market has grown strongly as PET resins have replaced glass in carbonated soft drinks, bottled water, and food containers.

[0004]Dimethyl terephthalate (DMT) is primarily used in the manufacture of polyethylene terephthalate (PET) for fiber, film, container plastics, and specialty plastics applications.

[0005]The largest sector for polyester is the fiber market, where it is used to make clothing, home textiles such as bed sheets and curtains, carpets and rugs, and industrial products such as tire cords, seat belts, hoses, and ropes. PET film is used in electrical applications such as metal foil dielectric capacitors and food packaging.

SUMMARY OF THE INVENTION

[0006] Disclosed herein is a process for depolymerizing polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG); the process comprising: (i) mixing the feedstock comprising polyethylene terephthalate (PET) with a first portion of methanol to form a first mixture; (ii) adding sodium methoxide to the first mixture; (iii) mixing; and (iv) adding a second portion of methanol thereby forming a second mixture; thereby forming dimethyl terephthalate (DMT) and monoethylene glycol (MEG).

[0007]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is between about 0.1 and about 0.5 kg/kg of feedstock.

[0008] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.3 kg/kg of feedstock.

[0009]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 15 minutes to about 120 minutes.

[00010]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 60 minutes.

[00011]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 50°C to about 100°C.

[00012]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 60°C to about 90°C.

[00013]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 60°C.

[00014]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 80°C.

[00015]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 120 minutes.

[00016]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 30 minutes.

[00017]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 40°C to about 100°C.

[00018]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 85°C and about 90°C.

[00019] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 5.0 wt %.

[00020] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.5 wt % and about 1.5 wt %.

[00021] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture at about 0.7 wt%.

[00022]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied in fractions at predetermined times.

[00023] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 1 minute to about 60 minutes after the addition of sodium methoxide.

[00024] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 30 minutes after the addition of sodium methoxide.

[00025] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is between about 50 g/kg of feedstock and about 100 g/kg of feedstock.

[00026] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 30 minutes to about 90 minutes after the addition of sodium methoxide.

[00027] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 60 minutes after the addition of sodium methoxide.

[00028] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is between about 100 g/kg of feedstock and about 200 g/kg of feedstock.

[00029] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 60 minutes to about 120 minutes after the addition of sodium methoxide.

[00030] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 90 minutes after the addition of sodium methoxide.

[00031] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is between about 100 g/kg of feedstock and about 200 g/kg of feedstock.

[00032] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously.

[00033] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate between about 50 g/hr/kg of feedstock and about 100 g/hr/kg of feedstock.

[00034] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:2 and about 1:28 (mol/mol).

[00035] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:5 and about 1:20 (mol/mol).

[00036] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:10 and about 1:20 (mol/mol).

[00037] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:10 and about 1:15 (mol/mol).

[00038]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), dimethyl terephthalate is obtained in at least 90 mole % yield.

[00039]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), dimethyl terephthalate is obtained in at least about 95 mole % yield.

[00040] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), dimethyl terephthalate is obtained in at least about 99 mole % yield.

[00041]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), monoethylene glycol is obtained in at least about 80 mole % yield.

[00042] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), monoethylene glycol is obtained in at least about 85 mole % yield.

[00043]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), monoethylene glycol is obtained in at least about 90 mole % yield.

[00044]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the feedstock comprising polyethylene terephthalate (PET) is provided in particulate form.

[00045] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the average particle size is between about 0.1 mm and about 20 mm.

[00046] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the average particle size is between about 5 mm and about 10 mm.

[00047]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the average particle size is up to about 6 mm.

[00048] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the average particle size is up to about 8 mm.

DETAILED DESCRIPTION OF THE INVENTION

[00049]Dimethyl terephthalate (DMT) is used in the production of polyesters, including polyethylene terephthalate (PET), trimethylene polyterephthalate (PTT), and polybutylene terephthalate (PBT). Because DMT is volatile, it is an intermediate in some schemes for recycling PET, for example from plastic bottles. Hydrogenation of DMT affords the diol 1,4-cyclohexanedimethanol, which is a useful monomer in the formation of polyester resins.

[00050]DMT has been produced in a number of ways. Conventionally, and still of commercial value, it is the direct esterification of terephthalic acid. Alternatively, it is prepared by alternating oxidation and methyl esterification steps of para-xylene via methyl para-toluate. The method for producing DMT from para-xylene and methanol consists of four main steps: oxidation, esterification, distillation, and crystallization. A mixture of para-xylene and para-toluic ester is oxidized with air in the presence of a transition metal (Co/Mn) catalyst. The resulting acidic mixture from oxidation is esterified with methanol to produce a mixture of esters. The crude ester mixture is distilled to remove all heavy boiler products and residues produced; the lighter esters are recycled to the oxidation section. The crude DMT is then crystallized to remove DMT isomers, residual acids, and aromatic aldehydes.

[00051]An improvement in the production of DMT and MEG from PET recycling: Due to the increasing use of PET in the packaging and fiber (carpet and other textile) industries, there is a need for an efficient, low energy, high throughput and cost-effective system of forming DMT and MEG from PET.

RAW MATERIAL

[00052] A process for the depolymerization of polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG) is described herein.

[00053] In some embodiments, the feedstock comprising polyethylene terephthalate also comprises contaminants, such as additional polymers (e.g., polyethylene, polypropylene, polyvinyl chloride (PVC), polycarbonate (PC), polyvinylidene chloride (PVDC), and polyamides), paper, dyes, dirt, ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), cellulose, glue, or any combination thereof. In some embodiments, the feedstock comprises between about 5% and about 30% contaminants.

[00054] Mishra et al. (Kinetic and thermodynamic study of methanolysis of poly(ethylene terephthalate) waste powder. Polym. Int. 52: 337-342 (2003)) showed that an increase in the particle size of PET flakes causes a decrease in depolymerization. Mishra et al. reported 127.5 μm as the optimal particle size. There is a need for a depolymerization process that allows for the use of larger particles of feedstock. In some embodiments, the feedstock comprising polyethylene terephthalate (PET) is provided in particulate form. In some embodiments, the average particle size is between about 0.1 mm and about 20 mm. In some embodiments, the average particle size is between about 5 mm and about 10 mm. In some embodiments, the average particle size is up to about 5 mm. In some embodiments, the average particle size is up to about 6 mm. In some embodiments, the average particle size is up to about 7 mm. In some embodiments, the average particle size is up to about 8 mm. In some embodiments, the average particle size is up to about 9 mm. In some embodiments, the average particle size is up to about 10 mm. In some embodiments, the average particle size is up to about 11 mm. In some embodiments, the average particle size is up to about 12 mm. In some embodiments, the average particle size is up to about 13 mm. In some embodiments, the average particle size is up to about 14 mm. In some embodiments, the average particle size is up to about 15 mm. In some embodiments, the average particle size is up to about 16 mm. In some embodiments, the average particle size is up to about 17 mm. In some embodiments, the average particle size is up to about 18 mm. In some embodiments, the average particle size is up to about 19 mm. In some embodiments, the average particle size is up to about 20 mm.

DMT

[00055] A process for the depolymerization of polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG) is described herein.

[00056] In some embodiments, the DMT contains less than about 10% impurity (w/w). In some embodiments, the DMT contains less than about 9% impurity (w/w). In some embodiments, the DMT contains less than about 8% impurity (w/w). In some embodiments, the DMT contains less than about 7% impurity (w/w). In some embodiments, the DMT contains less than about 6% impurity (w/w). In some embodiments, the DMT contains less than about 5% impurity (w/w). In some embodiments, the DMT contains less than about 4% impurity (w/w). In some embodiments, the DMT contains less than about 3% impurity (w/w). In some embodiments, the DMT contains less than about 2% impurity (w/w). In some embodiments, the DMT contains less than about 1% impurity (w/w). In some embodiments, the DMT contains less than about 0.5% impurity (w/w). In some embodiments, the DMT contains less than about 0.4% impurity (w/w). In some embodiments, the DMT contains less than about 0.3% impurity (w/w). In some embodiments, the DMT contains less than about 0.2% impurity (w/w). In some embodiments, the DMT contains less than about 0.1% impurity (w/w).

[00057] In some embodiments, the DMT contains less than about 250 ppm of any metals, less than about 240 ppm of any metals, less than about 230 ppm of any metals, less than about 220 ppm of any metals, less than about 210 ppm of any metals, less than about 200 ppm of any metals, less than about 190 ppm of any metals, less than about 180 ppm of any metals, less than about 170 ppm of any metals, less than about 160 ppm of any metals, less than about 150 ppm of any metals, less than about 140 ppm of any metals, less than about 130 ppm of any metals, less than about 120 ppm of any metals, less than about 110 ppm of any metals, less than about 100 ppm of any metals, less than about 90 ppm of any metals, less than about 80 ppm of any metals, less than about 70 ppm of any metals, less than about 60 ppm of any metals, less than about 50 ppm of any metals, less than about 40 ppm of any metals, less than about 30 ppm of any metals, less than about 20 ppm of any metals, less than about 10 ppm of any metals, less than about 5 ppm of any metals, less than about 4 ppm of any metals, less than about 3 ppm of any metals, less than about 2 ppm of any metals, less than about 1 ppm of any metals, less than about 0.9 ppm of any metals, less than about 0.8 ppm of any metals, less than about 0.7 ppm of any metals, less than about 0.6 ppm of any metals, less than about 0.5 ppm of any metals, less than about 0.4 ppm of any metals, less than about 0.3 ppm of any metals, less than about 0.2 ppm of any metals, less than about 0.1 ppm of any metals, less than about 0.09 ppm of any metals, less than about 0.08 ppm of any metals, less than about 0.07 ppm of any metals, less than about 0.06 ppm of any metals, less than about 0.05 ppm of any metals, less than about 0.04 ppm of any metals, less than about 0.03 ppm of any metals, less than about 0.02 ppm of any metals, or less than about 0.01 ppm of any metals.

[00058] In some embodiments, the DMT contains less than about 10 ppm sodium methoxide, less than about 5 ppm sodium methoxide, less than about 4 ppm sodium methoxide, less than about 3 ppm sodium methoxide, less than about 2 ppm sodium methoxide, less than about 1 ppm sodium methoxide, less than about 0.9 ppm sodium methoxide, less than about 0.8 ppm sodium methoxide, less than about 0.7 ppm sodium methoxide, less than about 0.6 ppm sodium methoxide, less than about 0.5 ppm sodium methoxide, less than about 0.4 ppm sodium methoxide, less than about 0.3 ppm sodium methoxide, less than about 0.2 ppm sodium methoxide, less than about 0.3 ppm sodium methoxide, less than about 0.4 ... than about 0.1 ppm sodium methoxide, less than about 0.09 ppm sodium methoxide, less than about 0.08 ppm sodium methoxide, less than about 0.07 ppm sodium methoxide, less than about 0.06 ppm sodium methoxide, less than about 0.05 ppm sodium methoxide, less than about 0.04 ppm sodium methoxide, less than about 0.03 ppm sodium methoxide, less than about 0.02 ppm sodium methoxide, or less than about 0.01 ppm sodium methoxide.

[00059] In some embodiments, DMT is obtained in between about 50 and about 99 molar % yield. In some embodiments, DMT is obtained in between about 60 and about 99 molar % yield. In some embodiments, DMT is obtained in between about 70 and about 99 molar % yield. In some embodiments, DMT is obtained in between about 80 and about 99 molar % yield. In some embodiments, DMT is obtained in between about 85 and about 99 molar % yield. In some embodiments, DMT is obtained in between about 90 and about 99 molar % yield. In some embodiments, DMT is obtained in at least about 50 molar % yield. In some embodiments, DMT is obtained in at least about 55 molar % yield. In some embodiments, the DMT is obtained in at least about 60 mole % yield. In some embodiments, the DMT is obtained in at least about 65 mole % yield. In some embodiments, the DMT is obtained in at least about 70 mole % yield. In some embodiments, the DMT is obtained in at least about 75 mole % yield. In some embodiments, the DMT is obtained in at least about 80 mole % yield. In some embodiments, the DMT is obtained in at least about 85 mole % yield. In some embodiments, the DMT is obtained in at least about 90 mole % yield. In some embodiments, the DMT is obtained in at least about 95 mole % yield. In some embodiments, the DMT is obtained in at least about 99 mole % yield.

MEG

[00060] A process for the depolymerization of polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG) is described herein.

[00061] In some embodiments, the MEG contains less than about 10% impurity (w/w). In some embodiments, the MEG contains less than about 9% impurity (w/w). In some embodiments, the MEG contains less than about 8% impurity (w/w). In some embodiments, the MEG contains less than about 7% impurity (w/w). In some embodiments, the MEG contains less than about 6% impurity (w/w). In some embodiments, the MEG contains less than about 5% impurity (w/w). In some embodiments, the MEG contains less than about 4% impurity (w/w). In some embodiments, the MEG contains less than about 3% impurity (w/w). In some embodiments, the MEG contains less than about 2% impurity (w/w). In some embodiments, the MEG contains less than about 1% impurity (w/w). In some embodiments, the MEG contains less than about 0.5% impurity (w/w). In some embodiments, the MEG contains less than about 0.4% impurity (w/w). In some embodiments, the MEG contains less than about 0.3% impurity (w/w). In some embodiments, the MEG contains less than about 0.2% impurity (w/w). In some embodiments, the MEG contains less than about 0.1% impurity (w/w).

[00062] In some embodiments, the MEG is obtained in between about 50 and about 99 mole % yield. In some embodiments, the MEG is obtained in between about 60 and about 99 mole % yield. In some embodiments, the MEG is obtained in between about 70 and about 99 mole % yield. In some embodiments, the MEG is obtained in between about 80 and about 99 mole % yield. In some embodiments, the MEG is obtained in between about 85 and about 99 mole % yield. In some embodiments, the MEG is obtained in between about 90 and about 99 mole % yield. In some embodiments, the MEG is obtained in at least about 50 mole % yield. In some embodiments, the MEG is obtained in at least about 55 mole % yield. In some embodiments, the MEG is obtained in at least about 60 mole % yield. In some embodiments, the MEG is obtained in at least about 65 mole % yield. In some embodiments, the MEG is obtained in at least about 70 mole % yield. In some embodiments, the MEG is obtained in at least about 75 mole % yield. In some embodiments, the MEG is obtained in at least about 80 mole % yield. In some embodiments, the MEG is obtained in at least about 85 mole % yield. In some embodiments, the MEG is obtained in at least about 90 mole % yield. In some embodiments, the MEG is obtained in at least about 95 mole % yield. In some embodiments, the MEG is obtained in at least about 99 mole % yield.

SODIUM METHOXIDE

[00063] A process for the depolymerization of polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG) is described herein.

[00064] In some embodiments, the process described herein comprises a catalytic amount of sodium methoxide. In some embodiments, the process described herein comprises a substoichiometric amount of sodium methoxide.

[00065] "Substoichiometric amount" as used herein is used to indicate that the amount of material used is less than a stoichiometric amount. The term is used herein interchangeably with "catalytic amount." In some embodiments, a substoichiometric amount is less than or equal to about 95% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 90% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 85% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 80% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 75% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 70% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 65% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 60% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 55% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 50% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 45% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 40% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 35% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 30% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 25% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 20% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 15% of a stoichiometric amount. In some embodiments, a substoichiometric amount is less than or equal to about 10% of a stoichiometric amount.

[00066]"Stoichiometric amount" as used herein is used to indicate that the amount of material used is equivalent to the number of ester bonds present in the polyester.

[00067] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:2 and about 1:28 (mol/mol). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:5 and about 1:20 (mol/mol). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:10 and about 1:20 (mol/mol). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the ratio of sodium methoxide to polyethylene terephthalate (PET) is between about 1:10 and about 1:15 (mol/mol).

DEPOLYMERIZATION PROCESS

[00068] Described herein is a process for depolymerizing polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG); the process comprising: (i) mixing the feedstock comprising polyethylene terephthalate (PET) with a first portion of methanol to form a first mixture; (ii) adding sodium methoxide to the first mixture; (iii) mixing; and (iv) adding a second portion of methanol thereby forming a second mixture; thereby forming dimethyl terephthalate (DMT) and monoethylene glycol (MEG).

Step (i)

[00069]In some embodiments, the process described herein comprises pre-treating polyethylene terephthalate (PET) with a first portion of methanol solvent to swell the polyethylene terephthalate (PET) prior to the addition of sodium methoxide.

[00070] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is between about 0.1 and about 0.5 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is between about 0.2 and about 0.4 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is between about 0.1 and about 0.3 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is between about 0.3 and about 0.5 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.1 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.2 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.3 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.4 kg/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first portion of methanol is about 0.5 kg/kg of feedstock.

[00071] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 15 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 15 minutes to about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 15 minutes to about 60 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 30 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 60 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 45 minutes to about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 45 minutes to about 60 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 60 minutes to about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 15 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 20 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 25 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 30 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 35 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 40 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 45 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 50 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 55 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 60 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 65 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 70 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 75 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 80 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 85 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 95 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 100 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 105 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 110 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 115 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted for about 120 minutes.

[00072] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 25°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 25°C and about 60°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 25°C and about 80°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 50°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature between about 60°C and about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 25°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 30°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 35°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 40°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 45°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 50°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 55°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 60°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 65°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 70°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 75°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 80°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 85°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 95° C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (i) is conducted at a temperature of about 100° C.

Step (iii)

[00073] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 60 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 45 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes to about 30 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 30 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 60 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 90 minutes to about 120 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 10 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 15 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 20 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 25 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 30 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 35 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 40 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 45 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 50 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 55 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 60 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 65 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 70 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 75 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 80 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 85 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 90 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 95 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 100 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 105 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 110 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 115 minutes. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted for about 120 minutes.

[00074] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 40°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 50°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 60°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 70°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 80°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature between about 85°C and about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 40°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 45°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 50°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 55°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 60°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 65°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 70°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 75°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 80°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 85°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 95°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iii) is conducted at a temperature of about 100°C.

Step (iv)

[00075] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), methanol is consumed during the depolymerization process to form dimethyl terephthalate (DMT). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second portion of methanol is added.

[00076] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 5.0 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 4.0 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 3.0 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 2.0 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.2 wt % and about 1.5 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture between about 0.5 wt % and about 1.0 wt %. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture at about 0.7 wt%. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture at about 0.2 wt %, about 0.3 wt %, about 0.4 wt %, about 0.5 wt %, about 0.6 wt %, about 0.7 wt %, about 0.8 wt %, about 0.9 wt %, about 1 wt %, about 1.1 wt %, about 1.2 wt %, about 1.3 wt %, about 1.4 wt %, about 1.5 wt %, about 1.6 wt %, about 1.7 wt %, about 1.8 wt %, about 1.9 wt %, about 2 wt %, about 2.1 wt %, about 2.2 wt %, about 2.3 wt %, about 2.4 wt %, about 2.5 wt %, about 2.6 wt %, about 2.7 wt %, about 2.8 wt %, about 2.9 wt %, about 3 wt %, about 3.1 wt %, about 3.2 wt %, about 3.3 wt %, about 3.4 wt %, about 3.5 wt %, about 3.6 wt %, about 3.7 wt %, about 3.8 wt %, about 3.9 wt %, about 4 wt %, about 4.1 wt %, about 4.2 wt %, about 4.3 wt %, about 4.4 wt %, about 4.5 wt %, about 4.6 wt %, about 4.7 wt%, about 4.8 wt%, about 4.9 wt% or about 5 wt%.

[00077] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature between about 25°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature between about 25°C and about 60°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature between about 25°C and about 80°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature between about 50°C and about 100°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature between about 60°C and about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 25°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 30°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 35°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 40°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 45°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 50°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 55°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 60°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 65°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 70°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 75°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 80°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 85°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 90°C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 95° C. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted at a temperature of about 100° C.

[00078] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted for a total time of between about 1 hour and about 10 hours. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted for a total time of between about 1 hour and about 8 hours. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted for a total time of between about 1 hour and about 5 hours. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted for a total time of between about 4 hours and about 6 hours. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), step (iv) is conducted for a total time between about 3 hours and about 7 hours.

Sequential addition

[00079] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied sequentially at predetermined times in step (iv). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied in fractions at predetermined times in step (iv). In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied in one, two, three, four, five, six, seven, eight, nine, or ten fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied in one, two, three, four, or five fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in one, two, or three fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in two or three fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in two fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in three fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in four fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in five fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in six fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in seven fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in eight fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in nine fractions. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is provided in ten fractions.

[00080]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the mixture is blended between each fraction addition.

[00081] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 1 minute to about 60 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 15 minutes to about 45 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 1 minute after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 5 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 10 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 15 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 20 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 25 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 30 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 35 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 40 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 45 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 50 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 55 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a first fraction of the second portion of methanol is provided about 60 minutes after the addition of sodium methoxide.

[00082] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is between about 10 g/kg of feedstock and about 100 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is between about 50 g/kg of feedstock and about 100 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is between about 50 g/kg of feedstock and about 80 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 10 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 20 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 30 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 40 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 50 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 60 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 70 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 80 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 90 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the first fraction of the second portion of methanol is about 100 g/kg of feedstock.

[00083] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 30 minutes to about 90 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 45 minutes to about 75 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 30 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 35 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 40 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 45 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 50 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 55 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 60 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 65 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 70 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 75 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 80 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 85 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a second fraction of the second portion of methanol is provided about 90 minutes after the addition of sodium methoxide.

[00084] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second methanol portion is between about 100 g/kg of feedstock and about 200 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second methanol portion is between about 100 g/kg of feedstock and about 150 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second methanol portion is about 100 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 110 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 120 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 130 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 140 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 150 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 160 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 170 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 180 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 190 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the second fraction of the second portion of methanol is about 200 g/kg of feedstock.

[00085] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 60 minutes to about 120 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 90 minutes to about 120 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 60 minutes to about 90 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 60 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 65 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 70 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 75 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 80 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 85 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 90 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 95 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 100 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 105 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 110 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 115 minutes after the addition of sodium methoxide. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), a third fraction of the second portion of methanol is provided about 120 minutes after the addition of sodium methoxide.

[00086] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is between about 100 g/kg of feedstock and about 200 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is between about 100 g/kg of feedstock and about 150 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 100 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 110 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 120 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 130 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 140 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 150 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 160 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 170 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 180 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 190 g/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the amount of the third fraction of the second portion of methanol is about 200 g/kg of feedstock.

Continuous addition

[00087]In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously in step (iv).

[00088] In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate between about 50 g/hr/kg of feedstock and about 100 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate between about 50 g/hr/kg of feedstock and about 90 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate between about 50 g/hr/kg of feedstock and about 80 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate between about 50 g/hr/kg of feedstock and about 70 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 50 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 60 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 70 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 80 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 90 g/hr/kg of feedstock. In some embodiments of a process for depolymerizing polyethylene terephthalate (PET), the second portion of methanol is supplied continuously at a rate of about 100 g/hr/kg of feedstock.

SPECIFIC TERMINOLOGY

[00089]The section headings used in this document are for organizational purposes only and should not be construed as limiting the subject matter described.

[00090]Unless otherwise defined, all technical and scientific terms used in this document have the same meaning as is commonly understood to which the claimed subject matter belongs. In the event that there is a plurality of definitions for terms in this document, those in this section prevail.

[00091]It should be understood that the general description and detailed description are exemplary and explanatory only and are not restrictive of any claimed subject matter. In this application, the use of the singular includes the plural, unless specifically indicated otherwise. It should be noted that, as used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents, unless the context clearly dictates otherwise. In this application, the use of "or" means "and/or", unless otherwise indicated. In addition, the use of the term "including", as well as other forms, such as "includes", "include", and "included", is not limiting.

[00092]Unless the context otherwise requires, throughout the specification and claims that follow, the word "comprise" and its variations, such as, "comprise" and "comprising" are to be construed in an open and inclusive sense, i.e., as "including, but not limited to". Further, the headings provided herein are for convenience only and do not construe the scope or meaning of the claimed invention.

[00093] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly indicates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and/or," unless the content clearly indicates otherwise.

[00094]As used herein, the term "about" or "approximately" means within 10%, preferably within 10%, and most preferably within 5% of a given value or range.

[00095] As used herein, room temperature is a colloquial expression for the typical or preferred (climate-controlled) indoor temperature to which people are generally accustomed. It represents the small temperature range in which the air feels neither hot nor cold, approximately 21°C. In some embodiments, the room temperature is 25 ± 5°C. In some embodiments, the room temperature is 18°C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the °C. In some embodiments, the room temperature is 27°C. In some embodiments, the room temperature is 28°C. In some embodiments, the room temperature is 29°C. In some embodiments, the ambient temperature is 30°C.

[00096] As used herein and in the appended claims, depolymerization refers to a manner of breaking down a polymer into its starting material. It is essentially the opposite of polymerization. In some embodiments, depolymerization is achieved by methanolysis.

[00097]As used herein, the term "mol" when referring to PET is the molar quantity and is calculated using the molecular weight of the "PET" unit which is 192.17 g/mol.

[00098]Definitions of standard chemistry terms can be found in reference works including, but not limited to, Carey and Sundberg "Advanced Organic Chemistry 4th Ed." Vols. A (2000) and B (2001), Plenum Press, New York.

EXAMPLES

[00099]The following examples are intended to illustrate, but not to limit, the disclosed embodiments.

Example 1: Depolymerization of PET with sequential addition of methanol

[000100]To a 25 L reactor containing 10.00 kg of feedstock (particulate PET) was added 3.00 kg of methanol. The medium was stirred and heated at 60°C for 1 h. Then, the temperature was raised to 85°C, after which sodium methoxide (30 kg/t feedstock) was added. The fractional addition of methanol was conducted as follows: 710 g was added 30 min after the addition of sodium methoxide, 1.21 kg after another 30 min, and a final 1.21 kg after another 30 min. The reaction medium was stirred at 85°C for a total of 8 to 10 h after the addition of sodium methoxide. The reaction yields were: 97% for DMT and 95% for MEG.

Example 2: Depolymerization of PET with partial removal of methanol and sequential addition of methanol

[000101]To a 25 L reactor containing 10.00 kg of feedstock (particulate PET) was added 6.00 kg of methanol. The medium was stirred and heated at 60°C for 1 h. Then, 3 kg of liquid were drained and the temperature was raised to 85°C, after which sodium methoxide (30 kg/t feedstock) was added. The fractional addition of methanol was conducted as follows: 1.21 kg was added 30 min after the addition of sodium methoxide, 1.21 kg after another 30 min, and a final 1.21 kg after another 30 min. The reaction medium was stirred at 85°C for a total of 8 to 10 h after the addition of sodium methoxide. The reaction yields were: 87% for DMT and 83% for MEG.

Example 3: Depolymerization of PET with partial removal of methanol and single addition of methanol

[000102]To a 25 L reactor containing 10.00 kg of feedstock (particulate PET) was added 6.00 kg of methanol. The medium was stirred and heated at 60°C for 1 h. Then, 2.2 kg of liquid was drained and the temperature increased to 85°C, after which sodium methoxide (30 kg/t feedstock) was added. After 30 min, 2.3 kg of methanol was added. The reaction medium was stirred at 85°C for a total of 8 to 10 h after the addition of sodium methoxide. The reaction yields were 80% for DMT and 93% for MEG.

Claims (43)

1. A process for the depolymerization of polyethylene terephthalate (PET) comprised in a feedstock to form dimethyl terephthalate (DMT) and monoethylene glycol (MEG); the process comprising: (i) mixing the feedstock comprising polyethylene terephthalate (PET) with a first portion of methanol to form a first mixture; (ii) subsequent to (i), adding sodium methoxide to the first mixture; (iii) mixing; and (iv) adding a second portion of methanol thereby forming a second mixture; thereby forming dimethyl terephthalate (DMT) and monoethylene glycol (MEG), wherein DMT comprises less than 10% impurities (w/w). 2. The process of claim 1, wherein the amount of the first portion of methanol is from about 0.1 to about 0.5 kg/kg of feedstock. 3. Process according to claim 1 or 2, characterized in that the amount of the first portion of methanol is about 0.3 kg/kg of raw material. 4. Process according to any one of claims 1 to 3, characterized in that step (i) is carried out for about 15 minutes to about 120 minutes. 5. Process according to any one of claims 1 to 4, characterized in that step (i) is carried out for about 60 minutes. 6. Process according to any one of claims 1 to 5, characterized in that step (i) is carried out at a temperature of about 50°C to about 100°C. 7. Process according to any one of claims 1 to 6, characterized in that step (i) is carried out at a temperature of about 60°C to about 90°C. 8. Process according to any one of claims 1 to 7, characterized in that step (i) is carried out at a temperature of about 60°C. 9. Process according to any one of claims 1 to 7, characterized in that step (i) is carried out at a temperature of about 80°C. 10. Process according to any one of claims 1 to 9, characterized in that step (iii) is conducted for about 10 minutes to about 120 minutes. 11. Process according to any one of claims 1 to 10, characterized in that step (iii) is carried out for about 30 minutes. 12. Process according to any one of claims 1 to 11, characterized in that step (iii) is carried out at a temperature of about 40°C to about 100°C. 13. Process according to any one of claims 1 to 12, characterized in that step (iii) is carried out at a temperature of about 85°C and about 90°C. 14. The process of any one of claims 1 to 13, wherein the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture from about 0.2 wt. % to about 5.0 wt. %. 15. The process of any one of claims 1 to 14, wherein the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture from about 0.5 wt.% to about 1.5 wt.%. 16. The process of any one of claims 1 to 15, wherein the second portion of methanol is provided to maintain the concentration of sodium methoxide in the second mixture at about 0.7 wt%. 17. Process according to any one of claims 1 to 16, characterized in that the second portion of methanol is supplied in fractions at predetermined times. 18. The process of claim 17, wherein a first fraction of the second portion of methanol is provided about 1 minute to about 60 minutes after the addition of sodium methoxide. 19. The process of claim 18, wherein a first fraction of the second portion of methanol is provided about 30 minutes after the addition of sodium methoxide. 20. The process of claim 18 or 19, wherein the amount of the first fraction of the second portion of methanol is from about 50 g/kg of feedstock to about 100 g/kg of feedstock. 21. The process of any one of claims 17 to 20, wherein a second fraction of the second portion of methanol is provided about 30 minutes to about 90 minutes after the addition of sodium methoxide. 22. Process according to any one of claims 17 to 21, characterized in that a second fraction of the second portion of methanol is provided about 60 minutes after the addition of sodium methoxide. 23. The process of claim 21 or 22, wherein the amount of the second fraction of the second portion of methanol is from about 100 g/kg of feedstock to about 200 g/kg of feedstock. 24. The process of any one of claims 17 to 23, wherein a third fraction of the second portion of methanol is provided about 60 minutes to about 120 minutes after the addition of sodium methoxide. 25. Process according to any one of claims 17 to 24, characterized in that a third fraction of the second portion of methanol is provided about 90 minutes after the addition of sodium methoxide. 26. The process of claim 24 or 25, wherein the amount of the third fraction of the second portion of methanol is from about 100 g/kg of feedstock to about 200 g/kg of feedstock. 27. Process according to any one of claims 1 to 16, characterized in that the second portion of methanol is supplied continuously. 28. The process of claim 27, wherein the second portion of methanol is supplied continuously at a rate of about 50 g/h/kg feedstock to about 100 g/h/kg feedstock. 29. The process of any one of claims 1 to 28, wherein the ratio of sodium methoxide to polyethylene terephthalate (PET) is from about 1:2 to about 1:28 (mol/mol). 30. The process of any one of claims 1 to 29, wherein the ratio of sodium methoxide to polyethylene terephthalate (PET) is from about 1:5 to about 1:20 (mol/mol). 31. The process of any one of claims 1 to 30, wherein the ratio of sodium methoxide to polyethylene terephthalate (PET) is from about 1:10 to about 1:20 (mol/mol). 32. The process of any one of claims 1 to 31, wherein the ratio of sodium methoxide to polyethylene terephthalate (PET) is from about 1:10 to about 1:15 (mol/mol). 33. Process according to any one of claims 1 to 32, characterized in that dimethyl terephthalate is obtained in at least about 90 mol% yield. 34. Process according to any one of claims 1 to 32, characterized in that dimethyl terephthalate is obtained in at least about 95 mol% yield. 35. Process according to any one of claims 1 to 32, characterized in that dimethyl terephthalate is obtained in at least about 99 molar % yield. 36. Process according to any one of claims 1 to 35, characterized in that monoethylene glycol is obtained in at least about 80 mol% yield. 37. Process according to any one of claims 1 to 35, characterized in that monoethylene glycol is obtained in at least about 85 molar% yield. 38. Process according to any one of claims 1 to 35, characterized in that monoethylene glycol is obtained in at least about 90 mol% yield. 39. Process according to any one of claims 1 to 38, characterized in that the raw material comprising polyethylene terephthalate (PET) is provided in the form of particles. 40. The process of claim 39, wherein the average particle size is from about 0.1 mm to about 20 mm. 41. The process of claim 39 or 40, wherein the average particle size is from about 5 mm to about 10 mm. 42. The process of any one of claims 39 to 41, wherein the average particle size is up to about 6 mm. 43. The process of any one of claims 39 to 41, wherein the average particle size is up to about 8 mm.