Chemical recycling of waste plastic with enhanced filtrate processing

Abstract

A method of recycling waste plastic by introducing a first liquid stream which comprises a C4 to C14 alcohol, a C2 to C4 glycol, and one or more components heavier than the C4 to C14 alcohol and the C2 to C4 glycol into a first distillation column; separating the first liquid stream in the first distillation column to form an overhead stream comprising predominantly a mixture of the C4 to C14 alcohol and the C2 to C4 glycol and a bottoms stream comprising predominantly residual C4 to C14 alcohol and the components heavier than the C4 to C14 alcohol and the C2 to C4 glycol; contacting at least a portion of the overhead stream from the first distillation column with water in a liquid-liquid separation vessel to provide an organic stream comprising predominantly C4 to C14 alcohol and an aqueous stream comprising predominantly C2 to C4 glycol and water; and further separating the aqueous stream in a second distillation zone to provide a second distillation stream comprising predominantly water and a third distillation stream comprising predominantly C2 to C4 glycol.

Description

CHEMICAL RECYCLING OF WASTE PLASTIC WITH ENHANCED FILTRATE PROCESSINGBACKGROUND

[0001] This technology relates to the field of chemical recycling of waste plastic and, in particular, to the chemical recycling of polyesters.

[0002] Recycling of plastics has become an important issue facing society. Polyethylene terephthalate), or PET, is one of the most widely recycled plastics. Currently, most of the PET recycling is mechanical recycling, wherein the polyester is physically separated from other plastics, cleaned and re-processed to form recycled PET (rPET).

[0003] Mechanical recycling has limited utility and some drawbacks. For example, each time the PET is heated and re-heated during the mechanical recycling process, the PET undergoes degradation which ultimately makes it unsuitable for continued reuse. Chemical recycling is an alternative to mechanical recycling and includes chemical decomposition of the PET molecules back to its original monomers, usually terephthalic acid (TPA), dimethyl terephthalate (DMT) and ethylene glycol (EG), or bis(2-hydroxyethyl) terephthalate (BHET). These monomers are then purified and can be re-polymerized to form new PET polymers, which are identical to virgin PET material.

[0004] There are several types of chemical recycling, and these are typically categorized by the depolymerization agent utilized. Most commonly, depolymerization agents include, but are not limited to, water (used in “hydrolysis”), methanol (used in “methanolysis”), and ethylene glycol (used in “glycolysis”). When water is used as the depolymerization agent ( / .e., hydrolysis), PET is depolymerized to form TPA and EG, and when methanol is used as the depolymerization agent ( / .e., methanolysis), the monomers recovered are DMT and EG. When EG is used as the depolymerization agent ( / .e., glycolysis), bis(hydroxyethyl) terephthalate (BHET) or oligomers thereof (depending on how much ethylene glycol is used) is formed.

[0005] Regardless of the specific type of depolymerization utilized, most processes and facilities include downstream steps or zones for the separation and recovery of one or more organic compounds used in the process. For example, recovery of residual methanol, ethylene glycol, or other alcohol is advantageous since the recovered stream can be reused in the process, thereby reducing cost and energy usage. However, many of the alcohols and glycols present in these systems havesimilar boiling points, thereby making separation difficult, energy intensive, and / or inefficient.SUMMARY

[0006] In one aspect, the present technology concerns a method of recycling waste plastic, said method comprising: (a) introducing a first liquid stream comprising a C4 to C14 alcohol, a C2 to C4 glycol, and one or more components heavier than the C4 to C14 alcohol and the C2 to C4 glycol into a first distillation column; (b) separating the first liquid stream in the first distillation column to form an overhead stream comprising predominantly a mixture of the C4 to C14 alcohol and the 02 to 04 glycol and a bottoms stream comprising predominantly residual 04 to 014 alcohol and the components heavier than the 04 to 014 alcohol and the 02 to 04 glycol; (c) contacting at least a portion of the overhead stream from the first distillation column with water to provide an organic stream comprising predominantly 04 to C14 alcohol and an aqueous stream comprising predominantly 02 to 04 glycol and water; and (d) further separating the aqueous stream in a second distillation zone to provide a second distillation stream comprising predominantly water and a third distillation stream comprising predominantly 02 to 04 glycol.

[0007] In one aspect, the present technology concerns a method of recycling waste plastic, said method comprising: (a) depolymerizing waste plastic comprising poly(C2 to 04 alkylene) terephthalate with a 04 to C14 alcohol to form a reaction mixture comprising 04 to C14 dialkyl terephthalate; (b) transesterifying the 04 to C14 dialkyl terephthalate with a second alcohol to form a second reaction mixture comprising another dialkyl terephthalate; (c) separating at least a portion of the second reaction mixture to form a solids product including the another dialkyl terephthalate and a residual liquid phase including 04 to 014 alcohol, 02 to 04 glycol, and the second alcohol; (d) separating at least a portion of the residual liquid phase in a first distillation column to provide a first overhead stream comprising predominantly the second alcohol and a first bottoms stream comprising predominantly the 04 to C14 alcohol, the 02 to 04 glycol, and components heavier than the 04 to 014 alcohol and the 02 to 04 glycol; (e) separating at least a portion of the first bottoms stream in a second distillation column to provide a second overhead stream comprising predominantly a mixture of the 04 to 014 alcohol and the 02 to 04 glycol and a second bottoms stream comprising predominantly a mixture of the components heavier than the 04 to 014 alcohol and the 04 to C14 alcohol; (f) adding water to at least a portionof the second overhead stream and separating an organic stream comprising predominantly C4 to C14 alcohol and an aqueous stream comprising predominantly water and the C2 to C4 glycol; and (g) recovering at least a portion of the C2 to C4 glycol from the aqueous stream to provide a recycled content C2 to C4 glycol stream.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic block flow diagram illustrating the main steps and / or processing zones of a facility configured for the chemical recycling of waste plastic, including, for example, polyethylene terephthalate);

[0009] FIG. 2 is a schematic block flow diagram illustrating a portion of the chemical recycling facility shown in FIG. 1 and, in particular, a depolymerization step / zone configured according to embodiments of the present technology;

[0010] FIG. 3 is a schematic block flow diagram illustrating a portion of the chemical recycling facility shown in FIG. 1 and, in particular, a solid-liquid separation step / zone configured according to embodiments of the present technology;

[0011] FIG. 4 is a schematic block flow diagram illustrating a portion of the chemical recycling facility shown in FIG. 1 and, in particular, separation / purification zone for treating a stream of liquid filtrate according to embodiments of the present technology;

[0012] FIG. 5a is a schematic diagram of one possible column configuration for use in separation an aqueous stream of glycol in a glycol separation step / zone according to embodiments of the present technology, particularly illustrating use of a water removal column;

[0013] FIG. 5b is a schematic diagram of another possible column configuration for use in separation an aqueous stream of glycol in a glycol separation step / zone according to embodiments of the present technology, particularly illustrating use of a divided wall column; and

[0014] FIG. 5c is a schematic diagram of another possible column configuration for use in separation an aqueous stream of glycol in a glycol separation step / zone according to embodiments of the present technology, particularly illustrating use of a heavies removal column.DETAILED DESCRIPTION

[0015] We have discovered new methods and systems for improving the efficiency of the chemical recycling of waste plastic, including polyethyleneterephthalate), or PET. In particular, we have discovered improved methods and systems for recovering alcohols and glycols from the liquid filtrate stream after depolymerization. The methods and systems described herein provide reproducible separations that enhance catalyst recovery and return, as well as providing higher purity and enhanced recovery of ethylene glycol, as well as enhanced recovery of alcohols and glycols that can be reused within the facility.

[0016] Turning initially to FIG. 1 , the main process steps / zones of a facility 10 for the chemical recycling of waste plastic are illustrated. As shown in FIG. 1 , the chemical recycling facility 10 includes two basic steps: (1) depolymerization of waste plastic including polyester with a higher molecular weight alcohol to form depolymerization mixture, followed by (2) conversion of at least a portion of the depolymerization mixture to form recycled content dialkyl terephthalate (r-DAT) and recycled content glycol (r-glycol). Additionally, as shown in FIG. 1 , the chemical recycling facility 10 facilitates internal recycle of various reactants, catalysts, and alcohols, etc. used for these steps, thereby increasing efficiency, reducing waste, and improving the quality and purity of the final recycled content products.

[0017] In some embodiments, the chemical recycling process performed at the facility 10 may be a continuous process, or at least a portion may be carried out as a batch process (e.g., a semi-continuous process). In some embodiments, the facility 10 may be a pilot-scale facility but is not a lab-scale facility. As used herein, the term “pilot-scale” refers to a chemical recycling facility with a total waste plastic feed rate to the depolymerization reactor(s) of between 0.2 and 15 kilograms / min. In a pilot-scale facility, the waste plastic feed rate in the depolymerization reactor can be at least about 0.25, at least about 0.5, at least about 1 , at least about 2, at least about 2.5, at least about 5 kg / min and / or not more than about 12.5, not more than about 10, not more than about 7.5, not more than about 5, not more than about 2.5, or not more than about 2 kg / min, averaged over an onstream time of 250 days per calendar year. Lab-scale facilities are those conducted in a laboratory, typically in a batch-wise manner. Labscale processes can have a feed rate of less than 0.2, less than 0.1 , less than 0.05, less than 0.01 , or less than 0.005 kg waste plastic feed / min if conducted continuously or less than 5 kg waste plastic feed per batch if conducted in a batch-wise manner.

[0018] In some embodiments, the chemical recycling facility 10 may be a commercial-scale facility. As used herein, the term “commercial scale” refers to a chemical recycling facility with a total waste plastic feed rate to the depolymerization reactor(s) of greater than 15 kg / min. In some embodiments, a commercial-scale facilitycan have a feed rate of at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, or at least about 45 kg / min and / or not more than 500, not more than about 400, not more than about 300, not more than about 250, not more than about 100, not more than about 90, not more than about 85, not more than about 75, not more than about 70, not more than about 65, not more than about 60, or not more than about 55 kg / min, averaged over an onstream time of 300 days per calendar year. When the facility includes two or more polymerization reactors, the “feed rate” refers to the combined mass flow rate to each initial polymerization reactor in the facility.

[0019] The waste plastic stream introduced into the chemical recycling facility 10 via line 110 can include one or more types of waste plastic, including, for example at least one poly(C2 to C4 alkylene terephthalate). Examples of poly(C2 to C4 alkylene terephthalate) include polyethylene terephthalate, polypropylene terephthalate, and polybutylene terephthalate. In some embodiments, the poly(C2 to C4 alkylene terephthalate) may be an acid-modified and / or glycol-modified polyester and may include residues of diacids and / or diols in addition to residues of terephthalic acid (or dialkyl terephthalate) and C2 to C4 alkylene glycol. Such modified polyesters can include, but are not limited to, 1 ,4-cyclohexanedimethanol (CHDM)-modified PET, isophthalic acid (IPA)-modified PET, diethylene glycol (DEG)-modified PET, glycol- modified PET, neopentyl glycol (NPG)-modified PET, propane diol (PDO)-modified PET, butanediol (BDO)-modified PET, hexanediol (HDO)-modified PET, 2-methyl-2,4- pentanediol (MP diol)-modified PET, isosorbide-modified PET, poly(tetramethylene ether) glycol (PTMG)-modified PET, poly(ethylene) glycol (PEG)-modified PET, polycyclohexylenedimethylene terephthalate (PCT), cyclohexanedimethanol (CHDM)- containing copolyester, isosorbide-containing copolyester, or a combination thereof. In other embodiments, the poly(C2-C4)alkylene terephthalate can include polyethylene terephthalate (PET) that comprises residues of CHDM, IPA, DEG, NPG, PDO, BDO, HDO, MP diol, isosorbide, PTMG, PEG, or a combination thereof.

[0020] As used herein, the term “waste plastic stream” refers to a heterogeneous waste stream comprising various polymers and plastics. The waste plastic stream may include material that was recovered as manufacturing scrap, industrial waste, post-consumer waste, or a combination thereof. In certain embodiments, the recycled polyester(s) can be prior-used products that have been used and / or discarded. In certain embodiments, the waste plastic stream can comefrom various sources and / or in various forms, including but not limited to textiles, carpet, thermoformed materials, bottles, pellets, and film.

[0021] Other components in the waste plastic feed stream in line 110 may include other non-poly(C2 to C4 alkylene terephthalate), or non-PAT, waste plastics and / or other non-plastic waste components. Examples of non-PAT waste plastics can include, but are not limited to, polyesters other than the poly(C2 to C4 alkylene terephthalate), polyvinyl acetal, polyvinylbutyral (PVB), polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), cotton, polystyrene, polycarbonate, cellulose esters, polyacrylate, polymethacrylates, poly(lactic acid), polydimethylsiloxane, polysilane, polyethylene, polypropylene, polyolefins other than polyethylene and polypropylene, polyvinyl chloride (PVC), elastane, nylon, polyacrylates, polymethacrylate, poly(lactic acid), or combinations thereof. Non-plastic waste components present in the waste plastic stream may include, for example, natural fibers, calcium carbonate, titanium dioxide, inorganic fillers, dyes, pigments, color toners, colorants, plasticizers, adhesives, flame retardants, metals, aluminum, and iron, carbon black, or combinations thereof.

[0022] The waste plastic feed in line 110 shown in FIG. 1 can comprise poly(C2 to C4 alkylene terephthalate) in an amount of at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, or at least about 90 weight percent and / or up to 100 percent, or not more than about 99, not more than about 97, not more than about 95, not more than about 90, not more than about 85, not more than about 80, or not more than about 75 weight percent, based on the total weight of the waste plastic stream in line 110. The total amount of non-PAT components in the waste plastic feed stream can be 0 percent, or at least about 1 , at least about 2, at least about 5, at least about 10, at least about 15, at least about 20, or at least about 25 weight percent and / or not more than about 40, not more than about 35, not more than about 30, not more than about 25, not more than about 20, not more than about 15, or not more than about 10 weight percent, based on the total weight of the waste plastic stream in line 110.

[0023] Although not shown in FIG. 1 , plastic waste introduced into the facility 10 may undergo one or more pre-processing steps prior to entering the depolymerization step / zone 20 via line 110. Examples of suitable pre-processing steps include, but are not limited to, washing, drying, sorting, size reduction, and combinations thereof. The waste plastic stream in line 110 has already undergone one or more of these steps and is ready for depolymerization. In some embodiments, thewaste plastic in line 110 may be in the form of flakes, powder, pellets, and / or chunks. When pellets or chunks, the waste plastic may have a maximum dimension of not more than about 0.375, not more than about 0.30, not more than about 0.25, not more than about 0.20, or not more than about 0.10 inches.

[0024] In some embodiments, the waste plastic introduced into the depolymerization reactor (not shown) in depolymerization zone / step 20 can have a total moisture content of not more than about 10, not more than about 8, not more than about 7, not more than about 6, not more than about 5, not more than about 3, not more than about 2.5, not more than about 2, not more than about 1 .5, not more than about 1 .25, not more than about 1 , not more than about 0.75, or not more than about 0.5 weight percent, based on the total weight of the plastic. Additionally, or in the alternative, the waste plastic introduced into the depolymerization reactor can have a moisture content of at least about 0.01 , at least about 0.05, at least about 0.10, at least about 0.20, at least about 0.25, at least about 0.50, at least about 1 , at least about 1 .5, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, or at least about 5 weight percent, based on the total weight of the plastic.

[0025] The depolymerization step / zone 20 shown in FIG. 1 may be configured to reduce the molecular weight of the incoming plastic to form its constituent monomers via alcoholysis. For example, the poly(C2 to C4 alkylene terephthalate) introduced into the reactor may depolymerize in the presence of at least one C4 to C14 alcohol to form a C4 to C14 dialkyl terephthalate, along with a variety of other diesters, half-esters, dimers, oligomers, and combinations thereof. In some embodiments, the alcohol may be a C5 to C12 alcohol or a C6 to C10 alcohol, or it may be chosen from n-butanol, isobutanol, hexanol, 2-ethylhexanol, n-octanol, decanol, dodecanol, tetradecanol, or mixtures thereof. In some embodiments, the alcohol may be chosen from n-butanol, n-octanol, or 2-ethylhexanol. The amount of C4 to C14 alcohol added to the depolymerization step / zone 20 via line 116 can be at least about 0.5, at least about 1 , at least about 1 .5, at least about 2, or at least about 2.5 parts by weight and / or not more than about 12, not more than about 10, not more than about 8, not more than about 5, nor more than about 2.5, or not more than about 2 parts by weight based on 1 part by weight of the poly(C2 to 04 alkylene terephthalate) in the reaction mixture at the start of the depolymerization step.

[0026] Additionally, before depolymerization begins, the depolymerization reactor may include a composition comprising waste plastic and at least one alcohol,having properties and compositions as described herein. Prior to depolymerization, the composition may comprise little or no depolymerization products, such as, for example, terephthalyl components such as dimers and oligomers of the poly(C2 to C4 alkylene terephthalate), as well as various dialkyl esters and half esters, as well as terephthalate salts. Such components are generated in situ, and their presence indicates that depolymerization has occurred, and would not be present (or would be present in very small amounts) at or near the beginning of depolymerization. In some embodiments, at the beginning of depolymerization, these components may be present in an amount of less than about 10, less than about 7, less than about 5, less than about 3, less than about 1 , less than about 0.75, less than about 0.50, less than about 0.25, less than about 0.10, or less than about 0.05 weight percent, based on the total weight of the reaction mixture.

[0027] According to some embodiments of the present technology, at least one exogenous C2 to C8 glycol may optionally be added to the depolymerization step / zone 20 via line 140 to further enhance the depolymerization reaction. As used herein, the term “exogenous” refers to a glycol (or other component) added to the system from an external source and does not encompass components evolved in situ. Thus, although depolymerization of the poly(C2 to C4 alkylene terephthalate) via alcoholysis as described herein will result in evolution of alkylene glycol {e.g., ethylene glycol from PET) liberated during depolymerization, the exogeneous C2 to C8 glycol is added to the system as an additional component.

[0028] The poly(C2 to C4 alkylene terephthalate) added to the depolymerization step / zone 20 may or may not include incorporated residues of the exogenous C2 to C8 glycol prior to depolymerization. In other words, the poly(C2 to C4 alkylene terephthalate) may or may not have a glycol component residue that is the same as the exogenous C2 to C8 glycol. When such incorporated residues are present, the amount of C2 to C8 glycol present in the depolymerization reaction mixture after conclusion of the depolymerization reaction is higher than would be expected on a pure stoichiometric basis. That is, in such embodiments, the amount of C2 to C8 glycol present in the reaction mixture at the end of depolymerization can be at least about 5, at least about 7, at least about 10, at least about 12, at least about 15, at least about 20, at least about 22, at least about 24, at least about 26, at least about 28, or at least about 30 mole percent greater and / or not more than about 70, not more than about 65, not more than about 60, not more than about 55, not more than about 50, not more than about 45, or not more than about 40 mole percent greater than astoichiometric amount of the 02 to 08 glycol that would be present as a result of full depolymerization of the poly(C2 to 04 alkylene terephthalate) introduced into the depolymerization step / zone 20.

[0029] In some embodiments, particularly when the poly(C2 to 04 alkylene terephthalate) includes residues of the exogenous C2 to 08 glycol in very minor amounts (e.g., less than about 5 mole percent, based on the moles of poly (C2 to C4 alkylene terephthalate)), the total amount of 02 to 08 glycol can be present in even higher amounts at the end of depolymerization relative to what would be expected on a pure stochiometric basis. For example, in some embodiments, the depolymerization reaction mixture may include 02 to 08 glycol in an amount that is at least about 2, at least about 4, at least about 6, at least about 8, or at least about 10 times greater and / or not more than about 20, not more than about 18, not more than about 16, not more than about 14, or not more than about 12 times greater than a stoichiometric amount of the C2 to C8 glycol that would be present as a result of full depolymerization of the poly(C2 to C4 alkylene terephthalate) introduced into the depolymerization step / zone 20.

[0030] The exogenous C2 to C8 glycol, when used, can be added to the depolymerization step / zone 20 via line 140 either alone or in combination with the C4 to 014 alcohol added to the depolymerization step / zone 20 via line 116. Prior to (or at the beginning of) the depolymerization reaction, the exogenous 02 to 08 glycol can be added to the waste plastic or to a slurry formed from the waste plastic and the C4 to C14 alcohol. At the start of the depolymerization reaction, the exogenous C2 to C8 glycol may be present in the depolymerization reaction mixture in an amount of at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, at least about 5, or at least about 5.5 parts by weight and / or not more than about 30, not more than about 25, not more than about 20, not more than about 17.5, not more than about 15, not more than about 12.5, not more than about 10, or not more than about 7.5 parts by weight based on 100 parts of the C4 to C14 alcohol in the depolymerization reaction mixture. Additionally, the exogenous C2 to C8 glycol may be present in similar amounts expressed as a weight percent, based on the total weight of the exogeneous C2 to C8 glycol and the C4 to C14 alcohol; this may apply when the alcohol and glycol present in the depolymerization reaction mixture or product comprises, consists essentially of, or consists of C2 to C8 glycol and the C4 to C14 alcohol.

[0031] In some embodiments, the exogenous C2 to C8 glycol may be present in an amount of at least about 1 .5, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, or at least about 5 weight percent and / or not more than about 12.5, not more than about 12, not more than about 11 , not more than about 10, not more than about 8, or not more than about 7.5 weight percent, based on the total weight of the reaction mixture in the depolymerization reactor (not shown in FIG. 1) at the start of the depolymerization reaction.

[0032] Such a reaction mixture can include waste plastic and an alcohol, wherein the waste plastic comprises at least about 70, at least about 75, at least about 80, or at least about 85 of waste poly(C2 to C4 alkylene terephthalate) and not more than about 30, not more than about 25, not more than about 20, or not more than about 15 weight percent of non-poly(C2 to C4 alkylene terephthalate) waste plastic and / or non-plastic weight components, based on the total waste plastic, along with the at least one alcohol. The alcohol can include, for example, a C4 to C14 alcohol in an amount of at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 weight percent and an exogenous C2 to C8 glycol in an amount of not more than about 30, not more than about 25, not more than about 20, not more than 15, or not more than 10 weight percent, each based on the total weight of alcohol and glycol in the reaction mixture. Other suitable amounts of each of these components are provided elsewhere in this description.

[0033] When present, the exogenous C2 to C8 glycol can comprise at least one glycol chosen from linear or branched aliphatic glycols, including a C2 to C6 glycol or a C2 to C4 glycol. More specific examples of suitable C2 to 08 glycols include, but are not limited to, neopentyl glycol, propylene glycol, trimethylolpropane, 02 to 06 (or 04 or 05) alkylene diols, and combinations thereof. The 02 to 08 glycol may also comprise at least one C4 to C8 (or C4 to C6) ethereal diol. Other examples of suitable 02 to C8 glycols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and combinations thereof. In some embodiments, the C2 to C8 glycol can comprise, consist essentially of, or consist of ethylene glycol.

[0034] The depolymerization reaction performed in depolymerization step / zone 20 may be carried out in the presence of at least one esterification or transesterification catalyst (also referred to herein as the “depolymerization catalyst”) shown in FIG. 1 as entering via line 112. In some embodiments, the depolymerization catalyst may be chosen from Lewis Acids or Lewis Bases. Specifically, thedepolymerization catalyst may be chosen from metal acetates, titanium alkoxides, and tin species such as tin oxalate, monobutyltin oxide, monobutyltin tris(2- ethylhexanoate), or combinations thereof, or it may be chosen from potassium carbonate, potassium bicarbonate, potassium acetate, sodium acetate, titanium tetra(isopropoxide, monobutyltin tris(2-ethylhexanoate), or combinations thereof. In some embodiments, the depolymerization catalyst may be present in an amount of at least about 0.001 , at least about 0.005, at least about 0.0075, at least about 0.010 equivalents and / or not more than about 0.1 , not more than about 0.075, or not more than about 0.05 equivalents based on a PET repeat unit in the reaction mixture. However, little or no enzymes may be used during depolymerization, with the total enzyme content of the depolymerization reaction mixture being less than about 500, less than about 100, less than about 50, or less than about 25 ppm, based on the total weight of the reaction mixture.

[0035] In some embodiments, wherein an exogenous C2 to C8 glycol is used as a reaction additive, at least a portion of the depolymerization catalyst may be added with at least a portion of the exogenous C2 to C8 glycol. For example, at least a portion of the C2 to C8 glycol and at least a portion of the depolymerization catalyst may be combined to form a liquid catalyst mixture, which may be added to the depolymerization reactor (not shown in FIG. 1 ) via line 112. The catalyst may comprise solid or a liquid catalyst, and the combining step may be carried out at about ambient temperature. In some embodiments, the liquid catalyst mixture may be heated to a temperature within about 15, within about 10, within about 7, within about 5, or within about 3.5°C of the target depolymerization temperature during the mixing and / or just prior to adding the liquid catalyst mixture to the depolymerization reactor. Alternatively, the ambient temperature liquid catalyst mixture may be added to the depolymerization reactor when its temperature (e.g., the temperature of the reaction mixture within the depolymerization reactor) is within one or more of the above ranges. In other embodiments, the catalyst may be directly added to the depolymerization or reaction mixture as a powder or may be added as a concentrated solution with water.

[0036] In some embodiments, the internal reaction temperature of the depolymerization reaction performed in depolymerization step / zone 20 may be at least about 100, at least about 110, at least about 120, at least about 130, at least about 140, at least about 150, at least about 160, at least about 165, at least about 170, at least about 175, at least about 180, at least about 185, or at least about 190°C and / or not more than about 250, not more than about 240, not more than about 230, not morethan about 220, not more than about 215, not more than about 210, not more than about 205, not more than about 200, not more than about 195, not more than about 190, not more than about 185, not more than about 180, or not more than about 175°C. Unless otherwise noted, the temperatures described herein with respect to reaction vessels are the average temperatures of the liquid-phase reaction mixtures (also referred to as “internal” temperatures), while the temperatures of columns or vessels generally refer to the vapor-phase streams removed from a given vessel or process zone or step.

[0037] The internal reaction temperature may be chosen to provide desired reaction products while minimizing undesirable by-products and in order to achieve maximum efficiency and simplicity (in terms of equipment configuration). In some embodiments, the depolymerization step / zone 20 may be operated at the boiling point of the lowest-boiling component of the reaction mixture at ambient pressure. In other embodiments, the depolymerization reaction may be carried out under elevated pressure, particularly when lower carbon number alcohols are utilized, in order to maximize reaction rate and increase the boiling point of the entire reaction mixture. In some embodiments, the depolymerization reaction may be performed at a pressure of atmospheric, or up to a pressure of about 500 psi gauge (psig). The depolymerization reaction may be performed in an inert atmosphere (j.e., under an inert gas blanket or inert gas purge) such as, for example, a nitrogen atmosphere. When an inert gas purge is used, the flow rate can be less than about 500, less than about 250, or less than about 100 ml_ gas per minute per L of reaction mixture.

[0038] The depolymerization reaction can be carried out for a reaction time that is at least about 5, at least about 10, at least about 15, at least about 30, at least about 45 minutes, at least about 1 hour, or at least about 1 .5 hours and / or not more than about 10, not more than about 8, not more than about 6, not more than about 4, or not more than about 2 hours.

[0039] The reaction mixture in the depolymerization step / zone 20 may include waste plastic, catalyst, at least one C4 to C14 alcohol and optionally at least one exogenous C2 to C8 glycol, and water. According to some embodiments, the water content of the reaction mixture in the depolymerization reactor at the beginning of the depolymerization reaction can be at least about 0.1 , at least about 0.5, at least about 1 , or at least about 1 .5 weight percent and / or not more than about 10, not more than about 7.5, not more than about 5, or not more than about 3 weight percent, based on the total weight of the reaction mixture. The water can originate from a variety ofsources including, for example, the waste plastic, the incoming catalyst, and / or from one or more recycle streams within the facility.

[0040] The inventors of the present technology have discovered that continuous removal of water during at least a portion, or all, of the depolymerization reaction facilitates more efficient processing, including lower energy consumption and higher yields of purer products. In particular, continuous water removal increases the depolymerization rate and provides a low-viscosity depolymerization product with reduced cloudiness, which can be more easily and efficiently processed in downstream reaction steps / zones.

[0041] Turning now to FIG. 2, a schematic flow diagram illustrating a portion of the chemical recycling facility shown in FIG. 1 is provided, particularly illustrating one embodiment of a depolymerization step / zone 20 that includes continuous water removal. As shown in FIG. 2, the depolymerization step / zone 20 includes a depolymerization reactor 22 and a water separation step / zone 24 for continuously removing at least a portion of the water present in the depolymerization reactor 22. In some embodiments, water can be continuously removed from the depolymerization reactor 22 via water separation step / zone 24 for at least about 50, at least about 60, at least about 75, at least about 80, at least about 90, or at least about 95 percent of the total time the depolymerization reaction is performed in the reactor 22.

[0042] Water may enter the depolymerization reaction mixture from a variety of sources. In some embodiments, it may be introduced with the waste plastic, which may have a moisture content within one or more of the ranges provided herein. In some embodiments, the waste plastic may be hygroscopic and at least a portion of the water can be physically adsorbed onto and / or within the plastic itself. Thus, some of the water present in the depolymerization reaction mixture may be physically liberated from the waste plastic during depolymerization. Additionally, or in the alternative, at least a portion of the water may be present on the surface of at least a portion of the waste plastic and may originate from one or more upstream processing steps (e.g., washing or sink-float separation). In most embodiments, little to no water enters the depolymerization reaction via the C4 to C14 alcohol such that, for example, the C4 to C14 alcohol can have a total water content of not more than about 5, not more than about 3, not more than about 2, not more than about 1 .5, not more than about 1 , not more than about 0.5, or not more than about 0.1 weight percent, based on the total weight of C4 to C14 alcohol added to the depolymerization reactor 22 via line 116.

[0043] The inventors have discovered several effective methods for continuously removing water from the depolymerization reaction mixture in reactor 22. For example, in some embodiments, at least a portion of the reaction mixture may be withdrawn from the reactor 22 and simply routed for further processing or disposal, as shown generally by dashed line 163 in FIG. 2. In other embodiments, an adsorbent may be placed in a portion of the depolymerization reactor, such that the reaction mixture passes through the adsorbent, which removes at least a portion of the water during the reaction. Any suitable type of adsorbent can be used and may be chosen from one or more of molecular sieves, hygroscopic salts such as magnesium chloride, activated carbon, zeolites, clay, ion exchange resins, or combinations thereof.

[0044] In still other embodiments, a portion of the reaction mixture (e.g., a slip stream) withdrawn from depolymerization reactor 22 via line 162 can be routed to water separation step / zone 24, wherein a major portion of the water can be removed. The stream of reaction mixture in line 162 introduced into the water separation step / zone 24 can comprise water in an amount of at least about 1 , at least about 1 .5, at least about 2, at least about 2.5, at least about 3, at least about 3.5, at least about 4, at least about 4.5, at least about 5, at least about 10, at least about 20, or at least about 35 weight percent and / or not more than 90, not more than about 85, not more than about 80, not more than about 70, not more than about 60, not more than about 50, not more than about 40, not more than about 30, not more than about 20, not more than about 10, not more than about 8, not more than about 7, not more than about 6, not more than about 5.5, not more than about 5, not more than about 4.5, not more than about 4, not more than about 3.5, not more than about 3, not more than about 2.5, not more than about 2, or not more than about 1 .5 weight percent, based on the total weight of the stream. In some embodiments, the water separation step / zone 24 may remove at least about 50, at least about 60, at least about 75, at least about 80, or at least about 90 percent of the total weight of water introduced therein and can provide an aqueous stream in line 164 and a dehydrated depolymerization stream in line 166.

[0045] Any method or step for removing water from the stream of reaction mixture 162 in the water separation step / zone 24 can be utilized. In some embodiments, the stream of reaction mixture in line 162 can be a vapor stream and, depending on the specific components of the stream, it may comprise an azeotropic or non-azeotropic mixture of water and the C4 to C14 alcohol used in the depolymerization reaction. The flow rate of the vapor stream may be generated byadjusting (increasing) the temperature and / or (reducing) the pressure of the depolymerization reactor 22. When the stream of reaction mixture in line 162 is a vapor, the water separation step / zone 24 may comprise a water separation vessel chosen from one or more of a distillation column and condenser followed by a liquidliquid separator (e.g., decanter), a vapor-liquid separator (e.g., knock out drum), a packed bed adsorber including one or more of the previously-listed adsorbents, or combinations thereof. In such embodiments, the stream withdrawn from the vessel in line 164 may predominantly comprise the removed water, while the stream in line 166 may predominantly comprise the dehydrated C4 to C14 alcohol and other reaction mixture components.

[0046] In some embodiments, particularly when the 04 to 014 alcohol is less volatile than and / or does not azeotrope with water, the stream of reaction mixture in line 162 may predominantly comprise water, or it may comprise at least about 75, at least about 85, at least about 95, or all water, based on the total weight of the stream in line 162. (Note that these percentages do not account for stripping gas, when present, but are based only on the amount of water and / or reaction mixture withdrawn from the reactor.) When the stream in line 162 comprises predominantly water, it can be formed by passing a stripping gas through the mixture (as described below) or by adjusting the pressure and / or temperature of the reaction mixture. The water removed in line 162 may be cooled and condensed, and withdrawn from the process, while any residual organic components may be returned to the reactor via line 166.

[0047] In other embodiments, at least a portion of the water removal may be carried out by passing an inert stripping gas through the reaction mixture. As generally shown in FIG. 2, this can include introducing a stream of stripping gas in line 168 into the depolymerization reactor 22 (usually at or near the bottom of the reactor). The stripping gas, which can be chosen from one or more of nitrogen, argon, helium, or combinations thereof, may be passed through the reaction mixture at an average volumetric flow rate of at least about 0.1 , at least about 1 , at least about 2, at least about 5, or at least about 7.5 liters per minute (L / min) and / or not more than about 100, not more than about 75, not more than about 50, not more than about 25, or not more than about 10 L / min of gas per liter of reaction mixture, measured at the depolymerization reactor inlet. After exiting the depolymerization reactor 22 as shown in FIG. 2, the outlet gas stream in line 162, which includes the stripping gas and entrained liquid, can be introduced into the water separation step / zone 24 to separate out the stripping gas in line 167, the non-aqueous liquid components (including C4 toC14 alcohol) in line 166, and the separated aqueous phase in line 164. Such separations may be performed via one or more chosen from distillation, extraction, decantation, a packed adsorber, gas-liquid separation, or combinations thereof.

[0048] In still other embodiments, a stream of vapor from the reaction mixture within the depolymerization reactor 22 may be cooled and completely condensed in at least one condenser (not shown in FIG. 2) to provide a two-phase liquid stream. Thereafter, the liquid stream may be separated in a liquid-liquid separation vessel to provide an aqueous phase or stream and an organic phase or stream. At least a portion of the organic phase or stream may be returned to the depolymerization reactor 22, as generally represented by line 162 in FIG. 2, while the aqueous phase or stream may continuously, or intermittently, purged from the system, as generally represented by line 164. An example of a suitable device for performing this type of water separation is a Dean Stark apparatus.

[0049] Alternatively, in some embodiments, the stream of reaction mixture in line 162 withdrawn from the depolymerization reactor 22 may be a liquid stream comprising a mixture of water and C4 to C14 alcohol. When the stream of reaction mixture in line 162 is a liquid phase stream, the water separation step / zone 24 may include a vessel chosen from an extractor, a decanter, a packed bed adsorber including one or more of the previously-listed adsorbents, or combinations thereof. Liquid streams of water in line 164 and C4 to C14 alcohol in line 166 can be withdrawn and routed as discussed previously.

[0050] Regardless of the separation method used, the dehydrated C4 to C14 alcohol stream returned to the reactor 22 via line 166 may comprise less than about 10, less than about 7.5, less than about 5, less than about 3, less than about 2.5, less than about 2, less than about 1 , less than about 0.5, less than about 0.1 weight percent, less than about 5000, less than about 2500, less than about 2000, less than about 1500, less than about 1000, or less than 750 parts per million (ppm) by weight water, based on the total weight of the stream. The depolymerized reaction product withdrawn from the depolymerization reactor 22 via line 118 can also have a water content within one or more of the ranges above.

[0051] As a result of the continuous water removal, the rate of depolymerization increases, thereby shortening reaction time and increasing the efficiency of the system, at a given temperature. For example, use of continuous water removal according to embodiments of the present technology can reduce the time required to achieve at least about 75, at least about 80, at least about 85, or at leastabout 90 percent depolymerization of the initial amount of poly(C2 to C4 alkylene terephthalate) by at least about 1 .5, at least about 2, at least about 2.5, or at least about 3 times as compared to a depolymerization reaction performed under identical conditions but without water removal. Similarly, depolymerization reactions conducted with water removal according to embodiments of the present technology require less than about 8, less than about 6, less than about 5, less than about 4, less than about 3.5, less than about 3, or less than about 2 hours to depolymerize at least about 75, at least about 80, at least about 85, or at least about 90 percent of the initial amount of poly(C2 to C4 alkylene terephthalate) at a depolymerization mixture (internal) reaction temperature of 180°C. Similar reactions without water removal can require at least 10 or more hours for the same extent of depolymerization.

[0052] Referring back to FIG. 1 , a stream of the depolymerized product in line 118a may be withdrawn from the depolymerization step / zone 20. The depolymerization product stream in line 118a may include no poly(C2 to C4 alkylene terephthalate), as determined by visual inspection, and can include similar amounts of higher molecular weight monohydric alcohol (and C2 to C8 glycol additive, when present) as discussed previously with respect to the depolymerization step / zone 20. The stream of depolymerization product 118a may also include a liquid phase comprising at least about 25, at least about 30, at least about 40, at least about 45, or at least about 50 weight percent and / or not more than about 85, not more than about 80, not more than about 75, not more than about 70, not more than about 65, or not more than about 60 weight percent of dissolved terephthalyl components, based on the total weight of the stream. These terephthalyl components may comprise one or more of a number of terephthalate-based components including, but not limited to, monomers and oligomers of terephthalic diesters, diacids, half-esters, and combinations thereof.

[0053] In some embodiments, the depolymerization product stream in line 118a has a density of at least about 0.925, at least about 0.940, at least about 0.950, at least about 0.960, at least about 0.970, at least about 0.975, at least about 0.980, at least about 0.985, at least about 0.990, at least about 0.995, or at least about 1 .0 g / mL and / or not more than about 1 .1 , not more than about 1 .05, not more than about 1 .01 , not more than about 1.0, not more than about 0.990, not more than about 0.980, not more than about 0.975, or not more than about 0.970 g / mL at 25°C.

[0054] Additionally, or in the alternative, the depolymerization product stream in line 118a can have a viscosity of at least about 1 , at least about 5, at least about 10,at least about 20, at least about 25, at least about 30, at least about 40, at least about 50, at least about 60, at least about 75, at least about 80, at least about 90, at least about 100, at least about 110, at least about 125, at least about 130, at least about 140, or at least about 150 cP and / or not more than 300, not more than about 275, not more than about 250, not more than about 225, not more than about 200, not more than about 175, not more than about 150, not more than about 125, not more than about 100, or not more than about 50 cP, measured at 25°C according to the Flow Temperature Ramp test. The Flow Temperature Ramp test is performed in DHR rotational rheometer (commercially available from TA Instruments, New Castle, DE, USA) and begins with a sample temperature of 25°C. Thereafter, the sample is heated to a temperature of 60°C at a rate of 2°C / min. The shear rate used for this test is 100 s'1and a specific geometry of DIN concentric cylinders was employed. The depolymerization product stream in line 118a is not opaque or cloudy, as determined by visual inspection.

[0055] The stream of depolymerization product withdrawn from depolymerization step / zone 20 in line 118a may be cooled and the resulting cooled stream may be subjected to a solid-liquid separation step / zone 25 to remove at least a portion, or a major portion, of the solid impurities and coproducts. The cooling can help facilitate solidification of the impurities and coproducts (such as, for example, non- PAT solids as listed previously) from solution and may help minimize equipment and operating costs. In some embodiments, the temperature of the cooled stream entering the solid-liquid separation step / zone 25 can be at least about 20, at least about 25, at least about 30, at least about 35, or at least about 40°C and / or not more than about 100, not more than about 90, not more than about 80, not more than about 75, not more than about 70, not more than about 60, not more than about 50, or not more than about 45°C.

[0056] The cooled stream may then be subjected to a solid-liquid separation, wherein a portion or all of the solid components of the cooled stream can be removed to provide a liquid-phase depolymerization stream in line 118b. The solid-liquid separation step / zone 25 may utilize one or more separation techniques chosen from decantation, vacuum filtration, centrifugation, pressure filtration, hydrocyclones, or combinations thereof. Filter aids, including for example, diatomaceous earth, perlite, asbestos, cellulose, agricultural fibers, saw dust, rice hulls, ash, and fiber, may or may not be utilized.

[0057] In some embodiments of the present technology, at least one low density additive may be combined with the depolymerization reaction mixture prior to the solid-liquid separation step / zone 25 to provide a modified reaction mixture having a density less than the density of the initial depolymerization reaction mixture. Although not wishing to be bound by theory, it is believed that modification of the density of the liquid reaction mixture to a point below the density of the least dense non-PAT impurity (solid) may help facilitate more effective and efficient separation of the non-PAT components from the depolymerized product stream in the separation zone 25, thereby providing a purer feed stream to subsequent reaction zones (e.g., transesterification).

[0058] Turning now to FIG. 3, a schematic flow diagram of a portion of a chemical recycling facility is shown, particularly illustrating the main steps / zones for improved separation of non-PAT solids from the depolymerized reaction stream. As shown in FIG. 3, the depolymerized product stream in line 118a withdrawn from the depolymerization reactor 22 may be introduced into a solid-liquid separation zone 25, wherein the low density additive in line 150 may be combined with the depolymerized product stream in line 118a. In some embodiments, the low density additive in line 150 may be combined with the depolymerization product stream in line 118a before introduction into the solid-liquid separation step / zone 25, as also shown in FIG. 3. The density of the resulting modified reaction mixture may be reduced to a density lower than the density of the least dense (j.e., lowest density) non-PAT solid. As a result, the non-PAT solids can be more easily separated from the lower density liquid in subsequent solid-liquid separation vessels.

[0059] The non-PAT solids present in the depolymerization product stream in line 118a are those introduced with the waste plastic in line 110 that did not undergo depolymerization or dissolution during the depolymerization reaction. Specific examples of non-PAT solids are those mentioned previously. In some embodiments, the polymeric non-PAT solids in the depolymerization product stream in line 118a have an average density of greater than 0.90, at least about 0.91, at least about 0.92, at least about 0.93, at least about 0.94, at least about 0.95, at least about 0.96, at least about 0.97, at least about 0.98, or at least about 0.99 g / mL and / or not more than about 1 .5, not more than about 1 .4, not more than about 1 .3, not more than about 1 .25, not more than about 1 .2, not more than about 1.1 , not more than about 1 .05, not more than about 1 , or not more than about 0.95 g / mL, measured at 25°C. The least dense non-PAT solid can, in some embodiments, have a density greater than about 0.90, atleast about 0.91 , at least about 0.92, at least about 0.93, at least about 0.94, or at least about 0.95 g / mL and / or not more than about 1 , not more than about 0.99, not more than about 0.98, not more than about 0.97, not more than about 0.96, or not more than about 0.95 g / mL, measured at 25°C. Non-polymeric non-PAT solids (e.g., carbon black, calcium carbonate, and the like) can have a higher density that may be greater than about 1 .5, greater than about 1 .75, greater than about 2, greater than about 2.5, greater than about 3, greater than about 5, or even up to 10 g / mL or more, measured at 25°C.

[0060] In some embodiments, the low density additive can be a liquid additive having a density of not more than about 0.85, not more than about 0.84, not more than about 0.83, not more than about0.82, not more than about 0.81 , or not more than about 0.80 g / mL at 25°C. In some embodiments, the additive is a liquid and is not a solid at the processing conditions (e.g., temperature and pressure) of the adding step (e.g., the liquid additive and the process stream to which it is added). Additionally, or alternatively, the low density additive can have a density of at least about 0.65, at least about 0.67, at least about 0.70, at least about 0.72, at least about 0.75, or at least about 0.77 g / mL at 25°C.

[0061] Examples of suitable low density additives can include, but are not limited to, an alcohol chosen from a C1 to C12 alcohol, a C2 to C10 alcohol, a C1 to C10 alcohol, a C3 to C10 alcohol, a C1 to C8 alcohol, a 02 to 08 alcohol, a C3 to C8 alcohol, or combinations thereof, or one or more of an ether, an aromatic hydrocarbon, an alicyclic hydrocarbon, a ketone, and a nitrile. The low density additives may include saturated and / or unsaturated hydrocarbons, including straight chain, branched, cyclic, or alicyclic hydrocarbons. The ethers may be cyclic or alicyclic. More specific examples of suitable low density additives can include, but are not limited to, diethyl ether, diisopropyl ether, dibutyl ether, tert-butyl methyl ether, tetrahydrofuran, 2- methyltetrahydrofuran, benzene, toluene, xylene, hexane, heptane, cyclohexane, limonene, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl amyl ketone, acetonitrile, butyronitrile, methanol, ethanol, 1 -propanol, 2-propanol, 1- butanol, 2-butanol, pentanol, hexanol, heptanol, octanol, 2-ethylhexanol, and combinations thereof. In some embodiments, the low density additive can comprise one or more chosen from methanol, butanol, 2-ethylhexanol, acetone, or combinations thereof. In some embodiments, the low density additive may comprise the same 04 to 014 alcohol used during depolymerization and / or the same 01 to 03 alcohol used in transesterification.

[0062] In some embodiments, particularly when the temperature of the low density additive and reaction mixture being modified are above 140°C, the low density additive may not include any of the following components: dibutyl terephthalate (DBT), dioctyl terephthalate (DOTP), tetrahydrofuran (THF), ethanol, 2-ethyl hexanol (2-EH), 4-methylcyclohexanemethanol (MCHM), dimethylsulfoxide (DMSO), dimethylformamide (DMF), dimethyl terephthalate (DMT), 4- methylcyclohexanemethanol (MCHM), ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), 1 ,4-cyclohexanedimethanol (CHDM), polyethylene glycol) (PEG), neopentyl glycol (NPG), propane diol (PDO), butanediol (BDO), 2-methyl-2,4- pentanediol (MP diol), poly(tetramethylene ether)glycol (PTMG), ethylene carbonate (EC), and dimethyl carbonate (DMC). One or more of these may be used as the low density additive when the temperature of the additive and the temperature of the product stream during addition is 140°C or lower and, in particular, when the temperature of these streams during the combining step falls within the temperature ranges provided below.

[0063] According to some embodiments, it is preferable that the low density additive be at least partially, or nearly totally, miscible with the components present in the depolymerization product stream in line 118a. If the low density additive is at least partially, or totally, miscible, the low density additive can help increase the solubility of at least a portion of the depolymerization reaction products (e.g., C4 to C14 dialkyl terephthalate, as well as mixed esters, half-esters, oligomers, etc.), thereby further enhancing the downstream solid-liquid separation.

[0064] In some embodiments, the amount of low density additive combined with the depolymerization product stream in line 118a, as shown in FIG. 3, can be at least about 5, at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, at least about 100, at least about 105, at least about 110, at least about 115, at least about 120, at least about 125, at least about 130, at least about 135, at least about 140, at least about 145, or at least about 150 parts by weight and / or not more than about 500, not more than about 450, not more than about 400, not more than about 350, not more than about 300, not more than about 250, not more than about 200, not more than about 150, not more than about 140, not more than about 130, not more than about 125, not more than about 120, not more than about 110, not more thanabout 100, not more than about 90, not more than about 80, not more than about 75, not more than about 70, not more than about 60, not more than about 50, not more than about 40, not more than about 35, not more than about 25, not more than about 20, not more than about 15, not more than about 10, or not more than about 5 parts by weight based on 100 parts by weight of the depolymerized product stream prior to the combining.

[0065] The combining step can be performed at any temperature, but may, in some embodiments, be performed on the depolymerization product stream in line 118a after it has been cooled. The temperature of the cooled stream of depolymerized product in line 118a can be within the ranges provided previously. In some embodiments, the temperature of the cooled depolymerization product stream in line 118a just prior to the addition of the low density additive is at least ambient temperature and less than the boiling point of (i) the lowest boiling component of the cooled depolymerization product stream in line 118a and / or the boiling point of the low density additive. The temperature of the cooled depolymerization product stream in line 118a just prior to the adding of the low density additive can be not more than about 140, not more than about 130, not more than about 120, not more than about 110, not more than about 100, not more than about 95, not more than about 90, not more than about 85, not more than about 80, not more than about 75, not more than about 70, not more than about 65, or not more than about 60°C. Additionally, or in the alternative, the temperature of one or both streams during the combining can be at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, at least about 52, or at least about 55°C.

[0066] The modified depolymerized product stream can have a density of not more than about 0.95, not more than about 0.94, not more than about 0.93, not more than about 0.92, not more than about 0.91 , 0.90 or less, or not more than about 0.89, not more than about 0.88, not more than about 0.87, not more than about 0.86, not more than about 0.85, not more than about 0.84, not more than about 0.83, not more than about 0.82, not more than about 0.81 , not more than about 0.80, not more than about 0.75, or not more than about 0.70 g / mL at 25°C. The density of the modified depolymerized product stream can be at least about 0.025, at least about 0.04, at least about 0.05, at least about 0.06, or at least about 0.07 g / mL and / or not more than about 0.2, not more than about 0.175, not more than about 0.150, not more than about 0.125, not more than about 0.100, or not more than about 0.09 g / mL less (lower) than thedensity of the original depolymerized product stream in line 118 prior to addition of the low density additive.

[0067] In some embodiments, the modified depolymerized product stream can be subjected to a solid-liquid separation step in solid-liquid separation step / zone 25 to remove at least a portion of the solids, including non-PAT solids, present in the mixture. The modified depolymerized product stream can have a total insoluble solids content of ate least about 1 , at least about 1 .5, at least about 2, at least about 3.5, or at least about 5 weight percent and / or not more than about 10, not more than about 7, not more than about 5, not more than about 2, or not more than about 1 weight percent insoluble solids, based on the total weight of the stream.

[0068] In some embodiments, the modified depolymerized product stream can be heated before being separated and may, for example, have a temperature of at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, or at least about 65°C and / or not more than about 100, not more than about 95, not more than about 90, not more than about 85, not more than about 80, not more than about 75, or not more than about 70°C, but not higher than the boiling point of the lowest boiling component in the modified reaction mixture. Additionally, in some embodiments, the modified depolymerized product stream (heated or not) may be subjected to a hold time prior to the separating step. Such a hold time, when employed, can be in the range of from about at least about 1 minute, at least about 30, at least about 60, at least about 90, at least about 120, or at least about 180 minutes and / or not more than about 7, not more than about 5, not more than about 3, not more than about 2 days, not more than about 1 day, not more than about 12, not more than about 10, not more than about 8, not more than about 6, no more than about 2 hours, not more than about 1 hour, or not more than about 30 minutes.

[0069] The solid-liquid separation step / zone 25 may utilize any process configuration capable of removing at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 weight percent of the non- PAT solids from the modified depolymerized product stream. The resulting purified liquid stream withdrawn from the solid-liquid separation step may have a total insoluble solids content of not more than about 5, not more than about 3, not more than about 2, not more than about 1 , not more than about 0.5, not more than about 0.25, or not more than about 0.10 weight percent insoluble solids, based on the total weight of the purified liquid stream. Examples of suitable types of separators include, but are not limited to, hydrocyclones, centrifuges, decanters, and pressure filters. Whencentrifugation is used, it can be carried out in one or more centrifuges arranged in series and / or in parallel. The type of centrifuge is not limited, but can include, in some embodiments, a decanter centrifuge, a disc stack centrifuge, and combinations thereof. In other embodiments, the separation may be performed by gravity separation and without use of any type of filtration device.

[0070] In some embodiments, the temperature of the modified depolymerized product stream during the solid-liquid separation step can be at least about 10, at least about 15, at least about 20, or at least about 25°C and / or not more than about 100, not more than about 90, not more than about 80, not more than about 75, not more than about 70, not more than about 60, or not more than about 50°C. The separating step may be performed for at least about 1 minute, at least about 2, at least about 5, at least about 10, at least about 15, at least about 30, or at least about 45 minutes and / or not more than about 180, not more than about 150, not more than about 120, not more than about 90, not more than about 60, not more than about 45, not more than about 30, or not more than about 15 minutes. When the solids are separated by centrifugation, the centrifuging can be carried out at a gravitational force of at least about 1000, at least about 2000, at least about 2500, at least about 3500, or at least about 5000 G and / or not more than about 30,000, not more than about 27,000, not more than about 25,000, not more than about 20,000, not more than about 15,000, not more than about 10,000, or not more than about 5,000 G.

[0071] According to some embodiments, at least a portion of the solids recovered from the solid-liquid separation step / zone 25 via line 119 can optionally be reslurried with at least one solvent, including one or more of the low density additive compounds listed previously. In some embodiments, the solvent used to reslurry the solids removed from the depolymerization reaction stream in line 119 may comprise the same C4 to C14 alcohol used in depolymerization step / zone 20 and / or the same C1 to C3 alcohol used in the transesterification step / zone 30.

[0072] During the reslurrying step, the solvent and solids may be mixed, optionally under agitation (e.g., rolling, shaking, and / or stirring), at a liquid temperature of at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, or at least about 45°C and / or not more than about 100, not more than about 95, not more than about 90, not more than about 85, not more than about 80, not more than about 75, not more than about 70, not more than about 65, not more than about 60, not more than about 55, or not more than about 50°C, but lower than the boiling point of the solvent. The solvent may be added in an amount of at least about 1 , atleast about 2, at least about 5, at least about 10, at least about 15, or at least about 20 percent and / or not more than about 100, not more than about 85, not more than about 75, or not more than about 50 percent of the total weight of the solids.

[0073] After reslurrying, the solid-containing liquid stream may be subjected to another separation step carried out in the same or a different separation vessel used during the initial separating step. Again, a major portion, or at least about 70, at least about 75, at least about 80, or at least about 85 percent of the total weight of solids in the reslurried stream may be removed in this second solid-liquid separation vessel. The liquid stream may be combined and / or co-processed with the liquid stream withdrawn from the first solid-liquid separation step, and the solids may again be reslurried and further separated. This step may be repeated at least once, twice, or three or more times.

[0074] Referring again to FIG. 1 , the liquid-phase stream in line 118b withdrawn from the solid-liquid separation step / zone 25 may be introduced into a transesterification zone 30, wherein at least a portion of the dialkyl terephthalate components, including any C4 to C14 dialkyl terephthalate components formed during depolymerization in the upstream depolymerization step / zone 20 as well as various other terephthalyl components (e.g., half-ester terephthalates, mixed-esters, and various other terephthalate components), may be transesterified with an additional alcohol in line 120 to form another dialkyl terephthalate. In some embodiments, the alcohol introduced into the transesterification step / zone via line 120 can comprise a C1 to C3 alcohol, or it can comprise at least one chosen from ethanol or methanol, or it can comprise methanol. Although described herein with respect to a C1 to C3 alcohol, it should be understood that any suitable alcohol (or mixtures of alcohols) can be used without departing from the spirit of the present invention. When methanol is used, the resulting C1 to 03 dialkyl terephthalate product can comprise predominantly dimethyl terephthalate (DMT). The C1 to C3 alcohol introduced via line 120 can be present at the beginning of the transesterification reaction in an amount of at least about 2, at least about 5, or at least about 7.5 molar equivalents and / or not more than about 50, not more than about 36, not more than about 24, or not more than about 20 equivalents based on the total moles of terephthalate in the modified product stream.

[0075] In some embodiments, at least about 75, at least about 85, at least about 90, or all of, the 01 to 03 alcohol needed for the transesterification reaction may be added to the transesterification step / zone 30 via line 120, as shown in FIG. 1. Alternatively, or in addition, when a low density additive is used to enhanced separationin the solid-liquid separation step / zone 25, the low density additive may comprise, or be, the C1 to C3 alcohol used in the transesterification step / zone 30. In such cases, the C1 to 03 alcohol is added to the depolymerization reaction product, and the combined stream is centrifuged or otherwise subjected to solid-liquid separation to remove the non-PAT solids. The remaining liquid stream, which may include most or all of the C1 to 03 alcohol needed to perform the transesterification reaction may be present in the resulting liquid stream in line 118b, may simply be introduced into the transesterification step / zone 30, wherein the transesterification reaction can be performed. In some embodiments, the liquid stream in line 118b can be supplemented with additional 01 to 03 alcohol in or prior to introduction into the transesterification reactor (not shown). In other cases, no additional 01 to 03 alcohol may be added and transesterification can be carried out as described herein.

[0076] In some embodiments, the transesterification reaction can be carried out in two stages with the first being performed at an internal reaction temperature of at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, or at least about 50°C and / or not more than about 85, not more than about 80, not more than about 75, not more than about 70, nor more than about 65, or not more than about 60°C, and the second being performed at an internal reaction temperature of not more than about 37, not more than about 35, or not more than about 30°C. In some embodiments, the second stage transesterification can be conducted at a temperature that is at least about 2, at least about 5, at least about 10, or at least about 15°C and / or not more than about 50, not more than about 40, not more than about 30, not more than about 25, or not more than about 20°C lower than the temperature of the first stage transesterification.

[0077] Each stage can be held for a set time period before transitioning to the next stage. For example, the first higher temperature stage may be held for a first time period in the range of from about 15 to about 120 minutes, about 15 to about 90 minutes, or about 15 to about 60 minutes, while the second lower temperature stage (e.g., cooling stage) may be held for a second time period in the range of from about 5 to about 75 minutes, about 15 to 60 minutes, or about 15 to 45 minutes. The last stage may be held for up to about 24 hours, up to about 12 hours, up to about 2 hours, or up to about 1 hour. The pressure of the transesterification reaction step may be at or below atmospheric pressure sufficient to maintain the alcohol (e.g., 01 to 03 alcohol) in the reaction mixture and avoid its evaporation.

[0078] The transesterification reaction / step 30 can be carried out in the presence of a basic catalyst, as shown by line 121 in FIG. 1 . Examples of suitable catalysts can include, but are not limited to, metal C1-C14 alkoxides, metal carbonates, and metal hydroxides, wherein the metals can be chosen from lithium, sodium, or potassium. In some embodiments, the transesterification catalysts used in the step / zone 30 can be chosen from sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium 2-ethylhexylate, potassium 2-ethylhexylate, potassium carbonate, or combinations thereof. The catalyst may be present in the transesterification reaction mixture in an amount of at least about 0.005, at least about 0.010, or at least 0.020 equivalents and / or not more than about 0.20, not more than about 0.10, or not more than about 0.075 equivalents, based on the total moles of the terephthalate ester introduced into the transesterification step / zone 30.

[0079] In some embodiments, particularly when the C1 to C3 alcohol comprises methanol, the resulting product stream in line 122 withdrawn from the transesterification step / zone 30 can be a slurry of dimethyl terephthalate (DMT), or other C1 to C3 dialkyl terephthalate, in a liquid phase comprising the C1 to C3 alcohol, residual C4 to C14 alcohol, as well as residual catalyst and soluble terephthalate species (e.g., salts, oligomers, dimers, half-esters, etc.). As shown in FIG. 1 , the product slurry in line 122 can be subjected to a solid-liquid separation step or zone 40, wherein the solid terephthalate (e.g., DMT) can be isolated from the liquid phase. Any suitable type of solid-liquid separation can be used in step / zone 40 including, but not limited to, vacuum filtration, centrifugation, pressure filtration, and combinations thereof. In some embodiments, the solids can be washed with additional C1 to C3 alcohol (e.g., methanol) to remove residual C4 to C14 alcohol and other components.

[0080] Alternatively, in some embodiments, when the C4 to C14 alcohol used to depolymerize the waste plastic comprises 2-ethylhexanol, the resulting terephthalate can be converted to bis(2-ethylhexyl) terephthalate as described in U.S. Patent No. 5,101 ,064 and U.S. Patent No. 5,319,128, the entireties of which are incorporated herein by reference to the extent not inconsistent with the present disclosure.

[0081] As shown in FIG. 1 , the solids withdrawn from the solid-liquid separation zone 40 via line 124 can optionally be further purified in at least one purification step or zone 50, to provide purified recycled content dialkyl terephthalate (r-dialkyl terephthalate) in line 128. In some embodiments, the r-dialkyl terephthalate in line 124 or 128 can have a non-volatile impurity level of less than 0.5 percent, andan overall yield of at least about 75 or at least about 80 percent, based on the poly(C2 to C4 alkylene terephthalate) polymer fed to the depolymerization step / zone 20.

[0082] The liquid phase stream in line 126 withdrawn from the solid-liquid separation zone 40 may be introduced into a separation / purification step or zone 60 to further separate one or more of the components of the stream and, where possible, return at least a portion of the recovered components to various locations within the facility. For example, in some embodiments, at least a portion of the methanol (or other C1 to C3 alcohol) can be recovered and returned to the transesterification step / zone 30 via line 134 and / or to the solid-liquid separation step 25 via line 134a as shown in FIG. 1. Similarly, at least a portion of the C4 to C14 alcohol (optionally with depolymerization catalyst and / or soluble terephthalate components) may also be recovered and returned to the depolymerization step / zone 20 via line 132. Any suitable separation method or combination of methods can be used, including, but not limited to, distillation, extraction, and combinations thereof. For example, in some embodiments (and depending on the boiling points of the different components), the C1 to C3 alcohol can be recovered via distillation, while the C4 to C14 alcohol can be recovered from the C2 to 04 alkylene glycol formed from the depolymerization via liquid-liquid extraction.

[0083] Turning now to FIG. 4, a schematic block flow diagram illustrating a separation / purification step / zone 60 according to various embodiments of the present invention is provided. As shown in FIG. 4, a liquid filtrate stream in line 126 from the solid-liquid separation step / zone 40 may be introduced into a first vapor-liquid separator 62 (such as, for example, a first distillation column) of the separation / purification step / zone 60. The liquid filtrate stream in line 126 can include 04 to 014 alcohol, 01 to 03 alcohol, 02 to 04 glycol resulting from the depolymerization of poly(C2 to C4 alkylene terephthalate), and optionally 02 to C8 glycol added as an exogenous additive. Additionally, the liquid filtrate stream may comprise various soluble terephthalyl components (e.g., half-esters, mixed esters, oligomers, dimers, terephthalic acids, etc.), as well as residual depolymerization and / or transesterification catalysts.

[0084] In some embodiments, the liquid filtrate stream 126 introduced into the first vapor liquid separator 62 can comprise at least about 20, at least about 25, at least about 30, at least about 35, at least about 40, at least about 45, at least about 50, or at least about 55 percent and / or not more than about 85, not more than about 80, not more than about 75, not more than about 70, not more than about 65, not morethan about 60, not more than about 55, not more than about 50, not more than about 45, not more than about 40, or not more than about 35 weight percent of C1 to C3 alcohol, based on the total weight of the liquid stream.

[0085] As shown in FIG. 4, the liquid filtrate stream in line 126 may be separated in the first vapor-liquid separator 62 to provide an overhead stream comprising predominantly C1 to C3 alcohol and a bottoms stream comprising predominantly C4 to 014 alcohol, C2 to C4 glycol, exogenous C2 to 08 glycol (when present), and various components heavier than the glycols. The separation carried out in the first vapor-liquid separator 62 can be carried out at a temperature of at least about 30, at least about 35, at least about 40, or at least about 45°C and / or not more than about 80, not more than about 75, not more than about 70, not more than about 65, or not more than about 60°C.

[0086] The pressure of the separation can be at or below atmospheric pressure and can be within about 10, within about 5, within about 3, within about 2, or within about 1 psig of atmospheric pressure. In some embodiments, the separation in the first vapor-liquid separator 62 can be performed at a pressure of not more than about 750, not more than about 700, not more than about 650, not more than about 600, not more than about 550, not more than about 500, not more than about 450, not more than about 400, not more than about 350, not more than about 300, not more than about 250, not more than about 200, not more than about 150, not more than about 100, or not more than 50 mm Hg. Separator or column temperatures and pressures provided herein refer to overhead temperatures and pressures, unless otherwise noted.

[0087] The overhead stream in line 134 can comprise at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 99 weight percent of C1 to C3 alcohol, based on the total weight of the stream. In some embodiments, the overhead stream from the first vapor-liquid separator 62 in line 134 can include at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 99 weight percent of the total amount of C1 to C3 alcohol introduced into the separator 62 in line 126. As shown in FIG. 4, at least a portion of the overhead stream in line 134 may be reintroduced into (recycled to) the transesterification step / zone 30 and / or to the solid liquid separation zone 25 (not shown in FIG. 4).

[0088] The liquid bottoms stream withdrawn from the first vapor-liquid separator 62 (e.g., the methanol column) via line 142 comprises C4 to C14 alcohol, C2 to 04 glycol formed during depolymerization, and optionally exogenous 02 to 08 glycol added to the depolymerization reaction. In some embodiments the liquid bottoms stream in line 142 comprises at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, or at least about 40 weight percent and / or not more than about 65, not more than about 60, not more than about 55, not more than about 50, not more than about 45, not more than about 35, not more than about 30, or not more than about 25 weight percent of C2 to C4 glycol, based on the total weight of the stream.

[0089] Additionally, the stream in line 142 may also include C4 to 014 alcohol in an amount of at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, at least about 35, or at least about 40 weight percent and / or not more than about 65, not more than about 60, not more than about 55, not more than about 50, not more than about 45, not more than about 35, not more than about 30, or not more than about 25 weight percent of C4 to C14 alcohol, based on the total weight of the stream and, optionally, exogenous C2 to C8 glycol, in an amount of at least about 2, at least about 5, at least about 10, or at least about 15 weight percent and / or not more than about 30, not more than about 25, not more than about 20, not more than about 15, or not more than about 10 weight percent, based on the total weight of the stream in line 142.

[0090] In some embodiments, the amount of components heavier than the C4 to C14 alcohol, the C2 to C4 glycol, and optionally the exogenous C2 to 08 glycol, when present, ( / .e., heavy components) in the liquid stream in line 142 can be less than about 25, less than about 20, less than about 15, less than about 10, less than about 5, or less than about 2 weight percent, based on the total weight of the stream. These heavy components can include, but are not limited to, terephthalyl monomers and oligomers and salts, as well as residual catalysts.

[0091] As shown in FIG. 4, the bottoms stream from the first vapor-liquid separator 62 may be introduced into another vapor-liquid separator 64 (such as, for example, another distillation column), wherein the stream can be further separated to provide another overhead stream in line 146 and another liquid bottoms stream in line 144. In some embodiments, the second vapor-liquid separator 64 (e.g., the glycol separation column) can be operated such that a major portion, or nearly all, of the 02 to C4 glycol and at least a portion of the 04 to C14 alcohol are recovered in theoverhead stream. In some embodiments, only enough C4 to C14 glycol is recovered in the overhead stream from separator 64 to ensure that at least about 85, at least about 90, at least about 92, at least about 95, at least about 97, or at least about 99 percent of the total amount of C2 to 04 glycol introduced into the column is withdrawn in the overhead stream in line 146. The remaining C4 to C14 glycol is permitted to leave the column in the bottoms stream, which can be returned to the depolymerization step / zone 20 via line 145, as shown in FIG. 4. In some embodiments, the bottoms stream in line 144 may include less than about 10, less than about 7, less than about 5, less than about 2, or less than about 1 weight percent of the 02 to 04 glycol, based on the total weight of the stream.

[0092] The mixture of 02 to 04 glycol and 04 to C14 alcohol in the overhead stream from separator 64 in line 146 may or may not be an azeotropic mixture. The stream in line 146 may include at least about 85, at least about 90, at least about 95, at least about 97, or at least about 99 weight percent of the mixture of C2 to C4 glycol and C4 to 014 alcohol, based on the total weight of the stream. Thus, the stream in line 146 includes less than about 15, less than about 10, less than about 5, less than about 2, or less than about 1 weight percent of components other than this mixture. In some embodiments, the mixture can include the 02 to 04 glycol in an amount of at least about 5, at least about 10, at least about 15, at least about 20, or at least about 25 weight percent and / or not more than about 50, not more than about 45, not more than about 40, not more than about 35, or not more than about 30 weight percent, and / or it may include the C4 to C14 alcohol in an amount of at least about 50, at least about 55, at least about 60, at least about 65, or at least about 70 weight percent and / or not more than about 95, not more than about 90, not more than about 85, not more than about 80, or not more than about 75 weight percent, based on the total weight of the mixture.

[0093] The separation in the second vapor-liquid separator 64 (e.g., the glycol separation column) can be carried out at a temperature of at least about 80, at least about 85, at least about 90, at least about 95, at least about 100, at least about 105, at least about 110, at least about 115, at least about 120, or at least about 125°C and / or not more than about 195, not more than about 190, not more than about 185, not more than about 180, not more than about 175, not more than about 170, not more than about 165, not more than about 160, not more than about 155, not more than about 150, not more than about 145, not more than about 140, not more than about 135, or not more than about 130°C. The pressure in the separator 64 can be belowatmospheric and may, for example, be at least about 10, at least about 50, at least about 100, at least about 150, or at least about 200 mm Hg and / or not more than about 760, not more than about 750, not more than about 700, or not more than about 675 mm Hg.

[0094] According to some embodiments, a major portion of any salts present in the liquid filtrate such as for example, alkali metal salts, introduced to vapor-liquid separator 64 may be recovered in the bottoms stream 144, rather than in the overhead stream 146 with the C2 to C4 glycol. For example, in some embodiments, the feed stream to the separator 64 in line 142 can include alkali metal carboxylate salts and the stream can have an alkali metal ion concentration of at least about 100, at least about 500, at least about 1000, or at least about 2500 ppm and / or not more than about 1 , not more than about 0.75, not more than about 0.50, not more than about 0.25, not more than about 0.10, or not more than about 0.05 weight percent, based on the total weight of the stream, while the overhead stream from vapor-liquid separator 64 in line 146 can include less than about 2000, less than about 1000, less than about 750, less than about 500, or less than about 100 ppm by weight of alkali metal ions, based on the total weight of the overhead stream in line 146. Conversely, the bottoms stream withdrawn from vapor-liquid separator 64 in line 144 may include, for example, at least about 0.5, at least about 1 , or at least about 1 .5 weight percent and / or not more than about 5, not more than about 3, or not more than about 2 weight percent of alkali metal ions, based on the total weight of the bottoms stream in line 144.

[0095] Referring again to FIG. 4, the bottoms stream in line 144 withdrawn from vapor-liquid separator 64 may be reintroduced to the depolymerization step / zone 20 and used during depolymerization of additional waste plastic. In some embodiments, at least a portion of the bottoms stream in line 144 may be introduced to a different depolymerization reactor or zone (not shown), while in other embodiments, it may be reintroduced into the same depolymerization zone and / or reactor from which at least a portion of the C4 to C14 alcohol originated. Optionally, at least a portion of the stream in line 144 may be subjected to one or more processing steps (not shown) to remove one or more co-products, salts, or other impurities and the treated stream may be returned to the depolymerization step / zone 20. In other embodiments, the stream in line 144 is not further treated and is introduced directly into the depolymerization step / zone 20.

[0096] As shown in FIG. 4, the overhead stream from vapor-liquid separator 64, which comprises predominantly C2 to C4 glycol and C4 to C14 alcohol, can beintroduced into a liquid-liquid separation step or zone 68. In the liquid-liquid separation (LLS) step / zone 68, at least a portion of the overhead stream is contacted with water in line 154 to form a predominantly organic phase and a predominantly aqueous phase. The step of contacting the overhead 02 to 04 glycol / C4 to 014 alcohol stream with water can occur within (as shown in FIG. 4) or prior to introduction into (not shown in FIG. 4) a liquid-liquid separation vessel. In some embodiments, the amount of water added can be at least about 10, at least about 15, at least about 20, at least about 25, or at least about 30 percent and / or not more than about 500, not more than about 250, not more than about 100, not more than about 95, not more than about 90, not more than about 85, not more than about 80, not more than about 75, or not more than about 70 weight percent of the total amount of 02 to 04 glycol present in the overhead stream introduced into the LLS step / zone 68.

[0097] The water added to the LLS step / zone 68 results in the formation of separate organic and aqueous phases within the LLS vessel. Streams comprising these organic and aqueous phases can be withdrawn from the LLS step / zone 68 via lines 148 and 156, respectively. The resulting organic phase stream in line 148 predominantly comprises the C4 to C14 alcohol and less than about 15, less than about 10, less than about 5, less than about 3, less than about 2, less than about 1 , or less than about 0.5 weight percent water, based on the total weight of the phase or stream. The aqueous phase stream in line 156, on the other hand, comprises predominantly 02 to 04 glycol and at least about 35, at least about 40, at least about 45, at least about 50, at least about 55, at least about 60, or at least about 65 weight percent and / or not more than about 85, not more than about 80, or not more than about 75, or not more than about 70 weight percent water, based on the total weight of the stream or phase. As a result of the water addition, at least about 85, at least about 90, at least about 95, or at least about 99 weight percent of the 02 to 04 glycol enters the aqueous phase, while at least about 85, at least about 90, at least about 95, or at least about 99 weight percent of the C4 to C14 alcohol enters the organic phase, wherein both percentages are based on the amount of each respective component introduced into the LLS step / zone 68 (or vessel).

[0098] The LLS step / zone 68 may include one or more of any suitable type of liquid-liquid separation vessels. Examples include, but are not limited to, liquid-liquid extraction vessels (co-current or counter-current), decantation vessels (vertically- elongated or horizontally-elongated). In some embodiments, the liquid-liquid separation vessel may include a water inlet for introducing water into the vessel and afeed inlet for introducing at least a portion, or all, of the feed stream in line 146 into the vessel and, in some embodiments, the water inlet can be located at a higher vertical elevation than the feed inlet. In some embodiments, the water may be introduced into the upper one-half, upper one-third, or upper one-fourth of the total vertical height of the liquid-liquid separation vessel, regardless of whether the vessel itself is horizontally or vertically elongated. The separation vessel used in LLS step / zone 68 is not a vaporliquid separation vessel or distillation column, and both streams (aqueous and organic) removed from the LLS step / zone 68 (or vessel) are liquid and have a vapor fraction of less than about 0.05, less than about 0.025, or less than about 0.010.

[0099] In some embodiments, the contacting is carried out at a temperature of at least about 10, at least about 20, or at least about 25°C and / or not more than about 90, not more than about 85, not more than about 80, not more than about 75, not more than about 70, not more than about 65, not more than about 60, not more than about 55, not more than about 50, or not more than about 45°C. The pressure of the contacting step (or the LLS vessel) can be within about 5, about 2, or about 1 psi gauge of atmospheric pressure. Additionally, after the addition of water, the combined stream may be allowed to separate for a period of at least about 2, at least about 5, at least about 10, at least about 15, at least about 25, or at least about 30 minutes and / or not more than about 60, not more than about 45, not more than about 40, not more than about 35, not more than about 30, or not more than about 25 minutes.[000100] Thereafter, an organic stream may be withdrawn from the LLS step / zone 68 via line 148, as shown in FIG. 4. The organic stream in line 148 may include a major portion of the C4 to C14 alcohol introduced into the LLS step / zone 68. In some embodiments, the organic stream may comprise at least about 85, at least about 90, at least about 95, or at least about 98 weight percent of C4 to C14 alcohol, based on the total weight of the stream. It may also include not more than about 15, not more than about 10, not more than about 5, not more than about 2, or not more than about 1 weight percent of other components including C2 to C4 glycol, C2 to C8 glycol, and / or water.[000101]As shown in FIG. 4, at least a portion of the organic stream in line 148 can be reintroduced into the depolymerization step / zone 20 for reuse in depolymerization of additional waste plastic introduced into the depolymerization step / zone 20 via line 110. In some embodiments, a portion of the organic stream in line 148 may be subjected to purification in an organic stream purification step / zone 72 to remove non-04 to C14 alcohol components from the organic phase stream vialine 152. At least about 10, at least about 15, or at least about 20 percent and / or not more than about 70, not more than about 60, or not more than about 50 percent of the total mass flow rate of the organic stream in line 148 may be passed through the organic stream purification step / zone 72, with the balance of the stream being introduced directly into the depolymerization step / zone 20, as shown in FIG. 4.[000102] In some embodiments, at least about 50, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 percent of the total weight of compounds heavier than the C4 to C14 alcohol may be separated from the slipstream of organic phase introduced into the organic stream purification step / zone 72. Thus, the purified stream of C4 to C14 alcohol removed from the organic stream purification step / zone 72 via line 152 may include not more than about 0.5, not more than about 0.25, not more than about 0.10 weight percent of components heavier than the C4 to C14 alcohol. Any suitable separation method may be used in the purification step / zone 72, including, but not limited to, distillation, extraction, decantation, and combinations thereof.[000103] Alternatively, or in addition, at least a portion of the purified organic stream in line 152 may be reacted with at least one alkali metal hydroxide, such as for example, potassium hydroxide or sodium hydroxide, to form a C4 to C14 alkoxide. At least a portion, or all, of the 04 to 014 alkoxide can then be introduced into the transesterification step / zone 30 for use as a transesterification catalyst (not shown in FIG. 4). In some cases, transesterification catalyst may also be added to the transesterification zone / step 30 via line 121 , while, in other cases, all of the transesterification catalyst may originate from reaction of the C4 to C14 alcohol with an alkali metal hydroxide.[000104]As shown in FIG. 4, an aqueous stream in line 156 may also be withdrawn from the LLS step / zone 68. The aqueous stream may comprise a major portion of the 02 to 04 glycol and water present in the LLS step / zone 68 and may include little or no 04 to 014 alcohol. For example, the aqueous stream in line 156 may comprise at least about 10, at least about 15, at least about 20, at least about 25, at least about 30, or at least about 35 weight percent and / or not more than about 55, not more than about 50, not more than about 45, not more than about 40, not more than about 35, not more than about 30, not more than about 25, not more than about 20, or not more than about 15 weight percent of each of water and 02 to 04 glycol, individually, based on the total weight of the stream. There may be little or no 04 to 014 alcohol such as, for example, less than about 5, less than about 2, less than about1 , or less than about 0.5 weight percent C4 to C14 alcohol, based on the total weight of the stream.[000105]The improved efficiency of processes according to embodiments of the present technology minimizes the amounts of metal salts present in the aqueous glycol stream, thereby improving the overall quality of the final C2 to C4 glycol product. For example, the aqueous stream in line 156 withdrawn from the LLS step / zone 68 may comprise little or no alkali metal salts and in particular, may comprise less than about 2000, less than about 1000, less than about 750, less than about 500, less than about 250, or less than about 100 ppm by weight of alkali metal ions, based on the total weight of the stream.[000106] Referring again to FIG. 4, in some embodiments of the present technology, a neutralization agent may be added to the aqueous stream in line 156 (and / or to the liquid filtrate stream in line 126) via line 155 to neutralize at least a portion of the one or more catalysts present in the stream including, for example, the transesterification catalyst. In some embodiments, the neutralization agent may be acidic and can, for example, be chosen from mineral acids such as sulfuric, hydrochloric, and phosphoric acids, from sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, or toluenesulfonic acid, or carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, 2-ethylhexanoic acids, or combinations thereof. The neutralization agent comprises one chosen from sulfuric acid, acetic acid, 2-ethylhexanoic acid, or combinations thereof, or it can comprise acetic acid. In some embodiments, the temperature of the neutralization agent when combined with the aqueous stream in line 156 and / or the liquid filtrate in line 126 can be at least about 0, at least about 5, at least about 10, at least about 15, or at least about 20°C and / or not more than about 70, not more than about 65, not more than about 60, not more than about 55, or not more than about 50°C.[000107] As shown in FIG. 4, the aqueous stream in line 156 may be introduced into a glycol separation step / zone 74, wherein a major portion of the C2 to C4 glycol may be recovered. In some embodiments, the separation step / zone 74 may include one or more distillation columns configured to separate the incoming aqueous stream in line 156 to form a water stream and a stream of purified glycol, which includes recycled content glycol (r-glycol) formed in the depolymerization reaction, as well as exogeneous C2 to C8 glycol in some cases.[000108] In some embodiments, one or more steps of the separation may be carried out at a temperature of at least about 30, at least about 35, at least about 40,at least about 45, at least about 50, at least about 55, at least about 60, or at least about 65°C and / or not more than about 110, not more than about 105, not more than about 100, not more than about 95, not more than about 90, not more than about 85, or not more than about 80°C and a pressure of at least about 5, at least about 10, at least about 15, at least about 20, or at least about 25 mm Hg and / or not more than about 760, not more than about 700, not more than about 650, not more than about 600, not more than about 550, not more than about 500, not more than about 450, not more than about 400, not more than about 350, or not more than about 300 mm Hg. When multiple columns are utilized to perform the separation, each may have a temperature and pressure within these ranges, although the temperatures and pressures of each individual column may vary.[000109]The specific configuration of separation vessels within the glycol separation step / zone 74 may vary depending on the specific composition of the incoming aqueous stream in line 156 and the desired end product(s). FIGS. 5a through 5c provide schematic diagrams of three possible column configurations for the glycol separation step / zone 74.[000110]Turning initially to FIG. 5a, the aqueous stream in line 156 may be introduced into a first distillation column (e.g., a water removal column 82), wherein the stream may be separated to form an overhead vapor stream in line 158 and a bottoms liquid stream in line 159. The bottoms liquid stream in line 159 can predominantly comprise C2 to C4 glycol and some water, with the C2 to C4 glycol being present in an amount of at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 97 weight percent, based on the total weight of the stream. As shown in FIG. 5a, the water removal column 82 can be operated to remove at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 weight percent of water and components lighter than the C2 to C4 glycol, based on the total weight of these components introduced into the water removal column 82. The overhead stream in line 158 withdrawn from the water removal column 82 may comprise at least about 80, at least about 85, at least about 90, at least about 95, at least about 97, or at least about 99 weight percent water, based on the total weight of the stream in line 158.[000111]As shown in FIG. 5a, the liquid bottoms stream in line 159 can be introduced into a second distillation column (e.g., glycol column) 78 to form another overhead vapor stream in line 130 and another liquid bottoms stream in line 172. The overhead stream in line 130 comprises predominantly C2 to 04 glycol and can, forexample, comprise at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 99 weight percent of C2 to C4 glycol, based on the total weight of the stream. Optionally, the predominantly glycol stream in line 130 can include residual amounts of water and / or C4 to C14 glycol, but, if present, amounts of these components are not more than about 1 , not more than about 0.75, not more than about 0.5, or not more than about 0.25 weight percent, based on the total weight of the stream. The liquid bottoms stream in line 172 withdrawn from the glycol column 78 may comprise at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 weight percent of components heavier than the C2 to C4 glycol. When present, the exogenous C2 to C8 glycol may predominantly exit glycol separation column 78 in the overhead stream in line 130 or the bottoms stream in line 172, depending on the relative volatility of the specific 02 to 08 glycol selected.[000112] An alternative configuration for the glycol separation step / zone 74 is shown in FIG. 5b. In FIG. 5b, the feed stream in line 156 comprising water and the C2 to C4 glycol is introduced into a single distillation column 80, which is configured to provide an overhead stream in line 158 comprising predominantly water, a bottoms stream in line 172 comprising predominantly components heavier than the C2 to C4 glycol component and water, and a side draw stream in line 130 comprising predominantly 02 to 04 glycol (r-glycol). The streams in lines 158, 172, and 130 may have compositions similar to and that fall within one or more of the ranges described herein. In some embodiments, the single distillation column 80 may be a divided wall column.[000113]Turning now to FIG. 5c, the aqueous stream in line 156 can be introduced into a first column (e.g., a heavies removal column) 76, wherein it can be separated into an overhead vapor stream in line 174 and a bottoms liquid stream in line 172. The bottoms stream in line 172 comprises predominantly components heavier than the C2 to C4 glycol and water and these heavies can be present in an amount of at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 97 weight percent. The heavies removal column 76 can be operated to remove at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 percent of the total weight of components heavier than the 02 to 04 glycol and water, based on the total weight of these components introduced into the heavies removal column 76.[000114] As shown in FIG. 5c, the overhead stream withdrawn from the heavies removal column 76 in line 174 can comprise predominantly C2 to 04 glycol and water.In some embodiments, the overhead stream from the heavies removal column 76 can comprise at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, or at least about 80 weight percent and / or not more than about 90, not more than about 85, not more than about 80, not more than about 75, not more than about 70, or not more than about 65 weight percent of the C2 to C4 glycol, based on the total weight of the stream. This stream in line 174 may also comprise at least about 1 , at least about 10, at least about 15, at least about 20, or at least about 25 and / or not more than about 50, not more than about 40, not more than about 35, not more than about 30, not more than about 25, or not more than about 20 weight percent water, based on the total weight of the stream.[000115] As shown in FIG. 5c, at least a portion of the overhead stream in line 174 may be directed to a glycol separation column 78, which separates the feed into an overhead stream in line 158 comprising predominantly water and a bottoms stream in line 130 comprising predominantly C2 to C4 glycol. In particular, the water stream in line 158 may comprise at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, or at least about 99 weight percent water, based on the total weight of the stream. This stream in line 158 may also optionally include residual amounts of C4 to C14 alcohol such as, for example, amounts of less than about 25, less than about 20, less than about 15, less than about 10, less than about 5, or less than about 1 weight percent, based on the total weight of the stream.[000116]The bottoms stream in line 130 removed from the glycol separation column 78 in FIG. 5a may comprise a purified glycol product, including a recycled content glycol (r-glycol) product. In some embodiments, the glycol stream in line 130 may include at least about 75, at least about 80, at least about 85, at least about 90, at least about 95, at least about 97, at least about 99, or at least about 99.9 weight percent of the C2 to C4 glycol. Since at least a portion, or all, of the C2 to 04 glycol in the stream in line 130 was formed by depolymerization of the poly(C2 to 04 alkylene terephthalate), the glycol comprises r-glycol. In some embodiments, the glycol stream in line 130 can include at least about 50, at least about 55, at least about 60, at least about 65, at least about 70, at least about 75, at least about 80, at least about 85, at least about 90, or at least about 95 weight percent of recycled content C2 to 04 glycol. At least a portion of the recycled content may originate from waste plastic.[000117] Additionally, where one or more different glycols are present in the aqueous stream (from the depolymerization of glycol-modified PAT and / or from the addition of a C2 to C8 glycol to the depolymerization reaction), the glycol separationstep / zone 74 may be configured to recover individual streams including at least about 85, at least about 90, or at least about 95 weight percent of each of these glycol components. These additional glycols (including, for example, the exogeneous 02 to 08 glycol added during polymerization, when present) may be recovered in the r-glycol stream in line 130 or in an additional stream or side stream, depending on the specific configuration of the glycol separation step / zone 74. In some cases, these additional or exogenous glycols can be recovered in the water stream 158, which can be further separated in an additional vessel (not shown) to provide purified water and additional glycol. In some embodiments, at least a portion of the water in or originating from line 158 can be used to contact the incoming feed stream in line 146 of the LLS step / zone 68.[000118] In some embodiments, at least a portion of the r-dialkyl terephthalate (e.g., r-DMT) in line 128 and / or the r-glycol ( / .e., r-EG) in line 130 may be routed for further processing and / or storage in the same or a different chemical recycling facility. In some embodiments, at least a portion of one or both of these streams may be repolymerized under conventional reaction conditions to form recycled content poly(C2 to C4 alkylene terephthalate), r-PAT. Other end uses are contemplated within the scope of the present technology.EXAMPLES[000119]The following examples set forth methods in accordance with the disclosure. It is to be understood, however, that these examples are provided by way of illustration, and nothing therein should be taken as a limitation upon the overall scope.Example 1[000120]This example relates to the depolymerization of pelletized bottle flake PET with 2-ethylhexanol followed by centrifugation. Pelletized bottle flake PET which generally contains polyolefin and other impurities (98% PET, 1.800 kg; 9.3667 mol) and catalyst (potassium acetate, sodium acetate, potassium 2-ethylhexylate, sodium 2-ethylhexylate, etc.) (18.38 g; 0.1873 mol; 0.02 equiv) were slurried in 2-ethylhexanol (2.700 kg; 20.7326 mol; 2.21 equiv) in a 10-L reactor with an overhead stirrer, a Dean- Stark trap with a condenser, and a nitrogen inlet. The flask was heated to 185°C internally to consume the PET pellets and held for a total of 3.5 h. The mixture was cooled to 60°C and methanol (2.4 kg; 74.93 mol; 8.00 equiv; 50% based on the weight of the depolymerized mixture) was added and the mixture was allowed to cool toambient temperature. The theoretical content of the filtrate was 1.5 mmol total terephthalate per gram. The depolymerized mixture (7001.2 g) was added to centrifuge tubes and centrifuged for five minutes at 3000G at ambient temperature to result in a solid pellet and a clear liquid supernatant. The liquid was decanted with a few particles (6499.76 g of liquid and 399.82 g of insolubles).[000121]HPLC analysis was performed as follows: (150 x 4.6 mm Zorbax SB- 08 column, 40:60 (v:v) methanokwater (containing 0.1% trifluoroacetic acid) for 6.5 min, gradient to 75:25 (v:v) methanokwater (containing 0.1 % trifluoroacetic acid) for 1 min and hold for 5 min, gradient to 100% methanol for 1 min and hold for 6.5 min, 225 and 250 nm detection): bis(2-ethylhexyl) terephthalate, tp 17.3 min.; mixed ester, tp 15.8 min.Example 2[000122]This example relates to the transesterification of PET 2- ethylhexanolysis mixture with methanol. The PET 2-ethylhexanolysis mixture prepared as in Example 1 (1 .515 mmol / g; 500 g; 0.7575 mol) and methanol (97.1 g; 3.0299 mol; 4.0 equiv; 25% based on the weight of the depolymerized mixture) was slurried in a 1- L 3-neck round-bottom flask with an overhead stirrer, a thermocouple, and an air condenser with a nitrogen inlet. The flask was heated using a heating mantle set to 50°C, and once the reaction mixture equilibrated at 50°C, catalyst (25% sodium methoxide, potassium 2-ethylhexylate, sodium 2-ethylhexylate, potassium carbonate, etc.) in methanol (8.660 mL; 0.0379 mol; 0.05 equiv) was added. The mixture was stirred at 250 rpm at 50°C and precipitation with an attendant exotherm was noted starting at 6.5 minutes. After heating for 60 min at 50°C, the heating mantle was then removed. The mixture was allowed to cool to ambient temperature over 60 minutes and stirred at ambient temperature for one hour. The resulting precipitate was filtered, washed with methanol, and air-dried to afford 132.37 g of DMT as a white powder. The filtrate, consisting mainly of methanol, 2-ethylhexanol, and ethylene glycol according to GC, weighed 411 .72 g.[000123]1H NMR (CDCI3) results include: 5 8.11 (s, 4H); 3.96 (s, 3H). [000124]HPLC analysis was performed as described in Example 1 .[000125] GC analysis was performed as follows: (30 m x 0.25 mm DB-5 column, split ratio 20:1 , hold at 85 °C for 5 min, 85-300°C at 25 °C / min, hold at 300 °C for 4.4 min, injection volume 1 uL): EG, tp 3.0 min; 2-EH, tp 6.22 min; DMT, tp 10.75 min; MHET, tp 12.63 min; BHET, tp 14.26 min; DOTP, tp 17.1 min.Example 3[000126]This example relates to catalyst recycle for depolymerization of pelletized bottle flake PET with 2-ethylhexanol. The filtrate, as prepared in Example 2, was placed into a 1 L 4-neck round-bottom flask with a stir plate, stir bar, heating mantle, thermocouple, a short-path distillation head and a 1 L single-neck round-bottom receiving flask. The 4-neck flask was heated to 70°C to remove methanol by distillation from the reaction mixture. After methanol was removed, a Vigreux column was added, and the mixture was heated to 185°C internally and the 2-EH alcohol / EG azeotrope (vapor temperature: 177°C) was collected. The distillate was analyzed by GO and HPLC, which showed an EG / 2-EH ratio of 16:84. The azeotrope (145.98 g) was collected and cooled to ambient temperature. The residual bottoms (58.39 g), which contain EG, 2-EH, and catalyst were analyzed by GO and HPLC, as described in Examples 1 and 2.[000127] Pelletized bottle flake PET (98%, 148.24 g; 0.7575 mol) and 2- ethylhexanol (total = 218.4 g; 1.6767 mol; 2.21 equiv.) was added to the catalyst residue in a 1-L reactor with an overhead stirrer, a Dean-Stark trap with a condenser, and a nitrogen inlet. The flask was heated to 185°C internally to consume the PET pellets and held for a total of 7.5 h. The mixture was cooled to 60°C and bottled in a jar. The theoretical content of the filtrate was 2.284 mmol total terephthalate per gram. Example 4[000128]This example relates to catalyst recycle for depolymerization of pelletized bottle flake PET with 2-ethylhexanol. The filtrate, as prepared in Example 2, was placed into a 1 L 4-neck round-bottom flask with a stir plate, stir bar, heating mantle, thermocouple, a short-path distillation head and a 1 L single-neck round-bottom receiving flask. The 4-neck flask was heated 70°C to remove methanol by distillation from the reaction mixture. After methanol was removed, acetic acid (2.599 mL) was added to the pot. A Vigreux column was added, and the mixture was heated to 185°C internally and the 2-EH / EG azeotrope (vapor temperature: 177TC) was collected. The distillate was analyzed by GC and HPLC, which showed an EG / 2-EH ratio of 16:84. The azeotrope (146.69 g) was collected and cooled to ambient temperature. The residual bottoms (90.58 g), which contain EG, 2-EH, and catalyst were analyzed by GC and HPLC as described in Examples 1 and 2.[000129] Pelletized bottle flake PET (98%, 148.24 g; 0.7575 mol) and 2- ethylhexanol (total = 218.4 g; 1.6767 mol; 2.21 equiv.) was added to the catalyst residue in a 1-L reactor with an overhead stirrer, a Dean-Stark trap with a condenser,and a nitrogen inlet. The flask was heated to 185°C internally to consume the PET pellets and held for a total of 4 h. The mixture was cooled to 60°C, collected in a jar, and the mixture was allowed to cool to ambient temperature. The theoretical content of the filtrate was 2.121 mmol total terephthalate per gram.Example 5[000130]This example provides data related to catalyst recycle for depolymerization of pelletized bottle flake PET with 2-ethylhexanol. The filtrate, as prepared in Example 2, was placed into a 1 L 4-neck round-bottom flask with a stir plate, stir bar, heating mantle, thermocouple, a short-path distillation head and a 1 L single-neck round-bottom receiving flask. Acetic acid (2.599 ml_) was added to the pot. The 4-neck flask was heated to 70°C to remove methanol by distillation from the reaction mixture. After methanol was removed, a Vigreux column and a new receiving flask were added to the set-up. The mixture was heated to 180-185°C internally, and the 2-EH / EG azeotrope (vapor temperature: 177°C) was collected. The distillate was analyzed by GO and HPLC, which showed an EG / 2-EH ratio of 16:84. After the azeotrope was collected, the flask was cooled to ambient temperature. The residual bottoms (53.8 g), which contain EG, 2-EH, and catalyst were analyzed by GO and HPLC as described in Examples 1 and 2.[000131] Pelletized bottle flake PET (98%, 148.24 g; 0.7575 mol) and 2- ethylhexanol (total = 218.4 g; 1 .6767 mol; 2.21 equiv) was added to the catalyst residue in a 1 -L reactor with an overhead stirrer, a Dean-Stark trap with a condenser, and a nitrogen inlet. The flask was heated to 185°C internally to consume the PET pellets and held for a total of 5 h. The mixture was cooled to 60°C, collected in a jar, and the mixture was allowed to cool to ambient temperature. The theoretical content of the filtrate was 2.068 mmol total terephthalate per gram.Example 6[000132]This example provides data related to the extraction of EG with 0.25 g of water per 1 .0 g of EG. The distillate, as prepared in Example 4, was analyzed by GC to determine the amount of ethylene glycol. Water (0.25 g water / g EG) was added to the flask. The mixture was stirred for 30 seconds at ambient temperature. The two layers were separated, weighed, and analyzed via GC and HPLC, which showed 44% EG in the top layer and 56% EG in the bottom layer. The GC and HPLC parameters used are provided in Examples 1 and 2.Example 7[000133]This example provides data related to the extraction of EG with 0.75 g of water per 1 .0 g of EG. The distillate, as prepared in Example 4, was analyzed by GO to determine the amount of ethylene glycol. Water (0.75 g water / g EG) was added to the flask. The mixture was stirred for 30 seconds and allowed to settle into 2 layers. The two layers were separated, weighed, and analyzed on GO and HPLC, which showed 16% EG in the top layer and 84% EG in the bottom layer. The GO and HPLC parameters used are provided in Examples 1 and 2.Example 8[000134]This example provides the full liquids recovery process including distillation to obtain ethylene glycol. Depolymerization filtrate, as prepared in Example 2, was placed into a 10-L reactor with an overhead stirrer, a Dean-Stark trap with a condenser, and a nitrogen inlet and a receiving flask. The reactor was heated to 160°C (base temperature) to remove methanol by distillation from the reaction mixture. After methanol was removed, a portion of the filtrate (1881.3g) was added to a 3L 4-neck round-bottom flask with a stir plate, stir bar, heating mantle, thermocouple, a Vigreux column, a short-path distillation head and a 2L single-neck round-bottom receiving flask. The mixture was heated to 185°C internally and the 2-EH alcohol / EG azeotrope (vapor temperature: 177 °C) was collected. The distillate was analyzed by GC and HPLC, which showed an EG / 2-EH ratio of 20:77. The azeotrope (1423.28 g) was collected and cooled to ambient temperature. The residual bottoms (441 .96 g), which contain mostly EG, 2-EH, and catalyst were analyzed by GC and HPLC.[000135] Water (0.6 g water / 1 .0 g EG) was added to the flask containing the azeotropic distillate. The mixture was stirred for 30 seconds at ambient temperature. The two layers were separated, weighed, and analyzed via GC and HPLC, which showed 22% EG in the top layer and 78% EG in the bottom layer. The bottom layer was sequentially distilled under vacuum to remove water and then isolate ethylene glycol (197.39 g). The distilled ethylene glycol was assayed at 99.1% purity and had an APHA color of 4.72.DEFINITIONS[000136] It should be understood that the following is not intended to be an exclusive list of defined terms. Other definitions may be provided in the foregoing description, such as, for example, when accompanying the use of a defined term in context.[000137] As used herein, the terms “alcohol,” “monohydric alcohol,” and “monoalcohol” each refer to a hydroxy-functional hydrocarbon including a single -OH group (e.g., R-OH).[000138] As used herein, the term “glycol” refers to a hydroxy-functional hydrocarbon including two or more -OH groups and encompasses “diols” (e.g., 2 -OH groups) and “polyols” (e.g., 3+ -OH groups).[000139] As used herein, the terms “Cx” or “Cx hydrocarbon” or “Cx component” refers to a hydrocarbon compound including “x” total carbons per molecule, and encompasses all olefins, paraffins, aromatics, heterocyclic, and isomers having that number of carbon atoms. For example, each of normal, iso, and tertbutane and butene and butadiene molecules would fall under the general description “C4” or “C4 components.”[000140]As used herein, the term “isolating” or “isolation” refers to known methods of segregating solid and liquid materials.[000141] As used herein, the term “lighter” refers to a component or fraction having a lower boiling point than another component or fraction.[000142]As used herein, the term “heavier” refers to a component or fraction having a higher boiling point than another component or fraction.[000143]As used herein, the term “upstream” refers to an item of facility that is positioned prior to another item or facility in a given process flow and may include intervening items and / or facilities.[000144] As used herein, the term “downstream” refers to an item or facility that is positioned after another item or facility in a given process flow and may include intervening items and / or facilities.[000145]As used herein, the term “predominantly” means more than 50 percent by weight. For example, a predominantly propane stream, composition, feedstock, or product is a stream, composition, feedstock, or product that contains more than 50 weight percent propane.[000146]As used herein, the term “major portion” has the same meaning as “predominantly.”[000147] As used herein, the term “waste material” refers to used, scrap, and / or discarded material.[000148]As used herein, the term “fluid communication” refers to the direct or indirect fluid connection between two or more processing, storage, or transportation facilities or zones.[000149] As used herein, the terms “a,” “an,” and “the” mean one or more.[000150] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; Aand B in combination; Aand C in combination, B and C in combination; or A, B, and C in combination.[000151] As used herein, the phrase “at least a portion” includes at least a portion and up to and including the entire amount or time period.[000152] As used herein, the term “chemical recycling” refers to a waste plastic recycling process that includes a step of chemically converting waste plastic polymers into lower molecular weight polymers, oligomers, monomers, and / or non-polymeric molecules (e.g., hydrogen, carbon monoxide, methane, ethane, propane, ethylene, and propylene) that are useful by themselves and / or are useful as feedstocks to another chemical production process(es).[000153] As used herein, the terms “comprising,” “comprises,” and “comprise” are open-ended transition terms used to transition from a subject recited before the term to one or more elements recited after the term, where the element or elements listed after the transition term are not necessarily the only elements that make up the subject.[000154] As used herein, the terms “waste plastic” and “plastic waste” refer to used, scrap, and / or discarded plastic materials.CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS[000155]The preferred forms of the invention described above are to be used as illustration only and should not be used in a limiting sense to interpret the scope of the present invention. Modifications to the exemplary embodiments, set forth above, could be readily made by those skilled in the art without departing from the spirit of the present invention.[000156]The inventors hereby state their intent to rely on the Doctrine of Equivalents to determine and assess the reasonably fair scope of the present invention as it pertains to any apparatus not materially departing from but outside the literal scope of the invention as set forth in the following claims.ADDITIONAL CLAIM SUPPORTING DESCRIPTION[000157] In a first embodiment of the present technology, there is provided a method of recycling waste plastic, said method comprising: (a) introducing a first liquid stream comprising a 04 to C14 alcohol, a 02 to 04 glycol, and one or more components heavier than the C4 to C14 alcohol and the 02 to 04 glycol into a first distillation column; (b) separating the first liquid stream in the first distillation column to form an overhead stream comprising predominantly a mixture of the C4 to C14 alcohol and the 02 to 04 glycol and a bottoms stream comprising predominantly residual 04 to C14 alcohol and the components heavier than the 04 to C14 alcohol and the 02 to 04 glycol; (c) contacting at least a portion of the overhead stream from the first distillation column with water to provide an organic stream comprising predominantly 04 to 014 alcohol and an aqueous stream comprising predominantly 02 to 04 glycol and water; and (d) further separating the aqueous stream in a second distillation zone to provide a second distillation stream comprising predominantly water and a third distillation stream comprising predominantly 02 to 04 glycol.[000158] In a second embodiment of the present technology, there is provided a method of recycling waste plastic, said method comprising: (a) depolymerizing waste plastic comprising poly(C2 to 04 alkylene) terephthalate with a 04 to 014 alcohol to form a reaction mixture comprising 04 to C14 dialkyl terephthalate; (b) transesterifying the 04 to 014 dialkyl terephthalate with a second alcohol to form a second reaction mixture comprising another dialkyl terephthalate; (c) separating at least a portion of the second reaction mixture to form a solids product including the another dialkyl terephthalate and a residual liquid phase including 04 to 014 alcohol, 02 to 04 glycol, and the second alcohol; (d) separating at least a portion of the residual liquid phase in a first distillation column to provide a first overhead stream comprising predominantly the second alcohol and a first bottoms stream comprising predominantly the 04 to 014 alcohol, the 02 to 04 glycol, and components heavier than the 04 to 014 alcohol and the 02 to 04 glycol; (e) separating at least a portion of the first bottoms stream in a second distillation column to provide a second overhead stream comprising predominantly a mixture of the 04 to C14 alcohol and the 02 to 04 glycol and a second bottoms stream comprising predominantly a mixture of the components heavier than the 04 to C14 alcohol and the 04 to C14 alcohol; (f) adding water to at least a portion of the second overhead stream and separating an organic stream comprising predominantly 04 to 014 alcohol and an aqueous stream comprising predominantlywater and the C2 to C4 glycol; and (g) recovering at least a portion of the C2 to C4 glycol from the aqueous stream to provide a recycled content C2 to C4 glycol stream.[000159]The first and / or second embodiments described in the preceding paragraphs can also include one or more of the additional aspects / features listed in the following bullet pointed paragraphs. Each of the below additional features of the first and / or second embodiments can be standalone features or can be combined with one or more of the other additional features to the extent consistent. Additionally, the following bullet pointed paragraphs can be viewed as dependent claim features having levels of dependency indicated by the degree of indention in the bulleted list (i.e., a feature indented further than the feature(s) listed above it is considered dependent on the feature(s) listed above it).• wherein the exogenous C2 to 08 glycol is present at the beginning of the depolymerizing in an amount of at least about 2.5 (3, 3.5, 4, 4.5, 5, or 5.5) parts by weight and / or not more than about 25 (20, 17.5, 15, 12.5, 10, or 7.5) parts by weight of the C2 to C8 glycol based on 100 parts of the C4 to 014 alcohol in the reaction mixture.• wherein the separating of step f) in the second embodiment occurs within a liquid-liquid separation vessel. o wherein the adding of step f) in the second embodiment occurs within the liquid-liquid separation vessel. o wherein the adding of step f) in the second embodiment occurs prior to introduction of a combined stream into the liquid-liquid separation vessel.• further comprising prior to the introducing of step a) of the first embodiment, separating a the second alcohol from another liquid stream in another distillation column to provide a liquid product comprising the first liquid stream. o wherein the another liquid stream comprises at least about 20 (25, 30, 35, 40, 45, 50, or 55) weight percent and / or not more than about 85 (80, 75, 70, 65, 60, 55, 50, 45, 40, or 35) weight percent of the second alcohol, based on the total weight of the stream. o wherein the second alcohol is a C1 to C3 alcohol. o wherein the second alcohol is methanol. o further comprising removing another overhead stream from the another distillation column, wherein the another overhead streamcomprises at least about 55 (60, 65, 70, 75, 80, 85, 90, 95 or 99) weight percent of methanol, based on the total weight of the stream.■ wherein the another overhead stream comprises at least about 75 (80, 85, 90, 95, or 99) weight percent of the total amount of methanol introduced into the another distillation column in the another liquid stream. o wherein the separating is carried out at a pressure within about 10 psig (5, 3, 2, or 1) psig of atmospheric pressure. o wherein the separating is carried out at atmospheric pressure. o wherein the separating is carried out at a pressure below atmospheric pressure. o wherein the separating is carried out at a pressure of not more than about 750 (700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, or 50) mm Hg. o wherein the separating is carried out at a temperature of at least about 30 (35, 40, or 45)°C and / or not more than about 80 (75, 70, or 65)°C. o further comprising introducing at least a portion of the second alcohol into a transesterification zone.• wherein the first liquid stream or the first bottoms stream comprises at least about 10 (15, 20, 25, 30, 35, or 40) and / or not more than about 65 (60, 55, 50, 45, 40, 35, 30, or 25) weight percent of the C4 to C14 alcohol, based on the total weight of the first liquid stream.• wherein the first liquid stream or the first bottoms stream comprises at least about 10 (15, 20, 25, 30, 35, or 40) and / or not more than about 65 (60, 55, 50, 45, 40, 35, 30, or 25) weight percent of the C2 to C4 glycol, based on the total weight of the first stream.• wherein the first liquid stream or the first bottoms stream comprises not more than about 25 (15, 10, 5, or 2) weight percent of the components heavier than the C4 to C14 alcohol and the C2 to 04 glycol. o wherein the components heavier than the C4 to C14 alcohol and the C2 to C4 glycol comprise terephthalyl monomers and oligomers. o wherein the components heavier than the C4 to C14 alcohol and the C2 to C4 glycol comprise one or more catalysts.• wherein the overhead stream from the first distillation column in the first embodiment and the second distillation column in the second embodimentcomprises at least about 85 (90, 95, 97, or 99) weight percent of the mixture of C4 to C14 alcohol and C2 to C4 glycol, based on the total weight of the stream.• wherein the overhead stream from the first distillation column in the first embodiment and the second distillation column in the second embodiment comprises not more than about 15 (10, 5, 2, or 1 ) weight percent of components other than the mixture of the C4 to C14 alcohol and the 02 to C4 glycol, based on the total weight of the stream.• wherein the mixture of the C4 to C14 alcohol and the 02 to 04 glycol is not an azeotrope.• wherein the mixture of the 04 to C14 alcohol and the 02 to 04 glycol comprises at least about 50 (55, 60, 65, or 70) and / or not more than 95 (90, 85, 80, or 75) weight percent of the 04 to 014 alcohol and at least about 5 (10, 15, 20, or 25) and / or not more than about 50 (45, 40, 35, or 30) weight percent of the 02 to C4 glycol, based on the total weight of the mixture.• wherein the mixture of the C4 to 014 alcohol and the C2 to C4 glycol is an azeotrope.• wherein the separating of step b) is carried out at a pressure of at least about 10 (50, 100, 150, or 200) mm Hg and / or not more than about 760 (750, 700, or 675) mm Hg.• wherein the separating of step b) or step e) is carried out at a temperature of at least about 80 (85, 90, 95, 100, 105, 110, 115, 120, or 125)°C and / or not more than about 195 (190, 185, 180, 175, 170, 165, 160, 155, 150, 145, 140, 135, or 130)°C.• wherein at least a portion of the bottoms stream from the first or second distillation column is introduced into a depolymerization reactor and used to depolymerize waste polyethylene terephthalate (PET). o wherein at least a portion of the first liquid stream fed into the first or second distillation column originated from the same or a different depolymerization reactor. o further comprising prior to being introduced into the depolymerization reactor, treating at least a portion of the bottoms stream from the first or second distillation column to remove a major portion of one or more co-products to form a treated stream and introducing at least a portion of the treated stream into the depolymerization reactor.• wherein the liquid stream introduced into the first or second distillation column comprises one or more alkali metal carboxylate salts and wherein the concentration of alkali metal ions in the first liquid stream is not more than about 1 (0.75, 0.5, 0.25, 0.10, or 0.05) weight percent, based on the total weight of the stream.• wherein the overhead stream from the first or second distillation column introduced into the liquid-liquid separation vessel includes less than 2000 ppm (1000, 750, 500, or 100 ppm) by weight of alkali metal ions, based on the total weight of the overhead stream.• wherein the bottoms stream withdrawn from the first or second distillation column includes at least 0.5 (1 , or 1 .5) weight percent of metal alkali ions and / or not more than about 5 (3 or 2) weight percent of alkali metal ions, based on the total weight of the stream. o wherein the aqueous stream comprising predominantly C2 to C4 glycol and water withdrawn from the liquid-liquid separation vessel includes less than 2000 ppm (1000, 750, 500, 250, or 100 ppm) by weight of alkali metal ions, based on the total weight of the aqueous stream.• wherein the organic stream comprises not more than about 15 (10, 5, 2, 1, 0.5) weight percent water, based on the total weight of the stream.• wherein the aqueous stream comprises at least about 35 (40, 45, 50, 55, 60, or 65) weight percent and / or not more than about 80 (75, 70, 65, 60, or 55) weight percent of water, based on the total weight of the stream.• wherein each of the organic stream and aqueous stream have a vapor fraction of less than 0.05 (0.025, 0.01).• wherein the liquid-liquid separation vessel comprises at least one liquid-liquid extraction vessel. o wherein the liquid-liquid extraction vessel is a counter-current extraction vessel and at least a portion of the contacting is carried out in a countercurrent manner.• wherein the liquid-liquid separation vessel comprises at least one decantation vessel. o wherein the liquid-liquid decantation vessel is horizontally-elongated.o wherein the contacting includes combining at least a portion of the overhead stream with water to form a combined stream and decanting at least a portion of the combined stream in the decantation vessel.• wherein the liquid-liquid separation vessel does not include a vapor-liquid separation vessel (e.g., distillation column).• wherein the water is introduced into a first inlet of the liquid-liquid separation vessel and the overhead stream from the first distillation column is introduced into a second inlet of the liquid-liquid separation vessel located at a vertical location below the first inlet of the liquid-liquid separation vessel. o wherein the first inlet of the liquid-liquid separation vessel is located in the upper one-half (one-third, or one-fourth) of the total vertical height of the liquid-liquid separation vessel.• wherein the contacting of step c) or said adding of step f) includes adding water to the overhead stream from the first or second distillation column to form an aqueous mixture, wherein the amount of water added is at least about 10 (15, 20, 25, or 30) percent and / or not more than about 500 (250, 100, 95, 90, 85, 80, 75, or 70) weight percent of the total amount of C2 to C4 glycol in the overhead stream from the first distillation column to which the water is added.• wherein the contacting of step c) or adding of step f) is carried out at a temperature of at least about 10 (20, 25)°C and / or not more than 90 (80, 75, 70, 65, 60, 55, 50, or 45)°C.• wherein the contacting of step c) or adding of step f) is carried out at a pressure within about 5 (2, 1 ) psig of atmospheric pressure.• wherein the contacting of step c) or adding of step f) includes adding water to the overhead stream from the first or second distillation column to form an aqueous mixture and further comprising performing a phase separation on the aqueous mixture to provide the organic stream comprising predominantly C4 to C14 alcohol and the aqueous phase comprising predominantly C2 to C4 glycol and water. o wherein the phase separation is carried out in a decanter. o wherein the phase separation is carried out for a period of time of at least 2 (5, 10, 15, 25, 30) minutes and / or not more than about 60 (45, 40, 35, 30, or 25) minutes.o wherein the phase separation is carried out at a temperature of at least about 10 (20, or 25)°C and / or not more than about 90 (85, 80, 75, 70, 65, 60, 55, or 50)°C. o wherein the phase separation is carried out at atmospheric pressure.• wherein the aqueous stream comprises at least about 10 (15, 20, 25, 35, 40, or 45) weight percent and / or not more than about 55 (50, 45, 40, 35, 30, 25, 20, or 15) weight percent of water, based on the total weight of the aqueous stream.• wherein the aqueous stream comprises at least about 10 (15, 20, 25, 35, 40, or 45) weight percent and / or not more than about 55 (50, 45, 40, 35, 30, 25, 20, or 15) weight percent of C2 to C4 glycol, based on the total weight of the aqueous stream.• wherein the organic stream comprises at least about 65 (70, 75, 80, 85, 90, or 95) weight percent of C4 to C14 alcohol, based on the total weight of the stream.• further comprising introducing at least a portion of the organic stream comprising predominantly C4 to C14 alcohol to a depolymerization reactor for depolymerizing waste plastic. o wherein at least a portion of the first liquid stream originated from the same or a different depolymerization reactor. o prior to the introducing, separating at least a portion of the organic stream in at least one separation vessel to provide a purified organic stream, wherein at least a portion of the purified organic stream is introduced into the depolymerization reactor.■ wherein the separating removes at least 50 (60, 65, 70, 75, 80, 85, 90, or 95) percent of compounds heavier than the C4 to C14 alcohol.• wherein at least a portion of the further separating of step d) or recovering of step g) is carried out at a pressure of at least about 5 (10, 15, 20, or 25) mm Hg and / or not more than about 760 (700, 650, 600, 550, 500, 450, 400, 350, or 300) mm Hg.• wherein at least a portion of the further separating of step d) or recovering of step g) is carried out at a temperature of at least about 30 (35, 40, 45, 50, 55, 60, or 65)°C and / or not more than 110 (105, 100, 95, 90, 85, or 80)°C.• wherein the third distillation stream comprises predominantly recycled content C2 to C4 glycol. o wherein the recycled content C2 to C4 glycol is recycled content ethylene glycol. o further comprising polymerizing at least a portion of the C2 to C4 glycol with a dicarboxylic acid or ester to form recycled content polyester.• wherein the third distillation stream comprises at least about 75 (80, 85, 90, or 95) weight percent C2 to 04 glycol.• wherein the second distillation stream further comprises 04 to 014 alcohol.• wherein the further separating of step f) or recovering of step g) includes subjecting at least a portion of the aqueous stream to further distillation in one or more distillation columns in series to provide the second distillation stream comprising predominantly water and the third distillation stream comprising predominantly C2 to C4 glycol. o wherein the further distillation is conducted in a single column and the third distillation stream is a side draw stream.■ wherein the distillation column is a divided wall column. o wherein the further distillation is conducted in a heavies removal column followed by a glycol separation column, wherein the heavies column removes at least 75 (80, 85, 90, or 95) percent of components heavier than the C2 to C4 glycol and water, and the glycol column provides the second and third distillation streams. o wherein the further distillation is conducted in a water removal column followed by a glycol separation column, and wherein the second distillation stream is removed from the water removal column and the third distillation stream is removed from the glycol separation column.• wherein the further separating of step f) or recovering of step g) includes subjecting at least a portion of the aqueous stream to distillation in a water removal column to provide a fourth distillation stream comprising predominantly water and a fifth distillation stream comprising predominantly 02 to C4 glycol and components heavier than C2 to C4 glycol; and subjectingat least a portion of the fifth distillation stream to separation in another distillation column to provide a sixth distillation stream comprising predominantly 02 to 04 glycol and a seventh distillation stream comprising predominantly components heavier than 02 to 04 glycol.• wherein the further separating of step f) or recovering of step g) includes subjecting at least a portion of the aqueous stream to distillation in a heavies removal column to provide a fourth distillation stream comprising predominantly 02 to 04 glycol and water and fifth distillation stream comprising components heavier than the 02 to 04 glycol and water; and subjecting at least a portion of the fourth distillation stream to separation in another distillation column to provide a sixth distillation stream comprising predominantly water and a seventh distillation stream comprising predominantly 02 to 04 glycol. o wherein the fourth distillation stream comprises at least about 55 (60, 65, 70, 75, or 80) weight percent and / or not more than about 90 (85, 80, 75, 70, or 65) weight percent of the 02 to 04 glycol, based on the total weight of the stream. o wherein the fourth distillation stream comprises at least about 1 (10, 15, 20, 25) and / or not more than about 30 (40, 35, 30, 25, or 20) weight percent water, based on the total weight of the stream. o wherein the sixth distillation stream comprises at least about 90(85, 90, 95, 97, or 99) weight percent of water, based on the total weight of the stream. o wherein the sixth distillation stream comprises not more than about 10 (15, 10, 5, 2, or 1 ) weight percent of the C2 to C4 glycol. o wherein the seventh distillation stream comprises at least about 80 (85, 90, 95, 97, or 99) weight percent of the C2 to C4 glycol, based on the total weight of the stream.• further comprising, adding at least one neutralization agent to the first liquid stream, residual liquid phase, or first bottoms stream to neutralize at least a portion of at least one catalyst present therein. o wherein the neutralization agent is acidic. o wherein the neutralization agent comprises one chosen from mineral acids such as sulfuric, hydrochloric, and phosphoric acids, from sulfonic acids such as methanesulfonic acid, benzenesulfonic acid, ortoluenesulfonic acid, or carboxylic acids such as formic acid, acetic acid, propionic acid, benzoic acid, 2-ethylhexanoic acids, or combinations thereof. o wherein the neutralization agent comprises one chosen from sulfuric acid, acetic acid, 2-ethylhexanoic acid, or combinations thereof. o wherein the neutralization agent comprises acetic acid. o wherein the temperature of the neutralization agent and / or the aqueous stream at or after the adding is at least about 0 (5, 10, 15, or 20)°C and / or not more than about 70 (65, 60, 55, or 50)°C.• wherein at least 50 (55, 60, 65, 70, 75, 80, 85, 90, or 95) weight percent of the C2 to C4 glycol comprises recycled content C2 to C4 glycol and wherein the recycled content originates from waste plastic.• wherein the poly(C2 to C4 alkylene terephthalate) comprises polyethylene terephthalate.• wherein the poly(C2 to C4 alkylene terephthalate) comprises a glycol-modified and / or acid-modified poly(C2 to C4 alkylene terephthalate).• wherein the waste plastic added to the depolymerization reactor comprises at least about 60 (65, 70, 75, 80, 85, 90, or 95) weight percent and / or up to 100 (not more than about 99, 95, 90, 85, or 80) weight percent of poly(C2 to C4 alkylene terephthalate).• wherein the waste plastic further comprises at least one non-poly(C2 to C4 alkylene terephthalate) (non-PAT) component chosen from non-PAT waste plastics, natural fibers, calcium carbonate, titanium dioxide, inorganic fillers, dyes, pigments, color toners, colorants, plasticizers, adhesives, flame retardants, metals, aluminum, and iron, carbon black, or combinations thereof. o wherein the non-PAT waste plastics include one or more chosen from polyesters other than the poly(C2 to C4 alkylene terephthalate), polyvinyl acetal, polyvinylbutyral (PVB), polyvinyl alcohol (PVOH), ethylene vinyl alcohol (EVOH), cotton, polystyrene, polycarbonate, cellulose esters, polyacrylate, polymethacrylates, poly(lactic acid), polydimethylsiloxane, polysilane, polyethylene, polypropylene, polyolefins other than polyethylene and polypropylene, polyvinyl chloride (PVC), elastane, nylon, polyacrylates, polymethacrylate, poly(lactic acid), or combinations thereof.o wherein the waste plastic introduced into the depolymerization reactor comprises at least about 1 (5, 10, 15, or 20) weight percent and / or not more than about 40 (35, 30, 25, 20, 15, 10, or 5) weight percent of polymers other than the poly(C2 to C4 alkylene terephthalate).• wherein the C4 to C14 alcohol is a C5 to C12 alcohol or a 06 to 010 alcohol.• wherein the C4 to C14 alcohol is chosen from n-butanol, isobutanol, hexanol, 2-ethylhexanol, n-octanol, decanol, dodecanol, tetradecanol, or mixtures thereof.• wherein the C4 to C14 alcohol is chosen from n-butanol, n-octanol, or 2- ethylhexanol.• wherein the depolymerization catalyst is an esterification or transesterification catalyst chosen from Lewis Acids and Lewis Bases. o wherein the depolymerization catalyst is chosen from metal acetates, titanium alkoxides, and tin species such as tin oxalate, monobutyltin oxide, monobutyltin tris(2-ethylhexanoate), or combinations thereof. o wherein the depolymerization catalyst is chosen from potassium carbonate, potassium bicarbonate, potassium acetate, titanium tetra(isopropoxide, monobutyltin tris(2-ethylhexanoate), or combinations thereof. o wherein the depolymerization catalyst comprises sodium acetate and the reaction mixture further comprises ethylene glycol as an exogeneous additive. o wherein the depolymerization reaction mixture comprises a depolymerization catalyst present in an amount of at least about 0.001 (0.005, 0.0075, or 0.010) equivalents and / or not more than about 0.1 (0.075 or 0.05) equivalents per PAT repeat unit.• wherein the method is a pilot-scale or commercial-scale method.• wherein the method is a continuous or semi-continuous method.• wherein the depolymerizing step is carried out at a temperature of at least about 100 (110, 120, 130, 140, 150, 160, 165, 170, 175, 180, 185, or 190)°C and / or not more than about 250 (240, 230, 220, 215, 210, 205, 200, 195, 190, 185, 180, or 175)°C.• wherein the depolymerizing is carried out at an average depolymerization temperature and an average depolymerization pressure, and wherein theaverage depolymerization temperature is within about 25 (20, 15, 10, 5, or 2)°C of the boiling point of the C4 to C14 alcohol at the depolymerization pressure. o wherein the depolymerization pressure is at least about 0.10 (0.25, 0.50, 0.75, or 1 ) bar, absolute, and / or not more than about 10 (7, 5, 2, or 1 .5) bar, absolute. o wherein the depolymerization pressure is atmospheric pressure.• wherein the depolymerizing step is carried out for a period of time of at least about 5 minutes (10, 15, 30, 45 minutes, 1 hour, or 1 .5 hours) and / or not more than about 10 (8, 6, 4, or 2) hours.• wherein the depolymerizing step is carried out in the presence of an inert gas (nitrogen).• wherein at least a portion of the waste plastic added to the depolymerization reactor is in a form chosen from flakes, powder, chunks, pellets, or combinations thereof. o wherein at least a portion of the waste plastic added to the depolymerization reactor is in the form of chunks and / or pellets each having a maximum dimension of not more than 0.375 inches (0.3, 0.25, 0.20, or 0.10) inches.• wherein the depolymerized product stream withdrawn from the depolymerizing step further comprises at least 5 (10, 15, 20, 25, 30, 35, 40, or 45) weight percent and / or not more than 80 (75, 70, 65, 60, 55, or 50) weight percent of terephthalyl components, based on the total weight of the composition.• wherein a stream of depolymerized product removed from the depolymerization reactor upon completion of the depolymerizing includes no poly(C2 to C4 alkylene) terephthalate, as measured by visual inspection.• wherein the reaction mixture has a viscosity of at least about 1 (5, 10, 15, 20, 25, 30, 35, or 40) cP and / or not more than about 300 (275, 250, 225, 200, 175, 150, 125, 100, or 75) cP at 25°C, measured at 25°C by the Flow Temperature Ramp method.• further comprising, prior to the reacting (or transesterifying) cooling the reaction mixture to a temperature of at least about 20 (25, 27, 30, 32, 35, 37, or 40)°C and / or not more than about 100 (90, 80, 75, 70, 60, 50, or 45)°C to form a cooled depolymerization product stream, and subjecting at least a portion ofthe cooled depolymerization product stream to the reacting (or transesterifying) of step b).• further comprising, prior to the transesterifying, cooling the reaction mixture to a temperature of at least about 20 (25, 27, 30, 32, 35, 37, or 40)°C and / or not more than about 100 (90, 80, 75, 70, 60, 50, or 45)°C to form a cooled depolymerization product stream, and subjecting at least a portion of the cooled depolymerization product stream to the transesterifying.• wherein the alcohol in the transesterifying is a C1 to C3 alcohol and the another dialkyl terephthalate comprises a C1 to C3 dialkyl terephthalate. o wherein the C1 to C3 alcohol used in the transesterifying step comprises at least one alcohol chosen from ethanol or methanol. o wherein the C1 to 03 alcohol used in the transesterifying step comprises methanol. o wherein the C1 to C3 alkyl terephthalate comprises dimethyl terephthalate. o wherein the transesterifying provides a product stream comprising the C1 to C3 dialkyl terephthalate and at least a portion of the C1 to C3 alcohol as well as at least a portion of the C4 to C14 alcohol and additional reaction co-products, and further comprising separating at least a portion of the 01 to 03 dialkyl terephthalate from the product stream to provide a recycled content 01 to C3 dialkyl terephthalate product and a liquid product stream. o further comprising, processing at least a portion of the liquid product stream to provide at least a stream predominantly comprising 04 to 014 alcohol, a stream predominantly comprising 01 to C3 alcohol, and a stream predominantly comprising recycled content 02 to 04 glycol.• wherein the depolymerization reaction mixture further comprises at least about 5 (10, 15, 20, or 25) and / or not more than about 35 (30, 25, 20, 15, 10, or 5) weight percent of at least one exogeneous C2 to 08 glycol, based on the total weight of the 04 to C14 alcohol and C2 to C8 glycol in the reaction mixture. o wherein at least a portion of the C2 to C8 glycol is added to the reaction mixture during the polymerization.• wherein at least a portion of the C2 to C4 glycol has recycled content and is present in the reaction mixture due to the depolymerization of poly(C2 to C4 alkylene terephthalate).• wherein the C4 to C14 alcohol is present in the reaction mixture in an amount of at least about 0.5 (1 , 1.5, 1 , or 2.5) parts by weight and / or not more than about 12 (10, 8, 5, 2.5, or 2) parts by weight based on 1 part by weight of poly(C2 to C4 alkylene terephthalate) present at the beginning of the depolymerizing.

Claims

CLAIMSWe claim -1 . A method of recycling waste plastic, said method comprising:(a) introducing a first liquid stream comprising a C4 to C14 alcohol, a C2 to C4 glycol, and one or more components heavier than the C4 to C14 alcohol and the C2 to C4 glycol into a first distillation column;(b) separating the first liquid stream in the first distillation column to form an overhead stream comprising predominantly a mixture of the C4 to C14 alcohol and the C2 to C4 glycol and a bottoms stream comprising predominantly residual C4 to C14 alcohol and the components heavier than the 04 to C14 alcohol and the 02 to 04 glycol;(c) contacting at least a portion of the overhead stream from the first distillation column with water in a liquid-liquid separation vessel to provide an organic stream comprising predominantly 04 to C14 alcohol and an aqueous stream comprising predominantly 02 to 04 glycol and water; and(d) further separating the aqueous stream in a second distillation zone to provide a second distillation stream comprising predominantly water and a third distillation stream comprising predominantly 02 to 04 glycol.

2. The method of claim 1 , wherein the contacting includes combining at least a portion of the overhead stream with water to form a combined stream and decanting at least a portion of the combined stream in a decanter.

3. The method of claim 2, wherein the amount of water in the combined stream is at least about 10 percent of the total amount of 02 to 04 glycol in the overhead stream from the first distillation column prior to the contacting, wherein the contacting is carried out at a temperature of at least about 10°C and / or not more than 90°C and wherein the contacting is carried out at a pressure within about 5 psig of atmospheric pressure.

4. The method of claim 1 , wherein the further separating of step (d) includes subjecting at least a portion of the aqueous stream to further distillation in one or more distillation columns to provide the second distillation stream comprising predominantly water and the third distillation stream comprising predominantly C2 to C4 glycol.

5. The method of claim 4, wherein the further distillation is conducted in a single distillation column and the third distillation stream is a side draw stream from the single distillation column.

6. The method of claim 4, wherein the further distillation is conducted in two distillation columns in series.

7. The method of claim 1 , wherein the first liquid stream introduced into the first distillation column comprises at least about 10 weight percent and not more than about 65 weight percent of the 04 to C14 alcohol, about 10 weight percent and not more than about 65 weight percent of the 02 to 04 glycol, and not more than about 25 weight percent of the components heavier than the 04 to 014 alcohol and the 02 to 04 glycol, wherein each percent is based on the total weight of the stream.

8. The method of claim 1 , wherein the mixture of the 04 to 014 alcohol and the 02 to 04 glycol in the overhead stream of the first distillation column comprises at least about 50 weight percent and not more than 95 weight percent of 04 to C14 alcohol and at least about 5 and not more than about 50 weight percent of 02 to 04 glycol, based on the total weight of the mixture.

9. The method of claim 1 , wherein the mixture of the 04 to 014 alcohol and the 02 to 04 glycol is an azeotrope.

10. The method of claim 1 , wherein the separating of step (b) is carried out at a pressure of at least about 10 mm Hg and not more than about 760 mm Hg and a temperature of at least about 80°C and not more than about 195°C.11 . The method of claim 1 , wherein the aqueous stream comprises at least about 10 weight percent and not more than about 55 weight percent water, at least about 10 weight percent and not more than about 55 weight percent of C2 to C4 glycol, each based on the total weight of the aqueous stream, and wherein the organic stream comprises at least about 65 weight percent of 04 to 014 alcohol, based on the total weight of the organic stream.

12. The method of claim 1 , further comprising introducing at least a portion of the organic stream comprising predominantly C4 to C14 alcohol to a depolymerization reactor for depolymerizing waste plastic.

13. The method of claim 1 , further comprising, adding at least one neutralization agent to the first liquid stream to neutralize at least a portion of at least one catalyst present in the first liquid stream, wherein the temperature of the neutralization agent at or after the adding is at least about 0°C and not more than about 70°C.

14. The method of claim 1 , wherein the C4 to C14 alcohol is chosen from n- butanol, isobutanol, hexanol, 2-ethylhexanol, n-octanol, decanol, dodecanol, tetradecanol, or mixtures thereof, and wherein the 02 to 04 glycol comprises ethylene glycol.

15. The method of claim 1 , further comprising depolymerizing waste plastic to form a depolymerized product stream and wherein the first liquid stream comprises at least a portion of the depolymerized product stream.

16. A method of recycling waste plastic, said method comprising:(a) depolymerizing waste plastic comprising poly(C2 to 04 alkylene) terephthalate with a 04 to C14 alcohol to form a reaction mixture comprising 04 to C14 dialkyl terephthalate;(b) transesterifying the 04 to C14 dialkyl terephthalate with a second alcohol to form a second reaction mixture comprising another dialkyl terephthalate;(c) separating at least a portion of the second reaction mixture to form a solids product including another dialkyl terephthalate and a residual liquid phase including 04 to 014 alcohol, 02 to 04 glycol, and the second alcohol;(d) separating at least a portion of the residual liquid phase in a first distillation column to provide a first overhead stream comprising predominantly the second alcohol and a first bottoms stream comprising predominantly the 04 to C14 alcohol, the 02 to 04 glycol, and components heavier than the 04 to C14 alcohol and the 02 to 04 glycol;(e) separating at least a portion of the first bottoms stream in a second distillation column to provide a second overhead stream comprising predominantly amixture of the C4 to C14 alcohol and the C2 to C4 glycol and a second bottoms stream comprising predominantly a mixture of the components heavier than the C4 to C14 alcohol and the C4 to C14 alcohol;(f) adding water to at least a portion of the second overhead stream and separating an organic stream comprising predominantly C4 to 014 alcohol and an aqueous stream comprising predominantly water and the C2 to 04 glycol; and(g) recovering at least a portion of the 02 to 04 glycol from the aqueous stream to provide a recycled content 02 to 04 glycol stream.

17. The method of claim 16, wherein the adding of step (f) includes adding water to the at least a portion of the second overhead stream prior to entering a liquidliquid separation vessel, and wherein the separating is carried out in the liquid-liquid separation vessel.

18. The method of claim 16, wherein the adding of step (f) includes adding water into a liquid-liquid separation vessel to contact the at least a portion of the second overhead stream within the liquid-liquid separation vessel.

19. The method of claim 16, wherein the second overhead stream comprises an azeotropic mixture of the C4 to C14 alcohol and the C2 to C4 glycol.

20. The method of claim 16, wherein the C4 to C14 alcohol is chosen from n- butanol, isobutanol, hexanol, 2-ethylhexanol, n-octanol, decanol, dodecanol, tetradecanol, and mixtures thereof and the second alcohol comprises methanol, and wherein the poly(C2 to 04 alkylene terephthalate) comprises polyethylene terephthalate).

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