A process for production of cyclohexanedimethanol from recycled polyethylene terephthalate

Abstract

A process for producing 1,4-cyclohexanedimethanol by depolymerizing one or more recycled terephthalate-based polyesters or copolyesters via solvolysis with one or more glycols or alcohols and contacting the depolymerization product with an ester hydrogenolysis catalyst and hydrogen to produce a hydrogenolysis product and contacting the hydrogenolysis product with a hydrogenation catalyst and hydrogen to produce 1,4- cyclohexanedimethanol.

Description

A PROCESS FOR PRODUCTION OF CYCLOHEXANEDIMETHANOL FROM RECYCLED POLYETHYLENE TEREPHTHALATEFIELD OF THE INVENTION

[0001] The present disclosure is a process wherein recycled terephthalate based copolyesters undergo a solvolysis with alcohol or glycol solvent to produce a depolymerized product containing terephthalate esters and oligomers, this depolymerized product undergoes hydrogenolysis to produce xylylene glycol (XG) and coproduct glycols using an ester hydrogenolysis catalyst, the XG then undergoes hydrogenation using an arene hydrogenation catalyst to produce cyclohexanedimethanol (CHDM). The present disclosure provides improved hydrogenolysis reaction times and conditions. In the present disclosure, the process to make XG is further improved by using a two-step approach which enables higher throughput and more efficient use of the catalyst.BACKGROUND

[0002] Efficient recycling of polyester plastics remains a significant challenge to achieving a circular economy as many waste polymers are unsuitable for mechanical recycling processes or they are often downcycled into lower value products. Historically, there have been several methods used to create systems capable of industrial scale depolymerization of polyethylene terephthalate (PET) into monomers, though existing methods are limited in their ability to efficiently recycle non-PET polyesters and copolyesters. One state-of-the-art method for industrial scale depolymerization of PET is methanolysis, taking waste polyethylene terephthalate and converting it to dimethyl terephthalate and ethylene glycol in the presence of methanol. This process has been demonstrated to be effective for circular chemical recycling of PET at full industrial scale; however, it is not optimized for the recovery of comonomers from polyesters other than dimethyl terephthalate and ethylene glycol. One alternative method of depolymerizing polyesters isdepolymerization of recycled polyesters by hydrogenolysis of the esters to produce alcohol monomers.

[0003] There are examples of catalytic hydrogenolysis of PET to xylene glycol and ethylene glycol, however, several problems are common for these chemical recycling technologies when applied to waste polyester recycling. These reactions often require the use of expensive and sometimes toxic organic solvents (like hexafluoroisopropanol and 1 ,4 dioxane). These reactions also have long reaction times increasing the associated cost and reducing the throughput. These challenges among others have so far been prohibitive in the translation of hydrogenative depolymerization to an industrial scale.

[0004] In the present disclosure, a process capable of overcoming these limitations of hydrogenolysis of waste polyesters as a large-scale method for the chemical recycling is enabled. Furthermore, the process described herein can be used to depolymerize terephthalate-based waste polyester materials and convert the terephthalate portion into higher value cyclohexanedimethanol monomers for use in specialty copolyesters.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIGURE 1 Fossil based CHDM compared to recycled CHDM (rCHDM) production from recycled polyesters and / or copolyesters.

[0006] FIGURE 2 Process to produce recycled CHDM from recycled polyesters and copolyesters via solvolysis (a), hydrogenolysis (b), and hydrogenation (c).

[0007] FIGURE 3 Process to produce rCHDM from rPET via solvolysis (a), hydrogenolysis (b), and hydrogenation (c).

[0008] FIGURE 4 Process to produce rCHDM from rPET via solvolysis (a), hydrogenolysis (b), and hydrogenation (c).

[0009] FIGURE 5 Synthesis of CHDM from BHET via hydrogenolysis and arene hydrogenation.

[0010] FIGURE 6 Example for hydrogenolysis of glycolysis mixture. BHET (20 mmol), Ru catalyst (1 mol%), EG (50 mL), 160°C, hydrogen (100 bar).DETAILED DESCRIPTION

[0011] Fossil feedstock-based CHDM is produced via a 2-step process from DMT (derived from p-xylene via terephthalic acid (TPA)). The route described here from recycled polyesters PET to recycled CHDM (FIGURE 1) has similar process steps, but significantly lower pressure and temperature requirements. This route as shown in FIG 2. consists of solvolysis (1), impurity removal (2), hydrogenolysis (3), catalyst separation (4), catalyst recycle (5), product separation (6), arene hydrogenation (7), and solvent recycle (8).

[0012] Homogeneous ruthenium catalysts with Triphos derived ligands (1 ,1 ,1-Tris(diphenylphosphinomethyl)ethane) are active for the hydrogenolysis of the ester bonds in polyesters and copolyesters including PET, however, like much of the limited academic work on PET hydrogenolysis, undesirable organic solvents (e.g. dioxane) are typically used, limiting the commercial viability. We found that hydrogenolysis of PET monomer or oligomers in EG is very fast. Utilization of product glycols, like EG or CHDM, for the glycolysis, both hydrogenolysis and hydrogenation steps, and recycle of the ruthenium catalyst; improves hydrogenolysis rate catalyst efficiency.

[0013] The removal of non-polyester impurities in post-consumer material is challenging. Using the glycolysis front-end to make a liquid oligomer enables non-polyester solids removal before (FIGURE 2 and FIGURE 3) or after hydrogenolysis (FIGURE 4), avoids undesirable organic solvents, and increases hydrogenolysis efficiency. Produced XG can then be hydrogenated using an arene hydrogenation catalyst to produce CHDM.

[0014] The present disclosure utilizes post-consumer polyester feedstocks to produce key monomer building blocks for both polyethylene terephthalate (PET) and specialty terephthalate based copolyesters that are used in many packaging and durable applications. This is achieved via a two-step hydrogenolysis and hydrogenation process. This approach offers advantages including broadening the range of polyester feedstocks which can bechemically recycled and upcycling of low value recycled PET waste into recycled CHDM (1 ,4-cyclohexanedimethanol) monomer for use in specialty copolyesters with a significantly lower carbon footprint than fossil based CHDM.

[0015] One aspect of the present disclosure is a process for the hydrogenolysis of waste terephthalate containing polyesters and copolyesters to produce recycled cyclohexanedimethanol and other diols. This process employs the use of a ruthenium phosphine ester hydrogenolysis catalyst and is capable of converting recycled polyesters into alcohol monomers without the use of undesirable organic solvents and has fast reaction times.

[0016] The present disclosure is a process for the production of recycled 1 ,4-cyclohexanedimethanol from waste polyesters and copolyester.

[0017] One aspect of the present disclosure is a two-step hydrogenolysis and hydrogenation process.

[0018] In one embodiment, the method is a three step process that comprises : step (a) a solvolysis reaction wherein terephthalate based polyester or copolyesters are contacted with ethylene glycol or another alcohol or glycol and a transesterification catalyst to produce the corresponding oligomers thereof based on the polyesters and / or copolyester compositions; step (b) a hydrogenolysis reaction wherein the oligomers are contacted with hydrogen in the presence of a an ester hydrogenolysis catalyst to form xylylene glycol and ethylene glycol, and step (c) the xylylene glycol is contacted with hydrogen in the presence of an arene hydrogenation catalyst to form 1 ,4-cyclohexanedimethanol.

[0019] In one embodiment, the method is a three step process that comprises: step (a) depolymerizing polyethylene terephthalate (PET) via glycolysis with ethylene glycol (EG) and optionally one or more other glycols to form a depolymerization product comprising bis(2-hydroxyethyl) terephthalate (BHET) and oligomers thereof; (b) contacting said depolymerization product with hydrogen and an ester hydrogenolysis catalyst to produce an hydrogenolysis product comprising p-xylylene glycol (pXG) andethylene glycol; and (c) contacting said pXG with hydrogen and a hydrogenation catalyst to produce a hydrogenation product comprising 1 ,4- cyclohexanedimethanol (1 ,4-CHDM).

[0020] In one embodiment, the method is a three step process that comprises step (a) depolymerizing a terephthalate based polyester or copolyester via glycolysis or alcoholysis (b) contacting said depolymerization product with hydrogen and an ester hydrogenolysis catalyst to produce a hydrogenolysis product comprising xylylene glycol (XG) and the corresponding coproduct glycols or alcohols; (c) contacting said XG with hydrogen and an hydrogenation catalyst to produce a hydrogenation product comprising cyclohexanedimethanol (CHDM).

[0021] In one embodiment, the method is a two-step process that comprises step (a) contacting bis(2-hydroxyethyl) terephthalate (BHET) or oligomers thereof with hydrogen and an ester hydrogenolysis catalyst to form a hydrogenolysis product comprising p-xylylene glycol and ethylene glycol; and (b) contacting said p-xylylene glycol (pXG) with hydrogen and a hydrogenation catalyst to form 1 ,4-cyclohexanedimethanol (1 ,4-CHDM).

[0022] In one embodiment, the depolymerizing step (a) further comprises the presence of a transesterification catalyst. In one embodiment, transesterification catalyst suitable for use in step (a) include catalytic metals such as manganese, lithium, zinc, titanium, tin, antimony, magnesium, sodium, potassium, or combinations thereof. In another embodiment, the transesterification catalyst in step (a) comprise one or more of acetates, carbonates, hydroxides, oxides (particularly soluble oxides), methoxides, fluorides, chlorides, bromides, iodides, phosphates, sulfates, nitrates. In another embodiment, the transesterification catalyst in step (a) comprise one or more of alkali metal C1-C14 alkoxides, alkali metal C1-C14 carboxylates, alkali metal hydroxides, alkali metal carbonates, and alkali metal halides.

[0023] In one embodiment, the ester hydrogenolysis catalyst in step (b) comprises a ruthenium catalyst or comprises a ruthenium containing compound. For example, in one embodiment, the ruthenium esterhydrogenolysis catalyst is formed by reacting a ruthenium-containing compound with a phosphorus ligand. In another embodiment, the Ru- containing compound can be a salt or a complex containing ruthenium. In another embodiment, the Ru-containing compound is one or more of the following: Ru(acac)3, [Ru(COD)(methylallyl)2], Ru(NBD)(methylallyl)2, Ru(ethylene)2(methylallyl)2, [(COD)RuCI2]n, RuCI3, [(PPh3)3Ru(H)(CO)CI], and [(cymanthren)RuCI2]2.

[0024] In one embodiment, the ruthenium ester hydrogenolysis catalyst is formed by reacting a ruthenium-containing compound with a phosphorus ligand and the phosphorus ligand has a structure of (R1 )C(CH2P(R2)(R3))3 wherein R1 is a C1-14 alkyl group or is a methyl group; R2 and R3 are independently selected from C1-C14 alkyl, cycloalkyl, or aryl groups substituted at the meta position. In another embodiment, the phosphorus ligand comprises a structure of

[0025] wherein R1 is a C1-14 alkyl group or is a methyl group; R2 and R3 are independently selected from C1-C14 alkyl, cycloalkyl, or aryl groups substituted at the meta position; and R4 and R5 are independently selected from hydrogen, C1-C6 alkyl, methoxide, C1-C6 alkoxide, chloride, or fluoride. In yet another embodiment, the phosphorus ligand comprises one of the following: 1 ,1 ,1-Tris(diphenylphosphino-methyl)ethane (Triphos), 1 ,1 , 1-Tris(di- (3,5-dimethylphenylphosphino-methyl)ethane (T riphos-Xylyl), 1 ,1 ,1 -tris(d i (3, 5- dimethoxyphenyl)phosphinomethyl)ethane (triphos-(OMe)2), 2-(Di-tert- butylphosphinomethyl-6-diethylaminomethyl)pyridine, Bis(2- (diphenylphosphino)ethyl)amine, or Bis(2-(diisopropylphosphino)ethyl)amine.

[0026] In one embodiment, the ruthenium catalyst is present in said hydrogenating step (b) in an amount of about 0.01 - 1 .0 mol% based on the total moles of terephthalate. In one embodiment, the ruthenium catalyst ispresent in said hydrogenating step (b) in an amount of about 0.5 mol% based on the total moles of terephthalate.

[0027] In one embodiment, the hydrogenolysis step (b) is performed at a hydrogen pressure of about 40-150 Bar or about 55-130 Bar or about 55 - 105 Bar. In one embodiment, the hydrogenolysis step (b) is performed at a temperature of from about 80 - 240°C. In one embodiment, the hydrogenolysis step (b) is performed at a temperature of about 140 - 200 °C. In one embodiment, the hydrogenolysis step (b) is performed at a temperature of from about 160°C.

[0028] One advantage of the present disclosure is that the process does not use potentially dangerous or peroxide forming solvents such as hexafluoroisopropanol, phenol, dichloromethane, tetrahydrofuran, or 1 ,4- dioxane. As an alternative, alcohols, such as ethylene glycol, are employed as the reaction solvent.

[0029] In addition, the process of the present disclosure utilizes in situ catalyst formation to overcome the air and moisture sensitivity often experiences in other systems. The use of solvolysis, glycolysis or alcoholysis in the first depolymerization step of the process allows for a wide range of polyesters and / or copolyesters that can be used as feedstocks to be recycled with a high tolerance to contaminants and enables purification before the catalytic hydrogenolysis.

[0030] In one embodiment, the depolymerization (solvolysis, glycolysis or alcoholysis) is categorized by the depolymerization agent used. For instance, depolymerization agents may include water, alcohols, or glycols. In some embodiments, water, methanol, or ethylene glycol are suitable for use.

[0031] If the depolymerization reactant is water, the products are terephthalic acid and ethylene glycol. If the depolymerization reactant is methanol, the products are dimethyl terephthalate and ethylene glycol. If the depolymerization reactant is ethylene glycol, the product is bis(hydroxyethyl) terephthalate (BHET) or oligomers thereof (depending on how much ethylene glycol is used).

[0032] In certain embodiments, depolymerization is by glycolysis and glycols such as ethylene glycol are used as the depolymerization agent or solvent. In other embodiments, depolymerization is by alcoholysis and alcohols such as methanol, 2-ethylhexanol (2-EH) are used as the depolymerization agent or solvent.

[0033] Examples of suitable polyesters can include those having repeating aromatic or cyclic units such as those containing a repeating terephthalate, isophthalate, or naphthalate units such as PET, modified PET, and PEN, or those containing repeating furanoate repeating units. Polyethylene terephthalate (PET) is also an example of a suitable polyester. As used herein, “PET” or “polyethylene terephthalate” refers to a homopolymer of polyethylene terephthalate, or to a polyethylene terephthalate modified with one or more acid and / or glycol modifiers and / or containing residues or moieties of other than ethylene glycol and terephthalic acid, such as isophthalic acid, 1 ,4-cyclohexanedicarboxylic acid, diethylene glycol, 2, 2,4,4- tetramethyl-1 ,3-cyclobutanediol (TMCD), cyclohexanedimethanol (CHDM), propylene glycol, isosorbide, 1 ,4-butanediol, 1 ,3-propane diol, and / or neopentylglycol (NPG). Also included within the definition of the terms “PET” and “polyethylene terephthalate” are polyesters having repeating terephthalate units (whether or not they contain repeating ethylene glycol based units) and one or more residues or moieties of a glycol including, for example, TMCD, CHDM, propylene glycol, or NPG, isosorbide, 1 ,4- butanediol, 1 ,3-propane diol, and / or diethylene glycol, or combinations thereof. Examples of polymers with repeat terephthalate units can include, but are not limited to, polypropylene terephthalate, polybutylene terephthalate, and copolyesters thereof. Examples of aliphatic polyesters can include, but are not limited to, polylactic acid (PLA), polyglycolic acid, polycaprolactones, and polyethylene adipates. In one or more embodiments, the polyesters may comprise mixed aliphatic-aromatic copolyesters including, for example, mixed terephthalates / adipates.

[0034] In one or more embodiments, the waste polyesters may comprise at least one type of polyester which include repeat terephthalate units in an amount of at least 1 , 2, 5, 10, 15, 20, 25, or 30 and / or not more than about 45, 40, 35, 30, 25, 20, 15, 10, 5, or 2 weight percent, based on the total weight of the stream or composition. Similar amounts of copolyesters having multiple cyclohexane dimethanol moieties, 2,2,4,4-tetramethyl-1 ,3-cyclobutanediol moieties, or combinations thereof may also be present.

[0035] In certain embodiments, terephthalate based copolyester suitable for use in the present disclosure include poly(C2-C4)alkylene terephthalates which may be further comprised of additional glycol and / or diacid residues, and include, for example, polyethylene terephthalate (PET), 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 combinations thereof.

[0036] The reaction times for this process are also significantly shorter than the reaction times often experienced in other systems. In one embodiment, the reaction times of the present disclosure range from 1-8 hours.

[0037] Another advantage of the present disclosure is that the hydrogenation catalyst can be recycled using membrane filtration, distillation, or other suitable methods known in the art.

[0038] In aspect, the process of the present disclosure utilizes glycolysis for the depolymerization of waste polyesters, including PET. In one embodiment, in step (a) the reactor is charged with PET and ethylene glycol with a catalytic amount of NaOAc (1 .5-2.5 mol%) or other transesterification catalyst. Heated to 180-200 °C and reacted for 2-4 hours.

[0039] In one embodiment, the transesterification catalyst in step (a) is chosen from alkali metal C1-C14 alkoxides, alkali metal hydroxides, and alkali metal carbonates. In one embodiment, the transesterification catalyst in step (a) is chosen from potassium hydroxide, sodium hydroxide, sodium methoxide, potassium methoxide, sodium 2-ethylhexylate and potassium carbonate. In another embodiment, examples of suitable transesterification catalysts include, but are not limited to, titanium alkoxides, tin (II) or (IV) esters, alkali metals or alkali earth metals (e.g., Li and Ca), manganese compounds, zinc compounds, magnesium acetates or benzoates, and combinations thereof.

[0040] In one embodiment, in step (b), the product mixture from step (a) is fed to an optional purification step to remove unreacted solid material or other undesirable components and resulting purified material fed to step (c).

[0041] In one embodiment, the material from step (b) is fed to an ester hydrogenolysis reactor where it is contacted with the ruthenium catalyst and hydrogen (at 40 - 150 Bar) and heated to a temperature of 80 - 240°C until the terephthalate units are substantially converted to xylylene glycol.

[0042] In one embodiment, the ruthenium catalyst is separated from the hydrogenation product using one of distillation, membrane filtration, extraction, or other suitable methods known in the art and recycled back to the hydrogenation reactor or optionally stored in a catalyst feed tank.

[0043] In one embodiment, the hydrogenation product is further separated by distillation or other separation methods known in the art to produce high purity xylylene glycol and ethylene glycol. In one embodiment, a portion of the ethylene glycol is optionally recycled back to the glycolysis reactor.

[0044] In one embodiment, xylene glycol is then fed to a hydrogenation unit containing an arene hydrogenation catalyst. In one embodiment, the arene hydrogenation catalyst is a combination of one or more precious or base metals selected from a group including Pt, Pd, Ni, Co, Rh, Ir, Cu, Co, Fe, Ru in the reduced metal or oxide form, either unsupported or supported on one or more materials on selected from a group consisting of silica, alumina, aluminosilicate, titania, zirconia, and carbon. In one embodiment, suitable hydrogenation catalysts include one or more of the following: Pt / C, Pd / C or Raney Ni (1 - 5 mol%). In another embodiment, the hydrogenation catalyst is one or more of Pt / C, Pt / AhOs, PtC>2, Pd / C, Pd / AhOs, PVAI2O3, PdO, RU / AI2O3, Ru / C, RUO2, Raney Ni (1 - 5 mol%), Pt-Rh, Pt-Rh / AhOs, or Pt-Sn / AhOs.

[0045] In one embodiment, the hydrogenation step (c) is further conducted in the presence of a solvent chosen from one or more of water; C1-C14 alcohols, methanol, butanol, 2-ethyl hexanol, 4-methyl cyclohexanemethanol; and C1-C14 glycols, ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), neopentyl glycol (NPG), cyclohexanedimethanol (CHDM), and xylylene glycol (XG).

[0046] In one embodiment, an alcohol solvent optionally may be used. In one embodiment, the xylene glycol is contacted with a catalyst, hydrogen (at 50 - 150 Bar) and heated to temperatures of 80 - 240°C until the xylylene glycol is substantially converted to cyclohexanedimethanol (CHDM).

[0047] The producedrecycled CHDM is purified by distillation or other known purification methods to a purity sufficient for use in copolyester synthesis.DEFINITIONS

[0048] 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.

[0049] As used herein, the terms “a,” “an,” and “the” mean one or more.

[0050] 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; A and B in combination; A and C in combination, B and C in combination; or A, B, and C in combination.

[0051] 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.

[0052] 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.

[0053] As used herein, the terms “including,” “include,” and “included” have the same open-ended meaning as “comprising,” “comprises,” and “comprise” provided above.

[0054] As used herein, the term “recycled content” refers to being or comprising a composition that is directly and / or indirectly derived from recycled material.

[0055] As used herein, the term “waste polyesters” refers to used, scrap, and / or discarded polyester materials.

[0056] The term “polyester”, as used herein, is intended to include “copolyesters” and is understood to mean a synthetic polymer prepared by the reaction of one or more difunctional carboxylic acids and / or multifunctional carboxylic acids with one or more difunctional hydroxyl compounds and / or multifunctional hydroxyl compounds, for example, branching agents.Typically, the difunctional carboxylic acid can be a dicarboxylic acid and the difunctional hydroxyl compound can be a dihydric alcohol, for example, glycols and diols. The term “glycol” as used herein includes, but is not limited to, diols, glycols, and / or multifunctional hydroxyl compounds, for example,branching agents. Alternatively, the difunctional carboxylic acid may be a hydroxy carboxylic acid, for example, p-hydroxybenzoic acid, and the difunctional hydroxyl compound may have an aromatic nucleus bearing 2 hydroxyl substituents, for example, hydroquinone. The term “residue”, as used herein, means any organic structure incorporated into a polymer through a polycondensation and / or an esterification reaction from the corresponding monomer. The term “repeating unit”, as used herein, means an organic structure having a dicarboxylic acid residue and a diol residue bonded through an ester group. Thus, for example, the dicarboxylic acid residues may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, and / or mixtures thereof. Furthermore, as used herein, the term “diacid” includes multifunctional acids, for example, branching agents. As used herein, therefore, the term “dicarboxylic acid” is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, and / or mixtures thereof, useful in a reaction process with a diol to make a polyester. As used herein, the term “terephthalic acid” is intended to include terephthalic acid itself and residues thereof as well as any derivative of terephthalic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, and / or mixtures thereof or residues thereof useful in a reaction process with a diol to make a polyester.

[0057] The polyesters used in the present disclosure typically can be prepared from dicarboxylic acids and diols which react in substantially equal proportions and are incorporated into the polyester polymer as their corresponding residues. The polyesters of the present disclosure, therefore, can contain substantially equal molar proportions of acid residues (100 mole%) and diol (and / or multifunctional hydroxyl compound) residues (100 mole%) such that the total moles of repeating units is equal to 100 mole%. The mole percentages provided in the present disclosure, therefore, may be based on the total moles of acid residues, the total moles of diol residues, orthe total moles of repeating units. For example, a polyester containing 10 mole% isophthalic acid, based on the total acid residues, means the polyester contains 10 mole% isophthalic acid residues out of a total of 100 mole% acid residues. Thus, there are 10 moles of isophthalic acid residues among every 100 moles of acid residues. In another example, a polyester containing 25 mole% 1 ,4-cyclohexanedimethanol, based on the total diol residues, means the polyester contains 25 mole% 1 ,4-cyclohexanedimethanol residues out of a total of 100 mole% diol residues. Thus, there are 25 moles of 1 ,4- cyclohexanedimethanol residues among every 100 moles of diol residues.

[0058] In certain embodiments, terephthalic acid or an ester thereof, for example, dimethyl terephthalate or a mixture of terephthalic acid residues and an ester thereof can make up a portion or all of the dicarboxylic acid component used to form the polyesters useful in the present disclosure. In certain embodiments, terephthalic acid residues can make up a portion or all of the dicarboxylic acid component used to form the polyesters useful in this disclosure. For the purposes of this disclosure, the terms “terephthalic acid” and “dimethyl terephthalate” are used interchangeably herein. In one embodiment, dimethyl terephthalate is part or all of the dicarboxylic acid component used to make the polyesters useful in the present disclosure. In embodiments, ranges of from 70 to 100 mole%; or 80 to 100 mole%; or 90 to 100 mole%; or 99 to 100 mole%; or 100 mole% terephthalic acid and / or dimethyl terephthalate and / or mixtures thereof may be used.

[0059] In addition to terephthalic acid, the dicarboxylic acid component of the polyesters useful in the present disclosure can comprise up to 30 mole%, up to 20 mole%, up to 10 mole%, up to 5 mole%, or up to 1 mole% of one or more modifying aromatic dicarboxylic acids. Yet another embodiment contains 0 mole% of modifying aromatic dicarboxylic acids. Thus, if present, it is contemplated that the amount of one or more modifying aromatic dicarboxylic acids can range from any of these preceding endpoint values including, for example, 0.01 to 10 mole%, from 0.01 to 5 mole% and from 0.01 to 1 mole%. In one embodiment, modifying aromatic dicarboxylic acids thatmay be used in the present disclosure include but are not limited to those having up to 20 carbon atoms, and which can be linear, para-oriented, or symmetrical. Examples of modifying aromatic dicarboxylic acids which may be used in this disclosure include, but are not limited to, isophthalic acid, 4,4'- biphenyldicarboxylic acid, 1 ,4-, 1 ,5-, 2,6-, 2,7-naphthalenedicarboxylic acid, and trans-4,4'-stilbenedicarboxylic acid, and esters thereof. In one embodiment, the modifying aromatic dicarboxylic acid is isophthalic acid.

[0060] The carboxylic acid component of the polyesters useful in the present disclosure can be further modified with up to 10 mole%, such as up to 5 mole% or up to 1 mole% of one or more aliphatic dicarboxylic acids containing 2-16 carbon atoms, for example, cyclohexanedicarboxylic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic and / or dodecanedioic dicarboxylic acids. Certain embodiments can also comprise 0.01 to 10 mole%, such as 0.1 to 10 mole%, 1 or 10 mole%, 5 to 10 mole% of one or more modifying aliphatic dicarboxylic acids. Yet another embodiment contains 0 mole% of modifying aliphatic dicarboxylic acids. The total mole% of the dicarboxylic acid component is 100 mole%. In one embodiment, adipic acid and / or glutaric acid are provided in the modifying aliphatic dicarboxylic acid component of the polyesters and are useful in the present disclosure.

[0061] Esters of terephthalic acid and the other modifying dicarboxylic acids or their corresponding esters and / or salts may be used instead of the dicarboxylic acids. Suitable examples of dicarboxylic acid esters include, but are not limited to, the dimethyl, diethyl, dipropyl, diisopropyl, dibutyl, and diphenyl esters. In one embodiment, the esters are chosen from at least one of the following: methyl, ethyl, propyl, isopropyl, and phenyl esters.

[0062] As used herein, the term “oligomer” refers to a polymeric species comprising in the range of from about 2 to about 20 chain lengths. As used herein, the term “monomer” refers to a polymeric species comprising about one chain lengths, while the term “polymer” refers to a polymeric species comprising greater than about 20 chain lengths.EXAMPLESExample 1 for hydrogenolysis of PET

[0063] Polyethylene terephthalate (5 g, 0.026 mol) was charged into a 100 mL reactor with ruthenium (III) acetylacetonate (0.104 g, 0.26 mmol) 26 mmol) and Triphos-Xylyl (0.206 g, 0.26 mmol). The reactor was then filled with ethylene glycol (50 mL) and the reactor was sealed. The system was then flushed with nitrogen twice and the reactor was then charged with hydrogen (105 bar). The pressure was maintained throughout from a surge tank. The reactor was then heated to 190 C and stirred at 1000 rpm for 8 hours. Once complete the reactor was allowed to cool and the product mixture analyzed by gas chromatography using mesitlyene as an internal standard. The results were 100% conversion of PET, yield of xylene glycol 95%.Example 2 for hydrogenolysis of Bis(2-Hydroxyethyl) terephthalate (BHET)

[0064] BHET (5 g, 0.02 mol) was charged into a 100 mL reactor with ruthenium (III) acetylacetonate (0.2 mmol, 79.7 mg) and Triphos-xylyl (0.2 mmol, 158.6 mg). The reactor was then filled with ethylene glycol (50 mL) and the reactor was sealed. The system was then flushed with nitrogen twice and the reactor was charged with hydrogen (105 Bar). The pressure was maintained throughout from a surge tank. The reactor was then heated to 160 C and stirred at 1000 rpm for 2 hours. Once complete the reactor was allowed to cool and the product mixture was analyzed by gas chromatography using mesitlyene as an internal standard. The results were 96 % yield of xylene glycol in 100 mins.Example 3 for hydrogenolysis of glycolysis mixture

[0065] BHET in ethylene glycol (21 g, 24 wt% BHET, 0.02 mol) was charged into a 100 mL reactor with ruthenium (III) acetylacetonate (0.2 mmol, 79.7 mg) and Triphos-xylyl (0.2 mmol, 158.6 mg). The reactor was then filled with ethylene glycol (50 mL) and the reactor was sealed. The system was then flushed with nitrogen twice and the reactor was charged with hydrogen (105 Bar). The pressure was maintained throughout from a surge tank. Thereactor was then heated to 160 C and stirred at 1000 rpm for 2 hours. Once complete the reactor was allowed to cool and the product mixture was analyzed by gas chromatography using mesitlyene as an internal standard.Example 4: Glycolysis of recycled PET oligomer

[0066] A 5L round-bottomed flask equipped with overhead stirring and a reflux condenser was charged with 2.5 kg recycled PET oligomer (produced by Eastman Chemical Company) and 2.48 L EG. Stirring was started at 50 RPM. The mixture was heated to reflux, and reflux was maintained for 6 h, internal temperature ranged from 175-185 °C during reflux. The vessel was allowed to cool to 100 °C, then the mixture was passed through a Buchner funnel to remove insoluble solids, yielding 3.2 kg glycolyzed rPET oligomer containing 18.5 wt% total terephthalates.Example 5: Hydrogenolysis of glycolyzed rPET oligomer

[0067] A 1 L titanium autoclave equipped with a gas entrainment impeller was charged with glycolyzed rPET oligomer from Example 4 (400 g, 18.5 wt% terephthalates), Ru(acac)3 (0.256 g), and triphos-xyl (0.542 g). The reactor was sealed, and the headspace was purged with N2. The reactor headspace was purged again with H2. The reactor was then pressurized to 200 psig H2, stirring was started at 1000 RPM, and the reactor was heated to 180 °C. Once the temperature reached 178 °C, the reactor was pressurized to 1288 psig H2. The reaction was allowed to proceed for 8h. After 8h, the reactor was cooled to RT, vented and the contents were collected. Conversion to XG was found to be 95% by 1 H NMR.Example 6: Isolation of XG from reaction product described in Example 5

[0068] A 500 mL round-bottomed flask was charged with 336 g of reaction product described in Example 5. The mixture was partially distilled at 100 Torr and 140-150 °C, giving 193 g of distillate consisting mostly of EG. Material from the boiling flask was chilled to 5 °C, then brought to 21 °C. The mixturewas passed through a filter. The filter cake was collected, yielding 31 .6 g crude XG, 85% yield.Example 7: Hydrogenation of XG from Example 6 to CHDM

[0069] A 100 mL Hastelloy stirred autoclave equipped with a catalyst basket was charged with recrystallized (from ethyl acetate) XG obtained from Example 6 (4.1 g). The catalyst basket was charged with a 2 wt% Ru / AI2O3 catalyst (1 .0 g). Ethanol (30 mL) was added to the reactor body. The reactor was sealed, and the headspace was purged with N2. The headspace was then purged with H2. The reactor was pressurized to 600 psig H2 and stirring was set to 1000 RPM. The reactor was heated to 100 °C, then the H2 pressure was increased to 850 psig. The reaction was allowed to proceed for 2 h. The reactor was cooled to RT, vented and the reaction mixture was analyzed by GC-FID. XG conversion is >99%, CHDM selectivity is 38% by GC-FID area%.Example 8: Comparative Example-Hydrogenation of commercially supplied XG

[0070] The same experiment was conducted as described in Example 7, but with commercially supplied XG (commercially available from Tokyo Chemical Industry, Co., Ltd. XG conversion is >99%, CHDM selectivity is 40% by GC-FID area%.The Control reactionsReaction of BHET in the absence of ligand

[0071] BHET (5 g, 0.02 mol) was charged into a 100 mL reactor with ruthenium (III) acetylacetonate (0.2 mmol, 79.7 mg). The reactor was then filled with ethylene glycol (50 mL) and the reactor was sealed. The system was then flushed with nitrogen twice and the reactor was charged with hydrogen (105 Bar). The pressure was maintained throughout from a surge tank. The reactor was then heated to 160 C and stirred at 1000 rpm for 6hours. Once complete the reactor was allowed to cool and the product mixture analyzed by gas chromatography using mesitlyene as an internal standard.

[0072] The results: Conversion: 0%, Yield of xylene glycol: 0%

[0073] Only BHET observed post reaction; no intermediate or product observed.Catalyst tolerance to chloride contamination

[0074] BHET (5 g, 0.02 mol) was spiked with NaCI (1 wt%, 0.05 g) was charged into a 100 mL reactor body with ruthenium (III) acetylacetonate (0.2 mmol, 79.7 mg) and Triphos-xylyl (0.2 mmol, 158.6 mg). The reactor was then filled with ethylene glycol (50 mL) and the reactor was sealed. The system was then flushed with nitrogen twice and the reactor was charged with hydrogen (105 Bar). The pressure was maintained throughout from a surge tank. The reactor was then heated to 160 C and stirred at 1000 rpm for 2 hours. Once complete the reactor was allowed to cool and the product mixture was analyzed by gas chromatography using mesitlyene as an internal standard.

[0075] The results: At 80 mins 98% yield of xylene glycol, 100% conversion of BHET. XRF of the post reaction mixture 835 ppm of chlorine.CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS

[0076] 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.

[0077] 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.

Claims

CLAIMSWhat is claimed is -1. A method for producing cyclohexanedimethanol (CHDM), said method comprising: (a) depolymerizing one or more recycled terephthalate-based polyesters or copolyesters or oligomers thereof via solvolysis with one or more glycols or alcohols (b) contacting said depolymerization product with hydrogen and an ester hydrogenolysis catalyst to produce a hydrogenolysis product comprising xylylene glycol (XG) and the corresponding coproduct glycols or alcohols; (c) contacting said XG with hydrogen and an arene hydrogenation catalyst to produce a hydrogenation product comprising cyclohexanedimethanol (CHDM).

2. A method for producing 1 ,4-cyclohexanedimethanol (1 ,4-CHDM), said method comprising: (a) depolymerizing recycled polyethylene terephthalate (PET) or oligomers thereof via glycolysis with ethylene glycol (EG) to form a depolymerization product comprising bis(2-hydroxyethyl) terephthalate (BHET) and oligomers thereof; (b) contacting said depolymerization product with hydrogen and an ester hydrogenolysis catalyst to produce an hydrogenolysis product comprising p-xylylene glycol (pXG), and ethylene glycol (EG); and (c) contacting said pXG with hydrogen and an arene hydrogenation catalyst to produce an arene hydrogenation product comprising 1 ,4- cyclohexanedimethanol (1 ,4-CHDM).

3. A method for producing 1 ,4-cyclohexanedimethanol (1 ,4-CHDM), said method comprising: (a) contacting bis(2-hydroxyethyl) terephthalate (BHET) or oligomers thereof with hydrogen and an ester hydrogenolysis catalyst to form a hydrogenolysis product comprising p-xylylene glycol and ethylene glycol; and (b) contacting said p-xylylene glycol (pXG) with hydrogen and an arene hydrogenation catalyst to form 1 ,4-cyclohexanedimethanol (1 ,4-CHDM).

4. The method of claim 1 , wherein said terephthalate-based polyester or copolyester comprises one or more of polybutylene terephthalate (PBT), polycyclohexylenedimethylene terephthalate (PCT), Polyethylene terephthalate (PET), PET containing up to 5 wt% isophthalate, glycol modified PET, copolyesters of CHDM, copolyesters of 2,2-4,4-tetramethyl-1 ,3- cyclobutanediol (TMCD) and copolyesters of dimethyl terephthalate (DMT).

5. The method of claim 1 , wherein said glycols or alcohols are selected from one or more of C1-C14 alcohols, methanol, butanol, 2-ethyl hexanol, 4- methylcyclohexanemethanol; and C1-C14 glycols, ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), neopentyl glycol (NPG), cyclohexanedimethanol (CHDM), and xylylene glycol (XG).

6. The method of claim 2, wherein step (b) further comprises hydrogenolysis of said BHET and the oligomers thereof to produce p-xylylene glycol (pXG) and ethylene glycol.

7. The method of claim 2 or claim 3, further comprising separating said ethylene glycol from said step (b) hydrogenolysis product to form recovered ethylene glycol.

8. The method of claim 1 , further comprising separating said glycols or alcohols from said step (b) hydrogenolysis product to form recovered glycols or alcohols.

9. The method of claim 8, wherein said glycols comprise one or more of EG, DEG, TEG, NPG, TMCD, 1 ,4-butanediol, or CHDM.

10. The method of claim 8, wherein said alcohols comprise one or more of C1-C14 alcohols, methanol, butanol, 2-ethyl hexanol, or 4- methylcyclohexanemethanol.11 . The method of claim 1 or claim 2, wherein said hydrogenation step (c) is conducted in the presence of a solvent chosen from one or more of water; C1-C14 alcohols, methanol, butanol, 2-ethyl hexanol, 4- methylcyclohexanemethanol; and C1-C14 glycols, ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), neopentyl glycol (NPG), cyclohexanedimethanol (CHDM), and xylylene glycol (XG).

12. The method of claim 6, further comprising recycling said recovered ethylene glycol to said depolymerizing step (a).

13. The method of claim 1 , claim 2, and claim 3 wherein said depolymerizing step (a) further comprises the presence of a transesterification catalyst.

14. The method of claim 10, wherein said transesterification catalyst in step (a) is a catalytic metal which comprises one or more of manganese, zinc, titanium, tin, antimony, magnesium, lithium, sodium, potassium, or combinations thereof and / or wherein said transesterification catalyst in step (a) comprises one or more of acetates, carbonates, hydroxides, oxides (particularly soluble oxides), methoxides, fluorides, chlorides, bromides, iodides, phosphates, sulfates, or nitrates; and / or wherein said transesterification catalyst in step (a) comprises one or more of alkali metal C1 -C14 alkoxides, alkali metal C1-C14 carboxylates, alkali metal hydroxides, alkali metal carbonates, or alkali metal halides.

15. The method of claim 1 , claim 2 or claim 3, wherein said ester hydrogenolysis catalyst in step (b) comprises a ruthenium catalyst or comprises a ruthenium containing compound.

16. The method of claim 15, wherein said ruthenium ester hydrogenolysis catalyst is formed by reacting a ruthenium-containing compound with a phosphorus ligand.

17. The method of claim 15, wherein said Ru-containing compound can be a salt or a complex containing ruthenium; or wherein said Ru-containing compound is one or more of the following: Ru(acac)3, [Ru(COD)(methylallyl)2], Ru(NBD)(methylallyl)2, Ru(ethylene)2(methylallyl)2, [(COD)RuCl2]n, RuCh, [(PPh3)3Ru(H)(CO)CI], and [(cymanthren)RuCI2]2.

18. The method of claim 16, wherein the phosphorus ligand comprises a structure ofwherein R1 is a methyl, ethyl or propyl group or a C1-14 alkyl group; R2 and R3 are independently selected from C1-C14 alkyl, C1-C14 cycloalkyl, or C1 -C14 aryl groups substituted at the 3 and 5 positions; and R4 and R5 are independently selected from hydrogen, C1-C6 alkyl, methoxide, C1-C6 alkoxide, chloride, or fluoride.

19. The method of claim 16, wherein the phosphorus ligand comprises a structure ofwherein R1 is a C1-14 alkyl group; and R4 and R5 are independently selected from hydrogen, C1-C6 alkyl, methoxide, C1-C6 alkoxide, chloride, or fluoride.

20. The method of claim 16, wherein the phosphorus ligand comprises one of the following: 1 ,1 ,1 -Tris(diphenylphosphino-methyl)ethane (Triphos), 1 ,1 ,1- T ris(di-(3,5-dimethylphenylphosphino-methyl)ethane (T riphos-Xylyl), 1 ,1 ,1- T ris(di(3,5-dimethoxyphenyl)phosphinomethyl)ethane (T riphos-(OMe)2), 2-( Di- tert-butylphosphinomethyl-6-diethylaminomethyl)pyridine, Bis(2-(diphenylphosphino)ethyl)amine, or Bis(2-(diisopropylphosphino)ethyl)amine.

21. The method of claim 17, wherein said ruthenium catalyst is present in said hydrogenating step (b) in an amount of about 0.001 - 1 mol% based on the total moles of terephthalate or BHET.

22. The method of claim 1 , claim 2 or claim 3, further comprising separating said ester hydrogenolysis catalyst from said step (b) hydrogenolysis product to form recovered ester hydrogenolysis catalyst.

23. The method of claim 26, further comprising recycling said recovered ester hydrogenolysis catalyst to said hydrogenolysis step (b).

24. The method of claim 23, wherein the separation of said ester hydrogenolysis catalyst is conducted by one or more of distillation, membrane filtration, extraction, or other separation methods.

25. The method of claim 1 or claim 2, wherein said depolymerizing of step (a) and said hydrogenolysis of step (b) are occurring at least partially concurrently and / or wherein said step depolymerizing step (a) and said hydrogenolysis step (b) are occurring or performed in a singular reaction vesseland / or wherein said step depolymerizing step (a) and said hydrogenolysis step (b) occur sequentially.

26. The method of claim 1 , claim 2 or claim 3, wherein said hydrogenation catalyst is a combination of a precious or base metal such as Pt, Pd, Ni, Co, Rh, Ir, Cu, Co, Fe, Ru as a metal or metal oxide, either unsupported or supported on a material on selected from a group consisting of silica, alumina, aluminosilicate, titania, zirconia, and carbon; or wherein said hydrogenation catalyst comprises Pt / C, Pt / Al2O3, PtC>2, Pd / C, Pd / AkOs, Pt / AkOs, PdO, RU / AI2O3, Ru / C, RuC , Raney Ni (1 - 5 mol%), Pt-Rh, Pt-Rh / AkOs, or Pt- Sn / AkOs, and combinations thereof.

27. The method of claim 1 , claim 2 or claim 3, wherein said hydrogenation step (c) is conducted in the presence of a solvent chosen from one or more of C1-C14 alcohols, methanol, butanol, 2-ethyl hexanol, 4-methyl cyclohexanemethanol; C1-C14 glycols, ethylene glycol (EG), diethylene glycol (DEG), triethylene glycol (TEG), neopentyl glycol (NPG), cyclohexanedimethanol (CHDM), and xylylene glycol (XG); and water.

28. The method of claim 1 , claim 2 or claim 3, wherein said hydrogenolysis step (b) is performed at a hydrogen pressure of about 40-150 Bar or about 55- 130 Bar or about 55 - 105 Bar and a temperature of from about 80 - 240 °C or at a temperature of about 140 - 200 °C and / or wherein said hydrogenation step (c) is performed at a hydrogen pressure of about 1 - 150 Bar and a temperature of about 20 - 240 °C, or at a pressure of about 50-120 Bar and a temperature of about 80 - 200 °C.

29. The method of claim 1 , claim 2 or claim 3, further comprising, prior to step (c), a step of separating impurities from said hydrogenolysis product to improve the purity of said xylylene glycol and / or further comprising, subsequentto step (c), a step of separating impurities from said hydrogenation product to improve the purity of said CHDM.

30. A method for forming a polyester with recycle content comprising reacting under polyester polymerization conditions a difunctional carboxylic acid, its ester or a combination thereof with CHDM formed via the method of claim 1 , claim 2 or claim 3.

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