Method for producing polyvinylcyclohexane by hydrogenation of waste polystyrene raw material

Abstract

A method for hydrogenating a waste aromatic-containing polymer is described. The method can include contacting a polymer solution containing the waste aromatic-containing polymer with an adsorbent to produce a treated polymer solution containing the waste aromatic-containing polymer. Hydrogenating the treated waste aromatic-containing polymer solution produces a polymer composition containing at least one hydrogenated and / or at least one partially hydrogenated aromatic ring.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of European Patent Application No. 22196383, filed September 19, 2022. The contents of all of the above-referenced disclosures are specifically incorporated herein by reference. [Technical Field]

[0002] FIELD OF THE INVENTION The present invention generally relates to a method for hydrogenating waste aromatic-containing polymers. The waste aromatic-containing polymers can include polystyrene, expanded polystyrene, or a combination thereof. [Background technology]

[0003] Plastic materials are used in a variety of applications (e.g., electronics, furniture, food packaging, commercial products, vehicles, aircraft, housing, insulation, etc.) due to their light weight, tunable properties, and moldability. However, due to their high durability, plastics pose increasing environmental challenges. To address this issue, plastic recycling methods have been researched. However, these methods are economically unviable (e.g., poor market demand and low usage) and / or do not produce recycled polymers with the same properties (e.g., mechanical properties, physical properties, etc.) as virgin / virgin polymers. To compensate for the inferior properties, recycled polymers are typically blended with virgin polymers, but the blending ratio rarely exceeds 20% even in less demanding applications. To address the polymer recycling issue, Cote and Vollmer et al. (Angewandte Chemie. Int. Ed. 2020, 59, 15402-15423) both describe a dissolution / precipitation process for separating one polymer from a mixture of waste polymers. Other methods for treating waste polymer solutions have been described. For example, Verma et al. (International Journal of Energy Research / Early View, https: / / doi.org / 10.1002 / er.8246) describe pyrolysis of waste expanded polystyrene and hydrogenation of the pyrolyzed polystyrene to produce fuel oil. Patent Document 2 by Motoyama et al. describes a method for producing alicyclic polymers. The method includes hydrogenating the aromatic rings of an aromatic polymer in the presence of an organic solvent using a metal fine particle catalyst containing at least one metal selected from the group consisting of ruthenium, rhodium, palladium, platinum, nickel, and cobalt.

[0004] Although solution-based processes for recycling waste polymers are known, challenges remain to make them cost-effective, preserve the properties of virgin polymers, and / or produce desirable end products. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Application Publication No. 2016 / 049782 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-013235 Summary of the Invention

[0006] A discovery has been made that provides a solution to at least one or more problems associated with the hydrogenation of waste aromatic-containing polymers. In one aspect, a process is disclosed that may include contacting a waste aromatic-containing polymer with an adsorbent to produce a treated waste polymer solution. The treated waste aromatic-containing polymer solution can be hydrogenated under conditions sufficient to produce a polymer composition that may include a hydrogenated or partially hydrogenated polymer (e.g., poly(vinylcyclohexane) (PVCH) from a polystyrene polymer). In the context of the present invention, the waste aromatic polymer may include polystyrene, expanded polystyrene, and / or high-density expanded polystyrene, or any combination or blend thereof. An advantage of using the method of the present invention is the ability to remove additives that are deleterious to hydrogenation conditions (e.g., co-stabilizers, anionic surfactants, nucleating agents, initiators, flame retardants, colorants, or mixtures thereof). Another advantage of the method of the present invention is that the densification and hydrogenation of the waste aromatic-containing polymer can be carried out in the same reactor. By treating the waste aromatic-containing polymer prior to hydrogenation, conversions of greater than 50% of the waste aromatic-containing polymer have been observed. These advantages can lead to economic benefits in the production of hydrogenated or partially hydrogenated polymers (e.g., poly(vinylcyclohexane) (PVCH) from polystyrene polymers). Furthermore, with regard to PVCH, the resulting PVCH has high heat resistance (T g =145°C), high thermo-oxidative resistance, high resistance to polar chemicals, and / or high resistance to UV and gamma radiation.

[0007] A method for hydrogenating waste aromatic-containing polymers is described. The method can include contacting the waste aromatic-containing polymer, including the waste aromatic-containing polymer and a solvent, with an adsorbent material to produce a treated waste aromatic-containing polymer solution. The waste aromatic-containing polymer in solution can be partially or completely solubilized in the solution. In some preferred embodiments, the polymer is completely solubilized in the solution. The adsorbent can be activated carbon, silica gel, molecular sieves, or a combination thereof. The adsorbent can be dispersed, partially solubilized, or completely solubilized in the solution. In a preferred embodiment, the adsorbent is dispersed in the solution. In one preferred embodiment, the adsorbent can be activated carbon. Contact conditions can include a temperature of 20°C to 30°C, atmospheric pressure, or a combination thereof, for 8 to 30 hours, preferably 10 hours. The adsorbent can be removed by filtration. The treated aromatic-containing polymer solution can be contacted with a hydrogenation catalyst in the presence of hydrogen (H) gas under conditions sufficient to produce at least one hydrogenated and / or at least one partially hydrogenated aromatic ring (e.g., PVCH).

[0008] In some embodiments, a method for hydrogenating a waste aromatic-containing polymer may include: (a) contacting a waste aromatic-containing polymer, including the waste aromatic-containing polymer, one or more additives, and a solvent, with an adsorbent material to produce a treated waste aromatic-containing polymer solution; (b) removing the adsorbent from the produced treated waste aromatic-containing polymer solution; and (c) contacting the treated waste aromatic-containing polymer solution with a hydrogenation catalyst in the presence of hydrogen (H) gas under conditions sufficient to produce at least one hydrogenated and / or at least one partially hydrogenated aromatic ring (e.g., PVCH). Contacting the waste aromatic-containing polymer with the adsorbent removes at least one of the additives from the waste aromatic-containing polymer. Non-limiting examples of additives include co-stabilizers, anionic surfactants, nucleating agents, initiators, flame retardants, colorants, or mixtures thereof. The aromatic-containing polymer solution may include an aromatic-containing polymer, a polar solvent, and a non-polar solvent. In a preferred embodiment, the aromatic-containing polymer can be waste polystyrene, expanded polystyrene, high-density expanded polystyrene, or a blend or mixture thereof, and the hydrogenated or partially hydrogenated polymer can include poly(vinylcyclohexane). The waste aromatic-containing polymer in solution can be partially or completely solubilized in the solution. In some preferred embodiments, the polymer is completely solubilized in the solution. The adsorbent can be activated carbon, silica gel, molecular sieves, or a combination thereof. The adsorbent can be dispersed, partially solubilized, or completely solubilized in the solution. In a preferred embodiment, the adsorbent is dispersed in the solution. In one preferred embodiment, the adsorbent can be activated carbon. The contact conditions for step (a) can include a temperature of 20°C to 30°C, atmospheric pressure, or a combination thereof, for 8 to 30 hours, preferably 10 hours.

[0009] In the method of the present invention, the aromatic-containing polymer can be waste polystyrene, expanded polystyrene, high-density expanded polystyrene, or a blend or mixture thereof. The hydrogenated or partially hydrogenated polymer can include poly(vinylcyclohexane). Non-limiting examples of non-polar solvents include C5-C12 linear alkanes, C5-C12 branched alkanes, or C5-C12 cyclic alkanes, or mixtures thereof (e.g., cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or mixtures thereof). Non-limiting examples of polar solvents include dichloromethane, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or mixtures thereof. In a preferred embodiment, the non-polar solvent can be cyclohexane, and the polar solvent can be dichloromethane. The volume ratio of the non-polar solvent to the polar solvent can range from 0.1:99.9 to 99.9:0.1, preferably 1:1. In some embodiments, it has also been discovered that including too much polar solvent (e.g., greater than 30% by volume) results in diminishing returns. For example, using a ratio higher than 30% by volume may not result in a significant further increase in the hydrogenation rate. In some embodiments, the hydrogenation rate in the reaction is increased by at least 1-fold, preferably 2-fold, more preferably 2.5-fold, and even more preferably 5-fold compared to the hydrogenation rate used under the same reaction conditions without treatment with a polar solvent and / or adsorbent.

[0010] Contact conditions for hydrogenating the treated aromatic-containing polymer solution can include a temperature of 100°C to 220°C, a pressure of 3.4 MPa to 7 MPa, or a combination thereof. Under these conditions, the waste aromatic-containing polymer is completely or at least partially solubilized in the solvent. Hydrogenation of the waste aromatic-containing polymer results in a hydrogenated or partially hydrogenated polymer composition, which can be free or substantially free of polymer scission components. The concentrations of the waste aromatic-containing polymer in the polymer solution in the adsorption process and / or the hydrogenation process can be the same or different. In some embodiments, the concentration of the waste aromatic-containing polymer in the polymer solution can range from 5% by weight to 20% by weight, preferably 8% by weight. In some embodiments, the hydrogenation catalyst can include platinum (Pt), palladium (Pd), ruthenium (Ru), or any combination thereof, or an alloy thereof. The hydrogenation catalyst can include a support (e.g., silica (SiO), alumina (AlO), or titania (TiO), or any combination thereof). The hydrogenation process can be a heterogeneous catalytic hydrogenation process because the catalyst can be dispersed or suspended in a solvent.

[0011] Other embodiments of the present invention are discussed throughout this application. Any embodiment discussed with respect to one aspect of the present invention applies equally to other aspects of the present invention, and any embodiment discussed with respect to other aspects of the present invention applies equally to one aspect of the present invention. Each embodiment described herein is understood to be an embodiment of the present invention that is applicable to other aspects of the present invention. It is contemplated that any embodiment or aspect discussed herein can be combined with other forms or aspects discussed herein and / or implemented with respect to any method or composition of the present invention, and vice versa. Furthermore, the compositions of the present invention can be used to achieve the methods of the present invention.

[0012] The following contains definitions of various terms and phrases used throughout this specification.

[0013] The term "waste aromatic-containing polymer" refers to a post-consumer polymer, copolymer, or block polymer, etc., having at least one aromatic ring. "Post-consumer" can refer, for example, to a polymer that has been previously used in an article of manufacture or a previous process. The method of the present invention can efficiently and effectively recycle post-consumer polymers. Non-limiting examples of waste polymers are post-consumer polystyrene, post-consumer polymethylstyrene, and post-consumer copolymers of styrene and at least one other monomer, such as α-methylstyrene, butadiene, isoprene, acrylonitrile, methyl acrylate, methyl methacrylate, maleic anhydride, and / or an olefin (e.g., ethylene or propylene). Examples of suitable copolymers include those formed from acrylonitrile, butadiene, and styrene; copolymers of acrylic esters, styrene, and acrylonitrile; copolymers of styrene and α-methylstyrene; and copolymers of propylene, dienes, and styrene, aromatic polyethers, especially polyphenylene oxides, aromatic polycarbonates, aromatic polyesters, aromatic polyamides, polyphenylenes, polyxylylenes, polyphenylene vinylenes, polyphenylene ethynylenes, polyphenylene sulfides, polyaryl ether ketones, aromatic polysulfones, aromatic polyether sulfones, aromatic polyimides, and mixtures thereof; and optionally copolymers with aliphatic compounds. Suitable substituents in the phenyl ring include C1-C4 alkyl groups (such as methyl or ethyl), C1-C4 alkoxy groups (such as methoxy or ethoxy), and / or aromatic elements (including phenyl, biphenyl, and naphthyl) fused thereto and bonded to the phenyl ring via a carbon atom or two carbon atoms. Suitable substituents on the vinyl group include C1-C4 alkyl groups such as methyl, ethyl, n- or isopropyl, particularly methyl in the alpha position.Suitable olefinic comonomers include ethylene, propylene, isoprene, isobutylene, butadiene, cyclohexadiene, cyclohexene, cyclopentadiene, optionally substituted norbornene, optionally substituted dicyclopentadiene, optionally substituted tetracyclododecene, dihydrocyclopentadiene, derivatives of maleic acid, preferably maleic anhydride, and derivatives of acrylonitrile, preferably acrylonitrile and methacrylonitrile.

[0014] The waste aromatic-containing polymer may have a (weight average) molecular weight Mw of 1,000 to 10,000,000, preferably 60,000 to 1,000,000, most preferably 70,000 to 600,000, and particularly 100,000 to 300,000, as measured by gel permeation chromatography (GPC) equipped with light scattering, refractive index, and UV detectors.

[0015] The waste aromatic-containing polymer may have a linear structure or may have branching positions with co-units (e.g., graft copolymers). The branching centers may include star-shaped or branched polymers, or other geometric forms of primary, secondary, tertiary, or, optionally, quaternary polymer structures. The copolymer may be a random copolymer, or alternatively, a block copolymer. Block copolymers include diblock, triblock, multiblock, and star block copolymers.

[0016] The term "alkane" means a saturated hydrocarbon. Alkanes can be straight-chain, branched-chain, or cyclic.

[0017] The term "hydrogenation activity" means the rate of hydrogenation of a polymer measured in moles of aromatic rings per hour per gram of catalyst metal at a particular reaction temperature, pressure, and / or polymer concentration.

[0018] The term "nanoparticle" refers to particles that exist on the nanometer (nm) scale, with diameters between 1 nm and 1000 nm.

[0019] The term "about" or "approximately" is defined as close to what would be understood by one of ordinary skill in the art. In one non-limiting embodiment, the term is defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0020] The terms "wt. %, "vol. %, " or "mole %" refer to the weight percentage, volume percentage, or mole percentage of a component, respectively, based on the total weight, volume, or moles of a material that includes the component. In one non-limiting example, 10 grams of a component in 100 grams of a material is 10% by weight of the component.

[0021] The term "substantially" and variations thereof are defined to include within 10%, within 5%, within 1%, or within 0.5%.

[0022] The terms "inhibiting," or "reducing," or "preventing," or "avoiding," or any variations of these terms, as used in the claims and / or specification, include any measurable decrease or complete inhibition to achieve a desired result.

[0023] The term "effective," as that term is used in the specification and / or claims, means sufficient to accomplish a desired, expected, or intended result.

[0024] In the claims or specification, the use of the terms "a" or "an," when used in conjunction with any of the terms "comprising," "including," "containing," or "having," may mean "one," but is also consistent with the meanings of "one or more," "at least one," and "one or more."

[0025] The words "comprising" (and any form of "comprising", such as "comprise" and "comprises"), "having" (and any form of "having", such as "have" and "has"), "including" (and any form of "including", such as "includes" and "include"), or "containing" (and any form of "containing", such as "contains" and "contain") are inclusive or open-ended and do not exclude additional, unrecited elements or method steps.

[0026] The process of the present invention can "comprise," "consist essentially of," or "consist of" specific components, ingredients, compositions, etc., as disclosed throughout the specification. Regarding the transitional phrase "essentially comprises," in one non-limiting aspect, a fundamental and novel feature of the process of the present invention is the ability to enhance the hydrogenation rate of waste aromatic-containing polymers to produce fully hydrogenated or partially hydrogenated aromatic-containing polymers. This can be done substantially without or without any cleavage of the hydrogenated or partially hydrogenated polymers.

[0027] Other objects, features, and advantages of the present invention will become apparent from the following drawings, detailed description, and examples. It should be understood, however, that the drawings, detailed description, and examples, while indicating specific embodiments of the present invention, are given by way of illustration only and are not meant to be limiting. Moreover, it is contemplated that various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from a particular embodiment can be combined with features from other embodiments. For example, features from one embodiment can be combined with features from any of the other embodiments. In further embodiments, additional features can be added to the specific embodiments described herein. [Brief explanation of the drawings]

[0028] Advantages of the present invention will become apparent to those skilled in the art with the benefit of the following detailed description and by reference to the accompanying drawings.

[0029] [Figure 1] 1 is a diagram of a system used to produce hydrogenated or partially hydrogenated aromatic-containing polymer from waste aromatic-containing polymer. The system includes a filtration system downstream of the reactor. The reactor can be used to produce 1) a treated reactant feed containing the waste aromatic-containing polymer, and 2) a hydrogenated or partially hydrogenated aromatic-containing polymer. [Figure 2] 1 is a diagram of a system used to produce hydrogenated or partially hydrogenated aromatic-containing polymer from waste aromatic-containing polymer, the system including a dissolution unit and an adsorption unit upstream of a hydrogenation reactor.

[0030] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings, which may not be to scale. DETAILED DESCRIPTION OF THE INVENTION

[0031] At least one solution has been discovered to some of the challenges associated with the hydrogenation of waste aromatic-containing polymers. This solution can include (1) cost-effective treatment to remove impurities that are harmful to hydrogenation, and (2) a solvent system that can enhance the production yield of hydrogenated aromatic-containing polymers. The impurities can be removed by adsorption. The solvent system can include polar and non-polar solvents. Without wishing to be bound by theory, it is believed that the addition of a polar solvent enhances mass transfer between the catalyst and the polymer. The polymer can be fully or partially solubilized in the solvent containing the solution.

[0032] These and other non-limiting aspects of the present invention are discussed in further detail in the following section with reference to FIGS.

[0033] A. System for treating and hydrogenating waste aromatic-containing polymers 1 shows a schematic diagram of a process for treating and hydrogenating waste aromatic-containing polymers using the method of the present invention. System 100 can include a reactor 102 and a filtration unit 104. Reactor 102 can be configured in fluid communication with filtration unit 104.

[0034] The reactor 102 can be any reactor (e.g., a batch reactor or a continuous reactor) suitable for contacting a polymer with an adsorbent and / or conducting polymer hydrogenation. The reactor 102 can be equipped with an adsorbent as described throughout this specification. The waste aromatic-containing polymer reactant feed 106 enters the reactor 102 and can contact the adsorbent. The reactant feed can be a mixture of a solvent described in Section D and a waste aromatic-containing polymer (see Section B). In one aspect, the solvent is a mixture of dichloromethane and cyclohexane, the waste aromatic-containing polymer is waste polystyrene resin, waste expanded polystyrene, waste high-density expanded polystyrene, or a combination or blend thereof, and the adsorbent is activated carbon. In some embodiments, a dissolution unit (see, e.g., the dissolution unit in Figure 2) is in fluid communication with the reactor 102. The dissolution unit can be used to dissolve and / or densify the waste aromatic-containing polymer to produce the reactant feed 106. The weight ratio of solvent to polymer can be 4:1, 9:1, 19:1, or any range or value therebetween. The solvent can fully solubilize or at least partially solubilize the spent aromatic-containing polymer, the hydrogenated spent aromatic-containing polymer, the partially hydrogenated spent aromatic-containing polymer, or a combination thereof. In some embodiments, the adsorbent is not solubilized by the solvent. The adsorbent can be dispersed in the reactant feed using agitation. Agitation of the reactant feed / adsorbent dispersion can be carried out at atmospheric pressure and at a temperature between 20°C and 30°C (e.g., 20°C, 25°C, 30°C, or any value or range therebetween). The contact time (stirring) can be 8 to 30 hours (e.g., 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30, or any range or value therebetween).

[0035] The reactant feed / adsorbent dispersion 108 can exit the reactor 102 and enter a filtration unit 104. In the filtration unit 104, the adsorbent can be removed from the reactant feed to produce a treated reactant feed. Filtration can include centrifugation, gravitational filtration, vacuum filtration, and the like. In some embodiments, a filter aid can be used. Non-limiting examples of filter aids can include diatomaceous earth, perlite, cellulose, paper, rice husk ash, or cellulose, or any combination thereof. In one preferred embodiment, diatomaceous earth (celite) is used as the filter aid.

[0036] The treated reactant feed 110 can exit the filtration unit 104 and enter the reactor 102. In some embodiments, the treated reactant feed can enter another reactor located downstream of the filtration unit 104. The reactor 102 can include a hydrogenation catalyst. The hydrogenation catalyst can be dispersed in the reactant feed. After purging the reactor 102 with nitrogen, an H reactant feed 112 can enter the reactor. The pressure of the reactor 102 can be maintained by the H reactant feed. The concentration of the spent aromatic-containing polymer can be the same or similar to that of the spent aromatic-containing polymer during the adsorption treatment. The temperature and pressure can vary depending on the reaction being performed. The temperature can be from 100°C to about 220°C, from 120°C to 190°C, from 150°C to 180°C, 190°C, 200°C, 210°C, or 220°C, or any value or range therebetween. The H2 pressure can range from about 3.45 MPa to 7 MPa, or 3.45, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, 4.3, 4.5, 5.0, 5.5, 6.0, 6.5, 6.9, 7.0, or any range or value therebetween. The treated reactant feed can be hydrogenated to produce polymer products, including hydrogenated or partially hydrogenated spent aromatic-containing polymers. The hydrogenation activity can be at least 10 moles of aromatic rings per gram of catalyst metal (e.g., Pt, Pd, and / or Ru) per hour at a reaction temperature of 120°C to 140°C and a pressure of 7 MPa. The hydrogenation level can be at least 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100%, or any range or value therebetween. The polymer product 114 exits the reactor 102 and can be sent to other processing equipment, stored, and / or transported. The polymer product can contain at least one hydrogenated, at least one partially hydrogenated aromatic ring, or both, or a mixture thereof. For example, waste polystyrene can be hydrogenated to produce poly(vinylcyclohexane). The produced polymer product is free of low molecular weight polymers due to polymer scission.

[0037] Referring to FIG. 2 , system 200 can include a dissolution unit 202, an adsorption unit 204, and reactor 102. A waste aromatic-containing polymer and a solvent can be added to dissolution unit 202 via inlet 206. In dissolution unit 202, the waste aromatic-containing polymer can be dissolved and / or densified to produce a waste aromatic-containing polymer reactant feed 208. The dissolution temperature can be any suitable temperature (e.g., 20° C. to 60° C., preferably 30° C. to 45° C.) to facilitate dissolution of the waste aromatic-containing polymer. The waste aromatic-containing polymer reactant feed 208 can exit dissolution unit 202 and enter adsorption unit 204. Adsorption unit 204 can be any known adsorption unit (e.g., a packed column, a pressure swing unit, etc.). Adsorption unit 204 can include one or more adsorbent beds filled with one or more adsorbents. In adsorption unit 204, the solution can contact the adsorbent to produce a treated waste aromatic-containing polymer reactant feed. Treated spent aromatics-containing polymer reactant feed 210 can exit adsorption unit 204 and enter reactor 102. Treated reactant feed 210 can be of the same or similar composition as treated reactant feed 110. In reactor 102, hydrogenation of the treated spent reactant feed can be carried out as described above to produce a polymer product that can contain at least one hydrogenated, at least one partially hydrogenated aromatic ring, or both, or a mixture thereof. Polymer product 212 exits reactor 102 and can be sent to other processing equipment, stored, and / or transported. In some embodiments, reactor 102 includes a filtration unit capable of filtering the catalyst from the polymer product. In other embodiments, polymer product 212 can be subjected to a filtration unit to remove the catalyst from the polymer product.

[0038] The reactor 102 can include one or more heating and / or cooling devices (e.g., insulation, electric heaters, jacketed heat exchangers) or controllers (e.g., computers, flow valves, automated valves, etc.) that can be used to control the reaction temperature and pressure of the reaction mixture. While only one reactor is shown, it should be understood that multiple reactors can be contained in a single unit, or multiple reactors can be contained in a single reactor unit. In some embodiments, a series of physically separated reactors can be used with interstage cooling / heating devices including heat exchangers, furnaces, direct-fired heaters, etc.

[0039] B. Waste Aromatic-Containing Polymer Reactant Feed The waste aromatic-containing polymer reactant feed can include a waste aromatic-containing polymer. The waste aromatic-containing polymer can include a polymer previously used in an application or manufactured article. Non-limiting examples of waste aromatic-containing polymers include waste polystyrene, waste expanded polystyrene, waste high-density expanded polystyrene, or blends thereof. The waste expanded polystyrene can contain 1% to 5% by weight, preferably 2% by weight, of polystyrene, with the remainder being air. The densified waste expanded polystyrene (EPS) can be waste expanded polystyrene from which the air has been removed. Densification can be achieved by mechanical or thermal methods. Mechanical methods can include applying sufficient pressure to the waste EPS to break the walls of the cellular structure and squeeze out the trapped air. Thermal densification can include heating the waste EPS to a temperature sufficient to release the trapped air. Mechanical and thermal densification agents are commercially known.

[0040] The waste aromatic-containing polymer may contain additives, some of which may be harmful to the hydrogenation reaction. Non-limiting examples of additives include co-stabilizers, anionic surfactants, nucleating agents, initiators, suspending aids, flame retardants, colorants, flow modifiers, UV absorbers, impact modifiers, antioxidants, or mixtures thereof.

[0041] Non-limiting examples of co-stabilizers include ammonium persulfate.

[0042] Non-limiting examples of anionic surfactants include ammonium lauryl sulfate, ammonium laureth sulfate, triethylamine lauryl sulfate, triethylamine laureth sulfate, triethanolamine lauryl sulfate, triethanolamine laureth sulfate, monoethanolamine lauryl sulfate, monoethanolamine laureth sulfate, diethanolamine lauryl sulfate, diethanolamine laureth sulfate, lauryl monoglyceride sodium sulfate, sodium lauryl sulfate, sodium laureth sulfate, potassium lauryl sulfate, potassium laureth sulfate, sodium lauryl sarcosinate, sodium lauroyl sarcosinate, lauryl sarcosine, cocoyl sarcosine, ammonium cocoyl sulfate, ammonium lauroyl sulfate, sodium cocoyl sulfate, sodium lauroyl sulfate, potassium cocoyl sulfate, potassium lauryl sulfate, triethanolamine lauryl sulfate, triethanolamine lauryl sulfate, monoethanolamine cocoyl sulfate, monoethanolamine lauryl sulfate, sodium tridecylbenzenesulfonate, sodium dodecylbenzenesulfonate, sodium cocoyl isethionate, and combinations thereof.

[0043] Non-limiting examples of nucleating agents include synthetic waxes, such as fully saturated homopolymers of ethylene, which have a high degree of linearity and crystallinity and can be referred to as polywaxes (e.g., Polywax 100, Polywax 500, Polywax 1000, etc.).

[0044] Non-limiting examples of initiators include benzoyl peroxide or tert-butyl peroxybenzoate, substituted or unsubstituted dibenzoyl peroxide, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, 2,2-di(tert-butylperoxy)butane, 1,1-di(tert-butylperoxy)cyclohexane, dicetyl peroxydicarbonate, dimyristyl peroxydicarbonate, 1,1,3,3-tetramethylbutyl peroxypivalate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5-trimethylbutylperoxy)pyrrolate, tert-butyl peroxyneodecanoate, tert-amyl peroxypivalate, tert-butyl peroxypivalate, di(3,5,5-trimethylbutylperoxy)pyrrolate, tert-butyl peroxypyrrolate, di(3,5,5-trimethylbutylperoxy) ... trimethylhexanoyl)peroxide, dilauroyl peroxide, didecanoyl peroxide, 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2-methylbutyronitrile), 2,5-dimethyl-2,5-di(2-ethylhexanoylperoxy)hexane, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-amylperoxy-2-ethylhexanoate, tert-butylperoxy-2-ethylhexanoate, tert-butylperoxydiethylacetate, tert-butylperoxyisobutyrate, and combinations of one or more of these initiators.

[0045] Examples of suspending aids include tricalcium phosphate, sodium dodecylbenzenesulfonate, hydroxyapatite, magnesium phosphate, or combinations thereof.

[0046] Non-limiting examples of flame retardants include organohalogen compounds such as hexabromocyclododecane, brominated styrene polymers such as styrene-butadiene copolymers, and derivatives of tetrabromobisphenol A tribromophenyl aryl ether. Common flame retardants include tetrabromobisphenol A bis(2,3-dibromo-2-methylpropyl ether) or hexabromocyclodecane.

[0047] Non-limiting examples of colorants include organic or inorganic pigments, dyes, or mixtures thereof, or combinations thereof. Non-limiting examples of inorganic pigments or dyes include metal oxides, iron oxide or titanium dioxide, strontium chromate or barium sulfate, aluminum flakes or particles, carbon black, talc, etc. Non-limiting examples of organic pigments or dyes are perylenes, phthalocyanine derivatives (e.g., copper phthalocyanine), indanthrones, benzimidazolones, quinacridones, perinones, azomethines, derivatives, fluorescent organic compounds, or mixtures thereof.

[0048] Non-limiting examples of antioxidants include sterically hindered phenolic compounds, aromatic amines, phosphite compounds, carbon black, etc. Non-limiting examples of phenolic antioxidants include 2,6-di-tert-butyl-4-methylphenol (CAS No. 128-37-0), pentaerythritol-tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (CAS No. 6683-19-8), octadecyl 3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 2082-79-3), 1,3,5-trimethyl-2,4,6-tris(3,5-di-t tert-butyl-4-hydroxybenzyl)benzene (CAS No. 1709-70-2), 2,2'-thiodiethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS No. 41484-35-9), calcium bis(ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate) (CAS No. 65140-91-2), 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)isocyanurate (CAS No. 276 76-62-6), 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (CAS number 40601-76-1), 3,3-bis(3-tert-butyl-4-hydroxyphenyl)ethylene butyrate (CAS number 32509-66-3), 4,4'-thiobis(2-tert-butyl-5-methylphenol) (CAS number 96-69-5), 2,2'-methylenebis(6-(1-methyl Cyclohexyl)-p-cresol) (CAS number 77-62-3), 3,3'-bis(3,5-di-tert-butyl-4-hydroxyphenyl)-N,N'-hexamethylenedipropionamide (CAS number 23128-74-7), 2,5,7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl)chroman-6-ol (CAS number 10191-41-0), 2,2-ethylidenebis(4,6-di-tert-butylphenol) (CAS number 35958-30-6), 1,1,3-Tris(2-methyl-4-hydroxy-5'-tert-butylphenyl)butane (CAS number 1843-03-4), 3,9-bis(1,1-dimethyl-2-(β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy)ethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (CAS number 90498-90-1); 1,6-Hexanediyl-bis(3,5-bis(1,1-dimethylethyl)-4-hydroxybenzene)propanoate (CAS number 35074-77-2), 2,6-di-tert-butyl-4 -nonylphenol (CAS No. 4306-88-1), 4,4'-butylindenebis(6-tert-butyl-3-methylphenol) (CAS No. 85-60-9); 2,2'-methylenebis(6-tert-butyl-methylphenol) (CAS No. 119-47-1), triethylene glycol-bis-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (CAS No. 36443-68-2), 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionic acid (CAS No. 171090-93-0), C, 13 ~C 15 Mixture of linear and branched alkyl esters, 2,2'-thiobis(6-tert-butyl-para-cresol) (CAS No. 90-66-4), diethyl-(3,5-di-tert-butyl-4-hydroxybenzyl)phosphate (CAS No. 976-56-7), 4,6-bis(octylthiomethyl)-orthocresol (CAS No. 110553-27-0), benzenepropanoic acid, octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (CAS No. 125643-61-0), 1,1,3-tris[2-methyl-4-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxy]-5-tert-butylphenyl]butane (CAS number 180002-86-2), mixed styrenated phenol (CAS number 61788-44-1), butylated and octylated phenol (CAS number 68610-06-0), and butylated reaction products of p-cresol and dicyclopentadiene (CAS number 68610-51-5).

[0049] Non-limiting examples of phosphite antioxidants include one of tris(2,4-di-tert-butylphenyl)phosphite (CAS No. 31570-04-4), tris(2,4-di-tert-butylphenyl)phosphate (CAS No. 95906-11-9), bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (CAS No. 26741-53-7), tetrakis(2,4-di-butylphenyl)-4,4′-biphenylene diphosphonite (CAS No. 119345-01-6), and bis(2,4-dicumylphenyl)pentaerythritol diphosphite (CAS No. 154862-43-8).

[0050] Non-limiting examples of UV stabilizers include hindered amine light stabilizers, hydroxybenzophenones, hydroxyphenylbenzotriazoles, cyanoacrylates, oxanilides, hydroxyphenyltriazines, and combinations thereof. Non-limiting examples of hindered amine light stabilizers include dimethyl succinate polymers with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (CAS No. 65447-77-0); poly[[6-((1,1,3,3-tetramethylbutyl)amino)-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexyl sameethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]] (CAS No. 70624-18-9); and 1,5,8,12-tetrakis[4,6-bis(N-butyl-N-1,2,2,6,6-pentamethyl-4-piperidylamino)-1,3,5-triazin-2-yl]-1,5,8,12-tetraazadodecane (CAS No. 106990-43-6).

[0051] Non-limiting examples of heat stabilizers include phenothiazine, p-methoxyphenol, cresol, benzhydrol, 2-methoxy-p-hydroquinone, 2,5-di-tert-butylquinoline, diisopropylamine, and distearyl thiodipropionate (CAS No. 693-36-7).

[0052] C. Adsorbents The adsorbent can be activated carbon, silica gel, molecular sieves, or a combination thereof. In a preferred embodiment, the adsorbent can be activated carbon. Generally, the ratio of adsorbent to waste aromatic-containing polymer can be 1:2 to 1:20, or 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19, 1:20, or any range or value therebetween. In some embodiments, the ratio of adsorbent to waste aromatic-containing polymer can be 1:2 to 1:6, preferably 1:4.

[0053] D. Solvent The solvent can include polar and / or nonpolar solvents. Non-limiting examples of polar solvents include dichloromethane, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or blends thereof. Non-polar solvents can include C5-C12 linear alkanes, C5-C12 branched alkanes, or C5-C12 cyclic alkanes, or blends thereof. Non-limiting examples of non-polar solvents can include cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or mixtures thereof. The volume ratio of the non-polar solvent to the polar solvent can be 0.1:99.9 to 99.9:0.1. Non-limiting examples of volume ratios include 1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, 10:1, 15:1, 20:1, or any value or range therebetween. The solvent can include any mixture of non-polar and polar solvents, so long as the volume ratio of non-polar solvent to polar solvent is maintained. Non-limiting examples of solvents include a mixture of dichloromethane and cyclopentane, a mixture of dichloromethane and cyclohexane, a mixture of dichloromethane and methylcyclohexane, a mixture of dichloromethane and ethylcyclohexane, a mixture of dichloromethane and cyclooctane, a mixture of dichloromethane and cycloheptane, a mixture of dichloromethane and dodecane, a mixture of dichloromethane and isopentane, or a mixture of dichloromethane and decahydronaphthalene.In another example, the solvent system can include a mixture of 1,2-dichloroethane and cyclopentane, a mixture of 1,2-dichloroethane and cyclohexane, a mixture of 1,2-dichloroethane and methylcyclohexane, a mixture of 1,2-dichloroethane and ethylcyclohexane, a mixture of 1,2-dichloroethane and cyclooctane, a mixture of 1,2-dichloroethane and cycloheptane, a mixture of 1,2-dichloroethane and dodecane, a mixture of 1,2-dichloroethane and isopentane, or a mixture of 1,2-dichloroethane and decahydronaphthalene. In another example, the solvent system can include a mixture of tetrahydrofuran (THF) and cyclopentane, a mixture of THF and cyclohexane, a mixture of THF and methylcyclohexane, a mixture of THF and ethylcyclohexane, a mixture of THF and cyclooctane, a mixture of THF and cycloheptane, a mixture of THF and dodecane, a mixture of THF and isopentane, or a mixture of THF and decahydronaphthalene. In yet another example, the solvent system may include a mixture of methyltetrahydrofuran (MTHF) and cyclopentane, a mixture of MTHF and cyclohexane, a mixture of MTHF and methylcyclohexane, a mixture of MTHF and ethylcyclohexane, a mixture of MTHF and cyclooctane, a mixture of MTHF and cycloheptane, a mixture of MTHF and dodecane, a mixture of MTHF and isopentane, or a mixture of MTHF and decahydronaphthalene. Other solvent combinations (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, etc.) are also within the scope of the present invention. The use of the adsorbents and solvents of the present invention can increase the hydrogenation reaction rate by 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, or more times compared to the hydrogenation reaction rate of the same reaction using untreated waste aromatic-containing polymer and a nonpolar solvent. The solvent system of the present invention can completely solubilize or at least partially solubilize waste aromatic-containing polymer, hydrogenated aromatic-containing polymer, partially hydrogenated aromatic-containing polymer, or a combination thereof.Generally, the waste polymer concentration in the solvent system of the present invention can be 5% to 20% by weight, or 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20% by weight, or any range or value therebetween. The waste polymer concentration can be the same or different between the adsorption and hydrogenation steps.

[0054] E. Catalyst The catalyst of the present invention can include commercially available catalysts capable of catalyzing the hydrogenation of aromatic-containing polymers. Non-limiting examples of catalysts include Sigma-Aldrich® (USA), Unicat (USA), BASF (Germany), Johnson Matthey (UK), Evonik (Germany), Clariant (Switzerland), etc. The catalyst can include one or more catalytic metals. In some aspects, the catalyst can include platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rd), or any combination thereof. In some embodiments, the catalyst is a bimetallic or trimetallic catalyst. Bimetallic catalysts include Pt, Pd, Ru, and / or Rd in combination with nickel (Ni), iridium (Ir), iron (Fe), copper (Cu), and / or silver (Ag) metals, or combinations thereof. The catalyst can be supported or unsupported. Non-limiting examples of supports include silica (SiO), alumina (AlO), or titania (TiO), or any combination thereof. In some embodiments, the catalyst is a Pt / AlO, Pt / SiO, or Pt / AlO catalyst. The total weight percent of metal in the supported catalyst can range from 40 wt% to 50 wt%, or 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45 wt%, 46 wt%, 47 wt%, 48 wt%, 49 wt%, or 50 wt%.

[0055] In one embodiment, the catalyst can include, based on the total weight of the catalyst, 0.05 wt% to 0.9 wt% Pt nanoparticles and 99.1 wt% to 99.95 wt% TiO, 0.20 wt% to 0.60 wt% Pt nanoparticles and 99.4 wt% to 99.8 wt% TiO, or 0.25 wt% to 0.50 wt% Pt nanoparticles and 99.5 wt% to 99.75 wt% TiO. 3 / g~0.35cm 3 / g, preferably 0.03 cm 3 / g~0.30cm 3 / g, more preferably 0.05 cm 3 / g~0.25cm 3 / g pore volume, 5m 2 / g~80m 2 / g, preferably 5m 2 / g~40m 2 / g, more preferably 5m 2 / g~20m 2 / g and / or a median pore diameter of less than 300 micrometers, preferably less than 100 microns.

[0056] In one embodiment, the catalyst can include, based on the total weight of the catalyst, 0.05 wt% to 0.9 wt% Pt nanoparticles and 99.1 wt% to 99.95 wt% SiO2, 0.20 wt% to 0.60 wt% Pt nanoparticles and 99.4 wt% to 99.8 wt% SiO2, or 0.25 wt% to 0.50 wt% Pt nanoparticles and 99.5 wt% to 99.75 wt% SiO2. 3 / g~0.35cm 3 / g, preferably 0.03 cm 3 / g~0.30cm 3 / g, more preferably 0.05 cm 3 / g~0.25cm 3 / g pore volume, 5m 2 / g~80m 2 / g, preferably 5m 2 / g~40m 2 / g, more preferably 5m 2 / g~20m 2 / g and / or a median pore diameter of less than 300 microns, preferably less than 100 microns.

[0057] In one embodiment, the catalyst can include, based on the total weight of the catalyst, 0.05 wt% to 0.9 wt% Pt nanoparticles and 99.1 wt% to 99.95 wt% Al2O3, 0.20 wt% to 0.60 wt% Pt nanoparticles and 99.4 wt% to 99.8 wt% Al2O3, or 0.25 wt% to 0.50 wt% Pt nanoparticles and 99.5 wt% to 99.75 wt% Al2O3. 3 / g~0.35cm 3 / g, preferably 0.03 cm 3 / g~0.30cm 3 / g, more preferably 0.05 cm 3 / g~0.25cm 3 / g pore volume, 5m 2 / g~80m 2 / g, preferably 5m 2 / g~40m 2 / g, more preferably 5m 2 / g~20m 2 / g and / or a median pore diameter of less than 300 micrometers, preferably less than 100 microns.

[0058] Example The present invention will now be described in further detail by way of specific examples. The following examples are provided for illustrative purposes only and are not intended to limit the present invention in any manner. Those skilled in the art will readily recognize a variety of non-critical parameters that can be changed or modified to achieve substantially the same results.

[0059] Example 1 (Treatment of polymer solution containing waste aromatic polymer) High-density expanded polystyrene beads (2 g, Big Joe®, Grand Rapids, MI) were dissolved in a 1:1 mixture of dichloromethane and cyclohexane (31.63 g) to prepare a polymer solution (6 wt %). Activated carbon (0.5 g) was added to the solution, which was stirred overnight and filtered through Celite to produce a treated polymer solution.

[0060] Example 2 (Hydrogenation of Treated Polymer Solution) A Pt / Al2O3 catalyst (0.45 wt% Pt, 0.2 g) prepared according to Wu et al. in International Publication No. 2022 / 013751 was placed in a stainless steel reactor (Parr Series 5000 Multiple Reactor System, Parr Instrument Company, 100 mL) along with the treated polymer solution (30 mL total). The reactor was first purged five times with N2, then five times with H2 to remove air and moisture, and then charged with high-pressure H2 to 1000 psi (6.9 MPa). After reaching the desired pressure, the reactor contents were heated at a rate of 3 °C / min to a set temperature of 120 °C and maintained at the final set temperature for several hours. After the reaction was complete, the reactor was cooled to room temperature, the pressure was reduced to atmospheric pressure (101 kPa), the reactor contents were recovered, and the solid catalyst was separated from the polymer solution using centrifugation or filtration. 25% conversion was observed after 0.64 h, 50% conversion after 0.76 h, 75% conversion after 0.9 h, and maximum conversion (100%) was achieved at 1.16 h.

[0061] Example 3 Comparative Example - Hydrogenation of Untreated EPS Beads The procedure of Example 1 was followed, except that the temperature was increased to 140° C. and cyclohexane was used as the solvent (i.e., no polar solvent was used). Conversion only reached 20% after 10.75 hours, with a maximum conversion of 35%.

[0062] As shown in the examples, the process of the present invention provides a methodology that can maximize the conversion of waste aromatic-containing polymers into useful polymer products, including poly(vinylcyclohexane).

[0063] Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions, and alterations can be made herein without departing from the spirit and scope of the embodiments, as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the processes, machines, manufacture, compositions of matter, means, methods, and steps described in the specification. As one skilled in the art will readily appreciate from the foregoing disclosure, presently existing or hereafter developed processes, machines, manufacture, compositions of matter, means, methods, or steps can be utilized that perform substantially the same function or achieve substantially the same results as those corresponding to the embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims

1. A method for hydrogenating waste aromatic polymers, wherein the method is: (a) A treated waste aroma-containing polymer solution is produced by contacting a waste aroma-containing polymer, one or more additives, and a solvent with an adsorbent material. (b) Removing the adsorbent from the manufactured treated waste aromatic polymer solution, (c) Hydrogen (H) under conditions sufficient to produce at least one hydrogenation and / or at least one partially hydrogenated aromatic ring ２ This includes contacting the treated waste aromatic-containing polymer solution with a hydrogenation catalyst in the presence of a gas, The method wherein at least one additive is removed from the treated waste aromatic polymer solution, and the one or more additives include a co-stabilizer, anionic surfactant, nucleating agent, initiator, flame retardant, colorant, or a mixture thereof.

2. The method according to claim 1, wherein the waste aromatic-containing polymer comprises waste polystyrene, waste expanded polystyrene, waste high-density expanded polystyrene, or a blend thereof, and the hydrogenated or partially hydrogenated polymer comprises poly(vinylcyclohexane).

3. The method according to claim 1, wherein the adsorbent is activated carbon, silica gel, molecular sieve, or a combination thereof, preferably activated carbon.

4. The method according to any one of claims 1 to 3, wherein the solvent comprises a polar solvent, a nonpolar solvent, or a mixture thereof.

5. The method according to claim 4, wherein the nonpolar solvent is a C5-C12 straight chain, branched chain, or cyclic alkane, or a mixture thereof.

6. The method according to any one of claims 1 to 3, wherein the solvent is cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, cyclopentane, decahydronaphthalene, or a mixture thereof.

7. The method according to claim 4, wherein the polar solvent is dichloromethane, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or a mixture thereof.

8. The method according to claim 4, wherein the nonpolar solvent is cyclohexane and the polar solvent is dichloromethane.

9. The method according to claim 4, wherein the volume ratio of the nonpolar solvent to the polar solvent is 0.1:99.9 to 99.9:0.1, preferably 1:

1.

10. The method according to any one of claims 1 to 3, wherein the contact conditions of step (a) include a temperature of 20°C to 30°C, atmospheric pressure, or a combination thereof, and a duration of 8 to 30 hours, preferably 10 hours.

11. The method according to any one of claims 1 to 3, wherein the contact conditions of step (c) include a temperature of 100°C to 220°C, a pressure of 3.4 MPa to 6.9 MPa, or a combination thereof.

12. The hydrogenation catalyst comprises platinum (Pt), palladium (Pd), ruthenium (Ru), or any combination thereof, or an alloy thereof, on a support, wherein the support is silica (SiO ２ ), alumina (Al ２ O ３ ), or titania (TiO ２ The method according to any one of claims 1 to 3, including, or any combination thereof.

13. The method according to any one of claims 1 to 3, wherein the concentration of the waste aromatic-containing polymer in the polymer solution in step (a), step (b), or both is 5% to 20% by weight, preferably 8% by weight.

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