Process for producing polyvinyl cyclohexane via hydrogenation of waste polystyrene source

Abstract

A process for the hydrogenation of spent aromatic-containing polymers is described. In some embodiments, a method may include contacting a polymer solution including a spent aromatic polymer with an adsorbent to produce a treated polymer solution including a spent aromatic polymer. Hydrogenation of the treated spent aromatic polymer-containing solution produces a polymer composition comprising at least one hydrogenated and / or at least one partially hydrogenated aromatic ring.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of European Patent Application No. 22196383 filed on September 19, 2022. The entire contents of the above disclosure are specifically incorporated herein by reference. Technical Field

[0003] The present invention generally relates to a process for hydrogenating waste aromatic-containing polymers. The waste aromatic-containing polymers may include polystyrene, expanded polystyrene, or a combination thereof. Background Art

[0004] Plastic materials are used in a variety of materials (e.g., electronics, furniture, food packaging, commercial products, vehicle products, aircraft products, housing products, insulation materials, etc.) due to their light weight, adjustable properties, and ability to be formed / molded. However, durability makes plastics an increasingly serious environmental problem. To address this problem, methods for recycling plastics have been studied. However, these methods suffer from economic feasibility (e.g., poor market demand and low-end uses) and / or cannot produce recycled polymers with the same properties as new / original polymers (e.g., mechanical properties, physical properties, etc.). In order to compensate for the inferior properties, recycled polymers are typically blended with new polymers at a ratio that rarely exceeds 20%, even for less stringent applications. In order to address the polymer recycling problem, Cote's International Application Publication No. WO2016049782 and Vollmer et al. (Angewandte Chemie. Int. Ed. 2020, 59, 15402-15423) both describe a dissolution / precipitation method for separating a 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 the pyrolysis of waste expanded polystyrene and then hydrogenation of the pyrolyzed polystyrene to produce fuel oil. Japanese Patent Application Publication No. 2009013235A by Motoyama et al. describes a method for preparing alicyclic polymers. The method includes hydrogenating aromatic rings of aromatic polymers using a metal fine particle catalyst containing at least one metal selected from ruthenium, rhodium, palladium, platinum, nickel and cobalt in the presence of an organic solvent.

[0005] Although solution-based processes for recycling waste polymers are known, challenges remain in increasing cost-effectiveness, maintaining virgin polymer properties, and / or producing desired end products. Summary of the invention

[0006] Solutions to at least one or more problems associated with the hydrogenation of waste aromatic polymers have been discovered and provided. In one aspect, a method is disclosed that may include contacting a waste aromatic polymer solution with an adsorbent to produce a treated waste polymer solution. The treated waste aromatic polymer solution may be hydrogenated under conditions sufficient to produce a polymer composition that may include a hydrogenated or partially hydrogenated polymer (e.g., a polystyrene-based polymer to poly(vinylcyclohexane) (PVCH). In the context of the present invention, the waste aromatic polymer may include polystyrene, expanded polystyrene and / or densified expanded polystyrene, or any combination or blend thereof. An advantage of using the method of the present invention is that additives that are detrimental to the hydrogenation conditions (e.g., stabilizers, anionic surfactants, nucleating agents, initiators, flame retardants, colorants, or mixtures thereof) may be removed. The present invention Another advantage of the process 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 solution before hydrogenation, greater than 50% conversion of the waste aromatic-containing polymer can be observed. These advantages can lead to economic advantages in producing hydrogenated or partially hydrogenated polymers (e.g., polystyrenic polymers to poly(vinylcyclohexane) (PVCH)). Furthermore, in the case of PVCH, the resulting PVCH can be a fully aliphatic amorphous polymer with high heat resistance (Tg=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 polymers is described. One method may include contacting a waste aromatic polymer solution including waste aromatic polymers and a solvent with an adsorbent material to produce a treated waste aromatic polymer solution. The waste aromatic polymer in the solution may be partially or completely dissolved in the solution. In some preferred aspects, the polymer is completely dissolved in the solution. The adsorbent may be activated carbon, silica gel, molecular sieves, or a combination thereof. The adsorbent may be dispersed in the solution, partially dissolved in the solution, or completely dissolved in the solution. In a preferred embodiment, the adsorbent is dispersed in the solution. In a preferred aspect, the adsorbent may be activated carbon. The contact conditions may 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 may be removed by filtration. The treated aromatic polymer solution may be heated in a hydrogen atmosphere (H 2 ) gas under conditions sufficient to produce a polymer composition that can include at least one hydrogenated and / or at least one partially hydrogenated aromatic ring (e.g., PVCH).

[0008] In some aspects, a method for hydrogenating spent aromatic polymers may include (a) contacting a spent aromatic polymer solution including spent aromatic polymers, one or more additives, and a solvent with an adsorbent material to produce a treated spent aromatic polymer solution, (b) removing the adsorbent from the produced treated spent aromatic polymer solution, and (c) hydrogenating the spent aromatic polymer in the presence of hydrogen (H). 2 ) gas, under conditions sufficient to produce a polymer composition that can include at least one hydrogenated and / or at least one partially hydrogenated aromatic ring (e.g., PVCH), the treated waste aromatic polymer solution is contacted with a hydrogenation catalyst. Contacting the waste aromatic polymer solution with an adsorbent removes at least one of the additives from the waste aromatic polymer solution. Non-limiting examples of additives include stabilizers, anionic surfactants, nucleating agents, initiators, flame retardants, colorants, or mixtures thereof. The aromatic polymer solution may include aromatic polymers, polar solvents, and non-polar solvents. In preferred aspects, the aromatic polymer may be waste polystyrene, expanded polystyrene, densified expanded polystyrene, or blends or mixtures thereof, and the hydrogenated or partially hydrogenated polymer may include poly(vinyl cyclohexane). The waste aromatic polymer in the solution may be partially or completely dissolved in the solution. In some preferred aspects, the polymer is completely dissolved in the solution. The adsorbent may be activated carbon, silica gel, molecular sieves, or a combination thereof. The adsorbent may be dispersed in the solution, partially dissolved in the solution, or completely dissolved in the solution. In a preferred embodiment, the adsorbent is dispersed in the solution. In a preferred aspect, the adsorbent may be activated carbon. The contacting conditions of step (a) may 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 polymer can be waste polystyrene, expanded polystyrene, densified expanded polystyrene, or their blends or mixtures, and hydrogenated or partially hydrogenated polymers can include poly (vinyl cyclohexane). Non-limiting examples of non-polar solvents can include C5-C12 straight chain alkanes, C5-C12 branched alkanes or C5-C12 cyclic alkanes, or their mixtures (for example, cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or their mixtures). Non-limiting examples of polar solvents can include dichloromethane, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or their mixtures. In preferred aspects, non-polar solvents can be cyclohexane, and polar solvents can be dichloromethane. The volume ratio of non-polar solvent to polar solvent can be in the range of 0.1:99.9 to 99.9:0.1, preferably 1:1. In some aspects, it has also been found that including too much polar solvent (e.g., above 30% by volume) results in diminishing returns. For example, using above 30% by volume may not result in a further significant increase in the hydrogenation rate. In some aspects, the hydrogenation rate of the reaction is increased by at least 1 times, preferably 2 times, more preferably 2.5 times, or even more preferably 5 times, compared to the hydrogenation rate of the reaction without the polar solvent and / or treated with the adsorbent under the same reaction conditions.

[0010] The contact conditions for hydrogenation of the treated aromatic polymer-containing solution may 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 polymer may be completely dissolved or at least partially dissolved in the solvent. The hydrogenation of the waste aromatic polymer results in a hydrogenated or partially hydrogenated polymer composition, which may be free of or substantially free of a polymer cleavage composition. During the adsorption process and / or the hydrogenation process, the concentration of the waste aromatic polymer in the polymer solution may be the same or different. In some aspects, the concentration of the waste aromatic polymer in the polymer solution may be in the range of 5 wt % to 20 wt %, preferably 8 wt %. In some aspects, the hydrogenation catalyst may include platinum (Pt), palladium (Pd), ruthenium (Ru), or any combination thereof, or an alloy thereof. The hydrogenation catalyst may include a carrier (e.g., silica (SiO 2 ), aluminum oxide (Al 2 O 3 ) or titanium dioxide (TiO 2 ), or any combination thereof). The hydrogenation process may be a heterogeneous catalytic hydrogenation process, since the catalyst may be dispersed or suspended in a solvent.

[0011] Other embodiments of the present invention are discussed throughout the application. Any embodiment discussed about one aspect of the present invention is also applicable to other aspects of the present invention, and vice versa. Each embodiment described herein is understood to be an embodiment of the present invention applicable to other aspects of the present invention. It is expected that any embodiment or aspect discussed herein can be combined with other embodiments or aspects discussed herein and / or implemented about any method or composition of the present invention, and vice versa. In addition, composition of the present invention can be used to realize method of the present invention.

[0012] Included below are definitions of various terms and phrases used throughout this specification.

[0013] The term "waste aromatic-containing polymer" refers to a used polymer, a used copolymer, a used block polymer, etc., having at least one aromatic ring. Used can refer to a polymer that has been previously used, for example, in a manufactured article or in a previous process. The process of the present invention can efficiently and effectively recycle used polymers. Non-limiting examples of waste polymers are used polystyrene, used polymethylstyrene, and copolymers of used styrene and at least one other monomer, such as alpha-methylstyrene, butadiene, isoprene, acrylonitrile, methyl acrylate, methyl methacrylate, maleic anhydride and / or olefins (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, diene and styrene, aromatic polyethers, in particular polyphenylene (oxy) ethers, aromatic polycarbonates, aromatic polyesters, aromatic polyamides, polyphenylenes, polyxylenes, polyphenylene vinylenes, polyphenylene ethynylenes, polyphenylene sulfides, polyaryletherketones, aromatic polysulfones, aromatic polyethersulfones, 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 entities fused thereto and bonded to the phenyl ring via a carbon atom or via two carbon atoms, including phenyl, biphenyl and naphthyl. Suitable substituents on the vinyl group include C1-C4 alkyl groups, such as methyl, ethyl or n-propyl or isopropyl, especially methyl in the α-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 of 1000 to 10,000,000, preferably 60,000 to 1,000,000, most preferably 70,000 to 600,000, especially 100,000 to 300,000, as determined 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 sites due to co-units (e.g., graft copolymers). The branching centers may include star or branched polymers, or may include other geometric forms of primary, secondary, tertiary, or optionally quaternary polymer structures. The copolymers may be random copolymers or block copolymers. Block copolymers include diblock, triblock, multiblock, and star block copolymers.

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

[0017] The phrase "hydrogenation activity" refers to the measured rate of polymer hydrogenation in units of moles of aromatic rings per gram of catalytic metal per hour at a specific reaction temperature, pressure, and / or polymer concentration.

[0018] The term "nanoparticle" means a particle existing on a nanometer (nm) scale and having a diameter of 1 nm to 1000 nm.

[0019] The term "about" or "approximately" is defined as close as understood by one of ordinary skill in the art. In a 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 "weight %", "volume %" or "mole %" refer to the weight percentage of a component, the volume percentage of a component or the mole percentage of a component based on the total weight, total volume or total moles of the material including the component, respectively. In a non-limiting example, 10 grams of a component in 100 grams of material is 10 weight % of the component.

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

[0022] When used in the claims and / or specification, the terms "inhibit" or "reduce" or "prevent" or "avoid" or any variation of these terms includes any measurable reduction or complete inhibition to achieve the desired result.

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

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

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

[0026] The methods of the present invention may "comprise," "consist essentially of," or "consist of" the specific ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transition phrase "consisting essentially of," in one non-limiting aspect, a fundamental and novel feature of the methods of the present invention is their ability to increase the rate of hydrogenation of waste aromatic-containing polymers to produce fully hydrogenated or partially hydrogenated aromatic-containing polymers. This can be accomplished with substantially no or no polymer cleavage of the hydrogenated or partially hydrogenated polymers.

[0027] From the following drawings, specific embodiments and examples, other objects, features and advantages of the present invention will become apparent. However, it should be understood that although the drawings, specific embodiments and examples indicate specific embodiments of the present invention, they are only provided by way of illustration and are not intended to be limiting. In addition, it is expected that those skilled in the art will be aware of changes and modifications in the spirit and scope of the present invention from the specific embodiments. In other embodiments, features from specific embodiments can be combined with features from other embodiments. For example, features from an embodiment can be combined with features from any other embodiment. In other embodiments, additional features can be added to the specific embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 1Schematic representation of a system for producing hydrogenated or partially hydrogenated aromatic-containing polymers from waste aromatic-containing polymers. The system includes a filtration system downstream of a reactor. The reactor can be used to produce 1) a treated reactant feed including waste aromatic-containing polymers and 2) hydrogenated or partially hydrogenated aromatic-containing polymers.

[0030] Figure 2 Schematic diagram of a system for producing hydrogenated or partially hydrogenated aromatic polymers from waste aromatic polymers. The system includes a dissolution unit and an adsorption unit upstream of a hydrogenation reactor.

[0031] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be drawn to scale. DETAILED DESCRIPTION

[0032] At least one solution to some of the problems associated with hydrogenating spent aromatic-containing polymers has been discovered. The solution may include (1) a cost-effective process to remove impurities that are detrimental to hydrogenation, and (2) a solvent system that can improve the production of hydrogenated aromatic-containing polymers. Impurities may be removed by adsorption. The solvent system may include polar solvents and non-polar solvents. Without wishing to be bound by theory, it is believed that the addition of a polar solvent improves mass transfer between the catalyst and the polymer. The polymer may be fully or partially dissolved in the solvent-containing solution.

[0033] These and other non-limiting aspects of the present invention will be referred to in the following sections. Figure 1 and Figure 2 Discuss in more detail.

[0034] A. System for treating and hydrogenating spent aromatic polymers

[0035] Figure 1 A schematic diagram of a method for treating and hydrogenating waste aromatic polymers using the methods of the present invention is depicted. System 100 may include reactor 102 and filtration unit 104. Reactor 102 may be configured to be in fluid communication with filtration unit 104.

[0036] Reactor 102 can be any reactor suitable for contacting a polymer with an adsorbent and / or performing polymer hydrogenation (e.g., a batch reactor or a continuous reactor). Reactor 102 can include an adsorbent as described throughout the specification. A waste aromatic polymer reactant feed 106 can enter reactor 102 and contact the adsorbent. The reactant feed can be a mixture of a solvent described in Section D and waste aromatic polymers (see Section B). In one aspect, the solvent is a mixture of methylene chloride and cyclohexane, the waste aromatic polymer is waste polystyrene resin, waste expanded polystyrene, waste densified expanded polystyrene, or a combination or blend thereof, and the adsorbent is activated (wood) charcoal. In some embodiments, the dissolution unit (see, e.g., Figure 2 The dissolution unit in the reactor 102 is fluidically connected to the reactor 102. The dissolution unit can be used to dissolve and / or densify the waste aromatic polymer and produce the reactant feed 106. The mass ratio of the solvent to the polymer can be 4: 1, 9: 1, 19: 1 or any range or value therebetween. The solvent can completely dissolve or at least partially dissolve the waste aromatic polymer, the hydrogenated waste aromatic polymer, the partially hydrogenated waste aromatic polymer, or a combination thereof. In some aspects, the adsorbent is not dissolved by the solvent. The adsorbent can be dispersed in the reactant feed using stirring. The stirring of the reactant feed / adsorbent dispersion can be carried out at a temperature of 20° C. to 30° C. (e.g., 20° C., 25° C., 30° C. or any value or range therebetween) at atmospheric pressure. The contact time (agitation) 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).

[0037] Reactant feed / sorbent dispersion 108 can leave reactor 102 and enter filtration unit 104. In filtration unit 104, sorbent can be removed from reactant feed to produce treated reactant feed. Filtration can include centrifugation, gravity filtration, vacuum filtration, etc. In some aspects, filter aids can be used. Non-limiting examples of filter aids include diatomaceous earth, perlite, cellulose, paper, rice husk ash or cellulose, or any combination thereof. In a preferred aspect, diatomaceous earth (celite) is used as a filter aid.

[0038] The treated reactant feed 110 may exit the filtration unit 104 and enter the reactor 102. In some embodiments, the treated reactant feed may enter a different reactor located downstream of the filtration unit 104. The reactor 102 may include a hydrogenation catalyst. The hydrogenation catalyst may be dispersed in the reactant feed. After purging the reactor 102 with nitrogen, the hydrogenation catalyst may be dispersed in the reactor 102. 2Reactant feed 112 may enter the reactor. The pressure of the reactor 102 may be determined by H 2 The concentration of the spent aromatic polymer may be the same or similar to the concentration of the spent aromatic polymer during the adsorbent treatment. The temperature and pressure may vary depending on the reaction to be performed. The temperature may range from 100°C to about 220°C, 120°C to 190°C, 150°C to 180°C, 190°C, 200°C, 210°C or 220°C, or any value or range therebetween. 2 The pressure range may be 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. Hydrogenation of the treated reactant feed may produce a polymer product comprising hydrogenated or partially hydrogenated spent aromatic polymer. The hydrogenation activity may be at least 10 moles of aromatic rings per hour per gram of catalytic metal (e.g., Pt, Pd, and / or Ru) at a reaction temperature of 120° C. to 140° C. and a pressure of 7 MPa. The hydrogenation level may 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 can leave the reactor 102 and be sent to other processing units, storage and / or transportation. The polymer product can include 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(vinyl cyclohexane). The polymer product produced does not contain lower molecular weight polymers due to polymer fracture.

[0039] refer to Figure 2, the system 200 may include a dissolution unit 202, an adsorbent unit 204, and a reactor 102. Waste aromatic-containing polymers and solvents may be added to the dissolution unit 202 via an inlet 206. In the dissolution unit 202, the waste aromatic-containing polymers may be dissolved and / or densified to produce a waste aromatic-containing polymer reactant feed 208. The dissolution temperature may be any temperature suitable for promoting dissolution of the waste aromatic-containing polymers in the solvent (e.g., 20° C. to 60° C., preferably 30° C. to 45° C.). The waste aromatic-containing polymer reactant feed 208 may leave the dissolution unit 202 and enter the adsorption unit 204. The adsorption unit 204 may be any known adsorbent unit (e.g., a packed tower, a pressure swing unit, etc.). The adsorption unit 204 may include one or more adsorbent beds filled with one or more types of adsorbents. In the adsorption unit 204, the solution may contact the adsorbent to produce a treated waste aromatic-containing polymer reactant feed. Treated waste aromatic polymer-containing reactant feed 210 can leave adsorption unit 204 and enter reactor 102. Treated reactant feed 210 can be identical or similar to treated reactant feed 110 in composition. In reactor 102, the hydrogenation of treated waste reactant feed can be carried out as previously described to produce polymer products, which can include at least one hydrogenated, at least one partially hydrogenated aromatic ring, or both, or a mixture thereof. Polymer product 212 can leave reactor 102 and be sent to other processing units, storage and / or transportation. In some embodiments, reactor 102 includes a filtration unit capable of filtering catalyst from polymer product. In other embodiments, polymer product 212 can be provided to a filtration unit to remove catalyst from polymer product.

[0040] Reactor 102 may include one or more heating and / or cooling devices (e.g., insulators, electric heaters, jacketed heat exchangers) or controllers (e.g., computers, flow valves, automation values, etc.) that can be used to control the reaction temperature and pressure of the reaction mixture. Although only one reactor is shown, it should be understood that multiple reactors can be contained in one unit, or multiple reactors can be contained in one reactor unit. In some embodiments, a series of physically separated reactors with interstage cooling / heating devices (including heat exchangers, furnaces, combustion heaters, etc.) can be used.

[0041] B. Waste Aromatic Polymer-Containing Reactant Feed

[0042] The waste aromatic polymer reactant feed may include waste aromatic polymers. Waste aromatic polymers may include polymers that have previously been used in an article of application or manufacture. Non-limiting examples of waste aromatic polymers may include waste polystyrene, waste expanded polystyrene, waste densified expanded polystyrene, or blends thereof. Waste expanded polystyrene may include 1 wt % to 5 wt %, preferably 2 wt % polystyrene, the remainder being air. Densified waste expanded polystyrene (EPS) may be waste expanded polystyrene from which air has been removed. Densification may be accomplished by mechanical or thermal methods. Mechanical methods may include applying sufficient pressure to the waste EPS to break the walls of the honeycomb structure and squeeze out the trapped air. Thermal densification may include heating the waste EPS to a temperature sufficient to release the trapped air. Mechanical and thermal densifiers are commercially known.

[0043] The waste aromatic polymer may include additives. Some additives may be detrimental to the hydrogenation reaction. Non-limiting examples of additives may include stabilizers, anionic surfactants, nucleating agents, initiators, suspension aids, flame retardants, colorants, flow modifiers, UV absorbers, impact modifiers, antioxidants, or mixtures thereof.

[0044] A non-limiting example of a co-stabilizer includes ammonium persulfate.

[0045] 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, sodium lauryl monoglyceride sulfate, sodium lauryl sulfate, sodium laureth sulfate, potassium lauryl sulfate, and sodium glyceryl 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 tridecylbenzene sulfonate, sodium dodecylbenzene sulfonate, sodium cocoyl isethionate and combinations thereof.

[0046] Non-limiting examples of nucleating agents include synthetic waxes, such as fully saturated homopolymers of ethylene with high linearity and crystallinity. Synthetic waxes may be referred to as polyethylene waxes (e.g., polyethylene wax 100, polyethylene wax 500, polyethylene wax 1000, etc.).

[0047] Non-limiting examples of initiators include benzoyl peroxide or tert-butyl perbenzoate, 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-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-tetramethylbutyl peroxy 2-ethylhexanoate, tert-amyl peroxy 2-ethylhexanoate, tert-butyl peroxy 2-ethylhexanoate, tert-butyl peroxy diethylacetate, tert-butyl peroxy isobutyrate, and combinations of one or more of these initiators.

[0048] Non-limiting examples of suspending aids include tricalcium phosphate, sodium dodecylbenzene sulfonate, hydroxyapatite, magnesium phosphate, or combinations thereof.

[0049] Non-limiting examples of flame retardants include organic halogen compounds such as hexabromocyclododecane, brominated styrenic polymers such as styrene-butadiene copolymers, and derivatives of tetrabromobisphenol A tribromophenyl allyl ether. Common flame retardants may include tetrabromobisphenol A bis(2,3,-dibromo-2-methylpropyl ether) or hexabromocyclodecane.

[0050] The non-limiting examples of coloring agents include organic or inorganic pigments, dyes, or mixtures or combinations thereof. The non-limiting examples of inorganic pigments or dyes include metal oxides, iron oxides or titanium dioxide, strontium chromate or barium sulfate, aluminum flakes or particles, carbon black, talc, etc. The non-limiting examples of organic pigments or dyes include perylene, phthalocyanine derivatives (e.g., copper phthalocyanine), indanthrone, benzimidazolone, quinacridone, pyrenone, azomethine derivatives, fluorescent organic compounds, or mixtures thereof.

[0051] Non-limiting examples of antioxidants include sterically hindered phenol 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-tert-butyl-4-hydroxybenzyl)benzene (CAS No. 1709-70-2), 2,2'-thiodiethylenebis(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (CAS No. No.41484-35-9), calcium bis(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.27676-62-6), 1,3,5-tris(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-1,3,5-triazine-2,4,6-(1H,3H,5H)-trione (CAS No.40601-76-1), 3,3-bis(3-tert-butyl-4-hydroxyphenyl)ethylidenebutyrate (CAS No.32509-66-3), 4,4'-thiobis(2-tert-butyl-5-methylphenol) (CAS No.96-69-5), 2,2'-methylene-bis-(6-(1-methyl-cyclohexyl)-p-cresol) (CAS No.77-62-3), 3,3'-bis(3,5-di-tert-butyl-4-hydroxyphenyl)-N,N'-hexamethylenebispropionamide (CAS No.23128-74-7), 2,5,7,8-tetramethyl-2-(4',8',12'-trimethyltridecyl)-chroman-6-ol (CAS No.10191-41-0), 2,2-ethylidenebis(4,6-di-tert-butylphenol) (CAS No.35958-30-6), 1,1,3-tris(2-methyl-4-hydroxy-5'-tert-butylphenyl)butane (CAS No.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 No.90498-90-1), 1,6-hexanediyl-bis(3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl)propionate) (CAS No.35074-77-2), 2,6-di-tert-butyl-4-nonylphenol (CAS No.4306-88-1), 4,4'-butylenebis(6-tert-butyl-3-methylphenol (CAS No.85-60-9); 2,2'-methylenebis(6-tert-butyl-4-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 C. 13 To C 15 Mixture of straight-chain and branched alkyl esters (CAS No. 171090-93-0), 2,2'-thiobis(6-tert-butyl-p-cresol) (CAS No. 90-66-4), diethyl (3,5-di-tert-butyl-4-hydroxybenzyl) phosphate (CAS No. 976-56-7), 4,6-bis(octylthiomethyl)-o-cresol (CAS No. 110553-27-0), phenylpropionic acid, octyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (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 No. 180002-86-2), mixed styrenated phenols (CAS No.61788-44-1), butylated, octylated phenol (CAS No.68610-06-0), butylated reaction products of p-cresol and dicyclopentadiene (CAS No.68610-51-5).

[0052] Non-limiting examples of phosphite antioxidants include one of the following: 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); and tetrakis(2,4-dibutylphenyl)-4,4'-biphenyl diphosphite (CAS No. 119345-01-6) and bis(2,4-diisopropylphenyl) pentaerythritol diphosphite (CAS No. 154862-43-8).

[0053] Non-limiting examples of UV stabilizers include hindered amine light stabilizers, hydroxybenzophenones, hydroxyphenylbenzotriazoles, cyanoacrylates, oxalanilides, hydroxyphenyltriazines, and combinations thereof. Non-limiting examples of hindered amine light stabilizers include dimethyl succinate polymer with 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol (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-piperidinyl)imino]hexamethylene[2,2,6,6-tetramethyl-4-piperidinyl)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-piperidinylamino)-1,3,5-triazine-2-yl]-1,5,8,12-tetraazadodecane (CAS No.106990-43-6).

[0054] Non-limiting examples of heat stabilizers include phenothiazine, p-methoxyphenol, cresol, benzhydrol, 2-methoxy-hydroquinone, 2,5-di-tert-butylbenzoquinone, diisopropylamine, and distearyl thiodipropionate (CAS No. 693-36-7).

[0055] C. Adsorbent

[0056] The adsorbent can be activated carbon, silica gel, molecular sieve, or a combination thereof. In a preferred aspect, the adsorbent can be activated carbon. Typically, the ratio of adsorbent to waste aromatic polymers 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 aspects, the ratio of adsorbent to waste aromatic polymers can be 1:2 to 1:6, preferably 1:4.

[0057] D.Solvent

[0058] The solvent may include a polar solvent and / or a non-polar solvent. Non-limiting examples of polar solvents include methylene chloride, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or a blend thereof. Non-polar solvents may include C5 to C12 straight chain alkanes, C5 to C12 branched alkanes or C5 to C12 cyclic alkanes, or a blend thereof. Non-limiting examples of non-polar solvents may include cyclopentane, cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or a mixture thereof. The volume ratio of non-polar solvent to polar solvent may be 0.1:99.9 to 99.9:0.1. Non-limiting examples of volume ratios can 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 a non-polar solvent and a polar solvent, as long as the volume ratio of the non-polar solvent to the polar solvent is maintained. Non-limiting examples of solvents can include mixtures of dichloromethane and cyclopentane, mixtures of dichloromethane and cyclohexane, mixtures of dichloromethane and methylcyclohexane, mixtures of dichloromethane and ethylcyclohexane, mixtures of dichloromethane and cyclooctane, mixtures of dichloromethane and cycloheptane, mixtures of dichloromethane and dodecane, mixtures of dichloromethane and isopentane, or mixtures of dichloromethane and decalin. In another example, the solvent system may 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 decalin. In another example, the solvent system may 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 decalin.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 decalin. Other solvent combinations (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 15, 20 solvent combinations, etc.) are also within the scope of the present invention. Using the adsorbent and solvent of the present invention, the reaction hydrogenation rate can be increased by 1, 2, 2.5, 3, 3.5, 4, 4.5, 5 times or more compared to the reaction hydrogenation rate of the same reaction using untreated waste aromatic-containing polymers and non-polar solvents. The solvent system of the present invention can completely dissolve or at least partially dissolve waste aromatic-containing polymers, hydrogenated aromatic-containing polymers, partially hydrogenated aromatic-containing polymers, or combinations thereof. Typically, the waste polymer concentration in the solvent system of the present invention may be between 5 wt% and 20 wt%, or 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, or any range or value therebetween. The waste polymer concentration may be the same or different for the adsorbent step and the hydrogenation step.

[0059] E. Catalyst

[0060] The catalyst of the present invention may include commercial catalysts capable of catalyzing the hydrogenation of aromatic polymers. Non-limiting examples of catalysts include (USA), Unicat (USA), BASF (Germany), JohnsonMatthey (UK), Evonik (Germany), Clariant (Switzerland), etc. The catalyst includes one or more catalytic metals. In some aspects, the catalyst includes platinum (Pt), palladium (Pd), ruthenium (Ru), rhodium (Rd), or any combination thereof. In some embodiments, the catalyst is a bimetallic or trimetallic catalyst. The bimetallic catalyst may include Pt, Pd, Ru and / or Rd, in combination with nickel (Ni), iridium (Ir), iron (Fe), copper (Cu) and / or silver (Ag) metals, or a combination thereof. The catalyst may be supported or unsupported. Non-limiting examples of carriers include silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ) or titanium dioxide (TiO 2 ), or any combination thereof. In some aspects, the catalyst is Pt / Al 2 O 3 、Pt / SiO2 or Pt / Al 2 O 3 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 %.

[0061] In one embodiment, the catalyst may include 0.05 wt % to 0.9 wt % of Pt nanoparticles and 99.1 wt % to 99.95 wt % of TiO based on the total weight of the catalyst. 2 , 0.20 wt% to 0.60 wt% of Pt nanoparticles and 99.4 wt% to 99.8 wt% of TiO 2 , or 0.25 wt % to 0.50 wt % of Pt nanoparticles and 99.5 wt % to 99.75 wt % of TiO 2 Such a catalyst has a 0.01 cm 3 / g to 0.35cm 3 / g, preferably 0.03cm 3 / g to 0.30cm 3 / g, more preferably 0.05cm 3 / g to 0.25cm 3 / g pore volume, 5m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to 20m 2 / g surface area, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0062] In one embodiment, the catalyst may include 0.05 wt % to 0.9 wt % of Pt nanoparticles and 99.1 wt % to 99.95 wt % of SiO based on the total weight of the catalyst. 2 , 0.20 wt% to 0.60 wt% of Pt nanoparticles and 99.4 wt% to 99.8 wt% of SiO 2 , or 0.25 wt % to 0.50 wt % of Pt nanoparticles and 99.5 wt % to 99.75 wt % of SiO 2 Such a catalyst has a 0.01 cm 3 / g to 0.35cm 3 / g, preferably 0.03cm 3 / g to 0.30cm 3 / g, more preferably 0.05cm 3 / g to 0.25cm 3 / g pore volume, 5m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to 20m 2 / g surface area, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0063] In one embodiment, the catalyst may include 0.05 wt % to 0.9 wt % of Pt nanoparticles and 99.1 wt % to 99.95 wt % of Al based on the total weight of the catalyst. 2 O 3 , 0.20 wt% to 0.60 wt% of Pt nanoparticles and 99.4 wt% to 99.8 wt% of Al 2 O 3 , or 0.25 wt % to 0.50 wt % of Pt nanoparticles and 99.5 wt % to 99.75 wt % of Al 2 O 3 Such a catalyst has a 0.01 cm 3 / g to 0.35cm 3 / g, preferably 0.03cm 3 / g to 0.30cm 3 / g, more preferably 0.05cm 3 / g to 0.25cm 3 / g pore volume, 5m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to 20m 2 / g surface area, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0064] Example

[0065] The present invention will be described in more detail by specific examples. The following examples are provided for illustrative purposes only and are not intended to limit the present invention in any way. Those skilled in the art will readily recognize that various non-critical parameters that can be changed or modified to produce substantially the same result.

[0066] Example 1 (Treatment of a polymer solution containing waste aromatic polymers)

[0067] Densified expanded polystyrene beads (2 g, Big Grand Rapids, MI) was dissolved in a 1:1 mixture of dichloromethane and cyclohexane (31.63 g) to produce a polymer solution (6 wt%). Activated carbon (0.5 g) was added to the solution, stirred overnight, and filtered through celite to produce a treated polymer solution.

[0068] Example 2 (Hydrogenation of Treated Polymer Solution)

[0069] The Pt / Al prepared according to International Publication No. WO 2022 / 013751 of Wu et al. 2 O 3 The catalyst (0.45 wt% Pt, 0.2 g) was placed in a stainless steel reactor (Parr Series 5000 Multireactor System, Parr Instrument Company, 100 mL) along with the treated polymer solution (30 mL in total). The reactor was first heated with N 2 Purge five times, then rinse with H 2 Purge five times to remove air and moisture and use high pressure H 2 Fill to 1000psi (6.9MPa). After the desired pressure has been reached, the reactor contents are heated to a set temperature of 120°C at a rate of 3°C / min, and maintained at the final set temperature for several hours. After the reaction is complete, the reactor is cooled to room temperature, the pressure is vented to atmospheric pressure (101kPa), the contents in the reactor are recovered, and the solid catalyst is separated from the polymer solution using centrifugation or filtration. A conversion rate of 25% was observed after 0.64 hours, a conversion rate of 50% was observed after 0.76 hours, a conversion rate of 75% was observed after 0.9 hours, and a maximum conversion rate (100%) was reached within 1.16 hours.

[0070] Example 3 (Comparative Example - Hydrogenation of Untreated EPS Beads)

[0071] The procedure of Example 1 was followed, except that the temperature was raised to 140°C and cyclohexane was used as solvent (ie no polar solvent was used). The conversion reached 20% only after 10.75 hours, and the maximum conversion was 35%.

[0072] As shown in the examples, the process of the present invention provides a method that allows for maximum conversion of waste aromatic-containing polymers into useful polymer products including poly(vinylcyclohexane).

[0073] ****

[0074] Although the embodiments of the application and their advantages have been described in detail, it should be understood that, without departing from the spirit and scope of the embodiments defined by the appended claims, various changes, substitutions and variations can be made herein. In addition, the scope of the application is not intended to be limited to the specific embodiments of the process, machine, manufacture, material composition, device, method and step described in the specification. As those of ordinary skill in the art will easily realize from the above disclosure, it is possible to utilize the current existence or later development of the process, machine, manufacture, material composition, device, method or step that performs the function substantially the same as the corresponding embodiment described herein or realizes substantially the same result. Therefore, the appended claims are intended to include such process, machine, manufacture, material composition, device, method or step in their scope.

Claims

1. A process for the hydrogenation of waste aromatic polymers, the process comprising: (a) contacting a spent aromatic polymer-containing solution comprising spent aromatic polymer, one or more additives, and a solvent with an adsorbent material to produce a treated spent aromatic polymer-containing solution; (b) removing the adsorbent from the resulting treated spent aromatic polymer-containing solution; and (c) contacting the treated spent aromatic polymer-containing solution with a hydrogenation catalyst in the presence of hydrogen (H2) gas under conditions sufficient to produce a polymer composition comprising at least one hydrogenated and / or at least one partially hydrogenated aromatic ring, wherein at least one additive is removed from the treated waste aromatic polymer-containing solution, wherein the one or more additives include a co-stabilizer, an anionic surfactant, a nucleating agent, an initiator, a flame retardant, a colorant, or a mixture thereof.

2. The method of claim 1, wherein the waste aromatic-containing polymer comprises waste polystyrene, waste expanded polystyrene, waste densified expanded polystyrene, or blends thereof, and the hydrogenated or partially hydrogenated polymer comprises poly(vinyl cyclohexane).

3. The method according to any one of claims 1 to 2, 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 non-polar solvent, or a mixture thereof.

5. The method according to claim 4, wherein the non-polar solvent is a C5 to C12 linear, branched or cyclic alkane, or a mixture thereof.

6. The method according to any one of claims 4 to 5, wherein the solvent is cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, cyclopentane, decalin, or a mixture thereof.

7. The method according to any one of claims 4 to 6, wherein the polar solvent is dichloromethane, 1,2-dichloroethane, tetrahydrofuran, methyltetrahydrofuran, or a mixture thereof.

8. The process according to any one of claims 4 to 7, wherein the non-polar solvent is cyclohexane, and the polar solvent is dichloromethane.

9. The method according to any one of claims 4 to 8, wherein the volume ratio of the non-polar solvent to the polar solvent is 0.1:99.9 to 99.9:0.1, preferably 1:

1.

10. The method of any one of claims 1 to 9, wherein the contacting conditions of step (a) comprise a temperature of 20°C to 30°C, atmospheric pressure, or a combination thereof, for 8 to 30 hours, preferably 10 hours.

11. The method according to any one of claims 1 to 10, wherein the contacting conditions of step (b) comprise a temperature of 100°C to 220°C, a pressure of 3.4 MPa to 6.9 MPa, or a combination thereof.

12. The method of any one of claims 1 to 11, wherein the hydrogenation catalyst comprises platinum (Pt), palladium (Pd), ruthenium (Ru), or any combination thereof, or an alloy thereof on a support, wherein the support comprises silicon dioxide (SiO2), aluminum oxide (Al2O3) or titanium dioxide (TiO2), or any combination thereof.

13. The process of any one of claims 1 to 12, wherein the concentration of waste aromatic-containing polymer in the polymer solution of step (a), step (b), or both, is from 5 wt% to 20 wt%, preferably 8 wt%.

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