Hydrogenated modified styrene resin

Abstract

A method for hydrogenating aromatic polymers is described. The method comprises hydrogenating a polymer solution comprising an aromatic polymer and a mixture of a nonpolar solvent with a polar solvent having a dielectric constant greater than 7.6 at 25°C and a nonpolar solvent having a dielectric constant of 5 or less at 25°C, by contacting the polymer with a hydrogenation catalyst to produce a polymer composition comprising at least one hydrogenated and / or at least one partially hydrogenated aromatic ring. The volume ratio of the polar to nonpolar solvent ranges from 10:90 to 80:20.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] none Technical Field

[0003] The present invention generally relates to a process for hydrogenating aromatic polymers using a solvent system comprising a mixture of a nonpolar solvent and a polar solvent having a dielectric constant greater than 7.6 at 25°C. Background Art

[0004] Hydrogenation of aromatic polymers to saturated polymers can improve their physical properties, such as thermal properties, mechanical properties and oxidative stability. This hydrogenation process can use homogeneous catalysts and heterogeneous catalysts. Compared with homogeneous catalysts, heterogeneous catalysts have the advantage of being separated from the polymer solution. The heterogeneous catalytic hydrogenation of aromatic polymers (such as polystyrene) can be carried out in the solution phase using heterogeneous (solid) platinum (Pt) catalysts supported on oxides, carbonates or sulfates (such as Al2O3, SiO2, TiO2, CaCO3, BaSO4, etc.). The catalyst can be dispersed in hydrocarbon solvents such as cyclohexane or decahydronaphthalene (decahydronaphthalene). However, due to the steric hindrance of large and long polymer chains, mass transfer is limited, resulting in a lower reaction rate in the heterogeneous catalytic process. This may cause the polymer molecules to be unable to enter the catalytic active sites.

[0005] In order to avoid mass transfer limitations, bimetallic catalysts dispersed in various solvents have been described. For example, Chinese Patent Application Publication No. 109482170 describes the hydrogenation of polystyrene by dispersing a supported bimetallic catalyst in a tetrahydrofuran and hexamethylenetetramine solution. However, a disadvantage of this process is that the catalyst requires the use of a templated support material, which increases production cost and / or complexity. European Patent No. 1042374 by Wege et al. describes the use of polar solvents, such as ethers without α-hydrogen atoms near the ether functional group (e.g., methyl- / -butyl ether) and solvents suitable for hydrogenation reactions in the presence of nickel catalysts. However, a disadvantage of this process is that the catalyst life is limited. U.S. Patent No. 3,607,989 by Sonnabend describes the hydrogenation of polystyrene in an equal amount of 1,2-dichloromethane to obtain hydrogenated polystyrene, which is insoluble in 1,2-dichloromethane.

[0006] Although heterogeneous catalytic processes are known, reducing reaction times and improving cost-effectiveness remain challenges. Summary of the Invention

[0007] A discovery has provided a solution to at least one or more of the problems associated with hydrogenating aromatic polymers using heterogeneous catalytic systems. In one aspect, the solution includes using a solvent system (e.g., a solvent mixture) comprising a polar solvent and a non-polar solvent. A polar solvent is any solvent having a dielectric constant greater than 7.6 at 25°C and being stable under the hydrogenation conditions. A non-polar solvent is any solvent having a dielectric constant less than 5 at 25°C and being stable under the hydrogenation conditions. The ratio of polar solvent to non-polar solvent ranges from 10:90 to 80:20. The advantage of using such a solvent system is that the hydrogenation reaction rate can be increased by two times compared to the same reaction using only a non-polar solvent while maintaining the solubility of the hydrogenated product. A faster reaction rate can bring many benefits, such as reducing the batch time for producing hydrogenated or partially hydrogenated aromatic polymers while increasing production rates. Notably, the resulting hydrogenated product (e.g., PVCH) dissolves in the solvent system after cooling to ambient temperature, which makes the process more energy-efficient because the product solution does not need to be heated for transportation for downstream processing. For example, when the polymer product solution contacts or is subjected to relatively cold conditions (e.g., "cold spots") in the piping connecting the hydrogenation reactor and the polymer isolation equipment (e.g., flash chamber and devolatilization extruder), the polymer product remains dissolved, so the piping does not become clogged due to polymer precipitation. In addition, the use of volatile polar solvents facilitates solvent removal during downstream processing. These advantages can provide economic advantages for the production of hydrogenated or partially hydrogenated polymers (e.g., polystyrene polymers to poly(vinylcyclohexane) (PVCH)). Furthermore, relative to PVCH, the resulting PVCH can be a fully aliphatic, amorphous polymer with high heat resistance (Tg = 145°C), high resistance to thermal oxidation, high resistance to polar chemicals, and / or high resistance to UV and gamma radiation.

[0008] A method for hydrogenating aromatic polymers is described. One method comprises contacting an aromatic polymer solution with a hydrogenation catalyst in the presence of hydrogen (H2) under conditions sufficient to produce a polymer composition comprising at least one hydrogenated and / or at least one partially hydrogenated aromatic ring (e.g., PVCH). The aromatic polymer solution comprises an aromatic polymer, a polar solvent having a dielectric constant greater than 7.6 at 25°C, and a non-polar solvent. In a preferred aspect, the aromatic polymer is a polystyrene resin, and the hydrogenated or partially hydrogenated polymer comprises poly(vinylcyclohexane). Non-limiting examples of non-polar solvents include cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decalin, or mixtures thereof. The polar solvent has a dielectric constant of between 7.6 and 11 at 25°C (e.g., 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11 at 25°C). In a preferred aspect, the polar solvent has a dielectric constant of 9 at 25°C. Non-limiting examples of polar solvents include dichloromethane, 1,2-dichloroethane, or mixtures thereof. In a preferred aspect, the non-polar solvent is cyclohexane and the polar solvent is dichloromethane. The volume ratio of polar solvent to non-polar solvent ranges from 10:90 to 80:20, preferably from 30:70 to 70:30. In some aspects, it has also been found that including too much polar solvent (e.g., more than 30% by volume) leads to diminishing returns. For example, using a volume percentage higher than 30% may not result in a further significant increase in the hydrogenation rate. In some aspects, the hydrogenation reaction rate is increased by more than 1 times, preferably 2 times, more preferably 2.5 times, or even more preferably 5 times, compared to the hydrogenation reaction rate when no polar solvent is used under the same reaction conditions. The contact conditions include a temperature of 100°C to 220°C, a pressure of 3.4MPa to 7MPa, or a combination thereof. Under these conditions, the aromatic polymer is completely dissolved or at least partially dissolved in the solvent. The polymer concentration in the polymer solution is 5wt% to 20wt%, preferably 8wt% The hydrogenation of the aromatic polymer produces a hydrogenated or partially hydrogenated polymer composition, which may be free of or substantially free of a polymer cleavage composition. In some aspects, the hydrogenation catalyst comprises platinum (Pt), palladium (Pd), ruthenium (Ru) or any combination thereof, or an alloy thereof. The hydrogenation catalyst may comprise a support (e.g., silicon dioxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), or titanium dioxide (TiO 2 ), or any combination thereof). Since the catalyst can be dispersed or suspended in a solvent, the hydrogenation process may be a heterogeneous catalytic hydrogenation process.

[0009] This application discusses other embodiments of the present invention in its entirety. Any embodiment discussed for one aspect of the present invention is also applicable to other aspects of the present invention, and vice versa. Each embodiment described herein should be understood as applicable to embodiments of other aspects of the present invention. It is contemplated that any embodiment or aspect discussed herein can be combined with other embodiments or aspects discussed herein and / or implemented for any method or composition of the present invention, and vice versa. In addition, compositions of the present invention can be used to implement methods of the present invention.

[0010] The following includes definitions of various terms and phrases used in this specification.

[0011] The term "aromatic polymer" refers to a polymer, copolymer, block polymer, etc. having at least one aromatic ring. Non-limiting examples of polymers are polystyrene, polymethylstyrene, and copolymers of styrene with at least one other monomer, such as methylstyrene, butadiene, isoprene, acrylonitrile, methyl acrylate, methyl methacrylate, maleic anhydride, and / or an olefin (e.g., ethylene or propylene). Examples of suitable copolymers include copolymers formed from acrylonitrile, butadiene, and styrene, copolymers of acrylates, styrene, and acrylonitrile, copolymers of styrene and α-methylstyrene, and copolymers of propylene, dienes, and styrene, aromatic polyethers, in particular polyphenylene oxides, aromatic polycarbonates, aromatic polyesters, aromatic polyamides, polyphenylenes, polyxylenes, polyphenylene vinyls, polyphenylene acetylenes, polyphenylene sulfides, polyaryletherketones, aromatic polysulfones, aromatic polyethersulfones, aromatic polyimides, and mixtures thereof, and optionally copolymers with aliphatic compounds. Suitable substituents include C1-C4 alkyl, such as methyl or ethyl, C1-C4 alkoxy, such as methoxy or ethoxy, and / or condensed aromatic entities bonded thereon are connected to the phenyl ring by one carbon atom or two carbon atoms, including phenyl, biphenyl and naphthyl. Suitable substituents on the vinyl group include C1-C4 alkyl, such as methyl, ethyl, n-propyl or isopropyl, particularly the methyl in the α position. Suitable olefin comonomers include ethene, propylene, isoprene, isobutylene, butadiene, cyclohexadiene, cyclohexene, cyclopentadiene, optionally substituted norbornene, optionally substituted dicyclopentadiene, optionally substituted tetracyclododecene, dihydrocyclopentadiene, maleic acid derivatives (preferably maleic anhydride) and acrylonitrile derivatives (preferably acrylonitrile and methacrylonitrile).

[0012] The (weight average) molecular weight Mw of the aromatic-containing polymer may be from 1000 to 10,000,000, preferably from 60,000 to 1,000,000, most preferably from 70,000 to 600,000, especially from 100,000 to 300,000, as determined by gel permeation chromatography (GPC) equipped with light scattering, refractive index and UV detectors.

[0013] The aromatic polymer may have a linear chain structure or may have branching locations due to co-units (e.g., graft copolymers). The branching center may comprise a star or branched polymer or may comprise other geometric forms of a primary, secondary, tertiary, or optional quaternary polymer structure. The copolymer may be a random copolymer or a block copolymer. Block copolymers include diblock, triblock, multiblock, and star-shaped block copolymers.

[0014] The phrase "hydrogenation activity" refers to the rate of polymer hydrogenation measured at a specific reaction temperature, pressure, and / or polymer concentration and expressed in units of moles of aromatic rings per gram of catalytic metal per hour.

[0015] "Nanoparticles" refer to particles existing on the nanometer (nm) scale, with diameters between 1 nm and 1000 nm.

[0016] The term "non-polar" solvent refers to a solvent having a dielectric constant of less than 5 (e.g., see Brown et al., Organic Chemistry, 8th ed., 2018, pp. 389-390) and being stable to hydrogenation conditions. Non-limiting examples of non-polar solvents include cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or mixtures thereof.

[0017] The term "polar" solvent refers to a solvent having a dielectric constant greater than 7.6 and being stable to hydrogenation conditions. Non-limiting examples of polar solvents include dichloromethane, 1,2-dichloroethane, or mixtures thereof.

[0018] The term "stable to hydrogenation" refers to a composition (eg, an aromatic solvent) that does not react with hydrogen at temperatures between 100°C and 220°C and pressures between 3.4 MPa and 7 MPa.

[0019] The term "about" or "approximately" is defined as close to, as 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 "mol. %" refer to the weight percent, volume percent, or mole percent of a component, respectively, based on the total weight, total volume, or total moles of the material including the component. In a non-limiting example, 10 grams of a component in 100 grams of a material is 10 wt% 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] The terms "inhibit" or "reduce" or "prevent" or "avoid" or any variation of these terms when used in the claims and / or specification include any measurable reduction or complete inhibition to achieve the desired result.

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

[0024] In the claims or description, when “a” or “an” is used in conjunction with the terms “includes,” “comprising,” “containing,” or “having,” it 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 terms “comprise” (and any form of including, such as “comprises” and “comprises”), “have” (and any form of having, such as “have” and “has”), “include” (and any form of including, such as “includes” and “clude”), or “contain” (and any form of containing, such as “comprises” and “contains”) 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" specific ingredients, components, compositions, etc. disclosed throughout this 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 aromatic-containing polymers to produce fully hydrogenated or partially hydrogenated aromatic-containing polymers. This can be achieved with substantially no or no polymer fragmentation 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. However, it should be understood that although the drawings, detailed description and examples show specific embodiments of the present invention, they are given by way of illustration only and are not intended to be limiting. In addition, it is contemplated that variations 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 of a particular embodiment may be combined with features of other embodiments. For example, features of one embodiment may be combined with features of any other embodiment. In further embodiments, additional features may be added to the specific embodiments described herein. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] FIG1 is a schematic diagram of a reactor system for producing hydrogenated or partially hydrogenated aromatic-containing polymers using the solvent system of the present invention.

[0030] FIG2 is a graph showing the solubility of PVCH in the solvent system of the present invention and in 100% dichloromethane.

[0031] Figure 3 shows the rate of heterogeneous catalytic hydrogenation of polystyrene (PS) using cyclohexane as a comparative solvent and a solvent mixture of the present invention comprising 1:1 cyclohexane and dichloromethane (DCM) (by volume). Both solutions contained 8 wt.% polymer, 0.45 wt.% Pt / Al2O3 catalyst, a 10:1 PS:catalyst ratio, 140°C, 1000 psig (6.98 MPa).

[0032] FIG4 shows the time to 100% conversion versus dichloromethane concentration during heterogeneous catalytic hydrogenation of PS (8 wt.% polymer, 0.45 wt.% Pt / Al2O3 catalyst, 10:1 PS:catalyst ratio, 140°C, 1000 psig (6.98 (MPa)).

[0033] 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 drawn to scale. DETAILED DESCRIPTION

[0034] At least one solution to some of the problems associated with hydrogenating aromatic polymers has been discovered. The solution comprises a cost-effective solvent system that increases the yield of hydrogenated aromatic polymers. The solvent system comprises a polar solvent having a dielectric constant of at least 7.6 at 25°C and a non-polar solvent having a dielectric constant of less than 5 at 25°C, with the volume ratio of polar solvent to non-polar solvent being between 10:90 and 80:20. Without wishing to be bound by theory, it is believed that the addition of the polar solvent increases mass transfer between the catalyst and the polymer, while the non-polar solvent dissolves the hydrogenation product so that it does not precipitate out of solution upon cooling the reaction mixture.

[0035] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

[0036] A. Solvent System

[0037] The solvent system of the present invention includes a polar solvent and a non-polar solvent. The polar solvent has a dielectric constant of at least 7.6 at 25°C, preferably 7.6 to 11 at 25°C. Non-limiting examples of dielectric constant values ​​include 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, 9.1, 9.2, 9.3, 9.4, 9.5, 9.6, 9.7, 9.8, 9.9, 10.0, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9, 11.0, and any value or range therebetween. Non-limiting examples of polar solvents include dichloromethane and 1,2-dichloroethane. The dielectric constant of dichloromethane at 25°C is 8.93. The dielectric constant of 1,2-dichloroethane at 25°C is 10.36. Polar solvents do not include tetrahydrofuran or methyltetrahydrofuran. Non-limiting examples of non-polar solvents include cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene, or mixtures thereof. The volume ratio of polar solvent to non-polar solvent includes 10:90 to 80:20, or 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, or any value or range therebetween. The solvent system includes any mixture of non-polar solvents and polar solvents, as long as the volume ratio of non-polar solvent to polar solvent remains unchanged and / or the dielectric constant of the polar solvent at 25°C is greater than 7.6. Non-limiting examples of dual solvent systems include 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 includes 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. 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 solvent systems of the present invention, the hydrogenation rate of a reaction can be increased by a factor of greater than 1, 2, 2.5, 3, 3.5, 4, 4.5, 5, or more compared to the hydrogenation rate of the same reaction using only a non-polar solvent. The solvent systems of the present invention completely dissolve, or at least partially dissolve, the aromatic-containing polymer, hydrogenated aromatic-containing polymer, partially hydrogenated aromatic-containing polymer, or combinations thereof.The solvent system does not contain solvents that are unstable to the hydrogenation reaction. For example, aromatic solvents such as benzene, toluene, naphthalene, xylene, or mixtures thereof. Generally speaking, the polymer concentration in the solvent system of the present invention is 5 wt.% to 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.

[0038] B. Methods for Hydrogenating Aromatic-Containing Polymers

[0039] FIG1 shows a schematic diagram of a method for hydrogenating an aromatic polymer using a solvent system of the present invention. In some aspects, the process is a heterogeneous reaction. Reactor 100 may include an inlet 102 for polymer reactant feed, an inlet 104 for H2 reactant feed, a reaction zone 106 configured to be in fluid communication with inlets 102 and 104, and an outlet 108. Outlet 108 may be configured to be in fluid communication with reaction zone 106 and configured to remove a product stream from the reaction zone. Reactor 100 may be any reactor suitable for polymer hydrogenation (e.g., a batch reactor or a continuous reactor). Reaction zone 106 may include any catalyst capable of hydrogenating aromatic polymers. The polymer reactant feed may enter reaction zone 106 via inlet 102. The reactant feed may be a mixture of the solvent system of the present invention and an aromatic polymer. In one aspect, the solvent system is methylene chloride and cyclohexane, and the aromatic polymer is a polystyrene resin. The mass ratio of solvent to polymer may be 4:1, 9:1, 19:1, or any range or value therebetween. After purging the reactor with nitrogen through inlet 104, the H2 reactant feed can enter the reactor 100. In the reaction zone 106, the hydrogenation catalyst can be dispersed in the solvent system, and the aromatic polymer can be completely dissolved or at least partially dissolved in the solvent system. The pressure of the reactor 100 can be maintained by the H2 reactant feed. The product stream can be removed from the reaction zone 106 through the product outlet 108. The product stream can be sent to other processing units, storage and / or transportation. The product stream includes at least one hydrogenated aromatic ring, at least one partially hydrogenated aromatic ring, or both, or a mixture thereof. For example, polystyrene can be hydrogenated to form poly(vinylcyclohexane). Due to polymer fragmentation, the produced polymer product does not contain low molecular weight polymers. Under the conditions of a reaction temperature of 120°C to 140°C, a pressure of 6.9 MPa, and a polymer concentration of 8 wt.%, the hydrogenation activity can reach at least 10 moles of aromatic rings per gram of catalytic metal (e.g., Pt, Pd and / or Ru) per hour. The hydrogenation level may be at least 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%, or any range or value therebetween.

[0040] The temperature and pressure can vary according to the reaction to be carried out. The temperature range can be 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. The pressure (for example, H2 pressure) range can be about 2.1 MPa to 7 MPa, 3.45 MPa to 7 MPa or 2.1, 2.5, 3.0, 3.1, 3.2, 3.3, 3.4, 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, 7.0, or any range or value therebetween. The reaction pressure can be maintained by hydrogen pressure.

[0041] Reactor 100 can include one or more heating and / or cooling devices (e.g., insulation devices, electric heaters, jacketed heat exchangers) or controllers (e.g., computers, flow valves, automatic valves, 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 accommodated in a unit, or multiple reactors can be accommodated in a reactor unit. In some embodiments, a series of physically separated reactors can be used with interstage cooling / heating devices, including heat exchangers, furnaces, fired heaters, etc.

[0042] C. Catalyst

[0043] 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 catalyst or a trimetallic catalyst. The bimetallic catalyst can include Pt, Pd, Ru, Rd and nickel (Ni), iridium (Ir), iron (Fe), copper (Cu), silver (Ag) metal or a combination thereof. The catalyst can be supported or unsupported. Non-limiting examples of carriers include silicon dioxide (SiO2), aluminum oxide (Al2O3), or titanium dioxide (TiO2) or any combination thereof. In some aspects, the catalyst is Pt / Al2O3, Pt / SiO2 or Pt / Al2O3 catalyst. The total weight percentage of metal in the supported catalyst may be 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.%.

[0044] In one embodiment, the catalyst may include 0.05 wt.% to 0.9 wt.% Pt nanoparticles and 99.1 wt.% to 99.95 wt.% TiO2, 0.20 wt.% to 0.60 wt.% Pt nanoparticles and 99.4 wt.% to 99.8 wt.% TiO2, or 0.25 wt.% to 0.50 wt.% Pt nanoparticles and 99.5 wt.% to 99.75 wt.% TiO2, based on the total weight of the catalyst. The pore volume of such a catalyst is 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, with a surface area of ​​5m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to 20m 2 / g, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0045] In one embodiment, the catalyst comprises 0.05 wt.% to 0.9 wt.% of Pt nanoparticles and 99.1 wt.% to 99.95 wt.% of SiO2, 0.20 wt.% to 0.60 wt.% of Pt nanoparticles and 99.4 wt.% to 99.8 wt.% of SiO2, or 0.25 wt.% to 0.50 wt.% of Pt nanoparticles and 99.5 wt.% to 99.75 wt.% of SiO2, based on the total weight of the catalyst. The pore volume of such a catalyst is 0.01 cm 3 / g to 0.35cm 3 / g, preferably 0.03cm 3 / g to 0.30cm 3 / g, more preferably 0.05ccm 3 / g to 0.25cm 3 / g, with a surface area of ​​5m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to 20m 2 / g, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0046] In one embodiment, the catalyst includes 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, based on the total wt.% of the catalyst.

[0047] The pore volume of this type of catalyst is 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 cm 3 / g, surface area is m 2 / g to 80m 2 / g, preferably 5m 2 / g to 40m 2 / g, more preferably 5m 2 / g to m 2 / g, and / or a median pore size of less than 300 microns, preferably less than 100 microns.

[0048] Example

[0049] The present invention will be described in more detail below through specific examples.

[0050] The following examples are 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 a variety of non-critical parameters can be changed or modified to produce essentially the same results.

[0051] Example 1-5

[0052] (Hydrogenation of Polystyrene Using the Solvent System of the Present Invention)

[0053] Pt / Al2O3 catalyst (0.45 wt.% Pt, polystyrene to catalyst ratio of 10:1) prepared according to Wu et al. International Publication No. WO 2022 / 013751 was mixed with the required volumes of cyclohexane and dichloromethane (total volume 30 mL, solvent) and polystyrene (PS-155, (Saudi Arabia), weight-average molecular weight Mw = 235,000, 8 wt.%)) were placed in a stainless steel reactor (Parr Series 5000 Multireactor System, Parr Instrument Company, 100 ml). The reactor was first purged three times with H2, then purged three times with H2 to remove air and moisture, and then filled with high-pressure H2 to the desired reaction pressure, approximately 500 and 1000 psi (3.4 MPa to 6.9 MPa). After reaching the desired pressure, the reactor contents were heated at a rate of 1°C / min to a set temperature of 120°C and maintained at the final set temperature for several hours. After the reaction was completed, the reactor was cooled to room temperature, the pressure was released to atmospheric pressure (101 kPa), and the reactor contents were recovered and the solid catalyst was separated from the polymer solution by centrifugation or filtration. The time to 100% conversion was 1 hour.

[0054] Table 1

[0055]

[0056] *Yes - product is soluble at 25°C; No - product is partially or completely insoluble at 25°C.

[0057] Examples 6-10 (Hydrogenation of Polystyrene Using the Solvent System of the Invention)

[0058] The procedure of Example 1 was used except that the reaction temperature was increased to 140°C and the required volumes of cyclohexane and dichloromethane were used.

[0059] Table 2 summarizes the amounts of dichloromethane and cyclohexane used and the time to reach 100% conversion to poly(vinylcyclohexane) (PVCH).

[0060] Table 2

[0061]

[0062] *Yes - product is soluble at 25°C; No - product is partially or completely insoluble at 25°C.

[0063] ND = Not Determined

[0064] The solubility of PVCH reported in Examples 13 and 14 was determined by physically mixing PVCH with dichloromethane and cyclohexane in the indicated volume percentages. Based on the data from Examples 12 and 15, one skilled in the art of hydrogenation would expect the reaction times to be similar to those for Examples 12 and 15. As shown in Figure 2 and Tables 1 and 2, the solubility of the PVCH product is a function of solvent composition. Once the reaction mixture cools to room temperature, it is observed that the product PVCH is insoluble in 100% DCM solvent. Referring to Figure 2, when the DCM solvent concentration exceeds 80% by volume, the PVCH product becomes insoluble upon cooling to near or equal to ambient temperature.

[0065] Comparative Example A (Hydrogenation of Polystyrene Using Cyclohexane)

[0066] The procedure of Example 1 was followed, except that cyclohexane was used as the solvent (ie, no polar solvent was used). In Comparative Example A, the conversion of polystyrene was 100% after 3.28 hours at 120°C.

[0067] Comparative Example B (Hydrogenation of Polystyrene Using Cyclohexane)

[0068] The procedure of Examples 6-10 was followed except that cyclohexane was used as the solvent (ie, no polar solvent was used). In Comparative Example B, the polystyrene conversion was 100% after 1.33 hours at 140°C.

[0069] Figure 3 is a graph of the hydrogenation rates for Example 3 and Comparative Example A. The top line plots the hydrogenated polystyrene conversion (PS conversion %) versus time for the cyclohexane / dichloromethane solvent system of Example 3. The bottom line plots the hydrogenated polystyrene conversion (PS conversion %) versus time for Comparative Example A, which uses only cyclohexane as the solvent. As shown in Figure 2, a significant increase in reaction rate (i.e., a significant reduction (2.1-fold) in the time to reach 100% conversion) is observed when the polystyrene hydrogenation process is performed using the solvent system of the present invention (e.g., Example 3, using a 1:1 volume ratio of cyclohexane and dichloromethane) compared to cyclohexane (Comparative Example B). Notably, this increased activity allows the hydrogenation reaction to be completed in less than two hours at a temperature of 120°C using the solvent system of the present invention.

[0070] Figure 4 shows the time dependence of the conversion of polystyrene to PVCH during hydrogenation at 140°C based on the volume concentration of dichloromethane in the solvent system of the present invention (a mixture of cyclohexane and dichloromethane). A sharp decrease is observed from 1.33 hours for 0 vol.% dichloromethane (pure cyclohexane, Comparative Example B) to 0.85 hours for 50 vol.% dichloromethane (Example 8). Notably, the increased activity allows the hydrogenation reaction to be completed in less than one hour at 140°C using the solvent system of the present invention.

[0071] Although the embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and modifications can be made herein without departing from the spirit and scope of the embodiments defined by the appended claims. In addition, the scope of the present application is not limited to the specific embodiments of the processes, machines, manufactures, material compositions, devices, methods and steps described in the specification. It can be easily understood by those skilled in the art from the above disclosure that processes, machines, manufactures, material compositions, devices, methods or steps that are currently available or developed in the future and perform substantially the same functions as the corresponding embodiments described herein or achieve substantially the same results can be utilized. Therefore, the attached claims are intended to include these processes, machines, manufactures, material compositions, devices, methods or steps within their scope.

Claims

1. A method for hydrogenating aromatic polymers, characterized in that: The method comprises contacting an aromatic polymer solution with a hydrogenation catalyst in the presence of hydrogen (H2) at a temperature of 100°C to 220°C and a pressure of 3.4 MPa to 7 MPa to produce a polymer composition comprising at least one hydrogenated and / or at least one partially hydrogenated aromatic ring; wherein the aromatic polymer solution comprises an aromatic polymer, a polar solvent, and a non-polar solvent having a dielectric constant of 5 or less at 25° C., wherein the volume ratio of the polar solvent to the non-polar solvent ranges from 10:90 to 80:20, and the polar solvent is dichloromethane; Polymer compositions wherein the aromatic-containing polymer is polystyrene and the hydrogenated or partially hydrogenated aromatic rings include poly(vinylcyclohexane).

2. The method according to claim 1, characterized in that The non-polar solvent is cyclohexane, methylcyclohexane, ethylcyclohexane, cyclooctane, cycloheptane, dodecane, isopentane, decahydronaphthalene or a mixture thereof.

3. The method according to claim 1, characterized in that The non-polar solvent is cyclohexane.

4. The method according to claim 1, wherein The volume ratio of the polar solvent to the non-polar solvent is 20:80 to 80:

20.

5. The method according to claim 1, wherein The speed of the hydrogenation reaction is increased by more than 1 times compared with the speed of the hydrogenation reaction under the same reaction conditions without using a polar solvent.

6. The method according to claim 1, characterized in that The contact conditions include a temperature of 120° C. to 140° C. and a pressure of 3.4 MPa to 6.9 MPa.

7. The method according to claim 1, characterized in that The hydrogenation catalyst includes platinum (Pt), palladium (Pd), ruthenium (Ru), or any combination thereof, or an alloy thereof.

8. The method according to claim 1, characterized in that The hydrogenation catalyst comprises a support.

9. The method of claim 8, wherein the support comprises silica (SiO2), alumina (Al2O3), or titania (TiO2), or any combination thereof.

10. The method according to claim 1, characterized in that The polymer composition of the hydrogenated or partially hydrogenated aromatic rings does not undergo polymer scission.

11. The method according to claim 1, wherein The aromatic polymer is completely dissolved or at least partially dissolved in the solvent.

12. The method according to claim 1, characterized in that The polymer concentration in the polymer solution is 5 wt.% to 20 wt.%.

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