Catalytic hydrogenation of polymers

Abstract

A method for the hydrocracking of a polymer is provided, comprising the steps of feeding into a reactor a polymer, hydrogen gas, and a supported organometallic catalyst, the supported organometallic catalyst being formed from an organometallic complex pre-catalyst and an acidic metal oxide support, the polymer reacting with the supported organometallic catalyst in the presence of hydrogen gas at a predetermined temperature in the reactor to produce a reduced polymer product having a weight average molecular weight less than that of the polymer.

Description

[Technical Field]

[0001] Priority Claim This application claims priority to U.S. Provisional Application No. 63 / 223,583, filed on 20 July 2021, the entire contents of which are incorporated herein by reference.

[0002] Reference to government rights This invention was made with the support of the U.S. Government under DE-FG02-03ER15457, granted by the U.S. Department of Energy. The U.S. Government has certain rights to this invention. [Background technology]

[0003] The accumulation of consumer polymer waste is a growing concern, given the serious environmental damage it poses. Despite society's heavy reliance on these materials, less than 10% of consumer polymers in the United States are recycled, with the vast majority accumulating in landfills. Polypropylene (PP) and polyethylene (PE) materials account for the largest proportion of this waste polymer, and the small amount of these materials currently recycled is largely done through mechanical means. However, recycled polymers are always of lower value than newly produced polymers (made directly from pure monomers). Therefore, there is a growing effort to research methods for producing valuable polymer materials from consumer polymer waste. [Overview of the Initiative]

[0004] This disclosure provides a supported organometallic catalyst for depolymerizing polymers via hydrocracking, and a method using the supported organometallic catalyst. Hydrocracking is a chemical reaction involving the catalytic cleavage of carbon-carbon single bonds or carbon-heteroatom single bonds by hydrogen (H2). Using this method, long carbon chains in polymers such as polyolefins (e.g., polypropylene or polyethylene) can be converted into products with a lower molecular weight than the starting polymer.

[0005] The supported organometallic catalysts of this disclosure are highly electrophilic, formally cationic, and abundantly present single-site organometallic catalysts, chemically adsorbed onto an acidic metal oxide support (e.g., a strongly Brønsted acidic alumina sulfate support). The supported organometallic catalysts of this disclosure mediate rapid hydrocracking of molecular and polymeric saturated hydrocarbons under mild conditions, with a low catalyst load of 0.02 mol%, 0.5 atm of H2 / 90°C, and mild catalyst loads. In the case of polyethylene, quantitative hydrocracking of light hydrocarbons (e.g., hydrocarbons less than C9) proceeds within 48 minutes, and at 200°C / 2 atm of H2, the activity is 4000 mol (CH2 units)·mol (Zr). -1 ·h -1 It surpasses the previous results. Under similar solvent-free conditions, polyethylene-CO-1-octene, isotactic polypropylene, and used sandwich bags are rapidly hydrocracked into low molecular weight hydrocarbons. Such remarkable results can help reduce reliance on fossil fuels and find meaningful applications in addressing the recycling and reuse of the vast amounts of plastic waste in today's society.

[0006] Embodiments of this disclosure provide a method for the hydrocracking of a polymer as defined herein. The method includes the steps of supplying a polymer, hydrogen gas (H2), and a supported organometallic catalyst of this disclosure into a reactor. The supported organometallic catalyst is formed from an organometallic complex pre-catalyst of formula I and an acidic metal oxide support. The organometallic complex pre-catalyst of formula I is MR m L x Equation I (wherein m is between 0 and 6, x is between 0 and 6, M is a transition metal selected from the group consisting of transition metals of groups 3 to 8, R is independently selected from the group consisting of H, C1 to C8 hydrocarbyls, or halogens, and each L is independently selected from the group consisting of C1 to C12 substituted or unsubstituted hydrocarbyls). The values ​​of m and x depend on the oxidation state of M. The method further includes a step of reacting a polymer with a supported organometallic catalyst, wherein a reduced polymer product having a weight-average molecular weight smaller than the polymer is produced by stirring the mixture in the presence of hydrogen gas at a predetermined temperature in a reactor.

[0007] For various embodiments, M is selected from the group consisting of transition metals of Group 4, Group 5, Group 6, or Group 8. For various embodiments, M is selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, or Ni. Preferably, M is selected from the group consisting of transition metals of Group 4, Group 5, or Group 6. Preferably, M is selected from the group consisting of Ti, Zr, Hf, Nb, Ta, Mo, or W. Most preferably, M is derived from a Group 4 transition metal selected from the group consisting of Ti, Zr, or Hf. For various embodiments, M is also preferably selected from the group consisting of Zr or Hf, where m is 0 and each L is independently selected from C1-C12 alkyl groups.

[0008] For various embodiments, the hydrocarbyl L in formula I is independently selected from the group consisting of C1-C10 alkyl, C2-C10 alkenyl, or C5-C10 aryl. As used herein, the aryl may include multiple ring structures (e.g., fused rings). Preferably, L in formula I is neopentyl (e.g., 2,2-dimethylpropyl).

[0009] For various embodiments, the acidic metal oxide support is a sulfated metal oxide (e.g., a strongly Brønsted acidic oxide). For various embodiments, the sulfated metal oxide is selected from the group consisting of aluminum sulfate, zirconium(IV) sulfate, tin(IV) sulfate, hafnium(IV) sulfate, titanium(IV) sulfate, iron(III) sulfate, zinc(II) sulfate, silica sulfate, or combinations thereof.

[0010] For various embodiments, the predetermined temperature of this method is 60°C to 300°C. Preferably, the predetermined temperature of this method is 90°C to 200°C. More preferably, the predetermined temperature of this method is 110°C to 150°C.

[0011] For various embodiments, the step of reacting the polymer may include stirring the polymer with the supported organometallic catalyst at a speed of 500 rpm to 3000 rpm in the presence of hydrogen gas. Such stirring of the supported organometallic catalyst and the polymer ensures more complete mixing of the polymer and the supported organometallic catalyst.

[0012] For various embodiments, the weight-average molecular weight of the reduced polymer product produced according to the method of this disclosure is smaller than that of the starting polymer. For various embodiments, the reduced polymer product is at least one of the volatile product, oily product, or waxy product, as defined herein. For various embodiments, the reduced polymer product contains less than 5 wt% of waxy product based on the total weight of the reduced polymer product.

[0013] For various embodiments, the polymer is selected from the group consisting of polyolefins, polymers formed by polymerization of aromatic alkenes, or polymers formed by polymerization of conjugated dienes. For various embodiments, the polyolefin is preferably selected from the group consisting of polyethylene, polypropylene, C4-C12 linear or branched monoolefins, copolymers thereof, or combinations thereof. More preferably, the polyolefin is selected from the group consisting of polyethylene, polypropylene, or copolymers thereof.

[0014] For various embodiments, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.1 atmospheres to 100 atmospheres. Preferably, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.2 atmospheres to 50 atmospheres. More preferably, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.5 atmospheres to 4 atmospheres. For various embodiments, the step of reacting the polymer with the supported organometallic catalyst in the presence of hydrogen gas at a predetermined temperature lasts for a period of 0.25 hours to 24 hours. For various embodiments, the step of supplying the supported organometallic catalyst into the reactor includes supplying M in an amount of 0.01 mol percent (mol%) to 0.9 mol%, based on the monomer units of the polymer (e.g., the -C2H4- monomer units of polyethylene).

[0015] For various embodiments, the supported organometallic catalyst is represented by formula II. L y-x R x-z M n+ ··· O - (Acidic metal oxide support) Formula II In the formula: M is selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co and Ni; R is independently selected from hydrogen, halogen and L; each L is independently selected from C1-C12 saturated or unsaturated hydrocarbyl, or C1-C12 silylhydrocarbyl; n is 1, y is 3, x is 2 or 1, and z is 1 or 0. In some embodiments, n may be 2 or 3 when M is not in the maximum possible oxidation state. For example, when M is either Co or Fe, L2Co 2+ ··· O - (acidic metal oxide support) or L2Fe 2+ ··· O - (acidic metal oxide support), n may be 2, x may be 1, and z may be 1. In Formula II, "···" represents an electrostatic non-covalent bond between O of the support material and - M n+ , and " ··· O - " represents a weakly Lewis basic support material after deprotonation. Preferably, in Formula II, M is selected from the group consisting of Ti, Zr and Hf, each L is C3-C8 saturated or unsaturated hydrocarbyl, n is 1, y is 3, x=1, and z=1. More preferably, in Formula II, M is selected from the group consisting of Ti, Zr and Hf, each L is C5 saturated hydrocarbyl, n is 1, y is 3, x=1, and z=1.

[0016] Other main features and advantages of the present disclosure will become apparent to those skilled in the art upon review of the following drawings, detailed description and appended claims.

[0017] Exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] [Figure 1]An example of an existing catalyst consisting of a metal alkyl covalently bonded to a strongly Lewis-basic oxide support material is shown (Figure 1A). An example of the supported organometallic catalyst of the present invention consisting of a cationic metal alkyl on a very weakly Lewis-basic support having a loose ionic metal-support interaction (i.e., the metal and support material are not covalently bonded) is shown (Figure 1B).

[0019] [Figure 2] Table 6 shows the mass percentages of volatile products, DCM extracts, and solid products of the reduced polymer products.

[0020] [Figure 3] Table 7 shows the mass percentages of volatile products, DCM extracts, and solid products of the reduced polymer products.

[0021] [Figure 4] Table 8 shows the mass percentages of volatile products, DCM extracts, and solid products of the reduced polymer products.

[0022] [Figure 5] Table 13 shows the mass percentages of volatile products, oily products, and waxy products of the reduced polymer products.

[0023] [Figure 6] Table 14 shows the mass percentages of volatile products, oily products, and waxy products of the reduced polymer products.

[0024] [Figure 7] Table 17 shows the distribution of polyolefin hydrolysis products (volatile products, DCM extracts, and solid products) at various stirring speeds.

[0025] [Figure 8] Table 17 shows the mass percentages of volatile products, DCM extracts, and solid products of the reduced polymer products.

[0026] [Figure 9] Table 18 shows the distribution of hydrogenation products (volatile products, DCM extracts, and solid products) of polyolefins under given reaction conditions. [Modes for carrying out the invention]

[0027] This disclosure provides a process for depolymerizing a polymer by hydrocracking using a supported organometallic catalyst. Hydrocracking is a chemical reaction involving the catalytic cleavage of carbon-carbon single bonds or carbon-heteroatom single bonds by hydrogen (H2). In the method of the present invention, the polymer is combined with hydrogen and the supported organometallic catalyst of the present disclosure under relatively mild conditions selected to induce the hydrocracking of the polymer, yielding polymer fragments, i.e., low molecular weight products. By using the method of the present invention, long carbon chains of polymers such as polyolefins (e.g., polypropylene or polyethylene) can be converted into products with a molecular weight lower than that of the starting polymer.

[0028] Compared to existing methods for depolymerizing polymers, this disclosure utilizes supported organometallic catalysts under generally milder conditions, such as lower temperatures, lower H2 pressures, and smaller catalyst loads, while achieving consistently high reaction rates. Furthermore, while solvents can be used, no solvents are required in the methods of this disclosure. Simultaneously, embodiments of this disclosure make it possible to achieve extremely high activity, for example, activity two orders of magnitude higher than existing catalysts using similar conditions.

[0029] The supported organometallic catalysts of this disclosure are highly electrophilic, formally cationic, and abundantly present single-site organometallic catalysts, chemically adsorbed onto an acidic metal oxide support (e.g., a strongly Brønsted acidic alumina sulfate support). The supported organometallic catalysts of this disclosure mediate rapid hydrocracking of molecular and polymeric hydrocarbons (e.g., saturated hydrocarbons) under mild conditions, with a low catalyst load of 0.02 mol%, H2 at 0.5 atm / 90°C. In the case of polyethylene, quantitative hydrocracking of volatile hydrocarbons (e.g., light hydrocarbons less than C9) proceeds within 48 minutes, and at H2 pressure of 200°C / 2 atm, the activity is 4000 mol (CH2 units)·mol (Zr). -1 ·h -1 This surpasses the previous results. Under similar solvent-free conditions, polyethylene-co-1-octene, isotactic polypropylene, and used sandwich bags (e.g., low-density polyethylene) are rapidly hydrocracked into products with smaller molecular weights than the starting polymers. Such remarkable results can help address the recycling and reuse aspects of the large amounts of plastic waste in today's society and find meaningful applications that can help reduce reliance on fossil fuels.

[0030] definition Prior to disclosing and describing the compounds, components, compositions, and / or methods of the present invention, it should be understood that this disclosure is not limited to specific compounds, components, compositions, reactants, reaction conditions, parts, ligands, structures, etc., unless otherwise specified, and that they may be modified unless otherwise specified. It should also be understood that the terms used herein are intended solely to describe specific embodiments and are not intended to limit them.

[0031] It should also be noted that, as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include multiple references unless otherwise specified. For example, a reference to “a reduced polymer product” may include two or more reduced polymer products, thereby enabling “multiple reduced polymer products.” Similarly, a reference to “a halogen atom” in a “substituted with a halogen atom” part may include two or more halogen atoms, so that the part may be substituted with two or more halogen atoms; a reference to “a substituent” may include one or more substituents; a reference to “a ligand” may include one or more ligands, and so on.

[0032] As used herein, “polymer” includes linear or branched homopolymers or linear or branched copolymers. A polymer (e.g., homopolymer, copolymer, terpolymer, etc.) has two or more homogeneous or heterogeneous monomer (i.e., mer) units derived from one or more different monomers. A “homopolymer” is a polymer having all homogeneous polymer units (e.g., 100 wt% of polymer units are derived from ethylene, or 100 wt% of polymer units are derived from propylene). A “copolymer” is a polymer having two or more different polymer units, e.g., a polymer produced by copolymerizing ethylene with C3-C10 alpha-olefins, or a polymer produced by copolymerizing propylene with ethylene and / or C4-C10 alpha-olefins. A “terpolymer” is a polymer having three different polymer units. With respect to polymer units, “different” means that the polymer units are different from each other by at least one atom, or that the polymer units are isometrically different. Therefore, as used herein, the definition of copolymer includes terpolymers and the like.

[0033] The embodiments allow the polymer to be a polyolefin. Examples of polyolefins include homopolymers and / or copolymers produced from olefin monomers, such as polymers produced from ethylene (i.e., polyethylene), polymers produced from propylene (i.e., polypropylene), and homopolymers and / or copolymers produced from linear or branched C4-C12 monomers of higher alpha-olefins (e.g., linear or branched C4-C12 monoolefins). Examples of higher alpha-olefin monomers include, but are not limited to, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, and 3,5,5-trimethyl-1-hexene. Examples of polyolefins include ethylene-based polymers, in particular homopolymers of polyethylene (e.g., formed from 100 wt% ethylene), and those having 50 wt% or more ethylene. for exampleExamples of polyolefins include polyethylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, and ethylene-1-octene copolymers. Examples of polyolefins include propylene-based polymers, such as polypropylene homopolymers (formed from 100 wt% propylene) and those containing 50 wt% or more propylene. for example Examples of olefins that can be used include, but are not limited to, norbornene, norbornadiene, isobutylene, isoprene, vinylbenzocyclobutane, ethylene, ethylene(1-1-2 Similarly, in some embodiments, propylene copolymers can be produced by polymerizing propylene to a comonomer having at least one alpha-olefin having 4 to 15 carbon atoms, preferably 4 to 12 carbon atoms, and most preferably 4 to 8 carbon atoms, for example by a gas-phase polymerization process. In another embodiment, ethylene and / or propylene can be polymerized with at least two different comonomers (one of which may be a diene) to produce a terpolymer.

[0034] When used herein, the groups of transition metals discussed and claimed herein can be found in groups 4-10 of the IUPAC periodic table of elements as of 4 May 2022.

[0035] As used herein, the term "hydrocarbyl" refers to a monovalent group formed by removing one hydrogen atom from a hydrocarbon, such as, in particular, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, phenyl, benzyl, and naphthyl. Exemplary hydrocarbyls include alkyl, alkenyl, and aryl groups. Hydrocarbyls may be linear, branched, or cyclic.

[0036] As used herein, the term "substituted" in, for example, "substituted hydrocarbyl" means that the group following the term has at least one component selected from the group consisting of halogen radicals, hydroxyl groups, carbonyl groups, carboxyl groups, amine groups, phosphine groups, alkoxy groups, phenyl groups, naphthyl groups, (C1-C20) alkyl groups, (C2-C10) alkenyl groups, and combinations thereof, in place of one or more hydrogens at any position, unless another type of substitution, such as "alkyl substitution" or "aryl substitution," is specifically described. When the term "substituted" precedes an enumeration of possible substituents, the term is intended to apply to all components of that group. That is, the phrase "substituted alkyl, alkenyl, and aryl" shall be interpreted as "substituted alkyl, substituted alkenyl, and substituted aryl."

[0037] Where the term "sulfated" precedes an enumeration of possible sulfated metal oxides, this term is intended to apply to all components of that group. That is, the phrase "aluminum sulfated oxide, zirconium(IV) oxide, tin(IV) oxide, hafnium(IV) oxide, titanium(IV) oxide, iron(III) oxide, zinc(II) oxide, silica oxide, or any combination thereof" shall be interpreted as "aluminum sulfated oxide, zirconium(IV) sulfated oxide, tin(IV) sulfated oxide, hafnium(IV) sulfated oxide, titanium(IV) sulfated oxide, iron(III) sulfated oxide, zinc(II) sulfated oxide, silica sulfated oxide, or any combination thereof."

[0038] As used herein, the term "alkyl" refers to a branched or unbranched (e.g., linear) cyclic or acyclic saturated hydrocarbyl radical that typically lacks one hydrogen atom, but does not necessarily, contains one to 50 carbon atoms, more preferably one to 20 carbon atoms, and most preferably one to 10 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, hexyl, octyl, decyl, and cycloalkyl groups (e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopentylmethyl, and cyclohexylethyl).

[0039] As used herein, the term “alkenyl” refers to a branched or unbranched cyclic or acyclic hydrocarbyl radical comprising at least one double bond, and typically, but not necessarily, 2 to 50 carbon atoms, more preferably 2 to 20 carbon atoms, and most preferably 2 to 10 carbon atoms, such as, in particular, ethenyl, n-propenyl, isopropenyl, n-butenyl, isobutenyl, 4-octenyl, 2-decenyl, cyclopentenyl, cyclopentadienyl, cyclohexenyl, and cyclohexadienyl.

[0040] The term “aromatic” is used in its ordinary sense and includes unsaturated compounds that are essentially delocalized across multiple bonds on a ring. As used herein, the term “aromatic” typically refers to a group containing an aromatic ring or aromatic ring system with 5 to 50 carbon atoms, preferably 5 to 25 carbon atoms, and more preferably 5 to 16 carbon atoms. Typical neutral unsubstituted aromatic compounds include benzene, naphthalene, anthracene, phenanthrene, pyridine, pyrazine, imidazole, pyrazole, oxazole, thiophene, pyrrole, triazole, indole, and benzimidazole. Typical charged unsubstituted aromatic compounds include cyclopropenyl cations and cyclopentadienyl anions.

[0041] As used herein, the term "aryl" refers to a group containing, but not necessarily containing, an aromatic ring or aromatic ring system, typically containing 5 to 50 carbon atoms, preferably 5 to 20 carbon atoms, and more preferably 5 to 10 carbon atoms. Examples of aryl groups as used herein include groups containing a single aromatic ring or groups containing multiple aromatic rings, where the multiple aromatic rings are condensed, covalently bonded, or linked to a common group (e.g., a methylene or ethylene moiety). More specific examples of aryl groups include one aromatic ring or two or three aromatic rings that are condensed or linked, such as phenyl, naphthyl, biphenyl, terphenyl, anthracenyl, phenantrenyl, pyridinyl, pyrazinyl, imidazolyl, pyrazolyl, oxazolyl, thienyl, pyrrolyl, triazolyl, indolyl, and benzimidazolyl. The aryl group may be unsubstituted, or it may be substituted with a halogen (preferably fluorine, chlorine, or bromine, more preferably fluorine or bromine, even more preferably fluorine), a hydrocarbyl (e.g., alkyl, alkenyl, or alkynyl), a heterohydrocarbyl, or a heteroatomic group. In certain embodiments, the aryl substituent (substituent on the aryl group) contains 1 to 40 non-hydrogen atoms, preferably 1 to 20 non-hydrogen atoms, and more preferably 1 to 10 non-hydrogen atoms.Examples of substituted aryl groups include tolyl(methylphenyl), xylyl(dimethylphenyl), mesityl(trimethylphenyl), ethylphenyl, styryl, allylphenyl, propynylphenyl, chlorophenyl, fluorophenyl, difluorophenyl, trifluorophenyl, tetrafluorophenyl, pentafluorophenyl, pentafluorobiphenyl, methoxyphenyl, ethoxyphenyl, dimethoxyphenyl, trifluoromethylphenyl, bis(trifluoromethyl)phenyl, dimethylaminophenyl, dimethylaminoethylphenyl, phenoxyphenyl, methylcarboxyphenyl, ethylcarboxyphenyl, methoxynaphthyl, nitrophenyl, dinitrophenyl, cyanophenyl, dicyanophenyl, chloropyridinyl, methylimidazolyl, phenylpyrrolyl, and ethylthienyl.

[0042] As used herein, the term "halogen" refers to fluorine, chlorine, bromine, and iodine.

[0043] As used herein, the term "silylhydrocarbyl" means -SiR 1 R 2 R 3 It refers to a radical, and here, R 1 , R 2 and R 3 Each of these is independently selected from the group consisting of hydrides and optionally substituted alkyl, alkenyl, alkynyl, heteroatom-containing alkyl, heteroatom-containing alkenyl, heteroatom-containing alkynyl, aryl, heteroaryl, alkoxy, aryloxy, amino, silyl, and combinations thereof. In "silyl hydrocarbyl", the silicon atom may be directly bonded to the metal, or the carbon atom of "silyl hydrocarbyl" may be directly bonded to the metal.

[0044] The term "saturated" means that it does not contain carbon-carbon double bonds, carbon-carbon triple bonds, or (in heteroatom-containing groups) carbon-nitrogen, carbon-phosphorus, or carbon-silicon double or triple bonds.

[0045] When used herein, "weight-average molecular weight" (M w The term Mw refers to the mass of individual polymer chains that contribute to the total molecular weight of a polymer, and as is well known in the art, Mw is calculated from the weight fraction distribution of molecules of varying sizes. Mw can be measured by gel permeation chromatography (GPC), osmotics, light scattering, viscosity, freezing point depression, boiling point elevation, ultracentrifugation, mass spectrometry, and end-group analysis, as is well known in the art.

[0046] As used herein, the terms “volatile product” or “volatile substance” refer to linear or branched hydrocarbons (where possible) having fewer than nine carbon atoms (e.g., less than C9).

[0047] As used herein, the terms “oil product” or “DCM extract” refer to a linear or branched hydrocarbon having 9 to 26 carbon atoms (e.g., C9 to C26).

[0048] As used herein, the terms “waxy product” or “solid” refer to a linear or branched hydrocarbon having 27 or more carbon atoms, wherein the number of carbon atoms is less than the number of carbon atoms of the original polymer from which the waxy product is formed according to this disclosure.

[0049] In this specification, the "~" symbol represents the word "approximately".

[0050] The abbreviation "atm" represents atmospheric pressure (1 atm = 101.325 kPa). The abbreviation "mol" represents mole, the abbreviation "℃" represents degrees Celsius, the abbreviation "kg" represents kilogram, the abbreviation "L" represents liter, the abbreviation "h" represents hour, the abbreviation "min" represents minute, the abbreviation "wt%" represents weight percentage, the abbreviation "ppm" represents parts per million, the abbreviation "mg" represents milligram, "rpm" represents revolutions per minute, and the abbreviation "μm" represents micrometer, i.e., 10⁻¹⁰ -6 It represents meters.

[0051] Polymers that can be depolymerized by hydrocracking using supported organometallic catalysts of this disclosure include polyolefins formed by polymerizing olefins (e.g., ethylene, propylene, hexene, octene, and combinations thereof). In this specification, the olefin may be an alphaolefin, as the polyolefin may be a polyalphaolefin. In various embodiments, the polymer is preferably selected from the group consisting of polyolefins, polymers (formed by polymerization of aromatic alkenes, e.g., styrene), and polymers (formed by polymerization of conjugated dienes, e.g., butadiene, isoprene, etc.). In various embodiments, the polyolefin is more preferably selected from the group consisting of polyethylene, polypropylene, linear or branched C4-C12 monoolefins, copolymers thereof, or combinations thereof. Most preferably, the polyolefin is polyethylene and polypropylene, copolymers thereof, or combinations thereof. The polymer may be linear or branched. The polymer may be a homopolymer or a copolymer. The polymer may have any tacticity and degree of tacticity, for example, isotactic, atactic, or syndiotactic with a degree greater than 90%. The polymer may have a variety of weight-average molecular weights (Mw), for example, in the range of 3 to 300 kg / mol, as is known in the art for various commercially available products.

[0052] Embodiments of this disclosure provide a method for the hydrocracking of polymers as defined herein, using a supported organometallic catalyst. The supported organometallic catalyst is formed from a specific combination of an acidic metal oxide support and an organometallic complex pre-catalyst. The supported organometallic catalysts of this disclosure, as defined herein, exhibit unexpectedly high activity in the hydrocracking of the disclosed polymers.

[0053] The hydrocracking method of this disclosure includes the step of supplying a polymer, hydrogen gas (H2), and a supported organometallic catalyst into a reactor. The supported organometallic catalyst is formed from an organometallic complex pre-catalyst of formula I and an acidic metal oxide support. The organometallic complex pre-catalyst of formula I is MR m Lx Equation I

[0054] In formula I, m is between 0 and 6, and x is between 0 and 6. As those skilled in the art will understand, the values ​​of m and x depend on the formal oxidation state of M in formula I. For example, when M is a group 4 transition metal (e.g., Zr, Hf, or Ti), m can be zero (0) and x can be 4. In a further example, when M is a group 5 transition metal (e.g., Nb or Ta), m can be 1 or 2 and x can be 3. In a further example, when M is a group 6 transition metal (e.g., W or Mo), m can be 1 or 2 and x can be 4. Other values ​​of m and x are, of course, also possible.

[0055] In various embodiments, M is a transition metal selected from the group consisting of Group 3 to Group 8 transition metals. In various embodiments, M is preferably selected from the group consisting of Group 4, Group 5, Group 6, or Group 8 transition metals. More preferably, M is selected from the group consisting of Group 4, Group 5, or Group 6 transition metals. Specific examples of M include those selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, or Ni. Preferably, M is selected from the group consisting of Ti, Zr, Hf, Nb, Ta, Mo, or W. Most preferably, M is derived from a Group 4 transition metal selected from the group consisting of Ti, Zr, or Hf.

[0056] In various embodiments, R is independently selected from the group consisting of H, C1-C8 hydrocarbyl, or halogen. If R is a halogen, it is preferably fluorine. If R is a hydrocarbyl, it is preferably C4-C8 hydrocarbyl. If R is a hydrocarbyl, it is more preferably C5-C6 hydrocarbyl. If R is a hydrocarbyl, it is most preferably C5 hydrocarbyl, where the (=CHtBu) portion is preferred when M is a group 5 transition metal, and the (≡CtBu) portion is preferred when M is a group 6 transition metal.

[0057] In various embodiments, each L is independently selected from the group consisting of C1-C12 substituted or unsubstituted hydrocarbyls. For various embodiments, the hydrocarbyl of L in formula I is independently selected from the group consisting of C1-C10 alkyls, C2-C10 alkenyls, or C5-C10 aryls. As used herein, the aryl may include multiple ring structures (e.g., fused rings). Preferably, in various embodiments, the hydrocarbyl of L in formula I is independently selected from the group consisting of C4-C7 alkyls, C3-C7 alkenyls, or C5-C8 aryls. Most preferably, L in formula I is neopentyl (abbreviated herein as "Np", e.g., 2,2-dimethylpropyl). For various embodiments, each L may be the same or different.

[0058] In a more specific embodiment, M is preferably selected from the group consisting of Zr or Hf. m is 0, and each L is independently selected from C1-C12 alkyl groups, where L is preferably neopentyl (e.g., 2,2-dimethylpropyl). Further examples of organometallic complex precatalysts of formula I include ZrNp4 (M=Zr, m=0, x=4 and L=Np), HfNp4 (M=Hf, m=0, x=4 and L=Np), TiNp4 (M=Ti, m=0, x=4 and L=Np), NbF2Np3 (M=Nb, m=2, R=F, x=3, L=Np), and Ta(=CH t Bu)Np3(M=Ta, m=1, R=(=CH t Bu), x=3, L=Np), Nb(CH t Bu)Np3(M=Nb, m=1, R=(=CH t Bu), x=3, L=Np), W(C) t Bu)Np3(M=W, m=1, R=(≡CtBu), x=3, L=Np), and Mo(C t Bu)Np3(M=Mo, m=1, R=(≡CtBu), x=3, L=Np) can be cited, but is not limited to these. Other exemplary organometallic complex precatalysts of formula I include MBz4(Bz=benzyl; M=Ti, Zr, Hf), MAllyl4(M=Ti, Zr, Hf), CrNp4, FeNp4, and CoNp3.

[0059] In various embodiments, the metal oxide used to form the acidic metal oxide support can be selected from the group consisting of aluminum oxide (Al2O3), silicon oxide (e.g., SiO2), nickel(II) oxide, zirconium(IV) oxide, tin(IV) oxide, hafnium(IV) oxide, titanium(IV) oxide, iron(III) oxide, zinc(II) oxide, or mixtures thereof. In various embodiments, the acid used to form the acidic metal oxide support can be selected from sulfuric acid, trifluoromethanesulfonic acid, fluorosulfonic acid, or fluorosulfonic acid + antimony pentafluoride ("magic acid"). For various embodiments, the acidic metal oxide support is a strongly Brønsted acidic oxide. Such oxides are generally classified as having a Hammett acidity function (i.e., H0) value greater than -15. Preferably, sulfated metal oxides can be used as the acidic metal oxide support. Exemplary sulfated metal oxides include alumina sulfate, silica sulfate, or combinations thereof. Alternatively, zeolite H-ZSM-5 may be used as the support material. In several embodiments, the support material is alumina sulfate.

[0060] The formation of acidic metal oxide supports can be achieved in several ways. For example, under atmospheric conditions, an acid (e.g., a 2.0 M aqueous sulfuric acid solution) can be added to a metal oxide (e.g., aluminum oxide) and stirred for a reaction time of 15 to 90 minutes. The proportion of the reaction mixture (e.g., the molar ratio of acid to oxide) can vary from 5:1 to 1:5. After the reaction time, the sulfated metal oxide is separated from the acid (e.g., by centrifugation), and then repeatedly rinsed with deionized (DI) water until the pH of the rinsed DI water reaches approximately 6. The resulting acidic metal oxide is then dried under vacuum at a temperature of 90 to 140°C for approximately 12 to 24 hours. The solid of the acidic metal oxide can be crushed (e.g., using a mortar and pestle) and sieved to a desired mesh (e.g., 180 mesh, 80 μm). Next, the acidic metal oxide can be calcined at a temperature of 400-650°C for 2-4 hours (for example, in a tubular furnace) while flowing O2 (approximately 2 L / min). After that, the acidic metal oxide is subjected to a vacuum (for example, connected to a high vacuum line and pumped to a low vacuum (for example, approximately 10°C)). -6 The acidic metal oxide is placed in a tubular furnace (reduced to Torre) at a temperature of 300-450°C for 1 hour. Then, the acidic metal oxide is cooled under vacuum and placed in an inert (e.g., argon) environment, where it can be removed or stored under an inert gas (e.g., argon).

[0061] In various embodiments, the supported organometallic catalyst is formed from an organometallic complex pre-catalyst of formula I and an acidic metal oxide support. The formation of the supported organometallic catalyst can be achieved by a chemioadsorption process (e.g., adsorption in which the adsorbed substance is held by electrostatic chemical bonding) as follows: The organometallic complex pre-catalyst of formula I and the acidic metal oxide support, in various molar ratios (1:20 to 5:20), are combined with a C4 to C8 organic solvent (e.g., n-pentane) at a temperature of 20 to 30°C to form a slurry. The slurry is reacted for 30 minutes to 4 hours. The resulting supported organometallic catalyst is then filtered, washed with unused organic solvent, and dried under vacuum for at least 1 hour. The supported organometallic catalyst is stored in an inert atmosphere (e.g., argon).

[0062] In various embodiments, the supported organometallic catalysts discussed herein are represented by formula II. L y-x R x-z M n+ ··· O - (Acidic metal oxide support) Formula II In the formula, M is selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, or Ni; R is independently selected from hydrogen, halogen, or L; each L is independently selected from saturated or unsaturated hydrocarbyls of C1-C12 or silyl hydrocarbyls of C1-C12; n is 1, y is 3, x is 2 or 1, and z is 1 or 0. In some embodiments, if M is not in the highest possible oxidation state, n may be 2 or 3. For example, when M is either Co or Fe, L2Co 2+ ··· O - (Acidic metal oxide support) or L2Fe 2+ ··· O - To obtain the (acidic metal oxide support), n can be 2, x can be 1, and z can be 1. In equation II, "..." represents the O of the support material. - and M n+ It represents an electrostatic non-covalent bond between and ··· O -'' represents a weakly Lewis basic support material after deprotonation. Preferably, for formula II, M is selected from the group consisting of Ti, Zr, or Hf, each L is a saturated or unsaturated hydrocarbyl of C3 to C8, n is 1, y is 3, x is 1, and z is 1. More preferably, for formula II, M is selected from the group consisting of Ti, Zr, or Hf, each L is a saturated hydrocarbyl of C5, n is 1, y is 3, x is 1, and z is 1. The supported organometallic catalyst may be an acidic metal oxide support material, where M is Ti, Zr, or Hf, L is neopentyl, n is 1, y is 3, x is 1, and z is 1. If R is a halogen, it is preferably fluorine. Further examples of supported organometallic catalysts represented by Equation II include those where R is absent, given that M=Zr, L=Np, n=1, y=3, x=1, and z=1; those where R is absent, given that M=Hf, L=Np, n=1, y=3, x=1, and z=1; those where R is absent, given that M=Ti, L=Np, n=1, y=3, x=1, and z=1; and those where M=Ta, L=Np, R=CH t Bu, n=1, y=3, x=2 and z=1; M=Nb, L=Np, R=F, n=1, y=3, x=2 and z=0; M=Nb, L=Np, R=CH t Bu, n=1, y=3, x=2 and z=1; M=W, L=Np, R=C t Bu, n=1, y=3, x=2 and z=1; and M=Ta, L=Np, R=C t Examples include Bu, n=1, y=3, x=2, and z=1.

[0063] A method for preparing a supported organometallic catalyst from an organometallic complex pre-catalyst of formula I and an acidic metal oxide support is also described in the following examples. In particular, the use of sulfuric acid treatment, calcination temperature, and inert solvent (e.g., dry hydrocarbon) when preparing the supported organometallic catalyst as described in the following examples helps to reliably achieve the desired supported organometallic catalyst. In one embodiment, the supported organometallic catalyst is of formula L2M + R···O - ···It can be represented by (acidic metal oxide support), where L and M are as defined herein, "+" represents the formal cation charge on M, R is hydrogen or L, and "..." represents the O of the support material. - and M + It represents an electrostatic non-covalent bond between and ··· O - This represents a weakly Lewis-basic support material after deprotonation.

[0064] The supported organometallic catalyst of this disclosure differs from existing catalysts represented by the formula shown in Figure 1A. In particular, in the supported organometallic catalyst of this disclosure, M is formally cationic, whereas in conventional catalysts, M is formally neutral. Furthermore, in the supported organometallic catalyst, M is non-covalently / electrostatically bonded to the support material, whereas in existing catalysts, M is covalently bonded. These differences are shown in Figures 1A and 1B. Figure 1A represents an existing catalyst, and Figure 1B represents an example of the supported organometallic catalyst of this disclosure.

[0065] The method of the present invention further includes the step of reacting a polymer specified herein with a supported organometallic catalyst in a reactor at a predetermined temperature in the presence of hydrogen gas to produce a reduced polymer product having a weight-average molecular weight smaller than that of the polymer. In various embodiments, the surface area of ​​the polymer can be increased by reduction operations before or during the reaction. Such reduction operations include, but are not limited to, chopping, shearing, pulverizing, shave, and / or grating the polymer into pieces smaller than those before the reduction operation.

[0066] The conditions used in this method include parameters such as a predetermined temperature, H2 pressure, time, and the amount of metal supported by the supported organometallic catalyst. Generally, these parameters are selected in combination to induce the desired hydrocracking reaction. Furthermore, the parameters can be adjusted to achieve the desired product or its yield, product distribution, activity, polymer conversion rate, or a combination thereof.

[0067] Examples of predetermined temperatures include those in the range of 60°C to 300°C. Preferably, the predetermined temperature is 90°C to 200°C. More preferably, the predetermined temperature is 110°C to 150°C.

[0068] For various embodiments, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.1 atmospheres to 100 atmospheres. Preferably, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.2 atmospheres to 50 atmospheres. More preferably, the step of supplying hydrogen gas to the reactor includes supplying hydrogen gas to the reactor at a pressure of 0.5 atmospheres to 4 atmospheres.

[0069] For various embodiments, the step of reacting the polymer may include stirring the polymer with the supported organometallic catalyst at a speed of 500 rpm to 3000 rpm in the presence of hydrogen gas. Such stirring of the supported organometallic catalyst and the polymer ensures more complete mixing of the polymer and the supported organometallic catalyst.

[0070] In various embodiments, the step of supplying a supported organometallic catalyst into the reactor includes supplying M in an amount of 0.01 mol% (mol%) to 0.9 mol% based on the monomer units of the polymer (e.g., the -C2H4- monomer units of polyethylene). For example, exemplary metal loading amounts include metal loading amounts in which the metal is in the range of 0.01 mol% to 0.6 mol% (based on monomer units, e.g., monomer units formed from ethylene). Preferably, the step of supplying a supported organometallic catalyst into the reactor includes supplying M in an amount of 0.005 mol% to 2.0 mol% based on the monomer units of the polymer.

[0071] This method can be carried out using various types of reactor systems (batch reactor systems, semi-batch reactor systems, plug-flow reactor systems, and continuous-flow reactor systems, etc.). The reactor volume can be sufficient to ensure that a sufficient amount of hydrogen (e.g., moles of hydrogen) relative to the polymer is present in the reactor so that the desired reduced polymer product is achieved. In various embodiments, continuous-flow reactor systems include tubular reactors, continuous stirred-tank reactor systems, fluidized-bed reactors, and fixed-bed reactors. To heat the reaction of this disclosure, the reactor may be equipped with a heating jacket and / or heating coil. Heat can be supplied to the reaction by supplying steam to the heating jacket and / or heating coil. Alternatively, the heating jacket and / or heating coil may be supplied with the heat required for the reaction of this disclosure using a thermal fluid system (e.g., a heat transfer oil or a water / glycol mixture). Other techniques for heating the reaction of this disclosure are also possible.

[0072] For various embodiments, the step of reacting the polymer with a supported organometallic catalyst in the presence of hydrogen gas at a predetermined temperature lasts for a period of 0.25 hours to 24 hours. Other examples of reaction times include those in the range of 0.25 hours to 8 hours and 0.25 hours to 1.5 hours. Depending on the reactivity of the catalyst, the predetermined temperature, and the hydrogen pressure in the reactor, the reaction time can be varied to achieve a desired product or product profile of a reduced polymer product having a weight-average molecular weight smaller than that of the polymer.

[0073] In various embodiments, the reduced polymer products (e.g., hydrocracked polymer products) produced according to the methods of this disclosure have a smaller weight-average molecular weight than the original polymer from which they are produced. The reduced polymer products produced by this method include fragments of the polymer being depolymerized (e.g., the starting polymer). The weight-average molecular weight of these fragments is smaller than that of the polymer itself. The reduced polymer products can be characterized as volatile products (with relatively small weight-average molecular weights and generally in a gaseous / volatile form), oily products (with more moderate weight-average molecular weights and generally in a liquid form), and waxy products (with higher weight-average molecular weights but still smaller than that of the original polymer).

[0074] Volatile products can be characterized by having fewer than 9 carbon atoms, oily products by having between 9 and 26 carbon atoms, and waxy products by having more than 26 carbon atoms (but still fewer than the original polymer). The exact carbon number range and molecular weight range of the products depend on the starting polymer and the specific conditions used. Similarly, the amount of each type of product depends on the starting polymer and the specific conditions. However, embodiments of this method can be characterized by producing mainly volatile and oily products. In several embodiments, the amount of waxy product produced may be less than 5 wt%, less than 4 wt%, or less than 3 wt%, based on the total weight of the reduced polymer product. Furthermore, this method can be characterized by the fact that the amount of product with a molecular weight greater than the polymer (e.g., the starting polymer) is essentially zero (i.e., less than 0.1 wt%). These values ​​may be mentioned for specific condition settings, e.g., 150°C, 2 atm of H2, 2 hours, and 0.06 mol% of metal. The reduced polymer product can be recovered and used as desired.

[0075] The method of the present invention (and the supported organometallic catalyst used therein) can be characterized by high activity and high conversion rate. Activity can be quantified by turnover frequency. The turnover frequency measured under specific conditions, e.g., 150°C, 2 atm of H2, 2 hours, and 0.06 mol% of metal, is at least 10 mol metal-mol substrate. -1 ·h -1 at least 100 moles of metal / molar substrate -1 ·h -1 at least 250 molar metal-molar substrate -1 ·h -1 , or at least 500 molar metal-molar substrate -1 ·h -1 It is possible. The conversion rate refers to the total weight of the dichloromethane-soluble fraction and gaseous fraction recovered after the reaction, as a percentage of the weight of the starting polymer. Under specific conditions, e.g., 150°C, 2 atm of H2, 2 hours, and 0.06 mol% metal, the conversion rate may be 10% or more, 50% or more, 90% or more, 95% or more, 98% or more, or 100%.

[0076] It should be noted that the results obtained using this method are not only surprising but also unexpected. Similar catalysts have been used to induce olefin polymerization and arene hydrogenation, but these are mechanistically different from the hydrogenolysis / depolymerization of polymers. This fact, and the inherent unpredictability at the heart of organometallic chemistry, makes the remarkable activity of the supported organometallic catalyst in the method of the present invention truly surprising. For example, the activity of the supported organometallic catalyst used in the following examples to depolymerize polyethylene with 0.06 mol% Zr metal at 150°C, 2 atm of H2 for 2 hours was measured to be about two orders of magnitude higher than that of existing catalysts (where Zr is formally neutral and covalently bonded to the metal oxide support). More specifically, the supported organometallic catalyst used in the examples can depolymerize polyethylene about 100 times faster than another catalyst (which does not use a sulfated oxide support, as used under similar conditions in "Dufaud, VR, et al., Angew Chem Int Edit 1998, 37(6), 806-810"). As another example, the supported organometallic catalyst used in the examples can depolymerize isotactic polypropylene about 180 times faster than another catalyst used under similar conditions by Dufaud et al. [Examples]

[0077] Materials and methods All procedures involving air-sensitive compounds and moisture-sensitive compounds must be performed under high vacuum (10 -5 ~10 -6 The process was carried out in flame-dried or oven-dried Schlenk-type glassware connected to a Toll line, or in an argon-filled MBRAUN glove box equipped with a high-volume recirculator (O2 less than 1 ppm), strictly eliminating oxygen (O2) and moisture (e.g., H2O). The argon used in the high-vacuum line (Airgas ultra-high purity (UHP) grade) was purified by passing it through a MnO / vermiculite and activated Davidson 4A molecular sieve column.

[0078] All solvents were dispensed from an activated alumina / CuO column immediately before use. n-pentane (Sigma-Aldrich) was further purified by drying on a Na / K alloy and then passing through a glass fiber filter in an argon glove box. Aluminum oxide (gamma, nanopowder 20-30 nm) was purchased from Nanostructured and Amorphous Materials Inc. Sulfuric acid (98%) was purchased from Fisher. n-hexadecane (C16) was purchased from Sigma-Aldrich and purified by heating on Na at 120°C for 48 hours (h), followed by degassing at room temperature (23°C), and further purified by passing through a 0.22 μm PTFE syringe filter three times immediately before use. n-hexadecane-d 34 (98%+D) was purchased from Cambridge Isotope Laboratories Inc. and purified using the same method as for C16. All polymer-containing components that would come into direct contact with C16 before the hydrocracking experiment (i.e., syringes, syringe filters, needles, Teflon reactor caps) were treated overnight in an argon-filled glove box before use. The oxygen (UHP grade) used for calcination was purchased from Airgas and used without further purification. Deuterium (Sigma-Aldrich) and hydrogen (H2, Airgas UHP grade) were purified by passing them through an oxygen / moisture trap (Matheson, model MTRP-0042-XX). Zirconium(IV) chloride and neopentyl magnesium chloride (1.0M Et2O solution) were purchased from Sigma-Aldrich and used without further purification. Tetra(neopentyl)zirconium (ZrNp4) was synthesized according to the literature procedure "Davidson, PJ; Lappert, MF; Pearce, RJ Organometal. Chem. 1973, 57, 269-277" at 70°C and approximately 10°C. -6 It was refined by sublimation in Thor's oak.

[0079] The polyolefin used in this example is Engage® 8402 polyolefin elastomer (0.902 g / cm³). 3Ethylene-octen copolymer with density (0.902 g / cm³); Engage (trademark) 8450 polyolefin elastomer (0.902 g / cm³) 3 Ethylene-octen copolymer with density (0.902 g / cm³); Affinity (trademark) 1850G polyolefin plastomer (0.902 g / cm³) 3 Polyethylene plastomer with density (0.87 g / cm³); Affinity (trademark) GA 1900 polyolefin plastomer (0.87 g / cm³) 3 There are polyethylene plastomers with a density of , all obtained from Dow®. In this example, all were used as is. Further polyolefins for this example were obtained from high-density polyethylene (HDPE) milk jugs and HDPE fruit pouch caps.

[0080] Laboratory-synthesized polyolefins were dried under high vacuum in a molten state (130-165°C) for 48 hours (h) before being used in the hydrocracking reaction. Immediately before use, shavings of the polyolefin were taken from the packs formed by the melt-drying process.

[0081] Physical and analytical measurements Inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis was performed by Galbraith Laboratories, Inc. (Knoxville, Tennessee). 1 H (500MHz) and 13 The 1C (125 MHz) NMR spectrum was obtained using a Bruker Avance III system equipped with a DCH cryoprobe. 1 H MAS (400MHz) and 13 Solid-state NMR measurements using C CP-MAS (100 MHz) were obtained using a Bruker Avance III system equipped with a 4 mm Bruker HX probe. The rotor speed was set to 14 kHz for all spectra.

[0082] Gas chromatography-mass spectrometry (GC-MS) analysis of the hydrocracking product mixture was performed on an Agilent GCMSD equipped with a DB5 column (oven program: 1.) held at 50°C for 2 minutes, 2.) heated at 30°C / min, 3.) held at 300°C for 2 minutes). 2 μL / injection and split-mode injection with a 100:1 splitting ratio were used. For GC-MS quantification of n-hexadecane, a target sample concentration of approximately 0.2 mg / mL was used, and four-point calibration (0.1 mg / mL, 0.2 mg / mL, 0.3 mg / mL, 0.4 mg / mL) was performed for each group of samples analyzed by GC-MS. Calibration standards were stored in airtight glassware with Teflon valves.

[0083] Diffuse reflectance infrared spectroscopy (DRIFTS) measurements were obtained using a Thermo 6700 infrared spectrometer equipped with a Harrick Praying Mantis DRIFTS attachment. A ZnS window was used as the DRIFTS cell. Anhydrous KBr was used as the background. The DRIFTS cell contained dry argon (less than 1 ppm O2 / less than 1 ppm H2O) from a glove box throughout all measurements. Surface area measurements were performed using a Micromeritics 3Flex surface characterizer. Brunauer-Emmett-Teller (BET) surface area was measured using nitrogen gas adsorption analysis according to "S. Brunauer, PHEmmett, E. Teller, J. Am. Chem. Soc. 1938, 60, 309-319".

[0084] X-ray absorption near-edge structure (XANES) and wide-area X-ray absorption fine structure (EXAFS) measurements at the K absorption edge (17998 eV) of Zr were performed at the 5BM-D beamline of the DND-CAT advanced synchrotron radiation facility in the United States. ΔE / E = 1.4 × 10⁻⁶ -4A dual Si(111) monochromator with a high energy resolution was used for energy selection. The X-ray energy was calibrated using metallic Zr foil. The incident X-ray intensity was measured using a spectroscopic-grade ionization chamber (FMB Oxford) filled with 600 (Thor) He and 100 (Thor) N2, and detuned to 60% of its maximum value for harmonic rejection. EXAFS spectra were collected in fluorescence mode using a passivation-injected planar silicon (PIPS) detector (Canberra). The sample and detector were positioned at 45 degrees and 90 degrees, respectively, with respect to the X-ray beam direction. Energy scanning was performed from 250 eV below the K absorption edge of Zr that generates the EXAFS spectrum to 550 eV above it.

[0085] Gel permeation chromatography (GPC) analysis was performed at 150°C using a Polymer Laboratories PL-GPC220 equipped with three PLgel 10 μm MIXED-B LS300 × 7.5 mm columns, with 1,2,4-trichlorobenzene stabilized with 0.0125% butylated hydroxytoluene. Calibration was performed using polystyrene standards (860–3,752,000 g / mol). Samples were prepared by dissolving the polymer in stabilized trichlorobenzene at 150°C and gently shaking overnight to obtain a solution concentration of approximately 1.0 mg / mL. Before measurement, samples were filtered through a 0.5 μm porous stainless steel filter.

[0086] AlS synthesis Under atmospheric conditions, 7.0 g of aluminum oxide was added to 288 mL of sulfuric acid (2.0 M aqueous solution prepared from deionized (DI) water) while stirring. After stirring the suspension for 30 minutes, it was centrifuged (4000 rpm for 5 minutes). The suspended solids were discarded, and the alumina was resuspended in DI water and centrifuged again. This process was repeated until the pH reached approximately 6 (typically a total of 7 washes). The resulting solid was heated at 120°C and approximately 10°C. -6The material was dried in a mortar for 18 hours. The solid was then crushed in a mortar and pestle and sieved to a 180-mesh (80 μm) sieve. The powder was loaded into a quartz boat, placed in a tubular furnace, and calcined at 550°C for 3 hours while flowing O2 (approximately 2 L / min). A high vacuum line was then connected to the tubular furnace, and the material was fermented for approximately 10 hours. -6 The furnace was pumped under reduced pressure at 450°C for 1 hour until it reached a thick state. The furnace was cooled under vacuum and placed in an argon glove box. AlS (white powder, 4.83 g) was recovered and stored in a sealed container under argon.

[0087] Chemisorption of ZrNp4 on AlS for the formation of supported organometallic catalysts (SOCs) In a dry reaction vessel fitted with frit on both sides, 25 mL of pentane was condensed over a sufficient mixture of ZrNp4 (66.67 mg, 0.177 mmol) and AlS (1.000 g). The resulting slurry was stirred at 25°C for 1 hour and then filtered. After chemiadsorption, the solids turned pale yellow. The impregnated carrier was collected on frit, washed five times with approximately 10 mL of n-pentane, and then dried in vacuum for 1 hour. 1 Using 1H-NMR, the presence of physically adsorbed (weakly bound) residual ZrNp4 was confirmed by directly adding approximately 10 mg of solid material to the NMR tube using benzene-d6 or toluene-d8 as the solvent. If residual organometallic compounds are present, ZrNp4 will be... 1 The catalyst was further washed with pentane as described above until it became invisible on the H-NMR spectrum. The catalyst was then stored in a sealed container at -40°C in an argon glove box until required for use. Alternatively, ZrNp4 and AlS were combined in a Teflon sealed valve, and then pentane was transferred into the valve under vacuum. This mixture was stirred at 25°C for 1 hour. The pentane was removed under vacuum, and the solids were removed for approximately 10 minutes. -6 After drying in a Toll for 1 hour, the catalyst was stored as described above. No difference in catalytic activity was observed in the catalyst preparation prepared by this alternative method. The amount of SOC(AlS / ZrNp2) loaded was measured by ICP-AES, and the Zr content was 1.40 wt% (average of two batches with Zr content of 1.38 wt% and 1.42 wt%). The BET surface area of ​​the catalyst due to N2 physicoadsorption was 184 m². 2The value was / g, therefore the Zr coverage was 0.50Zr / nm 2 That is the case.

[0088] Synthesis of AlS / ZrH2, AlS / ZrD2, and pAlS / ZrH2 (pentane-treated AlS / ZrH2) Synthesis of AlS / ZrH2. In a glove box, AlS / ZrNp2 (200 mg) was placed in a 75 mL glass pressure reactor. The reactor was sealed, connected to a high-pressure / high-vacuum line and evacuated, then filled with H2 at 1 atm (101.325 kPa). The reactor was heated to 150°C for 5 minutes and then evacuated. The color of the catalyst changed from pale yellow to colorless. This cycle was repeated once more. AlS / ZrH2 was then used for further reactions or measurements as needed. AlS / ZrD2 was synthesized in a similar manner to AlS / ZrH2 using D2 instead of H2. To synthesize pAlS / ZrH2, pentane (approximately 0.5 mL) was vacuum-transferred via a high-pressure / high-vacuum line into a 75 mL pressure reactor containing AlS / ZrNp2 (200 mg). The reactor was heated to 150°C for 5 minutes. A color change from colorless to pale yellow was observed during the first 30 seconds of heating. The catalyst was stored at -40°C in an argon glove box until needed.

[0089] A typical hexadecane hydrocracking procedure using AlS / ZrNp2: Inside the glove box, C16 was passed through a 0.22 μm PTFE syringe filter and directly added to a thick-walled glass pressure reactor containing a 10 mm oval-shaped stirring bar. AlS / ZrNp2 was added to the reactor and sealed with a threaded Teflon cap fitted with an American Standard Tapered Thread (NPT) valve. The container was carefully removed from the glove box and connected to the high-pressure / high-vacuum line. After degassing the reactor at room temperature for 90 seconds, it was filled with H2 at the required pressure. The reactor was placed in an oil bath set to the desired temperature and stirring was started at approximately 500 rpm. Once the thermocouple in the oil bath reached the reaction temperature, the time interval was started. At the end of the time interval, the reactor was removed from the oil bath and then cooled to room temperature in a water bath. At this point, headspace samples were taken as needed. The reactor was vented to air through the NPT valve. The inside of the Teflon cap and NPT valve were washed with approximately 5 mL of dichloromethane (DCM). These washings were added to the reactor. The washings were transferred to a syringe equipped with a 0.22 μm PTFE filter. The reactor was washed four times (x) with approximately 10 mL of clean DCM, and the washings from each wash were added to the syringe. The washings were placed directly into a 100 mL volumetric flask through the filter. The filter was washed four times with approximately 5 mL of clean DCM, and the washings were added to the volumetric flask. The pipette used to transfer the DCM solution was also washed with clean DCM and added to the volumetric flask. After diluting the solution to the calibration mark, it was further diluted to approximately 0.2 mg / mL using standard analytical techniques.

[0090] General polyolefin hydrocracking procedure: In a glove box, AlS / ZrNp2 and the desired amount of polyolefin sample were placed in a thick-walled glass pressure reactor containing a 10 mm oval stirrer, typically with a loading of approximately 15% by mass of SOC. Laboratory-prepared polyolefin samples were prepared by shearing from relatively large packs of pre-molten stock. Dow® polyolefin samples were used as is. Used polyolefin samples were subdivided using either a cheese grater or scissors. The reactor was sealed with a threaded Teflon cap fitted with an NPT valve. The container was carefully removed from the glove box and connected to the high-pressure / high-vacuum line. The reactor was degassed at room temperature for 90 seconds and then filled with 2 atmospheres of H2. The reactor was placed in an oil bath set to the desired temperature (90-200°C).

[0091] Once the polyolefin had melted and come into contact with the catalyst in the molten material, the time interval was started. Stirring was typically initially set to 300 rpm, then increased to approximately 800 rpm after the polyolefin viscosity had sufficiently decreased. At the end of the time interval, the reactor was removed from the oil bath and then air-cooled to room temperature. Headspace samples were taken at this point if necessary. Headspace samples were collected by diffusing the contents of the reactor into a 500 mL glass valve with a Teflon valve that was evacuated. Individual analytical samples were collected via septum and airtight headspace syringes (50 μL). The reactor was vented to air through the NPT valve. The inside of the Teflon cap and NPT valve were washed with approximately 5 mL of DCM. These washings were added to the reactor. Solids were isolated by suspending them in the DCM washings and then filtering. The reactor was thoroughly washed to remove all residues. The solids were washed approximately three times with 5 mL of DCM, and then dried overnight at approximately 1 Tor (133 Pascals) (solids fraction). DCM was removed from the filtrate (DCM extract fraction), and the resulting liquid was dried overnight at approximately 1 Tor (133 Pascals).

[0092] AlS / ZrNp2 results The results shown in Table 1 demonstrate the complete conversion rate of C16 using the general hexadecane hydrocracking procedure described above with AlS / ZrNp2. For the following data, Experiment "a" in Table 1 was conducted in a 500 mL reactor with 3.0 g of C16 and 200 mg of AlS / ZrNp2 (Zr 1.40 wt%) at 2 atm of H2. Experiment "b" in Table 1 was conducted in a 350 mL reactor with 1.483 g of C16 and 178 mg of AlS / ZrNp2 (Zr 0.17 wt%) at 2.5 atm of H2. The average carbon chain length was calculated assuming only straight chains existed. 1 This was estimated by 1H-NMR. As shown in Table 1, the conversion rate of C16 was 100%.

[0093] [Table 1]

[0094] Table 2 shows the data for the C16 hydrogenolysis reaction under varying pressures. The results in Table 2 indicate that there is no H2 pressure dependence (and consequently H2 concentration dependence), which is consistent with the zero-order reaction rate of H2. In the experiments in Table 2, 2.5 wt% AlS / ZrNp2 (Zr was 1.40 wt%) was present in the reactor. In experiment "a" in Table 2, 7 equivalents of H2 were present relative to C16.

[0095] [Table 2]

[0096] Table 3 shows data for the C16 hydrocracking reaction with varying catalyst loads in AlS / ZrNp2 (1.40 wt% Zr in the reactor, 0.6-5.44 wt% catalyst). The data shows the linear relationship (R) between conversion rate and catalyst load. 2 This value (=0.98451) suggests the first-order reaction rate with respect to the catalyst concentration.

[0097] [Table 3]

[0098] Table 4 presents data on the C16 hydrogenolysis conversion rate as a function of time for AlS / ZrNp2 (Zr content in the reactor is 1.40 wt%, SOC is 2.5 wt%). The data shows a linear relationship (R) between time and the C16 conversion rate. 2 This demonstrates that the kinetics (=0.9346) are of the pseudo-zero order, suggesting that the conditions used in the kinetic experiments were of the quasi-zero order.

[0099] [Table 4]

[0100] Table 5 presents data on the temperature dependence of C16 hydrocracking using AlS / ZrNp2 (1.40 wt% Zr in the reactor, 2.5 wt% catalyst). The data shows a linear relationship (R) between temperature and the conversion rate of C16. 2 This demonstrates a reaction ratio of 0.99924, which suggests a first-order reaction with respect to reaction temperature.

[0101] [Table 5]

[0102] Table 6 shows the results of a new laboratory-synthesized polyethylene homopolymer (M) using AlS / ZrNp2 (1.40 wt% Zr in the reactor, 12.5 wt% catalyst). n Approximately 9 kg·mol -1 We present data on the conversion rate of ) to gaseous hydrocarbons and DCM-soluble hydrocarbons as a function of time. Figure 2 shows the mass percentages of volatile substances, DCM extracts, and solid products of the reduced polymer products from Table 6.

[0103] [Table 6]

[0104] Table 7 presents data as a function of time for the conversion of fresh laboratory-synthesized isotactic polypropylene homopolymer (M n w is approximately 36 kg·mol -1 -1) into gaseous hydrocarbons and DCM-soluble hydrocarbons, using AlS / ZrNp2 (Zr in the reactor is 1.40 wt%, catalyst is 17 wt%). Figure 3 shows the mass percentages of volatiles, DCM extracts and solid products of the reduced polymer products in Table 7.

[0105]

Table 7

[0106] Table 8 presents data as a function of time for the conversion of fresh laboratory-synthesized polyethylene-co-1-octene (1-octene incorporation rate is 2.5%, M n w is approximately 7 kg·mol -1 -1) into gaseous hydrocarbons and DCM-soluble hydrocarbons, using AlS / ZrNp2 (Zr in the reactor is 1.40 wt%, catalyst is 13 wt%). Figure 4 shows the mass percentages of volatiles, DCM extracts and solid products of the reduced polymer products in Table 8.

[0107]

Table 8

[0108] Discussion of Results for AlS / ZrNp2 0 supported on acidic metal oxide, formally cationic Zr(IV) hydrocarbyl 0 is observed to be the fastest currently known catalyst for hydrogenolysis of polyolefins and alkanes under the reported reaction conditions. Compared with formally neutrally charged Zr catalysts supported on weakly acidic surfaces, this system shows an activity increase of at least two orders of magnitude. Kinetic experiments show that the reaction is zero-order with respect to both hexadecane and H2, and first-order with respect to the catalyst. Both DRIFTS and SSNMR provide evidence for the existence of Zr hydride as the active species.

[0109] The AlS / ZrNp2 SOC used in the above hydrocracking experiments of alkanes (C16) and polyolefins is formally a cationic (i.e., charged) Zr alkyl complex, adsorbed onto an acidic metal oxide support (e.g., a highly Brønsted acidic alumina sulfate support, Figure 1B) and activated by the acidic metal oxide support. In contrast, conventional Zr alkane and polyolefin hydrocracking catalysts are formally neutrally charged (i.e., uncharged) Zr complexes covalently bonded to a weakly Brønsted acidic support (Figure 1A). Despite having similar bulk stoichiometric compositions, this cationic non-covalent Zr alkyl complex is significantly superior to conventional catalysts, achieving a Zr load of 0.06 mol% (based on -C2H4- monomer units) on the acidic metal oxide support after only 2 hours at 150°C under a H2 pressure of 2 atmospheres, and cracking polyethylene and other polyolefins into volatile products (less than C9) and oily products (C9-C9). 26 ), and trace amounts of waxy products (C 26 ~C 60 This can be completely converted to approximately 3%. The organometallic complex precatalyst used in the above experiments, tetrakis(neopentyl)zirconium, is one of a series of electron-deficient Group 4 metal hydrocarbyls and hydrides that can be immobilized on acidic metal oxide supports, such as sulfated metal oxides (e.g., alumina sulfate). Although similar catalysts have been shown to be active in olefin polymerization and arene hydrogenation, it was entirely unexpected that they would activate saturated hydrocarbons and polyolefins to achieve high yields of depolymerization / hydrocracking products under relatively mild conditions. In fact, as demonstrated above, the exemplary catalyst shown in Figure 1B is extremely active for alkane hydrocracking, mediating the complete conversion of polyethylene, isotactic polypropylene, and polyethylene-co-1-octene to light hydrocarbons and waxes in less than 2 hours using low catalyst loads (0.06-0.13 mol% Zr) and mild conditions (150-190°C, 2 atm H2).

[0110] Formation of SOC by chemical adsorption of HfNp₄ on AlS Tetra(neopentyl)hafnium (HfNp₄) was synthesized according to the literature procedure "Davidson, P. J.; Lappert, M. F.; Pearce, R. J. Organometal. Chem. 1973, 57, 269-277" at 80°C and about 10 -6 purified by sublimation in torr. In a dry reaction vessel fitted with fritted discs on both sides, 25 mL of pentane was condensed onto a thoroughly mixed amount of HfNp₄ (84.0 mg, 0.181 mmol) and AlS (1.000 g). The resulting suspension was stirred at 25°C for 1 hour and then filtered. After chemical adsorption, the solid remained white. The impregnated support was collected on the fritted disc, washed 5 times with approximately 10 mL portions of n-pentane, and then dried in vacuum for 1 hour. The catalyst was then stored in a sealed container at 25°C in an argon glove box until required for use. The loading amount of SOC (AlS / HfNp₂) measured by ICP-AES showed that the Hf content was 3.28 wt%.

[0111] General procedure for C16 hydrocracking using AlS / HfNp₂ In a glove box, C16 was passed through a 0.22 μm PTFE syringe filter and directly charged into a thick-walled glass pressure reactor containing the desired amount of SOC. The reactor was sealed with a threaded Teflon cap fitted with an NPT valve. The vessel was then degassed for 90 seconds at room temperature and recharged with 2 atmospheres of H₂. The reactor was placed in an oil bath set at 150°C, and stirring was started at approximately 200 rpm. A time interval was started once the thermocouple of the oil bath reached 147°C. The time when all C16 was consumed was visually observed and recorded. Headspace samples and condensed samples were collected and characterized by GC-FID and GC-MS, respectively.

[0112] Table 9 shows the data for the C16 hydrogenolysis reaction under varying pressures. The results in Table 9 indicate that there is no H2 pressure dependence (and consequently H2 concentration dependence), which is consistent with the zero-order reaction rate of H2. In the experiment shown in Table 9, 4.2 wt% of SOC (AlS / HfNp2) was present in the reactor (Hf was 0.14 wt%).

[0113] [Table 9]

[0114] Table 10 shows data for the C16 hydrocracking reaction with AlS / HfNp2 (Hf = 3.28 wt%) with varying catalyst loads. The data shows a linear relationship (R) between conversion rate and catalyst load. 2 This shows a value of 0.9889, which suggests the first-order reaction rate with respect to SOC concentration.

[0115] [Table 10]

[0116] Table 11 shows data on temperature dependence in the hydrogenolysis of C16 using AlS / HfNp2 (Hf = 3.28 wt%). The data shows the linear relationship (R) between temperature and the conversion rate of C16. 2 This yields a value of 0.8404, which suggests a first-order reaction rate with respect to reaction temperature.

[0117] [Table 11]

[0118] Table 12 shows selected data from the hydrocracking reaction of polyethylene (Engage® 8402) in a 25 mL Parr autoclave, using AlS / HfNp2 (Hf = 3.28 wt%) and starting stirring at approximately 1500 rpm.

[0119] [Table 12]

[0120] Discussion of AlS / HfNp2 results AlS / HfNp2 SOC is a structural analog of AlS / ZrNp2 SOC, in which the metal is substituted with Hf. As shown in the data above, AlS / HfNp2 SOC can provide rapid catalytic activity for the hydrocracking of polyolefins and alkanes. Although the rate of hydrocracking is slower than that of the Zr catalyst under the same conditions, the Hf system has been observed to have higher thermal stability.

[0121] Ta(CH) on AlS t Formation of SOC by chemiadsorption of Bu)Np3 Ta(CH t Bu)Np3 was synthesized according to the literature procedure "Schrock, RR; Fellmann, JDJAm.Chem.Soc., 1978, 100, 3359". In a dry reaction vessel with dry frit on both sides, Ta(CH t A mixture of Bu)Np3 (100 mg, 0.215 mmol) and AlS (1.20 g) was vacuum-transferred with 20 mL of pentane. The resulting suspension was stirred at 25°C for 2 hours and then filtered. After chemiadsorption, the solids were pale yellow. The impregnated carrier was collected on frit, washed five times with approximately 10 mL of pentane, and then dried in vacuum for 1 hour. The catalyst was stored in an argon glove box at -40°C until needed. ICP-AES analysis revealed the AlS / Ta(CH t The SOC-loaded amount of Bu)Np was 2.75 wt% Ta.

[0122] Formation of SOC by chemical adsorption of TiNp4 on AlS TiNp4 was synthesized according to the literature procedure "Cheon, J.; Rogers, DM; Girolami GSJAm. Chem. Soc., 1997, 119, 6804". In a dry reaction vessel lined with dry frit on both sides, 20 mL of pentane was vacuum-transferred to a mixture of TiNp4 (53 mg, 0.159 mmol) and AlS (0.90 g). The resulting suspension was stirred at 25°C for 1 hour and then filtered. After chemiadsorption, the solids were pale yellow. The impregnated support was collected on frit, washed five times with approximately 10 mL of pentane, and then dried in vacuum for 1 hour. The catalyst was stored in an argon glove box at -40°C until needed. The SOC load in AlS / TiNp2 contained approximately 0.7 wt% Ti.

[0123] Formation of SOC by chemiadsorption of NbF2Np3 on AlS NbF2Np3 was synthesized according to the literature procedure "Schrock, RR; Fellmann, JDJAm. Chem. Soc., 1978, 100, 3359". In a dry reaction vessel lined with dry frit on both sides, 20 mL of pentane was vacuum-transferred to a mixture of NbF2Np3 (100 mg, 0.215 mmol) and AlS (1.20 g). The resulting suspension was stirred at 25°C for 2 hours and then filtered. The impregnated support was collected on the frit, washed five times with approximately 10 mL of pentane, and then dried in vacuum for 1 hour. The catalyst was stored in an argon glove box at -40°C until needed. The SOC load of AlS / NbF2Np contained approximately 1.4 wt% Nb.

[0124] Nb(CH) on AlS t Formation of SOC by chemiadsorption of Bu)Np3 NbCl2Np3 was synthesized according to the literature procedure "Schrock, RR; Fellmann, JDJAm. Chem. Soc., 1978, 100, 3359". 99 mg of NbCl2Np3 (0.26 mmol) was placed in a 50 mL Schlenk flask along with 10 mL of pentane and a stirring bar. The NbCl2Np3 solution was cooled in a dry ice-acetone bath for 10 minutes, after which a pentane solution of LiNp (46 mg, 0.58 mmol) was slowly added by cannula transfer. The resulting suspension was stirred for another 10 minutes and then warmed to 0°C in an ice bath. The suspension changed color from orange-yellow to wine-red. AlS (1.20 g) was placed in a dry reaction vessel fitted with dry frit on both sides, and then cooled in an ice bath. The wine-red suspension was added to an AlS support by cannula filtration. The resulting suspension was stirred at 0°C for 1 hour and then filtered. After chemiadsorption, the solid material exhibits a pale yellow color. The impregnated carrier was collected on frit, washed five times with approximately 10 mL of pentane, and then dried in vacuum for 1 hour. The catalyst was stored at -40°C in an argon glove box until needed. SOC(AlS / Nb(CH t The amount of Bu)Np loaded was approximately 1.4 wt% Nb.

[0125] W(C) on AlS t Formation of SOC by chemiadsorption of Bu)Np3 W(C t Bu)Np3 was synthesized according to the literature procedure "Dewan, JC; Schrock, RRJAm. Chem. Soc., 1978, 100, 6774". In a dry reaction vessel with dry frit on both sides, W(C) t A mixture of Bu)Np3 (105 mg, 0.225 mmol) and AlS (1.23 g) was heated in an oil bath at 66°C for 5 hours. 20 mL of pentane was vacuum-transferred to the resulting mixture, and then filtered. After chemiadsorption, the solids were light brown in color. The impregnated carrier was collected on frit, washed five times with approximately 10 mL of pentane, and then dried in vacuum for 1 hour. SOC was stored in an argon glove box at -40°C until needed. SOC(AlS / W(C) tThe amount of Bu)Np loaded was approximately 2.8 wt% for W.

[0126] Mo(C) on AlS t Formation of SOC by chemiadsorption of Bu)Np3 Mo(C t Bu)Np3 was synthesized according to the literature procedure "McCullough, LG; Schrock, RR; Dewan, JC; Murdzek, JCJAm. Chem. Soc., 1985, 107, 5987". Mo(C) was synthesized in a dry reaction vessel with dry frit on both sides. t A mixture of Bu)Np3 (52 mg, 0.137 mmol) and AlS (0.75 g) was heated in an oil bath at 50°C for 2 hours. 10 mL of pentane was transferred under vacuum to the resulting mixture, and then filtered. After chemiadsorption, the solids were light brown in color. The impregnated carrier was collected on frit, washed five times with approximately 10 mL of pentane, and then dried under vacuum for 1 hour. The catalyst was stored in an argon glove box at -40°C until needed. SOC(AlS / Mo(C) t The amount of Bu)Np loaded was approximately 1.4 wt% for W.

[0127] General C16 Hydrocracking Procedure for Initial SOC Screening In a glove box, C16 (typically about 1.5 g) was passed through a 0.22 μm PTFE syringe filter and directly added to a thick-walled glass pressure reactor (350 mL capacity) containing the desired amount of catalyst (typically about 170 mg). The reactor was sealed with a threaded Teflon cap fitted with an NPT valve. The container was then degassed at room temperature for 90 seconds and refilled with 2 atm of H2. The reactor was placed in an oil bath set to 150°C. When the thermocouple in the oil bath reached 147°C, the time interval was started. The time it took for all of the C16 to evaporate was recorded. Headspace samples and condensed samples were taken and characterized by GC-Fid and GC-MS, respectively.

[0128] AlS / Ta(CH t General polyolefin hydrocracking procedure for Bu)Np Inside the glove box, AlS / Ta(CH t Bu)Np and the desired amount of polyolefin sample were charged into a 350 mL thick-walled glass pressure reactor containing approximately 15% by mass of SOC. The reactor was sealed with a threaded Teflon cap fitted with an NPT valve. The reactor was degassed and refilled with 2 atmospheres of H2. The reactor was placed in an oil bath set to the desired temperature. Once the polyolefin had melted and come into contact with the catalyst, the time interval was started. Stirring was usually initially set to 300 rpm, and then increased to 600 rpm after the polyolefin viscosity had sufficiently decreased. At the end of the time interval, the vessel was removed from the oil bath and then air-cooled to room temperature. If necessary, a headspace sample was taken at this point. The reactor was aerated through the NPT valve and opened to air. Approximately 5 mL of DCM was used to wash the inside of the Teflon cap and NPT valve. These washings were added to the reactor. The solids were suspended in the DCM washings and then filtered for recovery. The reactor was washed a sufficient number of times to remove all residue. The solid collected on the frit was washed approximately three times with 5 mL of DCM, and then dried overnight in about 100 ml (waxy product). DCM was removed from the filtrate (DCM extracted fraction), and the resulting liquid was dried overnight in about 100 ml.

[0129] [Table 13]

[0130] Figure 5 shows the mass percentages of volatile products, oily products, and waxy products of the reduced polymer products listed in Table 13.

[0131] [Table 14]

[0132] Figure 6 shows the mass percentages of volatile products, oily products, and waxy products of the reduced polymer products listed in Table 14.

[0133] C16 Hydrocracking Inside the glove box, 300 mg of AlS / Ta(CH t Bu)Np was charged into a thick-walled glass pressure reactor (capacity 350 mL). The reactor was sealed with a threaded Teflon cap fitted with an NPT valve. The reactor was degassed, refilled with 2 atmospheres of H2, and then placed in a 200°C oil bath for 5 minutes. The reactor was degassed again, refilled with 1 atmosphere of C16 / H2 (1:1 ratio), and then placed in a 200°C oil bath for 4 hours. Headspace samples were measured by GC-Fid. The results are shown in Table 15. Table 15 shows the time intervals recorded for complete evaporation of C16 by hydrocracking according to the above method.

[0134] [Table 15]

[0135] conclusion When hydrocarbyl precursors of group V and group VI metals are chemically adsorbed onto acidic alumina sulfate (AlS), single-site cationic group V and group VI organometallic centers are generated, which were hyperactive in the hydrocracking of polyolefins. Ethane hydrocracking experiments reveal a novel CC bond activation mechanism for group V metals. Heavy metal catalysts exhibit higher thermal stability than the corresponding single-site Zr catalysts.

[0136] Polyolefin hydrocracking General high-pressure hydrocracking procedure using AlS / ZrNp2 Inside a glove box, a 25-100 mL Parr reactor, equipped with a magnetically coupled overhead stirrer and a PTFE reactor liner, was fitted with a catalyst (typically 10-3 wt%) and polyolefin. The reactor was sealed, removed from the glove box, and connected to a high vacuum / high pressure line. The reactor was then opened for approximately 10 minutes. -3After evacuating to Torre, the reactor was filled with H2 at the desired pressure (typically 18 atmospheres) at room temperature. The reactor was heated to the desired temperature and reaction temperature, and stirring (200-1900 rpm) was started to initiate the reaction. If the reaction was carried out at a temperature higher than 150°C, slow stirring (approximately 200 rpm) was used until the desired temperature was reached (typically 5-10 minutes). The reaction was allowed to proceed over the desired time interval. The time interval was set to begin when stirring was started. After the time interval had elapsed, stirring was stopped, the reactor was removed from the furnace, and cooled using forced air cooling. The reactor was depressurized, and headspace samples were taken as needed. The reaction mixture was post-treated as described in general polymer hydrocracking procedures.

[0137] Typical polyolefin hydrocracking procedure involving toluene swelling Polyolefin and SOC were charged into the reactor as described in the general polyolefin hydrocracking procedure using AlS / ZrNp2. Dry toluene (0.5-2.0 mL) was also added to the reactor. The reactor was sealed and removed from the glove box. The reactor was heated to the desired temperature with slow stirring for about 30 minutes. The toluene was then cooled under reduced pressure (approximately 10°C). -6 The material was removed using a Thor filter, and then the reactor was filled with H2 at the desired pressure. The reaction was carried out and post-treatment was performed as described in general polymer hydrocracking procedures.

[0138] Gas-phase NMR experiment 41.50 mg of catalyst was placed in a PTFE sealed NMR tube. A high-pressure / high-vacuum line was connected to the tube, and approximately 10 -6 The system was evacuated to Thor's chamber. The tube was filled with H2 at 1 atmosphere and then sealed (internal volume approximately 2.9 mL). NMR spectra were acquired at 10-minute intervals. Between these 10-minute intervals, the NMR tube was removed from the magnet and then shaken for approximately 2 minutes. After 90 minutes, the NMR tube was heated to 150°C for 30 minutes to complete the reaction. After this, the final spectrum was acquired and it was confirmed that the only hydrocarbons present were methane and ethane. 1¹H-NMR measurements were obtained using a Bruker Avance III (600 MHz) equipped with a BBFO smart probe. The following acquisition parameters were used to obtain the gas-phase NMR spectrum: acquisition time: 0.5 seconds, delay time: 20 seconds.

[0139] Activity calculations for polyolefin hydrolysis experiments The activity of polyolefin hydrolysis is calculated as follows: 1.) The reaction product is 14.026 g·mol. -1 1. Collect a sample containing only the "volatile substance" fraction and the "DCM extract" fraction, which have a molecular weight of (-CH2- units). 2.) Divide the molar amount of the product by the number of moles of Zr added to the reaction. 3.) Divide the resulting number by the reaction time (h). The resulting number represents the activity of the polymer hydrocracking reaction, expressed in the following units: (moles of CH2 from volatile substance and DCM extract)·(moles of Zr) -1 ·h -1 .

[0140] When a reaction is carried out for 45 minutes using 0.1g of SOC (containing 1.4wt% Zr), to produce 0.5g of DCM extract and volatile substances, the activity is calculated as follows. 0.5g / 14.026g(g·moles) -1 ) = 0.0356 moles (-CH2- units). • 0.1g of SOC contains 0.0014g of Zr, and 0.0014g of Zr / 91.22(g·mol) -1 Zr) = 1.535·10 -5 (moles of Zr) were added to the reaction. (0.0356 moles of -CH2- units) / (1.535·10) -5 Moles of Zr (0.75h) = 3097 (moles of CH2 units) (moles of Zr) -1 ·h -1 .

[0141] Table 16 shows the hydrogenolysis activity data for Dow® polyethylene resin, as performed in a glass reactor as described above. The reaction conditions were 200°C, 0.3g of SOC, 1.0g of polyethylene, and 2 atmospheres of H2. The reaction was continued until a considerable amount of the starting polymer was consumed, as confirmed by visual inspection.

[0142] [Table 16]

[0143] Table 17 shows the hydrogenolysis activity data for Dow® polyethylene resin, as performed in a Parr reactor (25 mL) as described above. The reaction conditions were 200°C, 0.03 g of catalyst, 1.0 g of polyethylene, and 18 atm of H2 (reactor filled at 30°C). The reaction was continued until a considerable amount of the starting polymer was consumed, as confirmed by visual inspection.

[0144] [Table 17]

[0145] Figure 7 shows the distribution of products (volatile substances, DCM extract, and solid products) from the hydrocracking of polymer products (volatile substances, DCM extract, and solid products) in Table 17 against the stirring speed. For the reaction conditions presented in Table 17, Figure 8 shows the distribution of products (volatile substances, DCM extract, and solid products) from the hydrocracking of Engage® 8402, Engage® 8450, and Affinity® 1850-G against the reaction time.

[0146] Table 18 shows the hydrocracking activity data for commercially available polyethylene resin with toluene swelling, conducted in a 350 mL glass reactor equipped with a magnetic stirrer as described above. The reaction conditions were 200°C, 0.1 g of catalyst per reaction cycle (0.0014 g of Zr), 1.0 g of commercially available polyethylene resin, and 2 atmospheres of H2. The reaction was continued until a considerable amount of the starting polymer was consumed, as confirmed by visual inspection.

[0147] [Table 18]

[0148] Figure 9 shows the distribution of hydrolysis products (volatile substances, DCM extract, and solid products) from Engage® 8402, milk jugs, and HDPE fruit pouch caps under the reaction conditions presented in Table 18.

[0149] The term “exemplary” is used herein to mean an example, case, or illustration. An embodiment or design described herein as “exemplary” should not necessarily be construed as being preferable or more advantageous than other embodiments or designs. Furthermore, for the purposes of this disclosure, unless otherwise specified, “a” or “an” means “one or more.”

[0150] Unless otherwise noted, all numerical values ​​of parameters in this disclosure begin with the term “approximately,” meaning approximate. This includes the variability inherent in the measurement of the relevant parameters, as will be understood by those skilled in the art. This also includes the exact values ​​of the disclosed numerical values ​​and values ​​close to the disclosed numerical values.

[0151] The foregoing description of exemplary embodiments of the Disclosure is provided for illustrative and explanatory purposes only. It is not intended to be exhaustive or to limit the Disclosure to the exact forms disclosed, and modifications and variations are possible in light of the foregoing teachings, or modifications and variations may be obtained from the practice of the Disclosure. The embodiments have been selected and described for the purpose of illustrating the principles of the Disclosure and as practical uses of the Disclosure to enable those skilled in the art to utilize the invention in various embodiments and with various modifications to suit specific intended uses. The scope of the Disclosure is intended to be defined by the following claims. The present invention includes the following embodiments. Section 1. A method for the hydrocracking of polymers, The process involves supplying the polymer, hydrogen gas, and supported organometallic catalyst into a reactor, wherein the supported organometallic catalyst is an organometallic complex pre-catalyst of formula I, MR m L x Equation I (In the formula, m is between 0 and 6, x is between 0 and 6, M is a transition metal selected from the group consisting of Group 3 to Group 8 transition metals, R is independently selected from the group consisting of H, C1-C8 hydrocarbyls, or halogens, and each L is independently selected from the group consisting of C1-C12 substituted or unsubstituted hydrocarbyls, where the values ​​of m and x depend on the oxidation state of M.) Acidic metal oxide support, Processes formed from, and In the reactor, in the presence of hydrogen gas, at a predetermined temperature, the polymer is reacted with the supported organometallic catalyst to produce a reduced polymer product having a weight-average molecular weight smaller than that of the polymer. Methods that include... Section 2. The method according to item 1, wherein M is selected from the group consisting of transition metals of Group 4, Group 5, Group 6, or Group 8. Section 3. The method according to item 2, wherein M is selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, or Ni. Section 4. The method according to claim 1, wherein the hydrocarbyl of L is independently selected from the group consisting of C1-C10 alkyl, C2-C10 alkenyl, or C5-C10 aryl. Section 5. The method according to item 1, wherein the predetermined temperature is 60°C or more and 300°C or less. Section 6. The method according to claim 1, wherein the reduced polymer product is at least one of a volatile product, an oily product, or a waxy product. Section 7. The method according to claim 6, wherein the reduced polymer product comprises less than 5 weight percent of the waxy product based on the total weight of the reduced polymer product. Section 8. The method according to claim 1, wherein the polymer is selected from the group consisting of polyolefins, polymers formed by polymerization of aromatic alkenes, or polymers formed by polymerization of conjugated dienes. Section 9. The method according to claim 8, wherein the polyolefin is selected from the group consisting of polyethylene, polypropylene, linear or branched C4-C12 monoolefins, copolymers thereof, or combinations thereof. Section 10. The method according to item 1, wherein M is selected from the group consisting of Zr or Hf, m is 0, and each L is independently selected from C1 to C12 alkyl groups. Section 11. The method according to item 10, wherein L is neopentyl. Section 12. The method according to any one of claims 1 to 11, wherein the acidic metal oxide support is a sulfated metal oxide. Section 13. The method according to claim 12, wherein the sulfated metal oxide is selected from the group consisting of sulfated aluminum oxide, sulfated zirconium(IV) oxide, sulfated tin(IV) oxide, sulfated hafnium(IV) oxide, sulfated titanium(IV) oxide, sulfated iron(III) oxide, sulfated zinc(II) oxide, sulfated silica oxide, or a combination thereof. Section 14. The method according to item 1, wherein the supported organometallic catalyst is represented by formula II. L y-x R x-z M n+ ··· O - (Acidic metal oxide support) Formula II (In the formula, M is selected from the group consisting of Zr, Hf, Ti, Nb, V, Cr, Mo, W, Ta, Co, or Ni; R is independently selected from hydrogen, halogen, or L; each L is independently selected from saturated or unsaturated C1-C12 hydrocarbyl or C1-C12 silyl hydrocarbyl; n is 1; y is 3; x is 2 or 1; and z is 1 or 0.) Section 17. The method according to item 16, wherein M is selected from the group consisting of Ti, Zr, or Hf, each L is a saturated or unsaturated hydrocarbyl of C3-C8, x is 1, and z is 1. Section 17. The method according to claim 1, wherein the step of supplying hydrogen gas to the reactor includes the step of supplying the hydrogen gas to the reactor at a pressure of 0.1 atmospheres or more and 100 atmospheres or less. Section 18. The method according to claim 1, wherein the step of reacting the polymer includes stirring the polymer at a speed of 500 rpm to 3000 rpm in the presence of the supported organometallic catalyst and hydrogen gas. Section 19. The method according to item 1, wherein the step of reacting the polymer with the supported organometallic catalyst and hydrogen gas at a predetermined temperature is performed over a period of 0.25 hours to 24 hours. Section 20. The method according to claim 1, wherein the step of supplying the supported organometallic catalyst into the reactor includes the step of supplying M in an amount of 0.01 mol percent (mol%) or more and 0.9 mol% or less based on the monomer units of the polymer. Section 21. Supported organometallic catalyst of formula II. L y-x R x-z M n+ ··· O - (Acidic metal oxide support) Formula II (In the formula, M is selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Ru, Co, or Ni; R is independently selected from hydrogen, halogen, or L; each L is independently selected from saturated or unsaturated C1-C12 hydrocarbyl or C1-C12 silyl hydrocarbyl; n is 1; y is 3; x is 2 or 1; and z is 1 or 0.) Section 22. A supported organometallic catalyst as described in item 21, wherein M is selected from the group consisting of Ti, Zr, or Hf, each L is a saturated or unsaturated hydrocarbyl of C3-C8, x is 1, and z is 1.

Claims

1. A method for the hydrocracking of polymers, The process involves supplying the polymer, hydrogen gas, and supported organometallic catalyst into a reactor, wherein the supported organometallic catalyst is an organometallic complex pre-catalyst of formula I, MR ｍ L ｘ Formula I (In the formula, m is between 0 and 6, x is between 1 and 6, M is a transition metal selected from group 3 to group 8 transition metals, R is independently selected from H, C1-C8 hydrocarbyl or halogen, and each L is independently selected from C1-C12 substituted hydrocarbyl, C1-C12 unsubstituted hydrocarbyl, or C1-C12 silyl hydrocarbyl, where the values ​​of m and x depend on the oxidation state of M.) Acidic metal oxide support, Processes formed from, and In the reactor, in the presence of hydrogen gas, at a predetermined temperature, the polymer is reacted with the supported organometallic catalyst to produce a reduced polymer product having a weight-average molecular weight smaller than that of the polymer. Includes, A method wherein the supported organometallic catalyst is represented by formula II. L y-u R u-z M n+ ...O- (acidic metal oxide support) Formula II In the equation, n is 1, y is 3, u is 2 or 1, and z is 1 or 0.

2. The method according to claim 1, wherein M is selected from Group 4, Group 5, Group 6, or Group 8 transition metals.

3. The method according to claim 1, wherein M is selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, or Ru.

4. The method according to claim 1, wherein L is independently selected from C1-C10 substituted or unsubstituted alkyl, C2-C10 substituted or unsubstituted alkenyl, or C5-C10 substituted or unsubstituted aryl.

5. The method according to claim 1, wherein the predetermined temperature is 60°C or more and 300°C or less.

6. The method according to claim 1, wherein the reduced polymer product is at least one of a volatile product, an oily product, or a waxy product.

7. The method according to claim 6, wherein the reduced polymer product comprises less than 5% by weight of the waxy product based on the total weight of the reduced polymer product.

8. The method according to claim 1, wherein the polymer is selected from a polymer formed by polymerization of a polyolefin, an aromatic alkene, or a polymer formed by polymerization of a conjugated diene.

9. The method according to claim 8, wherein the polyolefin is selected from polyethylene, polypropylene, linear or branched C4 to C12 monoolefins, copolymers thereof, or combinations thereof.

10. The method according to claim 1, wherein M is selected from Zr or Hf, m is 0, and each L is independently selected from C1 to C12 alkyl groups.

11. The method according to claim 1, wherein M is selected from Ti, Zr, or Hf, each L is a saturated or unsaturated hydrocarbyl of C3 to C8, u is 1, and z is 1.

12. The method according to claim 1, wherein L is neopentyl.

13. The method according to claim 1, wherein the acidic metal oxide support is a sulfated metal oxide.

14. The method according to claim 13, wherein the sulfated metal oxide is selected from sulfated aluminum oxide, sulfated zirconium(IV) oxide, sulfated tin(IV) oxide, sulfated hafnium(IV) oxide, sulfated titanium(IV) oxide, sulfated iron(III) oxide, sulfated zinc(II) oxide, sulfated silica oxide, or a combination thereof.

15. The method according to claim 1, wherein the step of supplying hydrogen gas to the reactor includes the step of supplying the hydrogen gas to the reactor at a pressure of 0.1 atmospheres or more and 100 atmospheres or less.

16. The method according to claim 1, wherein the step of reacting the polymer includes stirring the polymer at a speed of 500 rpm to 3000 rpm in the presence of the supported organometallic catalyst and the hydrogen gas.

17. The method according to claim 1, wherein the step of reacting the polymer with the supported organometallic catalyst and hydrogen gas at a predetermined temperature is performed over a period of 0.25 hours or more and 24 hours or less.

18. The method according to claim 1, wherein the step of supplying the supported organometallic catalyst into the reactor includes the step of supplying M in an amount of 0.01 mol percent (mol%) or more and 0.9 mol% or less based on the monomer units of the polymer.

19. Supported organometallic catalyst of formula II. L ｙ－ｕ R ｕ－ｚ M ｎ＋ ...O － (Acidic metal oxide support) Formula II (In the formula, M is selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Fe, or Ru; R is independently selected from hydrogen, halogens, or C1-C8 hydrocarbyls; each L is independently selected from C1-C12 saturated hydrocarbyls, C1-C12 unsaturated hydrocarbyls, or C1-C12 silyl hydrocarbyls; n is 1; y is 3; u is 2 or 1; and z is 1 or 0.)

20. The supported organometallic catalyst according to claim 19, wherein M is selected from Ti, Zr, or Hf, each L is a saturated or unsaturated hydrocarbyl of C3 to C8, u is 1, and z is 1.

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