Catalyst component for the productivity of a ziegler-natta olefin polymerization catalyst

Abstract

Graphene oxide (GO) / silicon dioxide (SiO2)-supported Ziegler-Natta (Z-N) catalysts are described. The catalysts include a Z-N catalyst attached to a GO / SiO2 support. The GO / SiO2 support has a GO:SiO2 weight ratio greater than 1:5 and includes at least 25 mole percent oxygen (O) atoms. Methods of making the catalysts and uses of the catalysts in alpha-olefin polymerization reactions are also described.

Description

[0001] The present invention relates generally to supported Ziegler-Natta catalysts, methods of making the catalysts, and the use of the catalysts in alpha-olefin polymerization reactions. In particular, the present invention relates to graphene oxide (GO) / silica (Si02) supported Ziegler-Natta (Z-N) catalysts (Z-N / GO / Si02). The catalysts can include Z-N catalysts attached to a GO / Si02 support having a GO:Si02 weight ratio of greater than 1 :5.

[0002] Ziegler-Natta catalysts can include an inert support material, a magnesium halide compound, a transition metal compound, one or more electron donor compounds, and an organoaluminum cocatalyst. The transition metal can have active catalytic properties, and the magnesium halide compound can act as a promoter to increase the overall catalytic productivity of the transition metal. The electron donor compounds and the organoaluminum cocatalyst assist in the polymerization of isotactic polymers. The silica support material is inactive and does not increase the rate of polymerization. Generally, Ziegler-Natta catalysts are small solid particles, but soluble forms and supported catalysts have also been used. Ziegler-Natta catalysts are particularly useful for the homopolymerization and copolymerization of ethylene, propylene, and other alpha olefins to produce films, fibers, and molded articles.

[0003] Ziegler-Natta catalyst supports are typically made from inert metal oxides such as silica and / or alumina. Ziegler-Natta catalysts modified with graphene are known. By way of example, in one review of graphene as a catalyst and initiator (Progress in Polymer Science, 2017, 67:48-76), Nia discloses graphene as a support for Ziegler-Natta catalysts. In these reactions, graphene flakes off into the resulting polymer, making the polymer conductive. Thus, the use of graphene presents a challenge if a non-conductive polymer is required.

[0004] Despite the current availability of research on Ziegler-Natta catalysts, there is a need for improved catalysts.

[0005] The present invention has been proposed to provide a solution to at least some of the problems associated with Ziegler-Natta catalyst systems. The premise of the present invention is the idea of using a mixture of graphene oxide and silica (GO / Si02) as a support material for Ziegler-Natta catalysts for the polymerization of alpha olefins.

[0006] In a specific aspect of the present application, a GO / SiO2supported Ziegler-Natta (Z-N) catalyst (Z-N / GO / SiO2) is described. The Z-N / GO / SiO2may comprise a Z-N catalyst attached to a GO / SiO2support. The GO / SiO2may have a GO:SiO2weight ratio of greater than 1 :5 (e.g. 1 :10 to 1 :50, preferably 1 :20). In the context of the present application, it is understood that 'greater than 1 :5' means that the numerator of the fraction is 1 and the denominator is greater than 5. The GO / SiO2may have a GO:SiO2weight ratio of 1 :10 to 1 :50.

[0007] The GO / SiO2support may, for example, have a GO:SiO2weight ratio of < 0.20. For example, the GO / SiO2support may, for example, have a GO:SiO2weight ratio of > 0.02 and < 0.10. Preferably, the GO:SiO2weight ratio in the GO / SiO2support is > 0.02 and < 0.09, more preferably > 0.03 and < 0.09, even more preferably > 0.03 and < 0.08.

[0008] The use of such GO / SiO2ratios in the support for the ethylene polymerization catalyst helps to increase the polymerization activity for ethylene homopolymerization and copolymerization, while at the same time producing polyethylene products with desired product properties, such as desired molecular weight, desired molecular weight distribution, and desired product appearance, including desired product color. Furthermore, the use of such GO / SiO2ratios in the support for the ethylene polymerization catalyst allows for polymerization at high polymerization rates, while at the same time not leading to the formation of too much bulk polymer in the polymerization reactor, which would require premature termination of the process to clean the reactor.

[0009] GO / SiO2ratios in the catalyst support that are outside the scope of the present application, i.e. where the amount of GO versus SiO2is higher than according to the scope of the present application, can lead to a deep coloring of the product obtained from the ethylene (co)polymerization reaction, and can lead to the formation of too much bulk polymer. GO / SiO2ratios in the catalyst support that are below the scope of the present application, i.e. where the amount of GO versus SiO2is lower than according to the scope of the present application, can lead to an inability to achieve productivity improvements.

[0010] The GO can include at least 25 mole percent oxygen (O) atoms (e.g., at least 30 mole percent, preferably at least 35 mole percent, more preferably 37 mole percent oxygen atoms). In some embodiments, the GO can include from 25 mole percent to 50 mole percent oxygen atoms, preferably from 30 mole percent to 45 mole percent oxygen atoms, or more preferably from 35 mole percent to 40 mole percent oxygen atoms. Notably, the GO is not reduced graphene oxide. The graphene oxide can be exfoliated or partially exfoliated graphene oxide. The Z-N / GO / Si02catalyst can be a reaction product of a GO / Si02, a magnesium (Mg) compound, an electron donor compound, a compound that can include titanium, zirconium, or vanadium, and a halogen compound. The Mg compound can be magnesium chloride, Mg(C4H9)2, a dialkyl magnesium, an alkyl alkyl' magnesium, an alkyl alkoxyl magnesium, a dialkoxyl magnesium, a chloro alkoxyl magnesium, a chloro hydroxyl magnesium, or any combination thereof. The compound that includes titanium, zirconium, or vanadium can include titanium tetrachloride, titanium ethoxide, bis-cyclopentadienyl titanium dichloride, zirconium tetrachloride, zirconium ethoxide, bis-cyclopentadienyl zirconium dichloride, vanadium tetrachloride, vanadium ethoxide, bis-cyclopentadienyl vanadium, or any combination thereof. In one embodiment, the catalyst can also include trimethyl aluminum. The halogen compound can be BCl3, A1C13, SiCl4, or PCI5, or any combination thereof. The electron donor compound can be an ester, an ether, a ketone, or a mixture thereof, preferably pentanone.

[0011] A method of making the Z-N / GO / Si02catalyst of the present application is also described. The method of producing the supported Z-N catalyst can include mixing graphene oxide (GO) with silicon dioxide (Si02) in a weight ratio greater than 1 :5 to form a GO / Si02mixture, dispersing the GO / Si02mixture in a liquid to form a dispersion. Mixing the GO and Si02may include combining the GO and Si02and stirring the mixture. The dispersion can be reacted with a reaction mixture of a magnesium compound, an electron donor compound, a halogen compound, and a transition metal compound (e.g., a compound that includes titanium, zirconium, or vanadium) under conditions sufficient to produce the Z-N / GO / Si02catalyst of the present application. The reaction mixture can be obtained by dissolving the magnesium compound, the halogen compound, the compound that includes titanium, zirconium, or vanadium in the electron donor compound. The reaction conditions can include a temperature of 15 to 120 °C at atmospheric pressure or slightly above atmospheric pressure (e.g., 0.01 MPa to 1 MPa). The reaction time can be at least 0.5 hours, or from 0.5 to 24 hours, or any range or value therein. The catalyst can be isolated and dried under a stream of inert gas, preferably nitrogen, at a temperature of 25 °C to 45 °C, or about 35 °C. An advantage of this synthesis is to allow the graphene oxide to be spread on the surface of the silicon dioxide during the synthesis of the catalyst, and subsequently during polymerization, the dispersed graphene oxide can easily exfoliate into the polymer matrix.

[0012] Methods of polymerizing alpha-olefins using any of the supported Z-N catalysts of the present application are described. The method of polymerizing an olefin can comprise contacting an activated Z-N / GO / SiO2 catalyst, preferably a Z-N catalyst of the present application. Activation of the Z-N / GO / SiO2 catalyst can occur by contacting the Z-N / GO / SiO2 catalyst with an aluminum compound, preferably triethylaluminum. The reaction can be conducted under an inert gas atmosphere. The gaseous reaction mixture can comprise an alpha-olefin (e.g., a Ci to C12 alpha-olefin) and optionally hydrogen (H2) under conditions sufficient to polymerize the alpha-olefin. H2 can be used to control the molecular weight of the polymer. The reaction conditions can be a temperature of 25 to 35 °C and / or a pressure of about 0.01 MPa of inert gas. In some embodiments, the alpha-olefin is ethylene, and the ethylene consumption is at least 50 N / hr for 60 minutes. As exemplified in a non-limiting manner in the examples, the productivity of the catalysts of the present application is 3 times that of a non-oxidized graphene supported catalyst.

[0013] Other embodiments of the present application are discussed throughout this application. Any embodiment discussed with respect to one aspect of the present application is also applicable to other aspects of the present application, and vice versa. Each embodiment described herein is understood to be an inventive embodiment applicable to other aspects of the present application. It is contemplated that any embodiment discussed herein can be implemented with respect to any method or composition of the present application, and vice versa. Furthermore, compositions of the present application can be used to achieve methods of the present application.

[0014] The following includes definitions of various terms and phrases used throughout this specification.

[0015] The term "about" or "approximately" is defined as nearly, as in the ordinary sense by a person of ordinary skill in the art. In a non-limiting embodiment, the term is defined as within 10%, preferably within 5%, more preferably within 1%, and most preferably within 0.5%.

[0016] The term "wt.%" "vol.%" or "mol.%" means the weight percent of a component, the volume percent of a component, or the mole percent of a component, respectively, based on the total weight, the total volume, or the total moles of material including the component. In a non-limiting example, 10 grams of a component in 100 grams of material is 10 wt.% of the component.

[0017] The terms "substantially" and variations thereof are defined to include a range of 10%, a range of 5%, a range of 1%, or a range of 0.5%.

[0018] The term "inhibit" or "reduce / decrease" or "prevent" or "avoid" or any variation of these terms, when used in the claims and / or specification includes any measurable decrease or complete inhibition to achieve the desired result.

[0019] The catalysts and processes of the present invention can "comprise," "consist essentially of," or "consist of" the particular ingredients, components, compositions, etc., disclosed herein. With respect to the transitional term "consisting essentially of," in one non-limiting aspect, the essential and novel characteristic of the Z-N / GO / SiO2catalysts of the present invention is their ability to catalyze the polymerization of alpha-olefins.

[0020] The advantages of the present invention can become apparent to one skilled in the art with the benefit of the following detailed description and upon reference to the drawings in which:

[0021] Figure 1 X-ray photoelectron spectrograms of graphene oxide used to prepare the catalysts of the present invention are depicted.

[0022] Figure 2 is a comparison of ethylene consumption versus production time for a comparative catalyst (lower line) and a catalyst of the present invention (upper line).

[0023] While the application is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings can not be to scale.

[0024] The present invention has been proposed to provide a solution to at least some of the problems associated with Ziegler-Natta catalysis of alpha-olefins. The premise of the present invention is the use of a Z-N catalyst attached to a hybrid graphene oxide-silica support material. Notably, and as exemplified in the examples, the Z-N / GO / SiO2catalysts of the present invention show better production than Z-N catalysts without graphene oxide, three times as much.

[0025] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

[0026] A. GO / Si Supported Z-N Catalysts

[0027] The catalyst of this invention may comprise a ZN catalyst bonded to a support material comprising graphene oxide and silica. Bonding can be achieved through covalent bonding between oxygen atoms in the support material and a metal (e.g., Mg, Ti, V, Zr, or the like) of the ZN catalyst. Other types of bonding may include ionic bonding and van der Waals interactions. Oxygen atoms in the support material may bind to carbon atoms in the graphene and / or silicon atoms in the silica material. Graphene oxide may comprise at least 25% by weight, or at least, equal to, or between any two of the following values ​​of elemental oxygen (O): 25% by weight, 26% by weight, 27% by weight, 28% by weight, 29% by weight, 30% by weight, 31% by weight, 32% by weight, 33% by weight, 34% by weight, 35% by weight, 36% by weight, 37% by weight, 38% by weight, 39% by weight, 40% by weight, 41% by weight, 42% by weight, 43% by weight, 44% by weight, 45% by weight, 46% by weight, 47% by weight, 48% by weight, 49% by weight, and 50% by weight. The GO:SiO2 weight ratio may be at least 1:5, or at least equal to or between any two of the following values: 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, and 1:50, or about 1:5 to 1:50, 1:10 to 1:40, or about 1:20. In some embodiments, the graphene may be exfoliated or partially exfoliated.

[0028] Silica can have a density of approximately 10 to approximately 1000 μm. 2 / g, preferably about 50 to about 700m 2 / g, and more preferably about 100 to about 600m 2 The specific surface area is measured per gram. Specific surface area can be determined using known standard tests, such as DIN 66131. ​​The granular silica can be irregularly shaped, hemispherical, microspheres, or a combination thereof. In some embodiments, the silica may be spherical and have an average particle size of about 5 to about 200 micrometers, or at least equal to or between any two of the following values: 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 micrometers. In some embodiments, fumed silica may be used.

[0029] The Zn catalyst can be a reaction product of GO / SiO2, magnesium (Mg) compounds, electron donor compounds, compounds containing Ti, Zr, or V, and halogen compounds. The Mg compound can be magnesium halide, dialkyl magnesium, alkylalkoxy magnesium, dialkoxy magnesium, chloroalkoxy magnesium, chlorohydroxy magnesium, or any combination thereof. In a preferred embodiment, the magnesium compound is magnesium chloride (MgCl2), dibutylmagnesium Mg(C4H9)2, or a combination thereof.

[0030] The titanium-containing compound can include titanium tetrachloride (TiCl4), titanium bromide (TiBr4), titanium alkoxide (Ti(OR)4) where R is a 2 to 20 alkyl group, bis-cyclopentadienyl titanium dichloride, or combinations thereof. Non-limiting examples of titanium alkoxide compounds include titanium tetraethoxide (Ti(OCH2CH3)4), titanium triethoxide chloride (Ti(OCH2CH3)3Cl), titanium diethoxide dichloride (Ti(OCH2CH3)2Cl2), titanium tetraisopropoxide (Ti(OPr)4), and titanium butoxide (Ti(OBu)4). The zirconium-containing compound can include zirconium tetrachloride (ZrCl4), zirconium ethoxide (Zr(OCH3)4), bis-cyclopentadienyl zirconium dichloride. The vanadium compound can include vanadium tetrachloride (VCl4), vanadium ethoxide (V(OCH3)4), bis-cyclopentadienyl vanadium, or any combination thereof.

[0031] The halogen compound can be boron trichloride (BC13), aluminum trichloride (A1C13), silicon tetrachloride (SiCl4), or phosphorus pentachloride (PC15), or any combination thereof.

[0032] The electron donor compound can be any electron donor known for use in Ziegler-Natta catalysis. The electron donor can include an amine, an amide, an ester, an ether, a ketone, a nitrile, an ether, a phosphine, a diether, a succinate, a phthalate, or a dialkoxybenzene, or mixtures thereof. In a preferred embodiment, the electron donor is pentanone. Examples of suitable electron donors include: carboxylic acids, carboxylic anhydrides, esters of carboxylic acids, halogenated carboxylic acids, alcohols, ethers, ketones, amines, amides, nitriles, aldehydes, alcoholates, sulfonamides, sulfides, thioesters, and other organic compounds containing heteroatoms such as nitrogen, oxygen, sulfur, and / or phosphorus. The molar ratio of the electron donor to magnesium can be 0.05 to 0.75, or more preferably 0.1 to 0.4.

[0033] Non-limiting examples of suitable carboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, propenoic acid, methacrylic acid, maleic acid, fumaric acid, tartaric acid, cyclohexanecarboxylic acid, cis-1,2-cyclohexanedicarboxylic acid, benzoic acid, p-tolylcarboxylic acid, naphthoic acid, phthalic acid, isophthalic acid, terephthalic acid, and / or hemimellitic acid. Non-limiting examples of anhydrides include anhydrides of the above-mentioned carboxylic acids, such as acetic anhydride, butyric anhydride, and methacrylic anhydride. Non-limiting examples of suitable esters include formate esters, acetate esters, acrylate esters, benzoate esters, phthalate esters, or any combination thereof. Formate esters can include butyl formate. Acetate esters can include ethyl acetate and butyl acetate. Acrylate esters can include ethyl acrylate, methyl methacrylate, and isobutyl methacrylate. Benzoate esters can include methyl benzoate and ethyl benzoate, methyl p-toluate, and ethyl-D-naphthoate. Phthalate esters can include monomethyl phthalate, dibutyl phthalate, diisobutyl phthalate, diallyl phthalate, and / or diphenyl phthalate. Non-limiting examples of suitable halogenated carboxylic acids can include halides of the above-mentioned carboxylic acids, such as acetyl chloride, acetyl bromide, propionyl chloride, butyryl chloride, butyryl iodide, benzoyl bromide, p-tolyl chloride, and / or phthaloyl dichloride. Non-limiting examples of suitable alcohols can include methanol, ethanol, butanol, isobutanol, xylenol, and benzyl alcohol. Non-limiting examples of suitable ethers are diethyl ether, dibutyl ether, diisopentyl ether, anisole, and ethyl phenyl ether, 2,2-diisobutyl-1,3-dimethoxypropane, 2,2-dicyclopentyl-1,3-dimethoxypropane, 2-ethyl-2-butyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, and / or 9,9-bis(methoxymethyl)fluorene. In addition, triethers can be used. Non-limiting examples of other organic compounds containing heteroatoms can include 2,2,6,6-tetramethylpiperidine, 2,6-dimethylpiperidine, 2-methylpyridine, 2-acetyl-4-methylpyridine, imidazole, benzonitrile, aniline, diethylamine, dibutylamine, benzenethiol, 2-methylthiophene, isopropyl mercaptan, diethyl sulfide, diphenyl sulfide, tetrahydrofuran, dioxane, dimethyl ether, diethyl ether, anisole, acetone, triphenylphosphine, triphenyl phosphite, diethyl phosphate, and / or diphenyl phosphate.

[0034] B. Preparation of Z-N / GO / SiO2 catalysts

[0035] A method of producing the Z-N / GO / silica catalyst of the present application is described. The method can include mixing GO with Si02 and dispersing the mixture in a liquid. The GO / Si02 dispersion can be reacted with components of the Ziegler-Natta catalyst system described herein to form the Z-N / GO / Si02 catalyst of the present application. The weight ratio of GO:Si02 can be at least 1 :5, or at least, equal to, or between any two of the following values: 1 :5, 1 :10, 1 :15, 1 :20, 1 :25, 1 :30, 1 :35, 1 :40, 1 :45, and 1 :50, or about 1 :5 to 1 :50, 1 :10 to 1 :40, or about 1 :20. The mixing can include stirring the two compounds at a slow speed (e.g., a slow rate per minute). The mixing can be performed at 20 to 50 °C, or any value or range therebetween, and at atmospheric pressure or near atmospheric pressure (e.g., about 0.0101 MPa). The liquid can be a hydrocarbon solvent that is unreactive to the Z-N catalyst. In some embodiments, the liquid can be an aliphatic hydrocarbon, an aromatic hydrocarbon compound, or a halogenated aromatic compound having 4 to 20 C atoms. Non-limiting examples of hydrocarbon solvents include one or more pentanes, one or more hexanes, one or more cyclohexanes, one or more heptanes, one or more cycloheptanes, toluene, xylene, benzene, heptane and chlorobenzene, and the like. The magnesium compound, the electron donor compound, the halogen compound, the titanium, zirconium, or vanadium compound can be added to the GO / Si02 dispersion in the listed order, one after the other. The reaction mixture can be stirred until the formation of the catalyst is complete (e.g., 1 hour to 24 hours, or 1, 2, 3, 5, 10, 15, 20, and 24 hours, or any range or value therebetween). The molar ratio of the Mg compound to the halogen compound can be 2: 1 to 10: 1, or about 1 :4. The molar ratio of Mg to the electron donor can be 0.5:20 to 1 : 10, or about 1 :2. The molar ratio of total titanium compound can be 0.1 : 10 to 1 : 10, or about 2.6: 1. In preferred embodiments, 1 to 4, or about 2 mmol Mg(Bu)2, 1 to 10, or about 4 mmol pentanone, 0.1 to 1, or about 0.5 mmol SiCl4, 0.1 to 1, or about 0.25 mmol Ti(OEt)4, and 0.1 to 1, or about 0.5 mmol TiCl4 can be added to the GO / Si02 dispersion.

[0036] Reaction conditions can include a temperature of 15 to 120 °C, or 20 to 100 °C, 30 to 70 °C, or at least, equal to, or between any two of the following values: 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 115 °C, and 120 °C. In some embodiments, the magnesium compound, halogen compound, and Ti-, Zr-, V-containing compound can be dissolved in the electron donor compound. The catalyst can be separated from the solvent using known catalyst separation techniques (e.g., filtration, centrifugation, etc.). After separation, the Z-N / GO / SiO2catalyst can be dried at a temperature of 25 to 45 °C, or at least, equal to, or between any two of the following values: 25 °C, 30 °C, 35 °C, 40 °C, and 45 °C, under a stream of inert gas (e.g., nitrogen).

[0037] Use of C.Z-N / GO / Silica Catalysts

[0038] The Z-N / GO / SiO2catalyst can be used in an alpha-olefin polymerization reaction. In some embodiments, a co-catalyst and / or scavenger compound can be added to the reaction medium. The co-catalyst can include an alkyl aluminum compound. Non-limiting examples of alkyl aluminum compounds include trimethyl aluminum, triisobutyl aluminum, triethyl aluminum, tri-n-octyl aluminum, n-octyl aluminum, n-hexyl aluminum, or any combination thereof. The Al:Ti-, Zr-, V-containing compound molar ratio can be 20: 1 to 300: 1 or 30: 1 to 200: 1 or any range or value therein.

[0039] The polymerization can be carried out in a continuous mode or in batch. Encompassed herein are slurry, bulk, and gas phase polymerization processes, multi-stage processes of each of these types of polymerization processes, or combinations of different types of polymerization processes in a multi-stage process. Preferred polymerization processes are single-stage gas phase processes or multi-stage, e.g., 2-stage, gas phase processes, wherein each stage uses a gas phase process. Examples of gas phase polymerization processes include stirred bed reactors and fluidized bed reactor systems; such processes are well known in the art. A typical gas phase alpha-olefin polymerization reactor system can include a reactor vessel to which one or more alpha-olefin monomers and a catalyst system can be added, and which contains a stirred bed of polymer particles forming. Optionally, hydrogen can be added to the process, such as for molecular weight control of the resulting polymer.

[0040] In the case of polymerization in liquid phase, a dispersing agent can be present. Suitable dispersing agents include, for example, n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, cyclohexane, benzene, toluene, xylene, and liquid propylene. The polymerization temperature can be from 0°C to 120°C, preferably from 25°C to 35°C. The polymerization time can vary, for example, from 1 to 10 hours, preferably from 2.5 to 3.5 hours. The pressure during polymerization can be from 0.1 to 6 MPa, preferably from 0.5 to 3 MPa.

[0041] In one non-limiting example, a dispersion of Z-N / GO / SiO2and a co-catalyst and / or a scavenger can be added to a solvent in a polymerization unit. A feed stream of an alpha-olefin (ethylene gas) can be introduced into the polymerization unit along with optional hydrogen. A suspension (which can include diluent) can be removed from the reactor intermittently or continuously, where volatile components can be optionally separated from the polymer after distillation and recycled to the reactor. In some embodiments, the ethylene consumption can be at least 50 N / hr for 60 minutes.

[0042] The polymers (and their blends) formed using the catalysts of the present application can include linear low density polyethylene, elastomers, plastomers, high density polyethylene, low density polyethylene, medium density polyethylene, polypropylene, polypropylene copolymers, and the like.

[0043] Accordingly, the present application relates to a graphene oxide (GO) / silica (SiO2) supported Ziegler-Natta (Z-N) catalyst (Z-N / GO / SiO2), the catalyst comprising a Z-N catalyst attached to a GO / SiO2support, wherein the GO / SiO2support has a GO:SiO2weight ratio of greater than 1 :5, and the GO comprises at least 25 mole % oxygen (O) atoms.

[0044] Preferably, in the supported Z-N catalyst, the GO:SiO2weight ratio is from 1 : 10 to 1 :50, preferably 1 :20.

[0045] The GO may, for example, comprise from 25 mole % to 50 mole % oxygen atoms, preferably from 30 mole % to 45 mole % oxygen atoms, or more preferably from 35 mole % to 40 mole % oxygen atoms, or wherein the GO comprises at least 30 mole %, preferably at least 35 mole %, more preferably 37 mole % oxygen atoms.

[0046] Preferably, the Z-N / GO / SiO2catalyst is the reaction product of: GO / SiO2, a magnesium (Mg) compound, an electron donor compound, a compound comprising titanium, zirconium, or vanadium, and a halogen compound.

[0047] The Mg compound can be, for example, magnesium chloride, Mg(C4H9)2, a dialkyl magnesium, an alkyl alkyl' magnesium, an alkyl alkoxyl magnesium, a dialkoxyl magnesium, a chloro alkoxyl magnesium, a chloro hydroxyl magnesium, or any combination thereof.

[0048] The compound comprising titanium, zirconium or vanadium can be, for example, titanium tetrachloride, titanium ethoxide, bis-cyclopentadienyl titanium dichloride, zirconium tetrachloride, zirconium ethoxide, bis-cyclopentadienyl zirconium dichloride, vanadium tetrachloride, vanadium ethoxide, vanadocene, or any combination thereof.

[0049] The supported Z-N catalyst preferably further comprises trimethylaluminum.

[0050] The halogen compound can be, for example, BCI3, AICI3, SiCI4, or PCI5.

[0051] The electron donor compound can be, for example, an ester, an ether, a ketone, or a mixture thereof, preferably pentanone.

[0052] The graphene oxide is preferably exfoliated or partially exfoliated graphene oxide.

[0053] In one embodiment, the present application also relates to a method of producing a supported Z-N catalyst, the method comprising:

[0054] (a) mixing graphene oxide (GO) with silicon dioxide (Si02) in a weight ratio greater than 1 :5 to form a GO / Si02mixture, preferably wherein mixing the GO and Si02comprises: combining the GO and Si02and stirring the mixture;

[0055] (b) dispersing the GO / Si02mixture in a liquid to form a dispersion; and

[0056] (c) reacting the dispersion with a reaction mixture of a magnesium compound, an electron donor compound, a halogen compound, and a compound comprising titanium, zirconium or vanadium under conditions sufficient to produce the Z-N / GO / Si02catalyst of any one of claims 1 to 10.

[0057] The reaction conditions preferably comprise a temperature of 15 to 120 °C. The reaction conditions preferably comprise a time of 30 to 120 min. The reaction conditions preferably comprise a temperature of 15 to 120 °C and a time of 30 to 120 min. The reaction conditions preferably comprise a temperature of 15 to 120 °C and a time of 60 min.

[0058] Preferably, the reaction mixture of step (c) is obtained by dissolving the magnesium compound, the halogen compound, the titanium compound in the electron donor compound.

[0059] The method more preferably comprises isolating the catalyst and drying the catalyst under a stream of inert gas, preferably nitrogen, at 25 to 45 °C or about 35 °C.

[0060] In another embodiment, the present application also relates to a process for polymerizing an alpha-olefin, preferably ethylene, the process comprising: contacting an activated Z-N / GO / SiO2 catalyst with a gaseous reaction mixture comprising an alpha-olefin and hydrogen (H2) under conditions sufficient to polymerize the alpha-olefin, preferably wherein the Z-N / GO / SiO2 catalyst is activated by contacting the Z-N / GO / SiO2 catalyst with an aluminum compound, preferably triethylaluminum, particularly preferably wherein the Z-N / GO / SiO2 catalyst is any one of the Z-N / GO / SiO2 catalysts according to claims 1 to 10.

[0061] In certain embodiments, the present application relates to a graphene oxide (GO) / silica (SiO2) supported Ziegler-Natta (Z-N) catalyst (Z-N / GO / SiO2), the catalyst comprising a Z-N catalyst attached to a GO / SiO2 support, wherein the GO / SiO2 support has a GO:SiO2 weight ratio of 1 : 10 to 1 : 50, and the GO comprises at least 25 mole% oxygen (O) atoms.

[0062] In certain embodiments, the present application relates to a graphene oxide (GO) / silica (SiO2) supported Ziegler-Natta (Z-N) catalyst (Z-N / GO / SiO2), the catalyst comprising a Z-N catalyst attached to a GO / SiO2 support, wherein the GO / SiO2 support has a GO:SiO2 weight ratio of < 0.20, preferably > 0.02 and < 0.10, more preferably > 0.02 and < 0.09, even more preferably > 0.03 and < 0.09, yet even more preferably > 0.03 and < 0.08, and the GO comprises at least 25 mole% oxygen (O) atoms.

[0063] In certain embodiments, the present application relates to a graphene oxide (GO) / silica (SiO2) supported Ziegler-Natta (Z-N) catalyst (Z-N / GO / SiO2), the catalyst comprising a Z-N catalyst attached to a GO / SiO2 support, wherein the GO / SiO2 support has a GO:SiO2 weight ratio of < 0.20, preferably > 0.02 and < 0.10, more preferably > 0.02 and < 0.09, even more preferably > 0.03 and < 0.09, yet even more preferably > 0.03 and < 0.08, wherein the GO comprises 25 mole% to 50 mole% oxygen atoms, preferably 30 mole% to 45 mole% oxygen atoms or more preferably 35 mole% to 40 mole% oxygen atoms, or wherein the GO comprises at least 30 mole%, preferably at least 35 mole%, more preferably 37 mole% oxygen atoms.

[0064] The application will be described in greater detail by way of specific embodiments. The following examples are provided for illustrative purposes only, and the examples are not intended to limit the application in any way. Those skilled in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

[0065] Example 1: Preparation of Z-N / GO / SiO2 catalyst

[0066] Graphene oxide (50 mg) was premixed with dry silica (1 g) in a weight ratio of 1 :20. The mixture was slurried in heptane and subsequently treated with Mg(Bu)2(2 mmol), pentanone (4 mmol), SiCl4(0.5 mmol), Ti(OEt)4(0.25 mmol), and TiCl4(0.5 mmol). The resulting dispersion was dried at about 35 °C to remove volatile materials and form a catalyst powder. The graphene oxide was analyzed using X-ray photoelectron spectroscopy (XPS). Table 1 lists the composition of the graphene oxide as determined from the XPS spectra shown in Figure 1

[0067] Table 1

[0068]

[0069] Example: Polymerization of ethylene using Z-N / GO / SiO2 catalyst

[0070] The catalyst of Example 1 and a comparative Ziegler-Natta catalyst not supported on graphene oxide (not made with graphene, made using the methodology of Example 1) were used in ethylene polymerization reactions with TEAL as cocatalyst and isopentane as medium. In a 1 L reactor, the catalyst, TEAL, and isopentane were loaded, and 3 bar of H2gas and up to 20 bar of total pressure of ethylene gas were added. The production rate of the reaction was found to be 3 times that of the AZ catalyst without graphene oxide. The dynamic curves of the standard Ziegler-Natta catalyst versus the GO-modified catalyst are shown in Figure 2

[0071] Table 2

[0072]

[0073] B.D: bulk density of the catalyst; Mn: number average molecular weight; Mw: weight average molecular weight; Mz: Z average molecular weight; PDI: dispersity index; Tm: melting temperature; Tc: crystallization temperature. Mn, Mw, Mz, and PDI were determined by gel permeation chromatography, using a refractive index detector and polystyrene standards. TM and TC were determined using differential scanning calorimetry.

[0074] ​​Comparative Example 3: Polymerization of ethylene using Z-N / GO catalyst

[0075] Graphene oxide (10 to 50 mg) was slurried in heptane and then treated with Mg(Bu)2(2 mmol), pentanone (4 mmol), SiCl4(0.5 mmol), Ti(OEt)4(0.25 mmol), and TiCl4(0.5 mmol). The resulting dispersion was dried at 25 to 60 °C to remove volatiles and form a comparative catalyst powder. The catalyst was evaluated as described in Example 2. The reaction was found to be very active, resulting in large chunks of polymer in the reactor, and the reaction terminated within 10 minutes of catalyst injection due to high torque on the stirrer and temperature rise above 110 °C. The results were repeated and showed the same behavior. Low quality polymer was produced using this catalyst.

Claims

1. A Ziegler-Natta catalyst supported on graphene oxide / silica, the catalyst comprising a Ziegler-Natta catalyst connected to a graphene oxide / silica support, wherein the graphene oxide / silica support has a graphene oxide:silica weight ratio of ≥ 0.02 and ≤ 0.20, and the graphene oxide contains 25 mol% to 50 mol% oxygen atoms.

2. The supported Ziegler-Natta catalyst according to claim 1, wherein the graphene oxide / silica support has a graphene oxide:silica weight ratio of ≥ 0.02 and ≤ 0.

10.

3. The supported Ziegler-Natta catalyst according to claim 1, wherein the graphene oxide / silica support has a graphene oxide:silica weight ratio of ≥ 0.02 and ≤ 0.

09.

4. The supported Ziegler-Natta catalyst according to claim 1, wherein the graphene oxide / silica support has a graphene oxide:silica weight ratio of ≥ 0.03 and ≤ 0.

09.

5. The supported Ziegler-Natta catalyst according to claim 1, wherein the graphene oxide / silica support has a graphene oxide:silica weight ratio of ≥ 0.03 and ≤ 0.

08.

6. The supported Ziegler-Natta catalyst according to claim 1, wherein the graphene oxide:silicon dioxide weight ratio is 1:

20.

7. The supported Ziegler-Natta catalyst according to any one of claims 1 to 6, wherein the graphene oxide comprises 30 mol% to 50 mol% oxygen atoms.

8. The supported Ziegler-Natta catalyst according to any one of claims 1 to 6, wherein the graphene oxide comprises 30 mol% to 45 mol% oxygen atoms.

9. The supported Ziegler-Natta catalyst according to any one of claims 1 to 6, wherein the graphene oxide comprises 35 mol% to 40 mol% oxygen atoms.

10. The supported Ziegler-Natta catalyst according to any one of claims 1 to 6, wherein the supported Ziegler-Natta catalyst is a reaction product of: graphene oxide / silica, a magnesium compound, an electron donor compound, a compound containing titanium, zirconium or vanadium, and a halogen compound.

11. The supported Ziegler-Natta catalyst according to claim 10, wherein the magnesium compound is magnesium chloride, Mg(C4H9)2, dialkyl magnesium, alkylalkyl magnesium, alkylalkoxy magnesium, dialkoxy magnesium, chloroalkoxy magnesium, chlorohydroxy magnesium, or any combination thereof.

12. The supported Ziegler-Natta catalyst according to claim 10, wherein the compound comprising titanium, zirconium, or vanadium is titanium tetrachloride, titanium ethoxylate, titanium dicerochloride, zirconium tetrachloride, zirconium ethoxylate, zirconium dicerochloride, vanadium tetrachloride, vanadium ethoxylate, vanadium dicerochloride, or any combination thereof.

13. The supported Ziegler-Natta catalyst according to claim 12, further comprising trimethylaluminum.

14. The supported Ziegler-Natta catalyst according to claim 10, wherein the halogen compound is BCl3, AlCl3, SiCl4 or PCl5.

15. The supported Ziegler-Natta catalyst according to claim 10, wherein the electron donor compound is an ester, ether, ketone, or a mixture thereof.

16. The supported Ziegler-Natta catalyst according to claim 10, wherein the electron donor compound is pentanone.

17. The supported Ziegler-Natta catalyst according to any one of claims 1 to 6, wherein the graphene oxide is exfoliated or partially exfoliated graphene oxide.

18. A method for producing a supported Ziegler-Natta catalyst according to any one of claims 1 to 17, the method comprising: (a) Graphene oxide and silicon dioxide are mixed at a weight ratio of < 0.20 to form a graphene oxide / silicon dioxide mixture; (b) Dispersing the graphene oxide / silica mixture in a liquid to form a dispersion; and (c) The dispersion is reacted with a reaction mixture of a magnesium compound, an electron donor compound, a halogen compound and a compound containing titanium, zirconium or vanadium under conditions sufficient to produce a Ziegler-Natta catalyst supported according to any one of claims 1 to 17.

19. The method of claim 18, wherein mixing the graphene oxide and silicon dioxide comprises: The graphene oxide and silicon dioxide are combined and the mixture is stirred.

20. The method of claim 18, wherein the reaction conditions comprise a temperature of 15 to 120°C and / or a time of 60 min.

21. The method according to any one of claims 18 to 20, wherein the reaction mixture in step (c) is obtained by dissolving the magnesium compound, the halogen compound, and the titanium compound in the electron donor compound.

22. The method according to any one of claims 18 to 20, further comprising separating and drying the catalyst under an inert gas stream at 25 to 45°C or at 35°C.

23. The method of claim 22, wherein the inert gas is nitrogen.

24. A method for polymerizing α-olefins, the method comprising: Under conditions sufficient for polymerization of α-olefins, an activated graphene oxide / silica-supported Ziegler-Natta catalyst is contacted with a gaseous reaction mixture containing the α-olefin and hydrogen (H2), wherein the graphene oxide / silica-supported Ziegler-Natta catalyst is any one of the graphene oxide / silica-supported Ziegler-Natta catalysts according to any one of claims 1 to 17.

25. The method of claim 24, wherein the α-olefin is ethylene.

26. The method of claim 24, wherein the graphene oxide / silica-supported Ziegler-Natta catalyst is activated by contacting the graphene oxide / silica-supported Ziegler-Natta catalyst with an aluminum compound.

27. The method of claim 26, wherein the aluminum compound is triethylaluminum.

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