RU2846035C2 - Gas-phase method of producing polypropylene random copolymers - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing a random polypropylene copolymer in a fluidised bed reactor, involving: supply of fluidised medium into reactor vessel containing layer of catalytically active polyolefin particles, wherein fluidised medium contains gaseous propylene, C2- and/or C4-C8-α-olefin comonomer (comonomers), hydrogen and at least one inert gas and/or propane, where the flow of the fluidised medium pulse, defined as (SGV[m/s])² * ρ_q [kg/m³], is 7.0 N/m² or more, where ρ_q is the density of the fluidised medium, and SGV is the surface velocity of the gas of the fluidised medium, and where the condensation level of the circulation gas of the reactor upon entering the reactor is about 17 wt. % or less.

EFFECT: providing stable functioning of reactor in absence of agglomeration of particles, sticking of polymer sheet and lumping.

15 cl, 1 dwg, 1 tbl, 11 ex

Description

LEVEL OF TECHNOLOGY

[0001] Polypropylene is a certain type of polyolefin polymer that generally has a linear structure based on propylene monomer. One type of polypropylene is a polypropylene random copolymer, which is produced using a propylene monomer and a comonomer(s) in the form of at least one other α-olefin, such as ethylene and/or 1-butene, which are randomly interspersed in the polypropylene chain. Polypropylene random copolymers exhibit properties that are particularly well suited for use in pipe, packaging, textile, molded article and other applications.

[0002] One method for producing polypropylene is typically referred to as gas-phase polymerization. During gas-phase polymerization, one or more monomers are contacted with a catalyst to form a bed of polymer particles that are maintained in a fluidized state by a fluidizing medium that contains the monomers. One typical gas-phase polymerization reactor includes a vessel containing a fluidized bed, a distributor plate (also called a distributor plate), and a product discharge system. A catalyst may be fed into the polymerization reactor and may contact an olefin monomer that forms part of the fluidizing medium.

[0003] When producing polypropylene using a gas phase process, it is important to maintain the operating temperature of the reactor by efficiently transferring heat from the polymer particles to the fluidizing gas. Failure to remove heat properly can result in softening and/or melting of the polymer particles, which can further cause particle agglomeration, polymer sheet sticking to the reactor walls, and, in the worst case, clumping and plugging of the distributor plate and product discharge system, requiring a reactor shutdown for cleaning, which typically takes the reactor out of service for many days.

[0004] Compared to other types of polypropylene, random copolymers are relatively more problematic from a manufacturing standpoint. For example, the presence of a comonomer can increase the heat of reaction and decrease the melting point of the polymer in the sense that more heat must be removed compared to the production of a homopolymer, and the polymer particles tend to become relatively "stickier." As such, efficient heat transfer from the polymer particles to the gas is particularly important in the production of polypropylene random copolymers. Even when proper operating guidelines are followed to select the proper reaction temperature, condensation level, and propylene partial pressure, the operation of a random copolymer can still be accompanied by problems such as polymer agglomeration, unstable reactor temperature, abnormal fluidized bed bulk density (FBD)/fluidized bed level, hot spots in the reactor, and the like.

[0005] Previous attempts to improve heat transfer in gas phase polypropylene processes have involved the use of mechanical agitators and the operation at relatively high superficial gas velocities. However, the addition of a mechanical agitator, while facilitating the mixing and stirring of the polymer particle bed in the reactor, has additional negative consequences, such as additional surfaces for potential fouling, reliability of moving parts in the reactor, sealing of the shaft at high operating pressure, concerns about power outages, and the like. In addition, due to the technical capabilities of the compressor for the cycle gas, there is a practical limit to the superficial gas velocity. As such, there is a need for further improvement.

ESSENCE OF THE INVENTION

[0006] The present disclosure is generally directed to a gas-phase method for producing a polypropylene random copolymer in a fluidized bed reactor. The method includes feeding a fluidizing medium into a reactor vessel containing a bed of catalytically active polyolefin particles.

[0007] In one embodiment, the fluidizing medium comprises gaseous propylene, C2 and/or C4-C8 α-olefin comonomers, hydrogen and at least one inert gas. The momentum flux of the fluidizing medium, defined as (SGV [m/sec]) ² * ρ _g [kg/m ³ ], is 7.0 N/m ² or more, and the condensation level of the reactor cycle gas upon entering the reactor is less than 25% (wt). In the above equation, ρ _g is the density of the fluidizing medium, and SGV is the superficial gas velocity of the fluidizing medium.

[0008] Other features and aspects of the present disclosure are discussed in more detail below.

BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a schematic illustration of one embodiment of a gas phase polymerization process in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing several illustrative embodiments, it should be understood that the invention is not limited to the details of construction or process steps presented in the following description of the invention. The invention is capable of adopting other embodiments and is implemented in practice or carried out in various ways.

[0011] In general, the present invention is directed to a gas-phase process for producing a polypropylene random copolymer in a fluidized bed reactor. As the inventors of the present invention have unexpectedly discovered, the stability of the reactor is at least partially dependent on the momentum flux of the fluidizing medium in the fluidized bed reactor. The momentum flux, as used herein, is defined as (SGV [m/sec]) ² * ρ _g [kg/m ³ ], where SGV is the superficial gas velocity of the fluidizing medium in the reaction zone of the fluidized bed reactor, and ρ _g is the density of the fluidizing medium in the reactor. When calculated as demonstrated in the above equation, the momentum flux has units of N/m ² . The superficial velocity of the fluidizing medium gas is defined as the volumetric flow rate of the fluidizing medium divided by the cross-sectional area of the reaction zone of the fluidized bed reactor.

[0012] As may be believed without intending to be bound by theory, increasing the superficial velocity of the fluidizing medium gas and increasing its density result in an increased particle-to-gas heat transfer coefficient, which results in more efficient removal of the heat of polymerization from the polymer particles to the fluidizing medium. More efficient heat transfer helps prevent the occurrence of hot spots that could cause softening or melting of the polymer. Ultimately, this more efficient heat transfer provides for very stable reactor operation without particle agglomeration, polymer sheet sticking, and clumping.

[0013] Although there are processes available to manipulate reactor conditions when such issues arise, it is preferable to be able to maintain stable operation in the absence of aggressive or delicate manipulation in order to prevent clumping in the reactor and to completely shut it down. As the inventors of the present invention have unexpectedly discovered, the pulse flux is a clear indicator of reactor stability, since reactors operating at low pulse flux tend to form lumps, reactors with medium pulse flux can operate continuously with some special manipulation, and reactors operating at high pulse flux tend to operate stably and reliably without the need for delicate manipulation while also ensuring good particle morphology of the granular polymer product.

[0014] As the inventors of the present invention have also discovered, due to the practical limit of the SGV of the fluidizing medium due to the compressor capacity in the recycle stream, the pulse flow can be increased by increasing the density of the fluidizing medium by increasing the total reactor pressure. Increasing the partial pressure of propylene gas can help to increase the total pressure and density of the gas, but it can also cause some operational problems that are intended to be prevented, such as overheating of the polymerization reaction medium, which results in hot spots and agglomeration of the polymer particles. In fact, the partial pressure of propylene and the partial pressure of the comonomer(s) must be maintained in a suitable range for use in order to ensure good catalyst productivity while avoiding overheating. Therefore, it has been found that deliberately increasing the partial pressure of an inert gas instead of the partial pressure of propylene or comonomer(s) is an effective yet safe way to increase the total reactor pressure and gas density, thereby increasing the pulse flux, without promoting "overactive" polymerization. For example, one inert gas that is commonly present as an impurity in the propylene gas feed is propane. It is therefore desirable to operate the random copolymerization reactor at a relatively high partial pressure of propane. This can be accomplished by maintaining a relatively high level of propane that accumulates in the reactor as a result of manipulation of the off-gas recovery system and/or by adding additional propane in the feed to the reactor.

[0015] Since the propylene feedstock contains only a very small amount of propane, and feeding additional propane may involve additional costs, such as a propane purification system, in addition to the cost of purchasing the propane, there could be a limit on the available propane that can be stored in the system. In addition, at very high propane levels in the reactor, there could be several negative consequences. For example, high propane levels can cause excessively high condensation of the cycle gas entering the reactor, which increases the pressure in the product discharge system (PDS) and reduces the resin temperature in the PDS and the product degassing column. This can lead to difficulties in achieving good degassing of the resin, increased loading on the off-gas recovery system, which could cause reduced operating efficiency (i.e., at increased ratios between consumed monomers and comonomers and final polymer product), and possible stickiness of the resin particles. Excessive condensation levels could also be a concern for insufficient mixing near the bottom of the reactor due to the relatively low effective gas velocity before the condensates evaporate. In this regard, the condensation level is typically about 25% or less, in some embodiments about 20% or less, and in some embodiments about 17% or less. Therefore, in additional or alternative embodiments, the inert gas used to increase the pulse flux may include non-condensable gases such as nitrogen. Nitrogen is typically present in the fluidizing medium as an inert gas. For example, nitrogen originates from the gas streams for purging nozzles and pressure measuring nozzles in a gas phase polymerization reactor. During reactor start-up, nitrogen is also used intensively as a fluidizing medium prior to the introduction of monomer and comonomer(s) into the reactor. As such, another convenient and advantageous way to increase the fluidizing medium pulse flow is to increase the partial pressure of nitrogen in the reactor. Preferably, the fluidizing medium has relatively high concentrations of both propane and nitrogen, as long as the concentration of condensable inert gases remains low enough to prevent excessive condensation of the cycle gas. However, despite the greatest possible ease of availability of these inert gases, any inert gas can be used to increase the total pressure and thus the density of the fluidizing medium, as long as it does not polymerize the monomer/comonomer or send the reaction mixture.

[0016] It has been found that the desired results in terms of stable and reliable copolymerization are provided by operating the reactor at a pulse flux of 7.0 N/m ² or more. Preferably, the pulse flux is 8.3 N/m ² or more, such as 8.5 N/m ² or more, such as 9 N/m ² or more, such as 9.5 N/m ² or more. Typically, the pulse flux is less than 20 N/m ² , such as less than 18 N/m ² , such as less than 15 N/m ² .

[0017] The superficial gas velocity (SGV) is limited at the lower end by the minimum fluidization velocity, which is the minimum velocity at which the bed of polymer particles becomes fluidized. Preferably, the SGV is 0.34 m/sec or more, such as 0.36 m/sec or more, such as 0.38 m/sec or more, such as 0.39 m/sec or more, such as 0.4 m/sec or more. The SGV is typically less than 0.6 m/sec, but is limited by the technical capabilities of the compressor or the velocity at which reactor operation becomes undesirable, such as excessive entrainment of fines from the reactor.

[0018] The gas density of the fluidizing medium ρ _g is preferably about 55 kg/m ³ or more, such as about 57 kg/m ³ or more, such as about 58 kg/m ³ or more, such as about 59 kg/m ³ or more, such as about 60 kg/m ³ or more. The gas density of the fluidizing medium is typically less than about 80 kg/m ³ , such as less than about 70 kg/m ³ .

[0019] According to the above description of the invention, the inert gas preferably comprises propane. In one embodiment, propane constitutes about 4% (mol) of the fluidizing medium and more, such as about 6% (mol) of the fluidizing medium and more, such as about 8% (mol) of the fluidizing medium and more, such as about 10% (mol) of the fluidizing medium and more, such as about 12% (mol) of the fluidizing medium and more. Typically, propane constitutes less than about 40% (mol) of the fluidizing medium, such as about 30% (mol) of the fluidizing medium and less, such as about 25% (wt) of the fluidizing medium and less, such as about 20% (wt) of the fluidizing medium and less.

[0020] In another embodiment, the inert gas comprises nitrogen. Preferably, nitrogen is about 4 mol% of the fluidizing medium or more, such as about 6 mol% of the fluidizing medium or more, such as about 7 mol% of the fluidizing medium or more, such as about 9 mol% of the fluidizing medium or more, such as about 11 mol% of the fluidizing medium or more, such as about 13 mol% of the fluidizing medium or more, such as about 15 mol% of the fluidizing medium or more, such as about 19 mol% of the fluidizing medium or more, such as about 25 mol% of the fluidizing medium or more. Typically, nitrogen makes up less than approximately 60 mol% of the fluidizing medium.

[0021] In one embodiment, the fluidizing medium contains both propane and nitrogen. Preferably, the sum of the mol % propane and the mol % nitrogen in the fluidizing medium is about 10% or more, such as about 16% or more, such as about 25% or more, such as about 32% or more. Typically, the sum of the mol % propane and the mol % nitrogen is less than about 70%.

[0022] In general, the polymerization described herein is carried out in a gas-phase fluidized bed reactor. The polymerization is carried out by reacting propylene and at least one olefin comonomer selected from _C2 and _C4-8 compounds with a catalyst system, preferably in the presence of hydrogen, to produce a propylene-based polymer. The catalyst system may be a metallocene catalyst system or a Ziegler-Natta catalyst system, or even a mixture of Ziegler-Natta catalysts and metallocene catalysts. Preferably, the catalyst system is a Ziegler-Natta catalyst system.

[0023] The propylene polymer may be a propylene copolymer (with a single comonomer) or a terpolymer (with two comonomers) or even with more comonomers. As used herein, the term propylene copolymer is used in a broad sense to refer to embodiments comprising a single comonomer or multiple comonomers, and thus includes terpolymers. When the polymer is a terpolymer, preferably one of the comonomers is ethylene. When using only one comonomer, the random copolymer is preferably a propylene random copolymer with ethylene or 1-butene. The polymerization temperature is preferably in the range of from about 50 to about 90°C, such as from about 55 to about 75°C, or alternatively from about 58 to about 68°C. In the presence of hydrogen, the ratio of hydrogen to propylene used in the polymerization is preferably in the range of from about 0.003 to about 0.25, such as from about 0.005 to 0.18.

[0024] The melt flow rate (MFR) of the produced propylene polymer, measured in accordance with ASTM D1238, is typically in the range of about 0.15 to about 400 g/10 min, wherein the MFR measurement includes the addition of an antioxidant to obtain stable, consistent measurements. Typically, the antioxidant used includes 2000 ppm Cyanox-2246, 2000 ppm Irgafos-168, or 1000 ppm ZnO, or equivalents thereof. Preferably, the melt flow rate is in the range of about 0.15 to about 250 g/10 min. More preferably, the melt flow rate is in the range of about 0.2 to about 200 g/10 min. This melt flow rate is measured on the material produced in the reactor without subsequent visbreaking.

[0025] Referring to FIGURE 1, one embodiment of a process for gas-phase polymerization in a fluidized bed reactor is illustrated for illustrative purposes only. As shown in FIGURE 1, the system includes a gas-phase reactor 10 that includes a reaction zone 12 and a velocity reduction zone 14. It is noteworthy that for the purposes of calculating the SGV, the cross-sectional area of the reaction zone should be used. In one illustrative embodiment, the ratio between the diameter and the height of the reaction zone can vary in the range from about 2:1 to about 7:1.

[0026] The reaction zone 12 comprises a bed of growing and grown polymer particles, polymerizable monomer(s) and other gaseous components (including inert gases and optionally hydrogen) in the form of a fluidizing medium that flows through the reaction zone. According to the above explanation of the invention, the SGV of the fluidizing medium (typically in a gaseous state in most parts of the reactor) is sufficient to produce a fluidized bed. For example, the superficial gas velocity may be greater than 1.5 times, such as greater than 2.5 times, such as greater than 4 times, greater than the minimum fluidization velocity.

[0027] Make-up fluidizing medium (such as fresh polyolefin monomer(s) to replace that consumed during polymerization) is generally introduced into the process at point 18 and combined with recycle process line 22 or at other locations in the circulation loop upstream of compressor 30. The composition of the recycle stream is typically measured using gas analyzer 21. The SGV value in reactor 10 can be adjusted by adjusting the flow rate of fluidizing medium passing compressor 30. Gas analyzer 21, as shown in FIGURE 1, can be positioned to test the recycle gas at a point between compressor 30 and heat exchanger 24.

[0028] The fluidizing medium contained in the recirculation stream 22 is fed into the reactor 10 in the direction of the bottom at a point 26 below the bed. The reactor 10 may include a gas distribution plate 28 to promote uniform fluidization of the bed and to provide support for the solid particles contained in the fluidized bed. The fluidizing medium passing from the bottom up through the bed and from the bed removes the heat of reaction generated by the exothermic polymerization reaction.

[0029] As shown in FIGURE 1, the fluidizing medium flows through the reactor 10 and enters the velocity reduction zone 14. In the velocity reduction zone 14, most of the particles fall back into the dense fluidized bed in the reaction zone 12 under the action of gravity, while a small amount of fine particles are carried out of the reactor by the fluidizing medium into the circulation loop.

[0030] The recirculating fluidizing medium is compressed in a compressor 30 and passed through a heat exchanger 24. The heat exchanger 24 is designed to remove the heat of the polymerization reaction absorbed by the fluidizing medium during passage through the reactor before the fluidizing medium is returned to the reactor 10. In one aspect, the reactor 10 may include a fluid flow deflector 32 installed at the inlet to the reactor to facilitate better distribution of the fluidizing medium in the space below the distribution plate 28, to prevent the polymer particles contained in the fluidizing medium from settling and agglomerating into a solid mass and to retain and capture or re-capture any particles and optionally condensed liquid that may settle or cease to be captured. The distribution plate 28 ensures the flow of the fluidizing medium into the fluidized bed in the reaction zone 12 at a uniform speed and a uniform amount of transferred fine particles and not necessarily a uniform amount of condensed liquid over the entire cross-sectional area of the reactor.

[0031] The granulated polyolefin polymer resin produced using this reaction is discharged from the reactor 10 through the process line 44.

[0032] In one embodiment, the polymerization catalyst enters the reactor 10 through a nozzle 42 via a process line 48.

[0033] The catalyst stream 48 comprises catalyst particles, optionally a suspending liquid such as mineral oil or liquid alkane, and a carrier fluid. The catalyst particles (for example, in the form of a suspension as a result of suspension in mineral oil) and the carrier fluid may be injected into the reactor 10 through the nozzle 42. Preferably, when calculated on a volume basis, the catalyst stream 4 8 mainly contains the carrier fluid. For example, the carrier fluid preferably accounts for more than 50%, such as more than 60%, such as more than 70%, of the volume of the catalyst stream 48.

[0034] The carrier fluid in the catalyst stream 48 may comprise a monomer, a comonomer, an inert hydrocarbon, an inert gas, or mixtures thereof. In one embodiment, for example, the carrier fluid is a liquid monomer, such as liquid propylene. When using liquid propylene as the carrier fluid, the flow rate of the catalyst stream 48 is generally greater than about 15 kg/hour, such as greater than about 25 kg/hour, such as greater than about 55 kg/hour. When using liquid propylene as the carrier fluid, the flow rate of the catalyst stream 48 is generally less than about 250 kg/hour, such as less than about 200 kg/hour.

[0035] Alternatively, the carrier fluid may be an inert gas, such as nitrogen gas. When the carrier fluid is nitrogen gas, the flow rate of the catalyst 48 may generally be greater than about 3 kg/hour, such as greater than about 5 kg/hour, such as greater than about 9 kg/hour, and generally less than about 55 kg/hour, such as less than about 45 kg/hour, such as less than about 30 kg/hour.

[0036] In addition to the catalyst stream 48, as shown in FIGURE 1, the system may further include a support gas stream 47, separate from the catalyst stream 48 until released into the reactor 10. In one embodiment, for example, the support gas stream 47 is fed into the gas-phase reactor 10 through a nozzle 42 in a manner such that the support gas is released at a tip of the tube very close to the tip of the catalyst injection tube. Typically, the support gas flows in a support tube that is coaxially arranged with the catalyst injection tube.

[0037] If present, the support gas stream generally comprises a monomer, a comonomer, an inert hydrocarbon, an inert gas, or mixtures thereof. In one embodiment, for example, the support gas may comprise a gaseous monomer, such as a gaseous olefin. In one particular embodiment, for example, the support gas may be vaporized propylene. Preferably, the support gas flow rate is greater than about 40 kg/hour, such as greater than about 50 kg/hour, such as greater than about 60 kg/hour. The support gas flow rate is preferably less than about 600 kg/hour, such as less than about 550 kg/hour, such as less than about 500 kg/hour.

[0038] In one embodiment, the catalyst system is a Ziegler-Natta catalyst composition. Ziegler-Natta catalyst compositions typically include a procatalyst comprising a transition metal halide (i.e., titanium, chromium, vanadium), a cocatalyst such as an organoaluminum compound, and optionally an external electron donor.

[0039] All different types of Ziegler-Natta catalysts can be used in the method of the present disclosure. The Ziegler-Natta catalyst includes a solid catalyst component. The solid catalyst component can include (i) magnesium, (ii) a compound of a transition metal element from groups IV through VIII of the periodic table, (iii) a halide, oxyhalide and/or alkoxide of (i) and/or (ii), and (iv) combinations of (i), (ii), and (iii). Non-limiting examples of suitable catalyst components include halides, oxyhalides, and alkoxides of magnesium, manganese, titanium, vanadium, chromium, molybdenum, zirconium, hafnium, and combinations thereof.

[0040] In one embodiment, producing a catalyst component comprises halogenating mixed alkoxides of magnesium and titanium.

[0041] In various embodiments, the catalyst component is a magnesium moiety compound (MagMo), a mixed magnesium-titanium compound (MagTi), or a benzoate-containing magnesium chloride compound (BenMag). In one embodiment, the catalyst precursor is a magnesium moiety precursor ("MagMo"). The MagMo precursor includes a magnesium moiety. Non-limiting examples of suitable magnesium moieties include anhydrous magnesium chloride and/or an alcohol adduct thereof, a magnesium alkoxide or aryloxide, a mixed magnesium alkoxyhalide, and/or a carboxylated magnesium dialkoxide or aryloxide. In one embodiment, the MagMo precursor is magnesium di(C _1-4 )alkoxide. In a further embodiment, the MagMo precursor is diethoxymagnesium.

[0042] In another embodiment, the catalyst component is a mixed magnesium/titanium compound ("MagTi"). The "MagTi precursor" is described by the formula Mg _d Ti(OR ^e ) _f X _g , wherein R is an aliphatic or aromatic hydrocarbon radical containing from 1 to 14 carbon atoms, or COR', wherein R' is an aliphatic or aromatic hydrocarbon radical containing from 1 to 14 carbon atoms; each OR ^e group is the same or different; X is independently a chlorine, bromine, or iodine atom, preferably chlorine; d is in the range of from 0.5 to 56, or from 2 to 4; f is in the range of from 2 to 116, or from 5 to 15; ag is in the range of 0.5 to 116 or 1 to 3. The precursors are obtained by controlled precipitation by removing the alcohol from the reaction mixture used in their preparation. In one embodiment, the reaction medium comprises a mixture of an aromatic liquid, in particular a chlorinated aromatic compound, most particularly chlorobenzene, with an alkanol, in particular ethanol. Suitable halogenating agents include titanium tetrabromide, titanium tetrachloride or titanium trichloride, in particular titanium tetrachloride. Removing the alkanol from the solution used in the halogenation results in the precipitation of a solid precursor having a particularly desirable morphology and surface area. In addition, the resulting precursors are generally particularly uniform in particle size.

[0043] In another embodiment, the catalyst precursor is a benzoate-containing magnesium chloride ("BenMag") material. As used herein, a "benzoate-containing magnesium chloride" ("BenMag") can be a catalyst (i.e., a halogenated catalyst component) comprising a benzoate internal electron donor. The BenMag material can also include a titanium moiety, such as a titanium halide. The benzoate internal donor is labile and can be replaced with other electron donors during catalyst synthesis. Non-limiting examples of suitable benzoate groups include ethyl benzoate, methyl benzoate, ethyl p-methoxybenzoate, methyl p-ethoxybenzoate, ethyl p-ethoxybenzoate, ethyl p-chlorobenzoate. In one embodiment, the benzoate group is ethyl benzoate. In one embodiment, the BenMag catalyst component may be a halogenation product of either catalyst component (i.e., a MagMo precursor or a MagTi precursor) in the presence of a benzoate compound.

[0044] In another embodiment, the solid catalyst component can be formed from a magnesium moiety, a titanium moiety, an epoxy compound, an organosilicon compound, and an internal electron donor. In one embodiment, an organophosphorus compound can also be introduced into the solid catalyst component. For example, in one embodiment, a halide-containing magnesium compound can be dissolved in a mixture that includes an epoxy compound, an organophosphorus compound, and a hydrocarbon solvent. The resulting solution can be treated with a titanium compound in the presence of an organosilicon compound and, optionally, an internal electron donor to form a solid precipitate. The solid precipitate can then be treated with additional amounts of a titanium compound. The titanium compound used to form the catalyst can be described by the following chemical formula:

wherein each R is independently C ₁ -C ₄ alkyl; X is Br, Cl or I; and g is 0, 1, 2, 3 or 4.

[0045] In some embodiments, the organosilicon compound is a monomeric or polymeric compound. The organosilicon compound may contain -Si-O-Si- groups within one molecule or between it and other molecules. Other illustrative examples of the organosilicon compound include polydialkylsiloxane and/or tetraalkoxysilane. Such compounds may be used individually or in combination. The organosilicon compound may be used in combination with aluminum alkoxides and an internal electron donor.

[0046] The aluminum alkoxide referred to above may be described by the formula Al(OR') ₃ , wherein each R' is individually a hydrocarbon containing up to 20 carbon atoms. This may include the case where each R' is individually methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, and the like.

[0047] Examples of magnesium halide-containing compounds include magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride. In one embodiment, the magnesium halide-containing compound is magnesium chloride.

[0048] Illustrative representation of epoxy compounds include, but are not limited to, glycidyl-containing compounds represented by the formula:

wherein "a" has a value from list 1, 2, 3, 4, or 5, X is F, Cl, Br, I, or methyl, and R ^a is H, alkyl, aryl, or cyclyl. In one embodiment, the alkyl epoxide is epichlorohydrin. In some embodiments, the epoxy compound is a haloalkyl epoxide or a nonhaloalkyl epoxide.

[0049] According to some embodiments, the epoxy compound is selected from the group consisting of ethylene oxide; propylene oxide; 1,2-epoxybutane; 2,3-epoxybutane; 1,2-epoxyhexane; 1,2-epoxyoctane; 1,2-epoxydecane; 1,2-epoxydecane; 1,2-epoxytetradecane; 1,2-epoxyhexadecane; 1,2-epoxyoctadecane; 7,8-epoxy-2-methyloctadecane; 2-vinyloxirane; 2-methyl-2-vinyloxirane; 1,2-epoxy-5-hexene; 1,2-epoxy-7-octene; 1-phenyl-2,3-epoxypropane; 1-(1-naphthyl)-2,3-epoxypropane; 1-cyclohexyl-3,4-epoxybutane; 1,3-butadiene dioxide; 1,2,7,8-diepoxyoctane; cyclopentene oxide; cyclooctene oxide; a-pinene oxide; 2,3-epoxynorbornane; limonene oxide; cyclodecane epoxide; 2,3,5,6-diepoxynorbornane; styrene oxide; 3-methylstyrene oxide; 1,2-epoxybutylbenzene; 1,2-epoxyoctylbenzene; stilbene oxide; 3-vinylstyrene oxide; 1-(1-methyl-1,2-epoxyethyl)-3-(1-methylvinyl)benzene; 1,4-bis(1,2-epoxypropyl)benzene; 1,3-bis(1,2-epoxy-1-methylethyl)benzene; 1,4-bis(1,2-epoxy-1-methylethyl)benzene; epifluorohydrin; epichlorohydrin; epibromohydrin; hexafluoropropylene oxide; 1,2-epoxy-4-fluorobutane; 1-(2,3-epoxypropyl)-4-fluorobenzene; 1-(3,4-epoxybutyl)-2-fluorobenzene; 1-(2,3-epoxypropyl)-4-chlorobenzene; 1-(3,4-epoxybutyl)-3-chlorobenzene; 4-fluoro-1,2-cyclohexene oxide; 6-chloro-2,3-epoxybicyclo[2.2.1]heptane; 4-fluorostyrene oxide; 1-(1,2-epoxypropyl)-3-trifluorobenzene; 3-acetyl-1,2-epoxypropane; 4-benzoyl-1,2-epoxybutane; 4-(4-benzoyl)phenyl-1,2-epoxybutane; 4,4'-bis(3,4-epoxybutyl)benzophenone; 3,4-epoxy-1-cyclohexanone; 2,3-epoxy-5-oxobicyclo[2.2.1]heptane; 3-acetylstyrene oxide; 4-(1,2-epoxypropyl)benzophenone; glycidyl methyl ether; butyl glycidyl ether; 2-ethylhexyl glycidyl ether; allyl glycidyl ether; ethyl 3,4-epoxybutyl ether; glycidylphenyl ether; glycidyl 4-tert-butylphenyl ether; glycidyl 4-chlorophenyl ether; glycidyl 4-methoxyphenyl ether; glycidyl 2-phenylphenyl ether; glycidyl 1-naphthyl ether; glycidyl 2-phenylphenyl ether; glycidyl 1-naphthyl ether; glycidyl 4-indolyl ether; glycidyl N-methyl-α-quinolone-4-yl ether; ethylene glycol diglycidyl ether; 1,4-butanediol diglycidyl ether; 1,2-diglycidyloxybenzene; 2,2-bis(4-glycidyloxyphenyl)propane; tris(4-glycidyloxyphenyl)methane; poly(oxypropylene) triol triglycidyl ether; glycidyl ether of phenol-formaldehyde novolac resin; 1,2-epoxy-4-methoxycyclohexane; 2,3-epoxy-5,6-dimethoxybicyclo[2.2.1]heptane; 4-methoxystyrene oxide; 1-(1,2-epoxybutyl)-2-phenoxybenzene; glycidyl formate; glycidyl acetate; 2,3-epoxybutyl acetate; glycidyl butyrate; glycidyl benzoate; diglycidyl terephthalate; poly(glycidyl acrylate); poly(glycidyl methacrylate); a copolymer of glycidyl acrylate with another monomer; a copolymer of glycidyl methacrylate with another monomer; 1,2-epoxy-4-methoxycarbonylcyclohexane; 2,3-epoxy-5-butoxycarbonylbicyclo[2.2.1]heptane; ethyl 4-(1,2-epoxyethyl)benzoate; methyl 3-(1,2-epoxybutyl)benzoate; methyl 3-(1,2-epoxybutyl)-5-phenylbenzoate; N,N-glycidylmethylacetamide; N,N-ethylglycidylpropionamide; N,N-glycidylmethylbenzamide; N-(4,5-epoxypentyl)-N-methylbenzamide; N,N-diglycidylaniline; bis(4-diglycidylaminophenyl)methane; poly(N,N-glycidylmethylacrylamide); 1,2-epoxy-3-(diphenylcarbamoyl)cyclohexane; 2, 3-epoxy-6-(dimethylcarbamoyl)bicyclo[2.2.1]heptane; 2-(dimethylcarbamoyl)styrene oxide; 4-(1,2-epoxybutyl)-N'-(dimethylcarbamoyl)biphenyl; 4-cyano-1,2-epoxybutane; 1-(3-cyanophenyl)-2,3-epoxybutane; 2-cyanostyrene oxide; and 6-cyano-1-(1,2-epoxy-2-phenylethyl)naphthalene.

[0050] As one example of an organophosphorus compound, esters of phosphoric acid, such as a trialkyl ester of phosphoric acid, can be used. Such compounds can be described by the formula:

wherein R ₁ , R ₂ and R ₃ are each independently selected from the group consisting of methyl, ethyl and linear or branched (C ₃ -C ₁₀ )alkyl groups. In one embodiment, the trialkyl ester of phosphoric acid is tributyl ester of phosphoric acid.

[0051] In yet another embodiment, a substantially spherical adduct of MgCl ₂ -nEtOH can be produced by a spray crystallization method. In this method, a melt of MgCl ₂ -nEtOH, where n is in the range of 1-6, is sprayed inside a vessel while simultaneously introducing an inert gas at a temperature in the range of 20-80 °C into the upper part of the vessel. The melt droplets transfer to a crystallization region, into which an inert gas is introduced at a temperature in the range of - 50 to 20 °C, crystallizing the melt droplets to form non-agglomerated solid particles of spherical shape. Thereafter, the spherical MgCl ₂ particles are sorted by size to obtain a desired size. Particles of an undesirable size can be sent for recycling. In preferred embodiments of the catalyst synthesis, the spherical _MgCl2 precursor has an average particle size (Malvern _d50 ) in the range between about 8-150 microns, preferably between 10-100 microns, and most preferably between 10-30 microns.

[0052] The catalyst component can be converted into a solid catalyst by halogenation.

Halogenation involves contacting a catalyst component with a halogenating agent in the presence of an internal electron donor. Halogenation converts a magnesium moiety present in the catalyst component into a magnesium halide support onto which a titanium moiety (such as a titanium halide) is deposited. Without wishing to be bound by any particular theory, it can be understood that during halogenation, the internal electron donor (1) controls the arrangement of the titanium on the magnesium-based support, (2) facilitates the conversion of the magnesium and titanium moieties to the corresponding halides, and (3) controls the crystallite size of the magnesium halide support during the conversion. Thus, provision of an internal electron donor imparts improved stereoselectivity to the catalyst composition.

[0053] In one embodiment, the halogenating agent is a titanium halide represented by the formula Ti(OR ^e ) _f X _h , where R and X are defined as set forth above, f is an integer ranging from 0 to 3, h is an integer ranging from 1 to 4; and f + h is 4. In one embodiment, the halogenating agent is TiCl ₄ . In a further embodiment, the halogenation is carried out in the presence of a chlorinated or non-chlorinated aromatic liquid, such as dichlorobenzene, o-chlorotoluene, chlorobenzene, benzene, toluene, or xylene. In yet another further embodiment, the halogenation is carried out using a mixture of a halogenating agent and a chlorinated aromatic liquid containing from 40 to 60 volume percent of a halogenating agent, such as TiCl ₄ .

[0054] During the halogenation, the reaction mixture may be heated. The catalyst component and the halogenating agent are contacted initially at a temperature of less than about 10°C, such as less than about 0°C, such as less than about 10°C, such as less than about -20°C, such as less than about -30°C. The initial temperature is generally greater than about -50°C, such as greater than about -40°C. The mixture is then heated at a rate in the range of 0.1 to 10.0°C/minute or at a rate in the range of 1.0 to 5.0°C/minute. The internal electron donor may be added later, after the initial contact period between the halogenating agent and the catalyst component. Halogenation temperatures range from 20°C to 150°C (or any value or subrange therebetween) or from 0°C to 120°C. Halogenation may be continued substantially in the absence of an internal electron donor for a period of 5 to 60 minutes or 10 to 50 minutes.

[0055] The manner in which the catalyst component, halogenating agent, and internal electron donor are contacted may vary. In one embodiment, the catalyst component is first contacted with a mixture containing the halogenating agent and the chlorinated aromatic compound. The resulting mixture is stirred and may be heated if desired. The internal electron donor is then added to the same reaction mixture without isolating or recovering the precursor. The above method may be implemented in a single reactor with the addition of the various ingredients controlled by automated process control means.

[0056] In one embodiment, the catalyst component is contacted with an internal electron donor prior to reacting with the halogenating agent.

[0057] The contact times of the catalyst component with the internal electron donor are at least 10 minutes or at least 15 minutes or at least 20 minutes or at least 1 hour at a temperature in the range of at least - 30°C or at least - 20°C or at least 10°C up to a temperature of 150°C or up to 120°C or up to 115°C or up to 110°C.

[0058] In one embodiment, the catalyst component, internal electron donor, and halogenating agent are added simultaneously or substantially simultaneously.

[0059] The halogenation procedure can be repeated one, two, three or more times, if desired. In one embodiment, the resulting solid material is removed from the reaction mixture and contacted one or more times, in the absence (or in the presence) of identical (or different) internal electron donor components, with a mixture of a halogenating agent in a chlorinated aromatic compound for at least about 10 minutes, or at least about 15 minutes, or at least about 20 minutes and up to about 10 hours, or up to about 45 minutes, or up to about 30 minutes, at a temperature in the range of at least about -20°C, or at least about 0°C, or at least about 10°C to a temperature of up to about 150°C, or up to about 120°C, or up to about 115°C.

[0060] Upon completion of the above halogenation procedure, the resulting solid catalyst composition is separated from the reaction medium used in the final process by filtration, such as to produce a wet filter cake. The wet filter cake may then be rinsed or washed with a liquid diluent to remove unreacted TiCl ₄ compound and may be dried to remove residual liquid, if desired. Typically, the resulting solid catalyst composition is washed one or more times with a "wash liquid" that is a liquid hydrocarbon, such as an aliphatic hydrocarbon such as isopentane, isooctane, isohexane, hexane, pentane, or octane. The solid catalyst composition may then be separated and dried or suspended in a hydrocarbon, especially a relatively heavy hydrocarbon such as mineral oil, for further storage or use.

[0061] In one embodiment, the resulting solid catalyst composition has a titanium content in the range of about 1.0 weight percent to about 6.0 weight percent based on the total weight of the solid, or about 1.5 weight percent to about 4.5 weight percent, or about 2.0 weight percent to about 3.5 weight percent. The weight ratio of titanium to magnesium in the solid catalyst composition is suitably in the range of between about 1:3 and about 1:160, or between about 1:4 and about 1:50, or between about 1:6 and 1:30. In one embodiment, the internal electron donor in the catalyst composition can be present at a molar ratio of the internal electron donor to magnesium in the range of about 0.005:1 to about 1:1, or about 0.01:1 to about 0.4:1. The mass percentage is obtained by calculating the total mass of the catalyst composition.

[0062] The catalyst composition may be further processed using one or more of the following techniques before or after isolation of the solid catalyst composition. The solid catalyst composition may be contacted (halogenated) with additional titanium halide compound if desired; it may be metathesized with an acid chloride such as phthaloyl dichloride or benzoyl chloride; and it may be rinsed or washed, thermally treated; or aged. The above additional techniques may be combined in any order or used separately or not at all.

[0063] According to the above description of the invention, the catalyst composition may include a combination of a magnesium moiety, a titanium moiety, and an internal electron donor. The catalyst composition is produced using the above-described halogenation technique, which converts the catalyst component and the internal electron donor into a combination of magnesium and titanium moieties, into which the internal electron donor is introduced. The catalyst component from which the catalyst composition is obtained may be any of the catalyst precursors described above, including a magnesium moiety precursor, a mixed magnesium/titanium precursor, a benzoate-containing magnesium chloride precursor, magnesium, titanium, epoxide, and a phosphorus-containing precursor, or a spherical precursor.

[0064] A variety of different types of internal electron donors may be incorporated into the solid catalyst component. In one embodiment, the internal electron donor is an aryl diester, such as a phenylene substituted diester. In one embodiment, the internal electron donor may have the following chemical structure:

where R ₁ , R ₂ , R ₃ and R ₄ in each case represent a hydrocarbyl group containing from 1 to 20 carbon atoms, wherein the hydrocarbyl group has a branched or linear structure or includes a cycloalkyl group containing from 7 to 15 carbon atoms, and where E ₁ and E ₂ are identical or different and are selected from the group consisting of alkyl containing from 1 to 20 carbon atoms, substituted alkyl containing from 1 to 20 carbon atoms, aryl containing from 1 to 20 carbon atoms, substituted aryl containing from 1 to 20 carbon atoms, or an inert functional group containing from 1 to 20 carbon atoms and optionally containing heteroatoms, and where X ₁ and X ₂ in each case represent O, S, an alkyl group or NR ₅ , and where R ₅ is a hydrocarbyl a group containing from 1 to 20 carbon atoms, or a hydrogen atom.

[0065] As used herein, the terms "hydrocarbyl" and "hydrocarbon" refer to substituents containing only hydrogen and carbon atoms, including branched or unbranched, saturated or unsaturated, cyclic, polycyclic, fused or acyclic moieties, and combinations thereof. Non-limiting examples of hydrocarbyl groups include alkyl, cycloalkyl, alkenyl, alkadienyl, cycloalkenyl, cycloalkadienyl, aryl, aralkyl, alkylaryl, and alkynyl groups.

[0066] As used herein, the terms "substituted hydrocarbyl" and "substituted hydrocarbon" refer to a hydrocarbyl group that is substituted with one or more non-hydrocarbyl substituent groups. One non-limiting example of a non-hydrocarbyl substituent group is a heteroatom. As used herein, a "heteroatom" refers to an atom other than carbon or hydrogen. A heteroatom can be a non-carbon atom of an element from Groups IV, V, VI, and VII of the periodic table. Non-limiting examples of heteroatoms include: halogen atoms (F, Cl, Br, I), N, O, P, B, S, and Si. A substituted hydrocarbyl group also includes a halohydrocarbyl group and a silicon-containing hydrocarbyl group. As used herein, the term "hydrocarbyl" group refers to a hydrocarbyl group that is substituted with one or more halogen atoms. As used in this document, the term "silicon-containing hydrocarbyl group" refers to a hydrocarbyl group that is substituted by one or more silicon atoms. The silicon atom(s) may or may not be in the carbon chain.

[0067] In one aspect, the substituted phenylene diester has the following structure (I): (I)

[0068] In one embodiment, structure (I) includes R ₁ and R ₃ , which are an isopropyl group. Each of R ₂ , R ₄ , and R ₅ -R ₁₄ is a hydrogen atom.

[0069] In one embodiment, structure (I) includes each of R ₁ , R ₅ , and R ₁₀ as a methyl group, and R ₃ is a tert-butyl group. Each of R ₂ , R ₄ , R ₆ -R ₉ , and R ₁₁ -R ₁₄ is a hydrogen atom.

[0070] In one embodiment, structure (I) comprises each of R ₁ , R ₇ , and R ₁₂ as a methyl group, and R ₃ is a tert-butyl group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₃ , and R ₁₄ is a hydrogen atom.

[0071] In one embodiment, structure (I) includes R ₁ as a methyl group and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is an ethyl group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0072] In one embodiment, structure (I) comprises each of R ₁ , R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ as a methyl group, and R ₃ is a tert-butyl group. Each of R ₂ , R ₄ , R ₆ , R ₈ , R ₁₁ and R ₁₃ is a hydrogen atom.

[0073] In one embodiment, structure (I) includes R ₁ as a methyl group and R ₃ is a tert-butyl group. Each of R ₅ , R ₇ , R ₉ , R ₁₀ , R ₁₂ and R ₁₄ is an isopropyl group. Each of R ₂ , R ₄ , R ₆ , R ₈ , R ₁₁ and R ₁₃ is a hydrogen atom.

[0074] In one embodiment, the substituted phenylene aromatic diester has a structure selected from the group consisting of structures (II) through (V), including alternatives for each of R ₁ through R ₁₄ , which are described in detail in U.S. Patent No. 8,536,372, which is incorporated herein by reference.

[0075] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is an ethoxy group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0076] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is a fluorine atom. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0077] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is a chlorine atom. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0078] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is a bromine atom. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0079] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is an iodine atom. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0080] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₆ , R ₇ , R ₁₁ , and R ₁₂ is a chlorine atom. Each of R ₂ , R ₄ , R ₅ , R ₈ , R ₉ , R ₁₀ , R _{13 ,} and R ₁₄ is a hydrogen atom.

[0081] In one embodiment, structure (I) includes R₁, which is a methyl group, and R₃ represents a tert-butyl group. Each of R₆, R₈, R₁₁and R₁₃represents a chlorine atom. Each of R₂, R₄, R₅, R₇, R₉, R₁₀, R₁₂and R₁₄represents a hydrogen atom.

[0082] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₂ , R ₄ , and R ₅ -R ₁₄ is a fluorine atom.

[0083] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is a trifluoromethyl group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0084] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is an ethoxycarbonyl group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0085] In one embodiment, R ₁ is a methyl group and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is an ethoxy group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0086] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a tert-butyl group. Each of R ₇ and R ₁₂ is a diethyl amino group. Each of R ₂ , R ₄ , R ₅ , R ₆ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₃ and R ₁₄ is a hydrogen atom.

[0087] In one embodiment, structure (I) includes R ₁ , which is a methyl group, and R ₃ is a 2,4,4-trimethylpentan-2-yl group. Each of R ₂ , R ₄ , and R ₅ -R ₁₄ is a hydrogen atom.

[0088] In one embodiment, structure (I) includes R ₁ and R ₃ , each of which is a sec-butyl group. Each of R ₂ , R ₄ , and R ₅ -R ₁₄ is a hydrogen atom.

[0089] In one embodiment, structure (I) includes R ₁ and R ₄ , which in each case are a methyl group. Each of R ₂ , R ₃ , R ₅ -R ₉ and R ₁₀ -R ₁₄ is a hydrogen atom.

[0090] In one embodiment, structure (I) includes R ₁ , which is a methyl group. R ₄ is an isopropyl group. Each of R ₂ , R3, R ₅ -R ₉ and R ₁₀ -R ₁₄ is a hydrogen atom.

[0091] In one embodiment, structure (I) includes R ₁ , R ₃ , and R ₄ , each of which is an isopropyl group. Each of R ₂ , R ₅ -R ₉ , and R ₁₀ -R ₁₄ is a hydrogen atom.

[0092] In another aspect, the internal electron donor can be a phthalate compound. For example, the phthalate compound can be dimethyl phthalate, diethyl phthalate, dipropyl phthalate, diisopropyl phthalate, dibutyl phthalate, diisobutyl phthalate, diamyl phthalate, diisoamyl phthalate, methyl butyl phthalate, ethyl butyl phthalate, or ethyl propyl phthalate.

[0093] In addition to the solid catalyst component as described above, the Ziegler-Natta catalyst system of the present disclosure may also include a cocatalyst. The cocatalyst may include hydrides, alkyls, or aryls of aluminum, lithium, zinc, tin, cadmium, beryllium, magnesium, and combinations thereof. In one embodiment, the cocatalyst is a hydrocarbyl aluminum cocatalyst of the formula R ₃ Al, wherein each R is an alkyl, cycloalkyl, aryl, or hydride radical; at least one R is a hydrocarbyl radical; two or three R radicals may be joined into a cyclic radical to form a heterocyclic structure; each R may be the same or different; and each R that is a hydrocarbyl radical contains from 1 to 20 carbon atoms, and preferably from 1 to 10 carbon atoms. In one further embodiment, each alkyl radical may be straight or branched chain, and such a hydrocarbyl radical may be a mixed radical, i.e., the radical may include alkyl, aryl and/or cycloalkyl groups. Non-limiting examples of suitable radicals are: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, n-hexyl, 2-methylpentyl, n-heptyl, n-octyl, isooctyl, 2-ethylhexyl, 5,5-dimethylhexyl, n-nonyl, n-decyl, isodecyl, n-undecyl, n-dodecyl.

[0094] Non-limiting examples of suitable hydrocarbyl aluminum compounds include the following: triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, di-n-hexylaluminum hydride, isobutylaluminum dihydride, n-hexylaluminum dihydride, diisobutylhexylaluminum, isobutyldihexylaluminum, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, tri-n-octylaluminum, tri-n-decylaluminum, tri-n-dodecylaluminum. In one embodiment, the cocatalyst is selected from triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, diisobutylaluminum hydride, and di-n-hexylaluminum hydride.

[0095] In one embodiment, the cocatalyst is triethylaluminum. The molar ratio of aluminum to titanium is in the range of from about 5:1 to about 500:1, or from about 10:1 to about 200:1, or from about 15:1 to about 150:1, or from about 20:1 to about 100:1. In another embodiment, the molar ratio of aluminum to titanium is about 45:1.

[0096] Suitable catalyst compositions may include a solid catalyst component, a cocatalyst, and an external electron donor, which may be a mixed external electron donor (M-EED) of two or more different components. Suitable external electron donors or "external donor" include one or more selectivity control agents (SCAs) and/or one or more activity limiting agents (ALAs). As used herein, an "external donor" is a component or composition comprising a mixture of components added independently of the formation of a procatalyst that modifies the performance of the catalyst. As used herein, an "activity limiting agent" is a composition that decreases the activity of the catalyst as the polymerization temperature in the presence of the catalyst increases above a threshold temperature (e.g., a temperature greater than about 95°C). "Selectivity controlling agent" is a composition that improves the tacticity of a polymer, where improved tacticity is generally understood to mean increased tacticity or decreased xylene soluble components, or both. As should be understood, the above definitions are not mutually exclusive, and a single compound may be classified, for example, as both an activity limiting agent and a selectivity controlling agent.

[0097] The selectivity control agent in accordance with the present disclosure is generally a silicon-containing compound. For example, in one aspect, the selectivity control agent can be an alkoxysilane.

[0098] In one embodiment, the alkoxysilane may be described by the following general formula: SiR _m (OR') _4-m (I), wherein R, independently at each occurrence, is a hydrogen atom or a hydrocarbyl or amino group optionally substituted with one or more substituents containing one or more heteroatoms from Groups 14, 15, 16, or 17, wherein said R contains up to 20 atoms not counting hydrogen and halogen atoms; R' is a C _1-4 alkyl group; and m is 0, 1, 2, or 3. In one embodiment, R is _C6-12 aryl, -alkyl, or -aralkyl, _C3-12 cycloalkyl, _C3-12 branched alkyl, or _C3-12 cyclic or -acyclic amino, R' is _C1-4 alkyl, am is 1 or 2. In one embodiment, for example, the second SCA can include n-propyltriethoxysilane. Other SCAs that can be used include propyltriethoxysilane or diisobutyldimethoxysilane.

[0099] In one embodiment, the catalyst system may include an activity limiting agent (ALA). The ALA inhibits or otherwise prevents disruption of the polymerization reactor and ensures continuity of the polymerization process. Typically, the activity of Ziegler-Natta catalysts increases as the reactor temperature increases to a very high level. Ziegler-Natta catalysts also typically maintain high activity near the melting point of the polymer produced. The heat generated by the exothermic polymerization reaction may promote the formation of agglomerates of polymer particles and may ultimately lead to disruption of the polymer production process. The ALA reduces the activity of the catalyst at elevated temperatures, thereby preventing disruption of the reactor, reducing (or preventing) particle agglomeration, and ensuring continuity of the polymerization process.

[00100] The activity limiting agent may be an ester of a carboxylic acid. The ester of an aliphatic carboxylic acid may be an ester of a _C4 - _C30 aliphatic acid, may be a mono- or poly-(two or more)-ester, may be straight-chain or branched, may be saturated or unsaturated, and any combination thereof. The _C4 - _C30 aliphatic acid ester may also be substituted with one or more substituents containing a heteroatom from Groups 14, 15, or 16. Non-limiting examples of suitable _C4 - _C30 aliphatic acid esters include _C1-20 alkyl esters of aliphatic _C4-30 monocarboxylic acids, _C1-20 alkyl esters of aliphatic _C8-20 monocarboxylic acids, _C1-4 allylic mono- and diesters of aliphatic _C4-20 monocarboxylic acids and -dicarboxylic acids, _C1-4 alkyl esters of aliphatic _C8-20 monocarboxylic acids and -dicarboxylic acids, and _C4-20 mono- or polycarboxylate derivatives of _C2-100 -(poly)glycols or C _2-100 -(poly)glycol ethers. In one further embodiment, the C ₄ -C ₃₀ -aliphatic acid ester can be laurate, myristate, palmitate, stearate, oleinates, sebacate, (poly)(alkylene glycol) mono- or -diacetates, (poly)(alkylene glycol) mono- or -dimyristates, (poly)(alkylene glycol) mono- or -dilaurates, (poly)(alkylene glycol) mono- or -dioleinates, glyceryl tri(acetate), glyceryl triester of C _2-40 -aliphatic carboxylic acids and mixtures thereof. In one further embodiment, the C ₄ -C ₃₀ -aliphatic ester is isopropyl myristate, di-n-butyl sebacate and/or pentyl valerate.

[00101] In one embodiment, the selectivity control agent and/or the activity limiting agent may be added to the reactor separately. In another embodiment, the selectivity control agent and the activity limiting agent may be pre-mixed with each other and then added to the reactor as a mixture. Additionally, the selectivity control agent and/or the activity limiting agent may be directly added to the reactor, such as a fluidized bed reactor. Alternatively, the selectivity control agent and/or the activity limiting agent may be indirectly added to the reactor volume by feeding, for example, through a circulation loop (e.g., line 22 in Figure 1). The selectivity control agent and the activity limiting agent may be combined with the reactor cycle gas in the circulation loop before being fed to the reactor.

[00102] In addition to Ziegler-Natta catalysts, a metallocene catalyst can also be used in the process of the present disclosure. Metallocene catalysts can include "half-sandwich" and "full-sandwich" compounds comprising one or more Cp ligands (cyclopentadienyl and ligands isolobal to cyclopentadienyl) bonded to at least one metal atom from Groups 3 through Group 12, and one or more leaving group(s) bonded to at least one metal atom.

[00103] The Cp Ligands are one or more members selected from rings or ring system(s), at least a portion of which includes π-linked systems, such as cycloalkadienyl ligands and heterocyclic analogs. The ring(s) or ring system(s) typically comprises atoms selected from atoms in Groups 13 to 16, and in some embodiments, the atoms that comprise the Cp Ligands are selected from carbon, nitrogen, oxygen, silicon, sulfur, phosphorus, germanium, boron, aluminum, and combinations thereof, wherein the carbon atoms comprise at least 50% of the members forming the rings. For example, the Cp Ligand(s) can be selected from substituted and unsubstituted cyclopentadienyl ligands and ligands that are isolobal to cyclopentadienyl. Non-limiting examples of such ligands include cyclopentadienyl, cyclopentaphenantrenyl, indenyl, benzindenyl, fluorenyl, octahydrofluorenyl, cyclooctatetraenyl, cyclopentacyclododecene, phenanthrindenyl, 3,4-benzofluorenyl, 9-phenylfluorenyl, 8-H-cyclopent[a]acenaphthylenyl, 7-H-dibenzofluorenyl, indeno[1,2-9]anthrene, thiophenoindenyl, thiophenofluorenyl, hydrogenated versions thereof (e.g., 4,5,6,7-tetrahydroindenyl or "H ₄ Ind"), substituted versions thereof (as described in more detail below), and heterocyclic versions thereof.

[00104] The metal atom "M" of the metallocene compound may be selected from atoms from groups 3 to 12 and atoms of the lanthanide group; or may be selected from atoms from groups 3 to 10; or may be selected from Sc, Ti, Zr, Hf, V, Nb, Ta, Mn, Re, Fe, Ru, Os, Co, Rh, Ir and Ni; or may be selected from atoms from groups 4, 5 and 6; or may be selected from atoms Ti, Zr or Hf; or may be Hf; or may be Zr. The oxidation state of the metal atom "M" may be in the range from 0 to +7; or may be +1, +2, +3, +4 or +5; or may be +2, +3 or +4. The groups bound to the metal atom "M" are such that the compounds described in the structures below and the structures are electrically neutral unless otherwise indicated. The Cp-Ligand(s) form at least one chemical bond with the metal atom M, which forms the "metallocene catalyst component". The Cp-Ligands differ from the leaving groups bound to the metal atom M in that they are not highly sensitive to substitution/elimination reactions.

[00105] In one embodiment, the metallocene catalyst may be described by the following formula:

where M is a metal from groups IIIB to VIII of the periodic table of elements;

(C ₅ R _x ) and (C ₅ R _m ) are identical or different cyclopentadienyl or substituted cyclopentadienyl groups bound to M;

R are identical or different and represent a hydrogen atom or a hydrocarbyl radical such as an alkyl, alkenyl, aryl, alkylaryl or arylalkyl radical containing from 1 to 20 carbon atoms, or two carbon atoms joined together to form a C ₄ -C ₆ ring;

R' is a C ₁ -C ₄ -substituted or -unsubstituted alkylene radical, a dialkyl- or diarylgermanium or -silicon or an alkyl- or arylphosphine or -amine radical bridging two rings (C ₅ R _x ) and (C ₅ R _m );

Q represents a hydrocarbyl radical such as an aryl, alkyl, alkenyl, alkylaryl or arylalkyl radical containing 1-20 carbon atoms, a hydrocarboxy radical containing 1-20 carbon atoms, or a halogen atom, and it may be identical to or different from other similar radicals;

z is 0 or 1;

y is 0, 1, or 2;

z is 0 when y is 0;

n is 0, 1, 2, 3 or 4 depending on the valence state of M;

and n-y is ≥1.

[00106] Illustrative, but non-limiting, examples of metallocenes represented by the formula above include dialkyl metallocenes such as

bis(cyclopentadienyl)titanium dimethyl,

bis(cyclopentadienyl)titanium diphenyl,

bis(cyclopentadienyl)zirconiumdimethyl,

bis(cyclopentadienyl)zirconiumbiphenyl,

bis(cyclopentadienyl)hafniumdimethyl and -diphenyl,

bis(cyclopentadienyl)titanedineopentyl,

bis(cyclopentadienyl)zirconiumdineopentyl,

bis(cyclopentadienyl)titanium dibenzyl,

bis(cyclopentadienyl)zirconium dibenzyl,

bis(cyclopentadienyl)vanadium dimethyl; monoalkyl metallocenes such as

as bis(cyclopentadienyl)titanium methyl chloride, bis(cyclopentadienyl) titanium ethyl chloride,

bis(cyclopentadienyl)titanium phenyl chloride,

bis(cyclopentadienyl)zirconium methyl chloride,

bis(cyclopentadienyl)zirconium ethyl chloride,

bis(cyclopentadienyl)zirconiumphenyl chloride,

bis(cyclopentadienyl)titanium methyl bromide; trialkylmetallocenes,

such as cyclopentadienyltitaniumtrimethyl,

cyclopentadienyl zirconium triphenyl and

cyclopentadienylzirconium trineopentyl, cyclopentadienylzirconium trimethyl,

cyclopentadienyl hafnium triphenyl,

cyclopentadienyl hafnium trineopentyl and

cyclopentadienyl hafnium trimethyl; monocyclopentadienyl

titanocenes such as pentamethylcyclopentadienyltitanium trichloride, pentaethylcyclopentadienyltitanium trichloride;

bis(pentamethylcyclopentadienyl)titanium diphenyl, a carbene described by the formula bis(cyclopentadienyl)titanium= _CH2 , and derivatives of this reagent; substituted bis(cyclopentadienyl)titanium(IV) compounds such as bis(indenyl)titanium diphenyl or -dichloride, bis(methylcyclopentadienyl)titanium diphenyl or -dihalides; dialkyl-, trialkyl-, tetraalkyl- and pentaalkylcyclopentadienyltitanium compounds such as bis(1,2-dimethylcyclopentadienyl)titanium diphenyl or -dichloride, bis(1,2-diethylcyclopentadienyl)titanium diphenyl or -dichloride; silicon-, phosphine-, amine- or carbon-bridged cyclopentadiene complexes such as dimethylsilyldicyclopentadienyltitanium diphenyl or -dichloride, methylphosphine dicyclopentadienyltitanium diphenyl or -dichloride, methylene dicyclopentadienyl titanium diphenyl or -dichloride and other dihalide complexes and the like; and also bridged metallocene compounds such as isopropyl(cyclopentadienyl)(fluorenyl)zirconium dichloride, isopropyl(cyclopentadienyl)(octahydrofluorenyl)zirconium dichloride, iphenylmethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride, diisopropylmethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride, diisobutylmethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride, di-tert-butylmethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride, cyclohexylidene(cyclopentadienyl)(fluorenyl)zirconium dichloride, diisopropylmethylene(2,5-dimethylcyclopentadienyl)(fluorenyl)zirconium dichloride, isopropyl(cyclopentadienyl)(fluorenyl)hafnium dichloride, diphenylmethylene(cyclopentadienyl)(fluorenyl)hafnium dichloride, diisopropylmethylene(cyclopentadienyl)(fluorenyl)hafnium dichloride, diisobutylmethylene(cyclopentadienyl)(fluorenyl)hafnium dichloride, di-tert-butylmethylene(cyclopentadienyl)(fluorenyl)hafnium dichloride, cyclohexylidene(cyclopentadienyl)(fluorenyl)hafnium dichloride, diisopropylmethylene(2,5-dimethylcyclopentadienyl)(fluorenyl)hafnium dichloride, isopropyl(cyclopentadienyl)(fluorenyl)titanium dichloride, diphenylmethylene(cyclopentadienyl)(fluorenyl)titanium dichloride, diisopropylmethylene(cyclopentadienyl)(fluorenyl)titanium dichloride, diisobutylmethylene(cyclopentadienyl)(fluorenyl)titanium dichloride, di-tert-butylmethylene(cyclopentadienyl)(fluorenyl)titanium dichloride, cyclohexylidene(cyclopentadienyl)(fluorenyl)titanium dichloride, diisopropylmethylene(2,5-dimethylcyclopentadienyl)(fluorenyl)titanium dichloride, racemic ethylenebis(1-indenyl)zirconium(IV) dichloride, racemic ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium(IV) dichloride, racemic dimethylsilylbis(1-indenyl)zirconium(IV) dichloride, racemic dichloride dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)zirconium(IV), racemic 1,1,2,2-tetramethylsilanylenebis(1-indenyl)zirconium(IV) dichloride, racemic 1,1,2,2-tetramethylsilanylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconium(IV) dichloride, ethylidene(1-indenyltetramethylcyclopentadienyl)zirconium(IV) dichloride, racemic dimethylsilylbis(2-methyl-4-tert-butyl-1-cyclopentadienyl)zirconium(IV) dichloride, racemic ethylenebis(1-indenyl)hafnium(IV) dichloride, racemic ethylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium(IV) dichloride, racemic dichloride dimethylsilylbis(1-indenyl)hafnium(IV), racemic dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)hafnium(IV) dichloride, racemic 1,1,2,2-tetramethylsilanylenebis(1-indenyl)hafnium(IV) dichloride, racemic 1,1,2,2-tetramethylsilanylenebis(4,5,6,7-tetrahydro-1-indenyl)hafnium(IV) dichloride, ethylidene(1-indenyl-2,3,4,5-tetramethyl-1-cyclopentadienyl)hafnium(IV) dichloride, racemic ethylenebis(1-indenyl)titanium(IV) dichloride, racemic ethylenebis(4,5,6,7-tetrahydro-1-indenyl)titanium(IV) dichloride, racemic dichloride dimethylsilylbis(1-indenyl)titanium(IV), racemic dimethylsilylbis(4,5,6,7-tetrahydro-1-indenyl)titanium(IV) dichloride, racemic 1,1,2,2-tetramethylsilanylenebis(1-indenyl)titanium(IV) dichloride, racemic 1,1,2,2-tetramethylsilanylenebis(4,5,6,7-tetrahydro-1-indenyl)titanium(IV) dichloride and ethylidene(1-indenyl-2,3,4,5-tetramethyl-1-cyclopentadienyl)titanium(IV) dichloride.

[00107] An activator may also be used together with the metallocene catalyst. The activator may, for example, be an alumoxane. Activators that may be used include corresponding compounds that are described by the following general formula:

where M ³ is a metal from groups IA, IIA and IIIA of the periodic table; M ⁴ is a metal from group IA of the periodic table; v is a number ranging from 0 to 1; each X ² is an atom of any halogen; c is a number ranging from 0 to 3; each R ³ is a monovalent hydrocarbon radical or a hydrogen atom; b is a number ranging from 1 to 4; and where b-c is at least 1.

[00108] Compounds containing only one metal from Groups IA, IIA or IIIA that are suitable for use in the practice of the invention include compounds described by the formula

where M ³ represents a metal from groups IA, IIA or IIIA, such as lithium, sodium, beryllium, barium, boron, aluminum, zinc, cadmium and gallium;

k is 1, 2, or 3 depending on the valence of M ³ , where this valence in turn usually depends on the particular group (i.e., IA, IIA, or IIIA) to which M ³ belongs; and

each R ³ may be any monovalent hydrocarbon radical. Examples of suitable R ³ groups include any of the R ³ groups mentioned above in connection with formula (V).

[00109] The present disclosure may be better understood by reference to the following examples.

EXAMPLES

[00110] Test methods:

[00111] The melt flow rate was measured in accordance with ASTM D1238-01 under conditions of 2.16 kg mass and 230°C.

[00112] The superficial gas velocity (SGV) was measured using a Venturi device.

[00113] The composition of the fluidizing medium was measured using a GC in real-time operation, which was often calibrated with a span gas to ensure that the sum of all components was between 99% and 101%.

[00114] The gas density (ρ _g ) was calculated instantly together with the gas composition, temperature and pressure using the BWR (Benedict-Webb-Rubin) equation.

[00115] The total pressure was measured with a manometer commonly used in the chemical industry.

[00116] Description of the catalysts used:

[00117] Catalyst 1 was prepared in accordance with Example 4 of US Patent Application 2010/0173769 A1.

[00118] Catalyst 2 was prepared in accordance with US Patent Application 20200283553 A1.

[00119] Catalyst 3 was prepared in accordance with Example 10 of U.S. Patent 9,593,182.

[00120] Catalyst 4 was prepared in accordance with U.S. Patent 5,604,172.

[00121] Description of external electron donors used:

[00122] Donor 1 was prepared in accordance with Example J1 of US Patent Application 2011/0152067 A1.

[00123] Donor 2 was prepared in accordance with Example H1 of US Patent Application 2011/0152067 A1.

[00124] Donor 3 was prepared in accordance with Example IE1 of US Patent Application 2019/0194438 A1.

[00125] Donor 4 was prepared in accordance with Example B1 of US Patent Application 2011/0152067 A1.

[00126] Donor 5 was prepared in accordance with Example II of US Patent Application 2011/0152067 A1.

[00127] Various polypropylene random copolymers were produced in industrial fluidized bed reactors. The operating conditions for each run are listed below in Table 1. In addition, the reactor stability was evaluated for each run. Runs 10 and 11 are comparative examples.

[00128] These and other modifications and variations of the present invention can be practiced by those skilled in the art without departing from the scope and spirit of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments can be interchanged in whole or in part. Furthermore, those skilled in the art should understand that the above description of the invention is given by way of example only and is not intended to limit the invention, as further described in such appended claims.

Claims (16)

1. A method for producing a polypropylene random copolymer in a fluidized bed reactor, comprising: feeding a fluidizing medium into a reactor vessel containing a bed of catalytically active polyolefin particles, wherein the fluidizing medium comprises gaseous propylene, a C2 and/or C4-C8 α-olefin comonomer(s), hydrogen and at least one inert gas and/or propane, wherein the momentum flux of the fluidizing medium, defined as (SGV [m/sec]) ² * ρ _q [kg/m ³ ], is 7.0 N/m ² or more, where ρ _q is the density of the fluidizing medium, and SGV is the superficial gas velocity of the fluidizing medium, and wherein the condensation level of the reactor circulating gas upon entering the reactor is approximately 17 wt.% or less. 2. The method according to item 1, wherein the pulse flow of the fluidizing medium is 8.3 N/ ^m2 or more. 3. The method according to claim 1, wherein the inert gas comprises nitrogen. 4. The method according to claim 1, wherein the fluidizing medium contains propane. 5. The method according to item 1, further comprising feeding a catalyst into the reactor vessel. 6. The method according to claim 1, wherein the SGV is 0.34 m/sec or more. 7. The method of claim 1, wherein the comonomers comprise ethylene. 8. The method according to claim 1, wherein the comonomers comprise 1-butene. 9. The method according to claim 1, wherein the polypropylene random copolymer contains propylene monomer units in an amount in the range from 80 to 99.5 mol%. 10. The method according to claim 1, wherein the fluidizing medium contains propane in an amount of 6 mol.% or more. 11. The method according to claim 1, wherein the fluidizing medium contains nitrogen in an amount of 11 mol.% or more. 12. The method according to claim 1, wherein the fluidizing medium contains nitrogen and propane in quantities such that the sum of the mol.% of nitrogen and the mol.% of propane is more than 10%. 13. The method according to claim 1, wherein the density of the fluidizing medium is more than 55 kg/ ^m3 . 14. The method according to item 1, where ρ _q is 70 kg/ ^m3 or less. 15. The method of claim 1, wherein propane constitutes less than 25 mol.% of the fluidizing medium.