Abstract: This disclosure relates to processes for producing polyolefins in a gas phase reactor using condensing agent(s) (CAs), and real-time calculation of the ratio of one type of CA to another CA within a CA composition. This disclosure provides methods for controlling condensed phase cooling in a gas phase reactor used to polymerize olefins. The polymerization may employ one or more polymerization catalysts to polymerize one or more olefin monomers, and may include introducing a first condensing agent and a second condensing agent in a ratio of first condensing agent to second condensing agent, which ratio is calculated by ascertaining a stick limit for a first condensing agent, calculating an equivalence factor relating the first condensing agent and a second condensing agent, ascertaining a total allowable condensing agent, and calculating a first amount of the first condensing agent removed and replaced by a second amount of the second condensing agent.

Abstract: A novel modified polypropylene resin is provided which makes it possible to provide, by an extrusion expansion method, expanded polypropylene-based resin particles having an expansion ratio which falls within a wide range and having a low open cell ratio. The novel modified polypropylene resin is obtained by a method of producing the modified polypropylene resin where the method includes a melting and kneading step of melting and kneading a particular random polypropylene resin, a conjugated diene compound, and a particular radical polymerization initiator to obtain the modified polypropylene resin.

Abstract: The present invention relates to a process for producing of solid particulate olefin polymerisation catalyst or catalyst carrier comprising forming a solution of the catalyst or a catalyst carrier in a solvent, subjecting the solution into an atomization by spraying the solution via a capillary vibrating spray nozzle with a capillary orifice having a diameter of 5 to 100 ?m generating a laminar jet of liquid, which disintegrates into liquid droplets entering into the spray-dryer, transforming the droplets with aid of a gas to solid particulate catalyst or carrier in the spray-dryer and recovering the solid particulate olefin polymerisation catalyst or carrier having particle size distribution defined by a volumetric SPAN of 0.7 or less. The invention further relates to the catalyst produced by the methods, and use thereof in olefin polymerisation process.

Abstract: This disclosure describes polymerization processes and processes for quenching polymerization reactions using reactive particulates, such as amorphous silica, as quenching agents, typically in solution or bulk polymerization processes.

Abstract: Embodiments of the present disclosure are directed towards method for modifying a polymer flow index. As an example, a method for modifying a polymer flow index can include providing monomers to a polymerization reactor, providing a chromium catalyst to the polymerization reactor, and providing an active amount of a flow index modifier to the polymerization reactor, wherein the flow index modifier is selected from carbon dioxide, carbon monoxide, 2,4-hexadiene, and combinations thereof.

Abstract: Embodiments of the invention provide a method of controlling a gas-phase polymerization process. The method includes determining a difference between a control variable of the polymerization process, such as the production rate, and the desired value of the control variable; adjusting or maintaining a first manipulated variable to at least partially compensate for the difference between the control variable and the desired value; and adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable.

Abstract: This invention relates to a co-oligomer having an Mn of 300 to 30,000 g/mol comprising 10 to 90 mol % propylene and 10 to 90 mol % of ethylene, wherein the oligomer has at least X % allyl chain ends, where: 1) X=(?0.94(mole % ethylene incorporated)+100), when 10 to 60 mole % ethylene is present in the co-oligomer, and 2) X=45, when greater than 60 and less than 70 mole % ethylene is present in the co-oligomer, and 3) X=(1.83*(mole % ethylene incorporated)?83), when 70 to 90 mole % ethylene is present in the co-oligomer. This invention also relates to a homo-oligomer, comprising propylene, wherein the oligomer has: at least 93% allyl chain ends, an Mn of about 500 to about 20,000 g/mol, an isobutyl chain end to allylic vinyl group ratio of 0.8:1 to 1.2:1.0, and less than 100 ppm aluminum. This invention also relates to a process of making homo-oligomer, comprising propylene, wherein the productivity is greater than 4500 g/mmol Hf (or Zr)/hour.

Abstract: Provided is a low-cost, highly active, environmentally friendly living radical polymerization method which does not require a radical initiator. Even if a catalyst is not used, a living radical polymerization method can be conducted by controlling the amount of the oxygen in the gaseous phase in the reaction vessel within a suitable range. A monomer having a radical-reactive unsaturated bond can be subjected to a radical polymerization reaction to obtain a polymer having narrow molecular weight distribution. The cost of the living radical polymerization can be remarkably reduced. The present invention eliminates the disadvantages of the conventional catalysts such as toxicity, low solubility, coloring/odor and the like, and is significantly more environmentally friendly and economically efficient than conventional living radical polymerization methods.

Abstract: Methods for gas phase olefin polymerization are provided. The method can include combining a spray dried catalyst system with a diluent to produce a catalyst slurry. The catalyst system can include a metallocene compound. Ethylene, a continuity additive, and the catalyst slurry can be introduced to a gas phase fluidized bed reactor. The reactor can be operated at conditions sufficient to produce a polyethylene. The spray dried catalyst system can have a catalyst productivity of at least 12,000 grams polyethylene per gram of the catalyst system.

Abstract: A method for transitioning from a Ziegler-Natta to a Phillips catalyst system for the olefin polymerization reaction in one reactor, preferably a gas phase reactor, is described. The method comprises the steps of a) discontinuing a first olefin polymerization reaction performed in the presence of the Ziegler-Natta catalyst system; b) performing a second olefin polymerization reaction in the presence of a further catalyst system comprising catalyst components (A) and (B) producing, respectively, a first and a second polyolefin fraction, wherein the Mw of the first polyolefin fraction is less than the Mw of the second polyolefin fraction and the initial activity of catalyst component (A) exceeds the initial activity of catalyst component (B); and c) performing a third olefin polymerization reaction the presence of the Phillips catalyst system.

Abstract: A process for introducing a catalyst powder based on a titanium compound supported on magnesium halide into a gas-phase olefin polymerization reactor, characterized in that it comprises: (a) storing the catalyst powder under an atmosphere of a liquid C3-C12 alkane; (b) withdrawing from step (a) a measured amount of said catalyst powder by means of a rotary valve; (c) transferring said metered amount of catalyst powder to a catalyst activation section by a continuous pick-up flow of a liquid C3-C12 alkane; (d) contacting the catalyst powder with a liquid phase comprising an organo-aluminum compound and optionally an external donor compound, at a temperature ranging from ?20° C. to 60° C.; (e) introducing the activated catalyst powder in one or more gas-phase olefin polymerization reactors, where a gaseous mixture comprising at least one alpha-olefin is subjected to polymerization.

Abstract: Use of a metallocene compound of general formula Ind2R?MQ2 as a component of a catalyst system in producing polyethylene, wherein each Ind is the same or different and is indenyl or substituted indenyl; R? is a bridge which comprises a C1 to C4 alkylene radical, a dialkyl germanium or silicon or siloxane, alkyl phosphine or amine, which bridge is substituted or unsubstituted, M is a Group IV metal or vanadium and each Q is hydrocarbyl having 1 to 20 carbon atoms or halogen; and the ratio of meso to racemic forms of the metallocene in the catalyst system is at least 1:3. The metallocene may be supported. The ethylene may be polymerized in a reaction medium that is substantially free of any external comonomer, with comonomer being formed in situ. The produced polyethylene may have long chain branching. The produced polyethylene may be atactic.

Abstract: The present invention provides methods of controlling a gas-phase polymerization process. The method includes determining a difference between a control variable of the polymerization process, such as the production rate, and the desired value of the control variable; adjusting or maintaining a first manipulated variable to at least partially compensate for the difference between the control variable and the desired value; and adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable. The first and second manipulated variables can include process variables such as the fluidized bed weight, the catalyst concentration, the concentration of one or more monomers, the flow of one or more comonomers, the ratio of one comonomer to another comonomer, the activator concentration, the ratio of an activator to selectivity control agent, the concentration of a chain transfer agent, and the retardant concentration.

Abstract: A process for the gas-phase polymerization of one or more alpha-olefins in the presence of a polymerization catalyst, the process comprising: at least a polymerization step wherein the polymer particles flow downward in densified form under the action of gravity so as to form a densified polymer bed; metering an anti-fouling agent in said polymerization step by means of at least N feeding lines placed at different heights of said densified polymer bed, N being the integer number satisfying the equation N?(1+0.08·H), where H is the height (expressed in meters) of the polymer bed.

Abstract: A highly active supported chromium catalyst composition for ethylene and other olefins polymerization and also for ethylene copolymerization with efficient incorporation of comonomer, produces polymers with superior spherical morphology, improved bulk density and almost 0% fines. The catalyst composition component includes at least one chromium compound, mainly chromium acetylacetonate, or chromium hexaflouroacetonylacetonate, or chromium diethylmalonate. One magnesium compound, or aluminum compound, metal alkoxy compound and defined polymer particles mainly chloromethylated cross linked styrene-DVB copolymer or polyvinylchloride. The catalyst composition, when used in conjunction with an organoaluminum compound or a mixture of organoaluminum compounds, can be used for olefin polymerization to produce medium or high density polyethylene and copolymers of ethylene with alpha-olefins having about 3 to 18 carbon atoms.

Abstract: A process for the polymerization of olefins carried out in a gas-phase reactor having interconnected polymerization zones, where the growing polymer particles flow upward through a first polymerization zone (riser) under fast fluidization or transport conditions, leave said riser and enter a second polymerization zone (downcomer) through which they flow downward under the action of gravity, leave said downcomer and are reintroduced into the riser, a gas recycle stream being withdrawn from said first polymerization zone, subjected to cooling below its dew point and then returned to said first polymerization zone, the process being characterized in that said gas recycle stream is cooled at a temperature Tc ranging from 0.05° C. to 3° C. below its dew point.

Abstract: A method for preparing a reactor for performance of a polymerization reaction, the method including providing at least one seed bed into the reactor; wherein the at least one seed bed includes at least one organometallic compound and polymer particles.

Abstract: Embodiments of the invention provide a method of controlling a gas-phase polymerization process. The method includes determining a difference between a control variable of the polymerization process, such as the production rate, and the desired value of the control variable; adjusting or maintaining a first manipulated variable to at least partially compensate for the difference between the control variable and the desired value; and adjusting or maintaining a second manipulated variable to at least partially compensate for the effect of adjusting or maintaining the first manipulated variable.

Abstract: A process for the production of an ethylene alpha-olefin copolymer is disclosed, the process including polymerizing ethylene and at least one alpha-olefin by contacting the ethylene and the at least one alpha-olefin with a metallocene catalyst in at least one gas phase reactor at a reactor pressure of from 0.7 to 70 bar and a reactor temperature of from 20° C. to 150° C. to form an ethylene alpha-olefin copolymer. The resulting ethylene alpha-olefin copolymer may have a density D of 0.927 g/cc or less, a melt index (I2) of from 0.1 to 100 dg/min, a MWD of from 1.5 to 5.0. The resulting ethylene alpha-olefin copolymer may also have a peak melting temperature Tmax second melt satisfying the following relation: Tmax second melt>D*398?245.

Abstract: A continuous gas-phase process for the polymerization of alpha-olefins, in particular ethylene, comprising passing an alpha-olefin monomer stream through an oil filter in order to reduce the amount of oil to less than 8 ppm, and polymerizing the thus purified monomer feed in gas-phase reactor; the reduction of the amount of oil improves the operability of the plant over time.

Abstract: A rubber composition having (A) an elastomer component in which the primary elastomer constituent is an ethylene-propylene elastomer polymerized in the gas phase with a metallocene catalyst and having a molecular weight of at least about 250,000; (B) a silicon-modified olefinic elastomer in an amount of from about 5 to about 50 parts per hundred parts of the elastomer component; (C) ground mica in an amount of from about 2.5 to about 30 parts per hundred parts of the elastomer component; and (D) a peroxide curative. The composition may be used in a vibration isolator which may be used in a belt drive system.

Abstract: A process for the preparation of a propylene copolymer composition having a Flexural modulus lower than 500 MPa, a total ethylene content higher than 9% and a Xylene soluble fraction at room temperature higher than 20% comprising at least one polymerization step carried out in a gas-phase polymerization reactor comprising at least two interconnected polymerization zones said process being characterized by the fact that at least 30% by weight of said xylene soluble fraction is produced in the polymerization step carried out in a gas-phase polymerization reactor comprising at least two interconnected polymerization zones.

Abstract: Method of changing from a polymerization using a first catalyst to a polymerization using a second catalyst which is incompatible with the first catalyst in a gas-phase reactor, which comprises the steps a) stopping of the polymerization reaction using the first catalyst, b) flushing of the reactor under polymerization conditions with at least one deactivating agent comprising a volatile constituent and a nonvolatile constituent in a weight ratio of from 0.1 to 1000, c) introduction of the second catalyst into the reactor and d) continuation of the polymerization using the second catalyst.

Abstract: Disclosed is a novel transition metal compound which is used for forming a metallocene catalyst for olefin polymerization. Specifically disclosed is a novel transition metal compound represented by the general formula below which enables to form a metallocene catalyst that has a balanced reactivity with ethylene and a comonomer selected from ?-olefins having 3-20 carbon atoms and enables to produce an ?-olefin polymer having a high molecular weight. Also specifically disclosed are a catalyst for olefin polymerization containing such a transition metal compound, and a method for producing a propylene/ethylene-?-olefin block copolymer wherein such a catalyst is used.

Abstract: Apparatus and methods for gas phase polymerization are provided. The method can include polymerizing one or more olefins at gas phase conditions in a reactor comprising one or more process exposed surfaces in the presence of a catalyst system; and treating at least a portion of the one or more process exposed surfaces prior to injecting the catalyst system to reduce the number of surface hydroxyls or access of the catalyst system to the surface hydroxyls on the process exposed surfaces.

Abstract: Catalysts useful for polymerizing olefins are disclosed. The catalysts comprise an activator and a Group 4 metal complex that incorporates a dianionic, tridentate 2-aryl-8-anilinoquinoline ligand. In one aspect, supported catalysts are prepared by first combining a boron compound having Lewis acidity with excess alumoxane to produce an activator mixture, followed by combining the activator mixture with a support and the tridentate, dianionic Group 4 metal complex. The catalysts are easy to synthesize, support, and activate, and they enable facile production of high-molecular-weight polyolefins.

Abstract: The present invention relates to a gas phase process for polymerizing one or more hydrocarbon monomer(s) in the presence of a catalyst system and a fluorinated hydrocarbon, where the fluorinated hydrocarbon is present at a partial pressure of 6.9 to 348 kPa in the reactor and the reactor temperature is from 30 to 120° C.

Abstract: A method for controlling a transition from an initial polymerization reaction to a target polymerization reaction in a manner that reduces significantly the amount of off-grade product having excessively low density produced during the transition, including steps of: during the transition, maintaining a first one of a concentration ratio and a feed ratio at an at least substantially constant value while implementing process changes in an effort to bring produced polymer into compliance with a target specification set and monitoring (without controlling) the other one of the concentration ratio and the feed ratio to generate first data; and during the transition, determining from the first data whether polymer having excessively low density is likely to be produced during the transition, and upon determining that polymer having excessively low density is likely to be produced during the transition, maintaining during the remaining portion of the transition the other ratio at a value that is at least substantia

Abstract: Process for preparing polyolefins having high molecular weights in the presence of a catalyst comprising an organic transition metal compound in a gas-phase fluidized-bed reactor, where the polyolefins prepared have a melt flow rate at 2.16 kg and 190° C. in accordance with ISO 1133 of less than 4 g/10 min. According to the present invention, a start-up phase during which a polyolefin having an increased melt flow rate of above 4 g/10 min is produced for a transitional period is provided. In this way, trouble-free start-up of the reactor is ensured even in the case of polymer products having a high molecular weight and a melt flow rate below 4 g/10 min and even when using catalysts based on organic transition metal compounds, in particular metallocene catalysts.

Abstract: A method for controlling sheeting in a gas phase reactor that includes producing a polyolefin with at least one metallocene catalyst and at least one static control agent in at least one gas phase reactor, measuring entrainment static using a static probe, and adjusting the concentration of the static control agent in response to changes in the measured entrainment static is disclosed.

Abstract: This invention relates to a process for maintaining heat transfer capacity of a cycle cooler while polymerizing olefin(s) in the presence of catalyst and a carboxylate metal salt by controlling the amount of carboxylate metal salt present in the reaction system. In particular, the invention relates to maintaining a cycle cooler performance parameter substantially constant while polymerizing olefin(s) in the presence of a carboxylate metal salt and a conventional-type transition metal polymerization catalyst compound, or a metallocene-type polymerization catalyst compound. This invention further relates to a process wherein the cycle cooler performance parameter is a heat transfer capacity of the cycle cooler, a pressure drop across the cooler, or a cooler approach temperature of a cycle cooler.

Abstract: A method of discharging polymer from a continuously operated polymerization reactor, wherein at least a monomer is polymerized to form polymer particles, the method comprising adjusting the discharge rate of the polymer particles by means of a piston valve having a piston element connected to an actuator, said actuator being able to modulate the piston stroke inside said piston valve.

Abstract: One exemplary method for message suppression comprises: providing first and second rules, each having one or more preconditions and a conclusion, wherein the first rule also has a suppressed-by attribute and at least one of the second preconditions is suppressing; evaluating the one or more first and second preconditions; identifying the first rule as true or false; displaying the message of the second rule if all of the second preconditions are met; identifying the first rule as suppressed if the second rule is named in the suppressed-by attribute; and inhibiting the message display of the suppressed rule or routing the message to second display. The system can comprise: a database containing knowledge of the production unit; a user interface, and at least one precondition, a suppressed by attribute, and one or more rules each having a conclusion and at least one suppressing precondition; an inference engine; and a display.

Abstract: A process for increasing a granular particle density of a polymeric product using at least one particle density promoting agent is described. The process includes passing a gaseous stream comprising at least one monomer through a fluidized bed reactor in the presence of a catalyst to form a polymeric product having a first granular particle density of less than or equal to about 850 kg/m3, contacting the polymeric product with at least one particle density promoting agent to increase the granular particle density of the polymeric product by at least 2%, withdrawing the polymeric product having an increased granular particle density and a recycle stream comprised of unreacted monomers, and cooling and reintroducing the recycle stream into the fluidized bed reactor with sufficient additional monomer to replace the monomer polymerized and withdrawn as the polymeric product.

Abstract: A process for the polymerisation of olefin monomers selected from (a) ethylene, (b) propylene (c) mixtures of ethylene and propylene and (d) mixtures of (a), (b) or (c) with one or more other alpha-olefins is performed in a polymerisation reactor in the presence of a supported polymerisation catalyst characterised in that prior to injection into the reactor said supported polymerisation catalyst in the form of a powder is contacted with an inert hydrocarbon liquid in a quantity sufficient to maintain said catalyst in powder form. The preferred inert hydrocarbon liquid is hexane. The supported polymerisation catalyst is preferably a supported metallocene catalyst. According to the process of the prescrit invention the level of fines associated with the polymer products is reduced in particular the level of fines having a diameter<125 ?m and microfines of diameter<50 ?m.

Abstract: The present invention relates to a continuous gas phase process comprising passing a recycle stream through a fluidized bed in a gas phase fluidized bed reactor, wherein the recycle stream comprises a low molecular weight dew point increasing component and a high molecular weight component, polymerizing an alpha-olefin monomer in the presence of a catalyst, and controlling an amount of the low molecular weight dew point increasing component in the recycle stream such that a dew point approach temperature of the recycle stream is less than the dew point approach temperature when operating with the higher molecular weight dew point increasing component alone.

Abstract: A process for the gas-phase polymerization of ?-olefÊns CH2?CHR, where R is hydrogen or a hydrocarbon radical having 1-12 carbon atoms, carried out in a first and a second interconnected polymerization zones, wherein the growing polymer particles flow through the first of said polymerization zones (riser) under fast fluidization conditions, leave said riser and enter the second of said polymerization zones (downcomer) through which they flow downward in a densified form, leave said downcomer and are reintroduced into said riser, in which process: (a) the gas mixture present in the riser is totally or partially prevented from entering the downcomer, and (b) the gaseous composition inside a portion of the downcomer is maintained substantially similar to the gaseous composition reacting in the riser.

Abstract: A process for making polyethylene having an uncommon but valuable balance of broad molecular weight distribution and a low level of long-chain branching is disclosed. The process comprises polymerizing ethylene in a single reactor in the presence of an ?-olefin and a catalyst comprising an activator and a supported dialkylsilyl-bridged bis(indeno[1,2-b]indolyl)zirconium complex. The polyethylene, which has an Mw/Mn greater than 10 and a viscosity enhancement factor (VEF) of less than 2.5, is valuable for making blown films.

Abstract: The present invention relates to the use of an additive for improving the flowability of fines and their reintroduction into a process for the continuous gas-phase (co-) polymerisation of olefins in a fluidized bed or sub-fluidized bed reactor.

Abstract: Techniques are provided for the prevention of reactor fouls in polymerization reactors. A technique is provided for limiting polymer particle size to prevent or limit the occurrence of reactor fouls associated with large polymer particles. A technique is also provided for measuring reactor temperature at one or more local hot spots of the reactor and for controlling the polymerization reaction based upon these temperature measurements. In particular, control of the reaction may be based on the hottest temperature, such that the hottest temperature in the reactor is maintained within the reactor fouling curve. A technique is also discussed for predicting reactor fouls by using statistical analyses, such as periodogram analysis, to identify leading indicators of impending fouls. Preventative measures may be performed upon identification of such a leading indicator. In addition, the statistical analyses may be used to identify catalysts having less propensity to foul.

Abstract: Embodiments of our invention relate to processes for transitioning among polymerization catalyst systems including processes for transitioning among olefin polymerization reactions using Ziegler-Natta catalysts systems and chromium-based catalyst systems. Among embodiments contemplated are a method of transitioning from a first catalyst to a second catalyst in an olefin polymerization reactor, comprising: adding to the reactor a deactivating agent (DA) selected from one of carbon monoxide, carbon dioxide, or combinations thereof; adding to the reactor a cocatalyst adsorbing agent (CAA), comprising an inorganic oxide selected from one of silica, alumina or combinations thereof; wherein the first catalyst comprises at least one conventional Ziegler-Natta catalyst, and a cocatalyst, wherein the second catalyst comprises at least one chromium-based catalyst, wherein the reactor is a gas-phase, fluidized bed reactor, and wherein the CAA is substantially free of transition metals.

Abstract: A process for controlling a continuous gas phase exothermic process in a reactor comprising: (i) effecting a gas phase exothermic reaction under a set of operating conditions in the presence of a cooling agent, the cooling agent having a pre-selected concentration and feed rate of an induced cooling agent; (ii) determining a maximum production rate (I) without regard to limitations due to the cooling agent under the operating conditions; (iii) determining a maximum production rate (II) with regard to limitations due to the cooling agent under the operating conditions; (iv) calculating an optimal concentration of the induced cooling agent such that the difference between (I) and (II) is minimized; and (v) adjusting the feed rate of the induced cooling agent to achieve the concentration value calculated in (iv).

Abstract: A process for producing a polymer of ethylene containing from 0.1 to 99% by mol of one or more derived units of alpha-olefins and optionally from 0 to 5% by mol polyene, comprising contacting ethylene, one or more alpha-olefins and optionally said polyene, in the presence of a catalyst system obtainable by contacting: a) a metallocene compound of formula (I): wherein M is zirconium, hafnium or titanium; X, is a hydrogen atom, a halogen atom, or a hydrocarbon group; R1 is a hydrocarbon group; R2, R3, R4 and R5 are hydrogen atoms, or hydrocarbon groups; R6 is a hydrocarbon group; L is a divalent bridging group, and T is a divalent radical of formula (II) or (III): wherein R8 and R9 are hydrogen or hydrocarbon groups; and b) an alumoxane or a compound capable of forming an alkyl metallocene cation.

Abstract: A process of producing polyethylene, the process comprising copolymerizing ethylene and an alpha-olefinic comonomer comprising from 3 to 8 carbon atoms in the presence of a chromium-based catalyst in a main polymerization reactor and, in a gas-phase preliminary reactor upstream of the main polymerization reactor, chemically treating the chromium-based catalyst with at least one treatment agent prior to introduction of the catalyst into the main polymerization reactor and releasing from the preliminary reactor waste gases produced during the chemical treatment.

Abstract: An improved process for the polymerization of olefin monomer selected from (a) ethylene, (b) propylene, (c) mixtures of ethylene and propylene and (d) mixtures of (a), (b) or (c) with one or more alpha-olefins in a fluidized bed gas phase reactor, said process comprising passing a gaseous mixture of said olefin monomers(s) through the fluidized bed under effective polymerization conditions to provide a polymer product containing unreacted monomer(s) and a gaseous effluent stream comprising unreacted monomer(s), removing the polymer product to a degassing vessel, recycling a first portion of the gaseous effluent stream to the fluidized bed and passing a second portion of the gaseous effluent stream to counter currently contact the polymer product in said degassing vessel to produce a polymer product having a reduced amount of unreacted monomer(s), characterized in that the improvements to the process comprise: (i) removing heavy hydrocarbons from the second portion of the effluent stream and returning said hyd

Abstract: Disclosed herein is a method of operating a polymerization reactor for a polymerization reaction comprising modifying a recycle gas composition to increase the heat capacity of the recycle gas wherein the recycle gas composition is modified by reducing or eliminating the nitrogen concentration in the recycle gas. In an embodiment, the nitrogen concentration is reduced or eliminated by reducing or eliminating one or more nitrogen input sources to the polymerization reactor and replacing the nitrogen with an alternate inert fluid (a gas or liquid that is inert to the catalyst and reactants). The alternate inert fluid has a higher heat capacity and a higher molecular weight than nitrogen. In an embodiment, the nitrogen utilized to convey a catalyst into the polymerization reactor is replaced with an alternate inert fluid. In an embodiment, the alternate inert fluid is ethane, propane, isobutane, or combinations thereof.

Abstract: A method for producing rotomoulding polyethylene by fluidized bed gas phase polymerisation of ethylene and the improved rotomoulding polyethylene obtainable by the process.

Abstract: The present invention relates to a continuous gas phase process comprising polymerizing one or more hydrocarbon monomer(s) in a fluidized bed reactor in the presence of a Ziegler-Natta-type catalyst system and a condensable fluid for a period of at least 12 hours where the bed temperature is less than the Critical Temperature and the dew point temperature of the gas composition in the reactor is within 25° C. of the bed temperature.

Abstract: Processes for reducing the ultra high molecular weight polymeric material content of a high density polyethylene produced with a bis-triarylsilyl chromate catalyst system are provided. Processes for reducing the gel content of articles produced from high density polyethylene are also provided. The gel content of the articles is reduced by using the high density polyethylene with reduced ultra high molecular weight polymeric material content to produce the articles. The processes described reduce the content of ultra high molecular weight polymeric material in comparison to conventional high density polyethylene by introducing at least one catalyst deactivator into a recycle gas line containing a recycle gas stream associated with the fluidized bed reactor. The at least one catalyst deactivator has a boiling point lower than the maximum temperature within the recycle gas line.

Abstract: A continuous process for the olefin polymerization in a fluidized bed reactor, said process comprising continuously passing a gaseous stream comprising one or more ?-olefin monomers through the fluidized bed in the presence of a polymerization catalyst under reactive conditions, withdrawing polymeric product and unreacted fluids from the reactor, cooling part of said unreacted fluids below the dew point to form a two-phase mixture of gas and condensed liquid and reintroducing said two-phase mixture into the reactor, the process being characterized in that said two-phase mixture is reintroduced under the distribution plate of the reactor so that a part of condensed liquid is separated from the gas and is successively fed above the fluidized bed through an external pipe connecting the bottom of the reactor to a point situated above the upper limit of the fluidized bed of polymer particles.