Controlling polymerization
阅读说明：本技术 控制聚合反应 (Controlling polymerization ) 是由 J·F·斯祖尔 D·托马斯 E·J·玛克尔 R·E·佩克诺 B·J·赛华佗斯凯 于 2019-03-20 设计创作，主要内容包括：本公开实施例涉及用于控制聚合反应的方法,所述方法包括确定用于气相聚合的瞬时密度模型,并且利用所述瞬时密度模型来监测所述聚合反应,以确定是否达到阈值瞬时密度。(Embodiments of the present disclosure relate to a method for controlling a polymerization reaction that includes determining an instantaneous density model for gas phase polymerization, and monitoring the polymerization reaction using the instantaneous density model to determine whether a threshold instantaneous density is reached.)
1. A method for controlling a polymerization reaction, the method comprising:
determining an instantaneous density model for gas phase polymerization of an activated metallocene complex, wherein the instantaneous density model incorporates:
a hydrogen concentration of the activated metallocene complex gas phase polymerization and a comonomer concentration of the activated metallocene complex gas phase polymerization; and is
Monitoring the polymerization reaction using the instantaneous density model to determine if a threshold instantaneous density is reached.
2. The method of claim 1, wherein the activated metallocene complex of the activated metallocene complex gas phase polymerization is provided by activating a metallocene complex represented by formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F.
3. The method of claim 1, wherein the instantaneous density incorporates instantaneous process conditions determined by mass balance between analyzer updates.
4. The method of any preceding claim, wherein the threshold instantaneous density is determined by a viscosity model.
5. The method of claim 1, wherein the threshold instantaneous density is determined from a viscosity model using instantaneous process conditions determined by mass balance between analyzer updates.
6. The method of any preceding claim, wherein the threshold instantaneous density is a preset value.
7. The method of any one of the preceding claims, comprising terminating the polymerization reaction when the threshold instantaneous density is reached.
8. The method of claim 6, wherein terminating the polymerization reaction comprises slowing and/or stopping the polymerization reaction.
9. The method of any one of claims 7 to 8, wherein terminating the polymerization reaction comprises injecting a termination material into a polymerization reactor.
10. The method of claim 9, wherein the termination material is carbon monoxide.
Technical Field
Embodiments of the present disclosure relate to methods for controlling polymerization reactions. More particularly, embodiments relate to determining an instantaneous density model for gas phase polymerization and monitoring a polymerization reaction using the instantaneous density model to determine whether a threshold instantaneous density is reached.
Background
The polymers are useful in a variety of products, including films and the like. Polymers may be formed by reacting one or more types of monomers in a polymerization reaction. The industry has been working to develop new and improved materials and/or methods that can be used to form polymers. In addition, there is a continuing effort to develop improved methods of controlling process operation, particularly during process anomalies and product level transitions.
Disclosure of Invention
The present disclosure provides a method of controlling a polymerization reaction, the method comprising: determining an instantaneous density model for an activated metallocene gas phase complex polymerization, wherein the instantaneous density model incorporates a hydrogen concentration of the activated metallocene complex gas phase polymerization and a comonomer concentration of the activated metallocene complex gas phase polymerization; and monitoring the polymerization reaction using the instantaneous density model to determine whether a threshold instantaneous density is reached.
One or more embodiments provide an activated metallocene complex that provides gas phase polymerization of the activated metallocene complex by activating the metallocene complex represented by the following formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F.
One or more embodiments provide that the instantaneous density incorporates instantaneous process conditions determined by mass balance between analyzer updates.
One or more embodiments provide for determining the threshold instantaneous density from a viscosity model.
One or more embodiments provide for determining the threshold instantaneous density from a viscosity model using instantaneous process conditions determined by mass balance between analyzer updates.
One or more embodiments provide that the threshold instantaneous density is a preset value.
One or more embodiments provide for terminating the polymerization reaction when the threshold instantaneous density is reached.
One or more embodiments provide that terminating the polymerization reaction includes slowing and/or stopping the polymerization reaction.
One or more embodiments provide that terminating the polymerization reaction includes injecting a termination material into the polymerization reactor.
One or more embodiments provide that the termination material is carbon monoxide.
The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The following description more particularly exemplifies illustrative embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each case, the enumerated lists are used only as representative groups and should not be construed as exclusive lists.
Drawings
FIG. 1 shows the density (g/cm)3) Relative to I2Plot of melt index.
Detailed Description
The polymer may have a variety of characteristics, such as density, melt index, and melt index ratio, among others. These characteristics can be varied by varying polymerization parameters such as hydrogen concentration, monomer concentration, reaction temperature, comonomer flow ratio and/or reaction temperature, etc. However, when using a particular polymer catalyst, various values of some polymer properties may be more sensitive, e.g., more susceptible to and/or have greater variation, than other polymer catalysts.
Activated metallocenes can be used as catalysts to produce a variety of different polymers. It has been found that metallocene complexes of the formula I,
wherein each n-Pr is n-propyl, and each X is independently CH 3Cl, Br or F, when activated and used as a polymerization catalyst, have an increased hydrogen response compared to many other activated metallocenes.
This increased hydrogen response can have a significant impact on polymerization with activated metallocene complexes of formula I. For example, for polymerizations using activated metallocene complexes of formula I, a reduction in hydrogen concentration may result in polymers with correspondingly significantly lower densities. This lower density can lead to an undesirable increase in bed stickiness, which can lead to the formation of a chuck in the polymerization reactor.
Previously, control systems have utilized analyzers to monitor the polymerization reaction. These analyzers, which are known in the art, have been used to monitor a number of variables, including concentration (e.g., hydrogen concentration), temperature, pressure, and flow rate, among others. In addition, previous control systems have utilized bed average density. As used herein, "bed average density" refers to the density of the polymer as it exits the polymerization reactor.
As mentioned, previous control systems have utilized analyzers to monitor the hydrogen concentration of the polymerization reaction. While these analyzers can be used to monitor hydrogen concentration over a specified time interval, these analyzers can be less effective when utilizing an increased hydrogen response catalyst, i.e., an activated metallocene complex of formula I. The analyzer is typically run in cycles of 2 minutes to 6 minutes or 10 minutes or possibly longer, indicating that the gas composition in the reactor as determined by the analyzer may be delayed. Due to the increased hydrogen response of the catalyst, even very brief reductions in hydrogen concentration over short periods of time can result in the production of polymers having correspondingly significantly lower densities. Furthermore, this significantly lower density may not be detected in time due to the operation of the analyzer cycle and bed average density monitoring.
The present disclosure provides methods for controlling a polymerization reaction. A method for controlling a polymerization reaction can include determining an instantaneous density model for gas phase polymerization of an activated metallocene complex, i.e., using a gas phase polymerization of an activated metallocene complex. In contrast to bed average density, which provides the density as the polymer exits the polymerization reactor, the instantaneous density model may provide the instantaneous density, i.e., the density of the polymer currently produced by the polymerization reaction within the polymerization reactor.
The instantaneous density model can incorporate (e.g., utilize) many known polymerization variables. Examples of such known polymerization variables include, but are not limited to, catalyst type, continuity aid type, catalyst density, number of polymerization reactor bed upsets, residence time, monomer concentration, monomer partial pressure, hydrogen concentration, hydrogen to monomer ratio, comonomer concentration, comonomer to monomer ratio, monomer feed rate, hydrogen to monomer flow ratio, comonomer to monomer flow ratio, nitrogen concentration, reactor vent rate, reactor pressure, bed temperature, reactor gas velocity, bed weight, bed height, fluidized bed density, catalyst feed rate, reactor production rate, catalyst active material balance, polymer melt index (I) 2) High load melt index (I) of the polymer21) Polymer melt flow ratio (I)21/I2) And polymer bulk density, etc.
The instantaneous density model may use analytical methods, numerical methods, or a combination thereof. For example, many of the polymerization variables incorporated by the instantaneous density model can be measured and used by the polymerization reaction currently taking place. Many of the polymerization variables incorporated by the instantaneous density model can be measured by previously occurring polymerization reactions. Many of the polymerization variables incorporated by the instantaneous density model can be calculated based on the polymerization reaction currently taking place. Many of the polymerization variables incorporated by the instantaneous density model can be calculated based on the polymerization reactions that occurred previously.
One or more embodiments of the present disclosure provide that the instantaneous density model is based on regression analysis. Regression analysis is a set of known statistical processes used to determine the relationships between variables. Regression analysis may utilize many of the polymerization variables discussed herein. One or more embodiments of the present disclosure provide for regression analysis to utilize a polymerization variable determined (e.g., measured) from a plurality of previously occurring polymerization reactions. For example, regression analysis may use polymerization variables determined from one, two, three, four, five, or more than five previously occurring polymerization reactions.
One or more embodiments of the present disclosure provide that the instantaneous density model is based on the instantaneous flow associated with the polymerization reaction currently occurring. For example, the instantaneous density model may be based on the material balance of the polymerization reactor. For example, the instantaneous density may incorporate (e.g., be based at least in part on) instantaneous process conditions determined by mass balance between analyzer updates.
The instantaneous density model may be used to determine whether the instantaneous density is below a threshold instantaneous density. The threshold instantaneous density is a density corresponding to an increase in the likelihood of an undesired increase in bed stickiness, which may result in the formation of a chuck in the polymerization reactor. Embodiments of the present disclosure provide that the threshold instantaneous density is less than a target density, e.g., a desired density of the polymer product. For example, if it is desired to produce a polymer having a density of 0.918g/cm3, the threshold instantaneous density will be less than 0.918g/cm 3. The threshold instantaneous density may have different values for different aggregations.
In some embodiments, the threshold instantaneous density is based on a sticky correlation, such as the sticky correlation described in WO 2014/039519a1, which is incorporated herein by reference. For example, a threshold instantaneous density may be determined (e.g., by calculation) from the viscosity model. For example, the viscosity correlation can be input from the values of a GC analyzer or from the same mass-balance transient process conditions used to determine the transient density. For example, the instantaneous density may be based at least in part on a viscosity model that uses instantaneous process conditions determined by a mass balance between analyzer updates. One or more embodiments provide that the threshold instantaneous density is a pre-programmed value, such as a preset value.
Embodiments of the present disclosure provide that an instantaneous density model can be used to monitor a polymerization reaction. Monitoring the polymerization reaction using the instantaneous density model may include determining whether a threshold instantaneous density is reached. One or more embodiments of the present disclosure provide that the polymerization reaction may be terminated if a threshold instantaneous density is reached. Because the instantaneous density model can provide instantaneous density, rather than bed average density, determining whether a threshold instantaneous density is reached can provide a number of advantages in polymer manufacture. For example, as mentioned, when a threshold instantaneous density is reached, the likelihood of an undesirable increase in bed stickiness increases, which may lead to the formation of a chuck in the polymerization reactor. Since the bed average density is the density of the polymer as it leaves the polymerization reactor, it can be determined that the bed average density of the polymerization is within process limits while the threshold instantaneous density is reached. Recovery of polymer production from cake formation may require extended downtime away from polymer production. However, polymer manufacture recovery (e.g., from terminating polymerization to a polymer within the limits of the desired process) is much faster than polymer manufacture from block-forming recovery. As used herein, "terminating polymerization" refers to slowing and/or stopping the polymerization reaction. The polymerization may be terminated by methods known in the art. For example, the termination of the polymerization can be carried out by injecting a known termination material into the polymerization reactor. For example, for some polymerizations, carbon monoxide may be used as a terminating material. Advantageously, if a threshold instantaneous density is reached, lump formation and the associated extended downtime to polymer manufacture may be reduced by terminating the polymerization.
Embodiments of the present disclosure provide for an instantaneous density model incorporating the activation of metallocene complexes represented by the following formula I:
wherein each n-Pr is n-propyl, and each X is independently CH3Cl, Br or F to provide an activated metallocene complex; the metallocene complexes represented by formula I can be prepared by known methods, such as by repeatedly deprotonating/metallizing aromatic ligands and introducing bridges and/or halogen derivatives thereofThe central atom. Known processes for preparing metallocenes are described in Journal of Organometallic chemistry, Vol.288, (1985), p.63-67, and EP-A-320762. Both documents are fully incorporated herein by reference. In addition, the metallocene complexes of the formula I and/or the correspondingly activated metallocene complexes can be used, for example, under the trade name XCATTMVP-100 is commercially available from Univek Technologies, LLC.
One or more embodiments of the present disclosure provide for utilizing supported metallocene complexes. The supported metallocene complex can include a metallocene complex of formula I and a support material. The supported metallocene complex may include other components known in the art.
The supported metallocene complexes can be formed by known methods. For example, the supported metallocene complex may be formed by a slurry method. The slurry may include a supported metallocene complex (i.e., a metallocene complex of formula I) and a support material component, and optionally other known components. For example, the slurry may include an activator, such as an alumoxane (alumoxane) and/or a modified alumoxane. The slurry may include an activator and/or a supported activator. In one embodiment, the slurry comprises a support material, an activator, and a metallocene complex of formula I. The molar ratio of the metal in the activator to the metal in the metallocene complex of formula I may be 1000:1 to 0.5:1, 300:1 to 1:1, or 150:1 to 1: 1. Combining the metallocene complex (i.e., the metallocene complex of formula I) with an activator can provide a catalyst, e.g., an activated metallocene complex.
The support material may be any inert particulate support material known in the art including, but not limited to, silica, fumed silica, alumina, clay or talc, as well as other support materials. In one embodiment, the slurry contains silica and an activator, such as methylalumoxane ("MAO"), modified methylalumoxane ("MMAO"), as discussed further below.
As used herein, the terms "support material", "support" and "carrier" may be used interchangeably and refer to any support material, including porous support materials such as talc, inorganic oxides and inorganic chlorides. The metallocene complex of the formula I may be on the same support as the activator, or the activator may be used in unsupported form, or may be deposited on a different support than the metallocene complex of the formula I. This may be accomplished by any technique commonly used in the art.
The support material may include one or more inorganic oxides, such as inorganic oxides of group 2, group 3, group 4, group 5, group 13, or group 14 elements. Inorganic oxides may include, but are not limited to, silica, alumina, titania, zirconia, boria, zinc oxide, magnesium oxide, or combinations thereof. Illustrative combinations of inorganic oxides can include, but are not limited to, alumina-silica, silica-titania, alumina-zirconia, alumina-titania, and the like. The support material may be or include alumina, silica, or a combination thereof. In one embodiment, the support material is silica.
Suitable commercially available silica supports may include, but are not limited to, ES757, ES70, and ES70W, available from PQ corporation (PQ corporation). Suitable commercially available silica-alumina supports can include, but are not limited to, those commercially available from
As used herein, the term "activator" refers to any supported or unsupported compound or combination of compounds that can activate a complex or catalyst component, for example, by generating a cationic species of the catalyst component. For example, this may include extracting at least one leaving group (an "X" group as described herein) from the metal center of the complex/catalyst component (e.g., a metallocene complex of formula I). The activator may also be referred to as a "cocatalyst".
The activator may comprise a Lewis acid (Lewis acid) or a non-coordinating ionic activator or an ionizing activator, or any other compound including a Lewis base (Lewis base), an aluminum alkyl, and/or a conventional co-catalyst. In addition to the above-mentioned methylaluminoxane ("MAO") and modified methylaluminoxane ("MMAO"), illustrative activators may include, but are not limited to, alumoxanes or modified alumoxanes and/or ionizing neutral or ionic compounds, such as dimethylanilinium tetrakis (pentafluorophenyl) borate, triphenylcarbenium tetrakis (pentafluorophenyl) borate, dimethylanilinium tetrakis (3,5- (CF) ammonium tetrakis (3,5- (CF)3)2Phenyl) borate, triphenylcarbenium tetrakis (3,5- (CF)3)2Phenyl) borate, dimethylanilinium tetrakis (perfluoronaphthyl) borate, triphenylcarbenium tetrakis (perfluoronaphthyl) borate, dimethylanilinium tetrakis (pentakis)Fluorophenyl) aluminate, triphenylcarbenium tetrakis (pentafluorophenyl) aluminate, dimethylanilinium tetrakis (perfluoronaphthyl) aluminate, triphenylcarbenium tetrakis (perfluoronaphthyl) aluminate, tris (perfluorophenyl) boron, tris (perfluoronaphthyl) boron, tris (perfluorophenyl) aluminum, tris (perfluoronaphthyl) aluminum, or any combination thereof.
The activator may or may not be directly bound to the surface of the support, or the activator may be modified to allow it to be bound to the surface of the support, for example, by a tethering agent. Such tethering agents may be derived from groups reactive with surface hydroxyl species. Non-limiting examples of reactive functional groups that can be used to create tethers include aluminum halides, aluminum hydrides, aluminum alkyls, aluminum aryls, aluminum alkoxides, silicon electrophiles, alkoxysilanes, aminosilanes, boranes.
Aluminoxanes can be referred to as oligomeric aluminum compounds having a-A1 (R) -O-subunit wherein R is an alkyl group. Examples of aluminoxanes include, but are not limited to, methylaluminoxane ("MAO"), modified methylaluminoxane ("MMAO"), ethylaluminoxane, isobutylaluminoxane, or combinations thereof. Aluminoxanes can be produced by hydrolysis of the corresponding trialkylaluminum compound. MMAO can be produced by hydrolyzing trimethylaluminum and higher trialkylaluminum (e.g., triisobutylaluminum). There are a variety of known methods for preparing aluminoxanes and modified aluminoxanes. Aluminoxanes may include Modified Methylaluminoxane ("MMAO") type 3A (commercially available from akzo chemicals, Inc.) under the trade designation Modified Methylaluminoxane type 3A, as discussed in U.S. patent No. 5,041,584). The source of MAO may be a solution having, for example, about 1 wt.% to about 50 wt.% MAO. Commercially available MAO solutions may include 10 wt.% and 30 wt.% MAO solutions, which are available from Albemarle Corporation, Baton Rouge, La.
One or more organoaluminum compounds, such as one or more alkylaluminum compounds, can be used in combination with the aluminoxane. Examples of alkyl aluminum compounds include, but are not limited to, diethyl aluminum ethoxide, diethyl aluminum chloride, diisobutyl aluminum hydride, and combinations thereof. Examples of other alkylaluminum compounds (e.g., trialkylaluminum compounds) include, but are not limited to, trimethylaluminum, triethylaluminum ("TEAL"), triisobutylaluminum ("TiBAl"), tri-n-hexylaluminum, tri-n-octylaluminum, tripropylaluminum, tributylaluminum, and combinations thereof.
As used herein, a "polymer" has two or more polymer units derived from monomers and/or comonomers. A "copolymer" is a polymer having two or more polymer units that are different from each other. Polymers and copolymers may be used interchangeably herein. As used herein, "polymerization" and/or "polymerization process" is a process for forming a polymer.
As used herein, when a polymer or copolymer is referred to as comprising (e.g., formed from) an olefin, the olefin present in such polymer or copolymer is an olefin in polymerized form. For example, when the ethylene content of the polymer is said to be from 75 wt% to 85 wt%, it is understood that the polymer units are derived from ethylene in the polymerization reaction and the derived units are present at from 75 wt% to 85 wt% based on the total weight of the polymer.
One or more embodiments of the present disclosure include polymers, i.e., polyethylenes, prepared from monomers, i.e., ethylene and/or linear or branched high carbon alpha-olefin comonomers containing from 3 to 20 carbon atoms. Examples of comonomers include, but are not limited to, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 3,5, 5-trimethyl-1-hexene, and combinations thereof. Examples of polymers include, but are not limited to, ethylene-based polymers having at least 50 wt% ethylene, including ethylene-1-butene, ethylene-1-hexene, and ethylene-1-octene, among others.
The polymer may comprise from 50 to 95 wt% ethylene, based on the total weight of the polymer. All individual values and subranges from 50 to 95 wt% are included; for example, the polymer may include a lower limit of 50, 60, or 70 wt% ethylene to an upper limit of 95, 90, or 85 wt% ethylene, based on the total weight of the polymer. The polymer may include from 5 wt% to 50 wt% comonomer, based on the total weight of the polymer. Including all individual values and subranges from 5 to 50 weight percent; for example, the polymer may include a comonomer with a lower limit of 5, 10, or 15 wt% to an upper limit of 50, 40, or 30 wt%, based on the total weight of the polymer.
Embodiments of the present disclosure provide that the polymer may have a density of 0.890g/cm3To 0.970g/cm3Density within the range. Comprises 0.890 to 0.970g/cm3All individual values and subranges of (a); for example, the polymer may have a lower limit of 0.890, 0.900, 0.910, or 0920g/cm3To an upper limit of 0.970, 0.960, 0.950 or 0.940g/cm3The density of (c). Density can be determined according to ASTM D-792.
Embodiments of the present disclosure provide that the polymer may have a melt index (MI/I) in a range from 0.01 dg/min to 1000 dg/min as measured according to ASTM-D-1238-E2). For example, the polymer can have an MI of 0.01 dg/min to 100 dg/min, 0.1 dg/min to 50 dg/min, or 0.1 dg/min to 10 dg/min.
Embodiments of the present disclosure provide that the polymer may have an Mn (number average molecular weight) of 5,000 to 75,000. Including all individual values and subranges from 5,000 to 75,000; for example, the polymer may have a lower limit of 5,000; 6,000; 7,000; 7,500; 8,000; or 8,500 to an upper limit of 75,000; 65,000; 55,000; 45,000; 35,000; 25,000; 24,000; 23,000; or 22,000 Mn. As known in the art, Mn can be determined by Gel Permeation Chromatography (GPC).
Embodiments of the present disclosure provide that the polymer may have a Mw (weight average molecular weight) of 60,000 to 110,000. Including all individual values and subranges from 60,000 to 110,000; for example, the polymer may have a lower limit of 60,000; 62, 500; 63,000; or 63,500 to an upper limit of 110,000; 109,000; 108,000; or a Mw of 107,000. As known in the art, Mw can be determined by GPC.
Embodiments of the present disclosure provide that the polymer may have a Mz (z average molecular weight) of 150,000 to 400,000. Including all individual values and subranges from 150,000 to 400,000; for example, the polymer may have a lower limit of 150,000; 155,000; 160,000; or 170,000 to an upper limit of 400,000; 375,000; 350,000; or an Mz of 325,000. Mz can be determined by GPC, as known in the art.
Embodiments of the present disclosure provide that the polymer may have a molecular weight distribution determined as a weight average molecular weight/number average molecular weight (Mw/Mn) of 3.00 to 8.00. Including all individual values and subranges from 3.00 to 8.00; for example, the polymer may have a lower limit of 3.00; 3.50; 4.00; or 4.50 to an upper limit of 8.00; 7.50 of; 7.00; or 6.50 Mw/Mn. As is known in the art, Mw/Mn can be determined by GPC analysis.
The polymer may be formed by a gas phase polymerization process using known equipment and reaction conditions (i.e., known polymerization conditions). The formation of the polymer is not limited to any particular type of gas phase polymerization system. As an example, the polymerization temperature may range from about 0 ℃ to about 300 ℃. Polymerization pressures and other polymerization conditions are known in the art.
Many embodiments of the present disclosure provide that polymers can be formed by a gas phase polymerization system at superatmospheric pressures in the range of 0.07 to 68.9 bar (1 to 1000psig), 3.45 to 27.6 bar (50 to 400psig), or 6.89 to 24.1 bar (100 to 350psig) at temperatures in the range of 30 ℃ to 130 ℃, 65 ℃ to 110 ℃, 75 ℃ to 120 ℃, or 80 ℃ to 120 ℃. For many embodiments, the operating temperature may be less than 112 ℃. Stirred and/or fluidized bed gas phase polymerization systems may be used.
In general, conventional fluidized bed gas phase polymerization processes can be carried out by continuously passing a monomer and comonomer containing stream through a fluidized bed reactor under reaction conditions and in the presence of a catalyst composition (e.g., a composition comprising a metallocene complex of formula I and an activator and/or a corresponding activated metallocene complex of formula I) at a rate sufficient to maintain the bed of solid particles in suspension. The stream comprising unreacted monomer may be continuously recovered from the reactor, compressed, cooled, optionally partially or fully condensed, and recycled back to the reactor. The product (i.e., polymer) can be withdrawn from the reactor and a replacement monomer can be added to the recycle stream. Gases inert to the catalyst composition and reactants may also be present in the gas stream. For example, the polymerization system may include, for example, a single reactor or two or more reactors in series.
The feed stream for the polymerization process may include monomer, comonomer, nitrogen, hydrogen, and may optionally include one or more non-reactive alkanes that may condense and serve to remove the heat of reaction during the polymerization process. Illustrative non-reactive alkanes include, but are not limited to, propane, butane, isobutane, pentane, isopentane, hexane, isomers thereof, and derivatives thereof. The feed may enter the reactor at a single location or at multiple different locations.
For the polymerization process, the catalyst (e.g., the metallocene complex of formula I including the activator and/or the corresponding activated metallocene complex of formula I) can be continuously fed into the reactor. A gas inert to the catalyst (e.g., nitrogen or argon) may be used to carry the catalyst into the reactor bed. In another embodiment, the catalyst may be provided in the form of a slurry in mineral oil or a liquid hydrocarbon or mixture (e.g., propane, butane, isopentane, hexane, heptane, or octane). The catalyst slurry may be mixed with a carrier fluid (e.g., nitrogen or argon or a liquid (e.g., isopentane or other C)3To C8) ) are delivered together into the reactor.
Examples of the invention
In examples, various terms and names of materials are used, including, for example, the following:
XCATTMVP-100 (activated metallocene complex of formula I, obtained by Union of Enyvalen technology, Inc.).
Melt index (I) according to ASTM D-1238-E2) (ii) a Density is determined according to ASTM D-792.
Using XCATTMVP-100 was subjected to five polymerizations. For the five polymerizations, a gas-phase fluidized-bed reactor was used, which had an internal diameter of 0.57m and a bed height of 4.0m, and a fluidized bed composed of polymer particles. The fluidizing gas is passed through the bed at a velocity of 1.8 to 2.2 feet per second. The fluidizing gas leaves the top of the reactor and passes through the recycle gas compressor and heat exchanger before re-entering the reactor below the distribution grid. A constant fluidized bed temperature is maintained by continuously adjusting the water temperature on the shell side of the shell and tube heat exchanger. Gaseous feed streams of ethylene (monomer), nitrogen and hydrogen, and 1-hexene (comonomer) were introduced into the recycle gas line. The reactor is operated at about 2068kP a, operating at total pressure of gauge pressure, and venting to a flare to control pressure. The individual flow rates of ethylene, nitrogen, hydrogen and 1-hexene were adjusted to maintain the desired target. The concentration of all gases was measured using an on-line gas chromatograph. The catalyst is fed semi-continuously at a rate to achieve a target polymer production rate in the range of 60 to 75 kg/hr. The fluidized bed is maintained at a constant height by withdrawing a portion of the bed at a rate equal to the rate of product formation. The product is removed semi-continuously through a series of valves into a fixed volume chamber. The nitrogen purge removes a substantial portion of the entrained and dissolved hydrocarbons in the fixed volume chamber. The product was further treated with a small amount of humidified nitrogen to deactivate any traces of residual catalyst and/or cocatalyst. A CA-300 feed commercially available from ewing technologies, llc was fed to the reactor at a rate sufficient to produce about 30ppmw in the final product. The polymerization conditions and/or product characteristics are reported in table 1.
TABLE 1
Based on XCATTMRegression analysis of VP-100 polymerizations 1-5 was used to provide the following equation:
equation 1:
equation 2:
the regression analysis utilized hydrogen concentration and comonomer concentration.
FIG. 1 shows the density (g/cm) generated using equations 1-23) Relative to I2Plot of melt index (dg/min). For the plots, the corresponding C will correspond to the various polymers6/C2The flow ratio was maintained at a constant of about 0.092.As shown in FIG. 1, polymer 120 corresponds to about 0.9177g/cm3And a melt index of about 0.94 dg/min; polymer 120 corresponds to about 296ppmv of H2And (4) concentration.
As shown in FIG. 1, the density of the polymer is plotted as H over the entire plot2The concentration decreases significantly. Corresponding to the lowest H in FIG. 12The concentration and lowest density polymer 130 corresponds to about 60ppmv of H2Concentration, and about 0.9097g/cm3And a melt index of about 0.05 dg/min.
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