GB2105355A - Gas phase method for producing copolymers of ethylene and higher alpha-olefins - Google Patents

Abstract

A gas phase method for making elastomeric copolymers of ethylene and higher alpha-olefins comprises contacting a gaseous reaction mixture of the monomers with a fluidized bed of inert support that has been sequentially surface-impregnated with catalyst components comprised of a hydrocarbon-soluble vanadium salt having a vanadium valence of 3 to 5, and an organoaluminium compound, at least one of which catalyst components contains a valence bonded halogen.

Description

SPECIFICATION Gas phase method for producing copolymers of ethylene and higher alpha-olefins The present invention relates to a method for preparing polymeric compositions. More specifically, it relates to a novel, gas-phase method for preparing elastomeric copolymers of ethylene and higher alpha-olefins or mixtures of higher alpha-olefins.

As is well known to those skilled in the art, various processes exist for the homopolymerization or copolymerization of alpha-olefins. For example, processes are known for polymerizing ethylene or propylene, either alone or in the presence of small quantities of other monomers, to produce plastics.

These plastics are typically used in such applications as blow and injection molding, extrusion coating, film and sheeting, pipe, wire and cable. Also for example, it is well known to copolymerize ethylene and propylene, alone or with third monomers such as non-conjugated dienes, to make elastomers.

Ethylene-propylene elastomers find many end-use applications due to their resistance to weather, good heat aging properties and their ability to be compounded with large quantities of fillers and plasticizers. Typical automotive uses are radiator and heater hose, vacuum tubing, weather stripping and sponge doorseals. Typical industrial uses are for sponge parts, gaskets and seals.

Due to their different properties and end uses, it is important to distinguish between those factors affecting elastomeric or plastic properties of alpha-olefin polymers. While such factors are many and complex, a major one of instant concern is that related to sequence distribution of the monomer residues throughout the polymer chain.

For polyolefin plastics, sequence distribution is of little consequence in determining polymer properties since primarily one monomer residue is present in the chain. Accordingly, in plastic copolymers the majority monomer will be present in the form of long monomeric blocks.

While sequence distribution is thus of little concern with respect to polymeric plastics, it is a critical factor to be considered with respect to elastomers. If the olefinic monomers tend to form long blocks which can crystallize, elastic properties of the polymer are not as good as in a polymer with short monomer sequences in the chain.

Titanium catalysts, which can produce stereo-regular propylene sequences, are particularly disadvantageous since creating blocks of either ethylene or propylene will lead to crystallinity in the polymer.

At a given comonomer composition, sequence distribution is primarily a function of the catalyst components chosen. It can thus be seen that the artisan must excercise extreme care in selecting a catalyst system for making elastomers, with their critical dependency on sequence distribution and stereoregularity. It can also be seen that, on the other hand, no such restrictions apply to the selection of a catalyst system for making plastic polymer.

To avoid crystallinity in copolymers, it is also necessary to use a catalyst that produces a material with a narrow compositional distribution so that fractions containing a high content of one monomer are not present.

It is primarily for the above-discussed reasons that gas-phase techniques have been successfully used for making plastic polymers only. For example, titanium compounds, widely accepted catalyst components used in gas-phase polymerization techniques, are generally known to make inferior elastomers, because these compounds tend to make blocky copolymers. There have been few published attempts at developing gas-phase methods for making elastomers, particularly ethylenepropylene elastomers, and none has gained wide acceptance.

British Patent 907,579 discloses a gas-phase fluidized-bed method for making ethylenepropylene copolymer which "resembles" rubber. The specified catalyst components include titanium trihalide or vanadium trihalide and an aluminum compound containing in the molecule aluminum-alkyl and aluminum-alkoxy linkages. The vanadium trihalide is a hydrocarbon-insoluble solid compound. This reference refers to the use of inert solid "diluents", such as silica, with the catalyst components, apparently to control the rate of reaction between the aluminum alkyl compound and the titaniumvanadium trihalide. As can be seen from the example presented in this reference, the yield of polymer was very low, only 16.2 grams of copolymer per mole of titanium.

British Patent 1,131,786 relates to an improved catalyst for polymerizing and copolymerizing olefins which catalyst is a nitrogenous condensation polymer obtained by treating an aminoplast carrier having free methylol groups with a compound of a metal from Group IV-a, V-a, or VI-a of the Periodic Table and activated with a metal from Group I, II or Ill of the Periodic Table. The Group IV-a, Va or VI-a metal compounds can be titanium or vanadium derivatives, e.g., TiCI4, VOCI3, VCl4. The Group I, II or Ill activators can be alkyl aluminum compounds. While the patent states that the polymerization reactions can be carried out in either the liquid phase or gas-phase, all examples appear to be in the liquid phase. In the examples which utilize a vanadium catalyst, a catalyst mixture containing vanadium and titanium is used.

British Patent 1,286,867 discloses a titanium tetrahalide-containing catalyst system for polymerizing or copolymerizing olefins in either a liquid phase of a gas phase process. The catalyst comprises titanium tetrahalide supported on anhydrous magnesium or zinc halide. The preferred method for preparing the catalyst (although liquid suspension treatment is disclosed) is to grind the support in the presence of the titanium compound. All examples in this reference demonstrate the homopolymerization of ethylene.

British Patent Application 2,033,911 A relates to the gas-phase copolymerization of ethylene and propylene in a fluidized bed using a catalyst consisting of an organo-aluminum compound and a solid carrier containing a magnesium-containing inorganic solid compound and a titanium/vanadium compound. This reference, however, is specific to making copolymers having densites of 0.910 to 0.945. Since elastomers have densities below 0.9, and plastics above 0.9, it can be seen that this reference is specific to making plastics. This is confirmed by the disclosed end uses for the products made, e.g., films, sheets, hollow containers, extrusion molding, etc. In every example, titanium tetrachloride catalyst is used, and this catalyst is attached to the support by ball milling.

British Patent Application 2,034,336 has a similar disclosure, but for making ethylene-butene-1 copolymer having a melt index of 0.01 to 10 and a density of 0.850 to 0.910 which is "neither a crystalline plastic nor an elastomer". The catalyst is attached to its solid carrier by ball milling, according to this reference.

British Patent Application 2,034,337, likewise, has a similar disclosure, but for making ethylenepropylene copolymer having a melt index of 0.01 to 10 and a density of 0.850 to 0.910 which is "neither a crystalline plastic nor an elastomer".

British Patent Application 2,053,246A discloses a gas-phase, fluidized-bed method for making ethylene-propylene copolymers in which the proportion by weight of units derived from propylene is from 33 to 66%, and in which at least 60% of the units derived from propylene are disposed in sequences of at least three successive units. The catalyst system contains a titanium compound which can either be added directly to the reaction vessel or on a solid carrier.

British Patent Application 2,053,935A discloses a gas-phase, fluidized bed method for making elastomeric ethylene-propylene-diene terpolymers, but uses as catalyst components organo-metallic compounds and titanium compounds produced by reducing titanium tetrachloride by means of an organo-aluminum compound at a temperature of -10 to 800 C and then heating the resulting precipitate in the presence of an excess of titanium tetrachloride at temperatures up to 11 50C, these operations being carried out in the presence of an electron donor or being associated with a treatment by an electron donor compound, such as a dialiphatic ether.

U.S. 3,634,384 relates to a catalyst system for homo or co-polymerization of ethylene which comprises a magnesium hydroxychloride reacted with the product of a titanium or vanadium tetrahalide-alkyl aluminum hydrocarbon-soluble complex reaction, the product of which is treated with organo-metallic compound or hydride of a Group I to Ill metal. While all examples demonstrate liquid phase processes, with all except one using TiCI4, the use of either liquid phase or gas-phase polymerization methods is disclosed.The catalyst is specifically disclosed as being made by, first, reacting the titanium or vanadium compound with the aluminum alkyl at very low temperatures, -300C to -780C, to form a soluble complex, and, then, reacting the soluble complex with a solid magnesium hydroxychloride solid also at very low temperatures, -300C to -780C. Such low temperature methods of preparation add significantly to the overall costs for making the catalyst.

According to the present invention there is provided a gas phase method for producing an elastomeric ethylene/higher alpha-olefin copolymer (as hereinafter defined) which comprises contacting a gaseous reaction mixture comprising ethylene monomer and higher alpha-olefin monomer, in the absence of liquid hydrocarbon solvent, with a fluidized bed comprising an inert support material that has been made catalytically active for copolymerization by sequential surface impregnation (as hereinafter defined) with, as catalyst components, a hydrocarbon-soluble vanadium salt having a vanadium valence of 3 to 5, and an organo aluminum compound, at least one of which catalyst components contains a valence bonded halogen, to form the desired copolymer.

By copolymer there is meant elastomers having at least two comonomers. Thus mixtures of higher alpha-olefins may be copolymerized with the ethylene by this gas phase method to make for example terpolymers. The method is particularly useful for producing copolymers of ethylene and propylene, or ethylene-propylene-non-conjugated diene terpolymers.

The term sequential surface impregnation as used herein means that the inert support material is treated with the active catalyst components in liquid or gaseous form, first with one component and then with the other. For example such surface impregnation can be accomplished by either dispersing untreated inert solid support material in a liquid solution of the respective active catalyst components or by suspending untreated inert solid support material in a gaseous stream of the respective components, e.g. in a fluidized bed process.

The higher alpha-olefins preferably used in the method include those containing 3 to 10 carbon atoms, e.g., propylene, butene-1 or pentene-1. Since the olefinic monomers must be gaseous under the practical limits of temperature and pressure within the reaction vessel, higher alpha-olefins having 3 to 5 carbon atoms are more preferred, i.e., propylene, butene-1 and pentene-1 . While higher alphaolefins having 3 or 4 carbon atoms are most preferred, methods in accordance with the present invention are considered to be particularly suitable for making elastomeric copolymers of ethylene and propylene. Accordingly, subsequent descriptions of methods in accordance with the present invention will be directed, but not limited, to ethylene-propylene systems.

As is well known to those skilled in the art, copolymers of ethylene and higher alpha-olefins such as propylene often include other polymerizable monomers. Typical of these other monomers may be non-conjugated dienes such as the following: A. straight chain acyclic dienes such as: 1,4-hexadiene; 1,6-octadiene; B. branched chain acyclic dienes such as: 5-methyl-1 ,4-hexadiene; 3,7-dimethyl-1 ,6-octadiene; 3,7-dimethyl-1,7 octadiene and the mixed isomers of dihydro-myrcene and dihydro ocimene; C. single ring alicyclic dienes such as: 1,4-cyclohexadiene; 1,5-cyclooctadiene; and 1,5 cyclododecadiene; D. multi-ring alicyclic fused and bridged ring dienes such as: tetrahydroindene; methyltetrahydro indene; dicyclopentadiene; bicyclo-(2,2,1 )-hepta-2,5-diene; alkenyl, alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as 5-methylene-2-norbornene (MNB). 5-ethylidene-2- norbornene (ENB), 5-propenyl-2-norbornene, 5-isopropylidene-2-norbornene, 5-(4- cyclocopentenyl)2-norbornene; 5-cyclohexylidene-2-norbornene.

Of the non-conjugated dienes typically used to prepare these copolymers, dienes containing at least one of the double bonds in a strained ring are preferred. The most preferred third monomer is 5ethylidene-2-norbornene (ENB). It should be kept in mind when practicing methods in accordance with the present invention that when another monomer is used, it should preferably be chosen according to its property of existing in the gaseous phase under the practical limits of temperature and pressure within the reaction vessel.

In performance of the invention at least one fluidized bed of inert support material is used. The term inert is here intended to mean that the support material substantially does not contain reactive surface sites or adsorbed materials which prevent formation of active catalyst, nor does it react with the monomers.

The inert support material contains sufficient sites on the surface to fix the catalyst either by complexation or valence bonding. It preferably has high surface area and porosity to allow free access of reactants to the catalyst sites. Surface areas in the range of 10-1000 m2/g and porosities in the range of 0.2-1.0 cc/g are particularly preferred.

Particle dimensions and shape are important from the standpoint of ease of handling in the particular polymerization process in which they are used. Very large particles will be difficult to transport and to suspend in a diluent during catalyst preparation, while very small support particles may produce small polymer particles which will be difficult to recover. Generally, it is preferred that the support particle size ranges from about 0.2 to 300 microns. In a fluidized bed reaction, support particles with an average size of about 25 to 1 50 microns give good fluidization characteristics. Silica gel grades 1 D56 and 1 D952, produced by W. R. Grace and Company, are examples of suitable materials. Fluidization is also enhanced by particles that are roughly spherical in shape, as opposed, for example, to particles in the shape of long cylinders or plates.Finally, the catalyst support should be resistant to attrition.

Examples of supports which may be used in the method of the invention are: A. inorganic oxides and mixed oxides such as silica, alumina, magnesia, titania and aluminum silicate.

B. carbon blacks C. zeolites D. silicon carbide E. magnesium-, aluminum- and silicon-containing minerals such as talc and kaolin.

The inorganic oxides are preferred. The most preferred support is silica.

It is well known that the inorganic oxides can contain water adsorbed on the surface. Since water is a catalyst poison, heat treatment of the oxide is necessary to reduce water content to very low levels.

The inorganic oxides are known to contain a certain number of -OH groups chemically bound at the surface which groups are capable of reacting with the catalyst components. Thus, the nature of the final catalyst obtained will depend to some extent upon the ratio of -OH groups to the amount of catalyst added to the support. The mole ratio of catalyst components to surface hydroxyl groups on the inert support material is preferably at least about 0.5, more preferably about 0.5 to 2.0.The concentration of -OH groups can be adjusted by calcining the oxide to eliminateOH as shown schematically by:

According to further aspects of the present invention, the inert support material is sequentially surface-impregnated with liquid or gaseous catalyst components before its use in the polymerization reaction. One advantage realized by this treatment of the inert support material, as opposed to prior art methods such as, but not limited to, ball milling or precipitation methods, is that the active catalyst species are highly and uniformly dispersed on the support, in what approaches a mono-molecular layer, about the support particles.This greatly enhances the catalyst activity, as well as, the ability of the catalyst to yield the proper alternating sequence distribution of monomeric units in the polymer chain necessary to impart elastomeric properties to the product made. "Sequential", of course, means that the catalyst is surface-impregnated with one of the vanadium and aluminum co-catalysts at a time. If surface-impregnated with both at the same time, a solid catalyst results which is not highly and uniformly dispersed on the support material. Surface-impregnation with the aluminum compound first is preferred.

Surface impregnation of the inert support with liquid or gaseous catalyst components can be achieved in various ways. Surface-impregnation with catalyst components in the liquid phase can be achieved, for example and in a preferred embodiment by mixing a dispersion of inert support material with liquid solution(s) of the catalyst components. Use of the vanadium or aluminum compound in solution, rather than neat, is preferred to avoid violent reactions. Surface-impregnation of the inert support material with gas-phase catalyst components could be achieved, for example, by suspending a fluidized bed of support material in a flowing gas stream of catalyst components, either neat or in gaseous solution, e.g., mixed with nitrogen or another inert gas.

A preferred procedure for preparing a catalyst system in accordance with the present invention is as follows: 1. An inorganic oxide support is heated to a temperature of about 200-7000C to drive off adsorbed water and to adjust the surface hydroxyl concentration. Enough time is provided (4-24 hours) for the support to reach equilibrium in regard to moisture and hydroxyl levels.

2. The support is then cooled to ambient temperature in a dry nitrogen atmosphere to avoid readsorption of moisture, and is then evacuated and repressurized several times with nitrogen to eliminate oxygen, which is a catalyst poison, from the pores of the support.

3. Under inert atmosphere, the support is slurried in a dry hydrocarbon diluent, essentially free of impurities that could react with the catalyst components. Suitable diluents are aliphatic, alicyclic and aromatic chlorinated and non-chlorinated hydrocarbons, e.g., isopentane.

4. To the agitated slurry, one of the catalyst components, either the aluminum or vanadium compound (the aluminum is preferred), is added, preferably in solution, e.g., in hexane, benzene, toluene, etc. Enough time (1/4 4 hours) is allowed for essentially all of the catalyst component to be completely adsorbed on the support surface. Reaction temperature can be about 0--1000C, but preferably about 1 0-300C.

5. The surface-impregnated support is removed from contact with the original diluent, either by filtration followed by washing with several portions of fresh diluent or by diluent evaporation. The support plus catalyst component is then suspended in clean diluent by agitation, and the second component of the catalyst is added to the mixture, also preferably as a solution.

6. Enough time is allowed (1/4---4 hours) for the second catalyst component to react with the first catalyst component already present on the support and become fixed to the support surface.

Reaction temperatures of about 0-400C are preferred to avoid loss of catalyst activity which occurs at higher temperatures.

7. The diluent is removed from the slurry either by evaporation or filtration, as described in step 5, and the formulated catalyst is completely freed of diluent by, for example, fluidization in an inert gas such as nitrogen. Excessive heating (about about 400 C) should be avoided during this step. The dry, free-flowing powder finally obtained is then added to the fluidized bed reactor.

The vanadium compound to be used in practicing methods in accordance with the present invention is a hydrocarbon-soluble vanadium salt in which the vanadium valence is 3 to 5. Of course, mixtures of these vanadium compounds can be used. Non-limiting, illustrative examples of these compounds are as follows: A. vanadyl trihalide, alkoxy halides and alkoxides such as VOCI3. VOCI2(OBu) where Bu=butyl and vo(oC2H5)3 B. vanadium tetrahalide and vanadium alkoxy halides such as VCI4 and VCI3 (OBu).

C. vanadium and vanadyl acetyl acetonates and chloroacetyl acetonates such as V(AcAc)3 and VOCI2(AcAc) where (AcAc) is an acetyl acetonate.

D. Vanadium halide-Lewis base complexes such as VCl3 . 2THF where THF is tetrahydrofuran.

The preferred vanadium compounds are VOCI3, VCI4 and VOCl2-OR where R is a hydrocarbon radical, preferably a C, to C,0 aliphatic or aromatic hydrocarbon radical such as ethyl. phenyl, isopropyl, butyl, propyl, n-butyl, i-butyl, t-butyl, hexyl, cyclohexyl, naphthyl, etc.

In terms of formulas, preferred vanadium compounds useful in practicing methods in accordance with the present invention would be at least one member selected from the group consisting of:

where x=O-3 and R=a hydrocarbon radical; VCly(OR)4-y, (2) where y=3-4 and R=a hydrocarbon radical;

where y=3 4 and R=a hydrocarbon radical;

where z=2-3 and (AcAc)=acetyl acetonate group;

where (AcAc)=acetyl acetonate group; and VCl3.nB, (6) where n=2-3 and B=Lewis base, such as tetrahydrofuran, which can form hydrocarbon-soluble complexes with VCl3.

In formulas 1,2 and 3 above, R preferably represents a C, to C,0 aliphatic or aromatic hydrocarbon radical such as ethyl, phenyl, isopropyl, butyl, propyl, n-butyl, i-butyl, t-butyl, hexyl, cyclohexyl, octyl, naphthyl, etc. The molar amount of vanadium compound on the support (vanadium concentration) is preferably about 0.01 to 0.5 millimole per gram of support, with about 0.02 to 0.3 being particularly preferred.

The co-catalyst used in practising methods according to the present invention is an organo aluminum compound, which are commonly termed aluminum alkyls by those skilled in the art although they do not necessarily contain alkyl groups. Of course, mixtures of these compounds can be used.

Illustrative examples of organo aluminum compounds are as follows: A. aluminum trialkyls such as AI(C2H5)3 and Al(i-Bu)3, where i-Bu=isobutyl.

B. aluminum alkyl chlorides such as Al(C2H5)2Ci, Al(C2Hs)CI2, and Ai(C2H5)Ci2 Al(C2H5)2C1.

C. aluminum alkyl alkoxides such as AlOC2H5-(C2H5)2.

D. aluminum alkyl hydrides such as (C2H5)2AIH.

The preferred aluminum alkyl compourids are diethyl aluminum chloride and aluminum ethyl sesquichloride.

In terms of chemical formulas, these compounds may be represented by at least one member selected from the group consisting of: AlClx'R3-x', (7) where x'=0-2 and R=a hydrocarbon radical; Ry'Al(OR)3-y', (8) where y'=1-2 and R=a hydrocarbon radical; and R2AIH, (9) where R=a hydrocarbon radical.

As with the vanadium salts, R preferably represents a C1 to C10 aliphatic radical or an aromatic radical.

For good catalyst performance, the molar amounts of catalyst components added to the support surface preferably provide an aluminum/vanadium (Al/V) ratio of about 1 0-200. While an Al/V ratio of about 1 5-100 is more preferred, 20--60 is most preferred. The vanadium salt/organo aluminum compound pair are selected for catalyst preparation such that at least one of the co-catalyst components contains a valence bonded halogen.

In addition to the vanadium salt and organo aluminum compounds, other compounds can be used for surface-impregnation of the inert support material. For example, a Lewis base or a magnesium compound could be used to modify the activity of the catalyst. In a preferred embodiment of the method, an organoaluminum compound which is effective for removing catalyst poisons, such as an aluminum alkyl is added during performance of the method to remove catalyst poisons during polymerisation.

Polymerization is carried out in the absence of liquid hydrocarbon solvents by directly contacting the monomeric reaction mixture, e.g., ethylene-propylene or ethylene-propylene-diene, in the gaseous phase with a fluidized bed of the inert support material surface-impregnated with the catalyst components. Preferably, unreacted monomer is recycled for additional contact with the fluidized bed.

For a better understanding of the invention, and to show how the same may be carried into effect, reference is made by way of example to the accompanying drawing which shows a fluidized bed reactor operating in accordance with the method of the invention. Referring to the drawing there is shown a reactor 10 comprising a gas dispersing plate 20, reaction zone 12 and velocity reduction zone 14.

The reaction zone 12 comprises a bed of growing polymer particles, formed polymer particles and a minor amount of catalyst particles fluidized by the continuous flow of polymerizable and modifying gaseous components in the form of make-up feed and recycle gas through the reaction zone. To maintain a viable fluidized bed, the mass gas flow rate through the bed must be above the minimum flow required for fluidization.

It is essential that the bed always contains particles to prevent the formation of localized "hot spots" and to entrap and distribute the particulate catalyst throughout the reaction zone. On start up, the reaction zone is usually charged with a base of particular polymer particles before gas flow is initiated. Such particles may be identical in nature to the polymer to be formed or different therefrom.

When different, they are withdrawn with the desired formed polymer particles as the first product.

Eventually, a fluidized bed of the desired polymer particles supplants the start-up bed.

The catalyst system in the fluidized bed is preferably stored for service in a reservoir 32 under a blanket of a gas which is inert to the stored material, such as nitrogen or argon.

Fluidization is achieved by a high rate of gas recycle to and through the bed, typically in the order of about 50 times the rate of feed of make-up gas. The pressure drop through the bed is dependent on the geometry of the reactor.

Make-up gas is fed to the bed at a rate equal to the rate at which it is consumed by polymerization and lost from the bed with withdrawn product. The composition of the make-up gas is determined by analysis of the gas leaving the bed. A gas analyzer determines the composition of the gas being recycled and the composition of the make-up gas is adjusted accordingly to maintain an essentially steady state gaseous composition within the reaction zone.

To insure complete fluidization, the recycle and make-up gas are both returned to the reactor at point 1 8 below the bed. A gas distribution plate 20 above the point of return aids in fluidizing the bed.

The portion of the gas stream which does not react in the bed constitutes the recycle gas which is removed from the polymerization zone, preferably by passing it into a velocity reduction zone 14 above the bed where entrained particles are given an opportunity to drop back into the bed. Particle return may be aided by a cyclone 22 which may be part of the velocity reduction zone or exterior thereto.

Where desired, the recycle gas may then be passed through a filter 24 designed to remove small particles at high gas flow rates to prevent dust from contacting heat transfer surfaces and compressor blades.

The recycle gas is compressed in a compressor 25 and then passed through a heat exchanger 26 wherein it is stripped of heat of reaction before it is returned to the bed. The compressor 25 can also be placed downstream of the heat exchanger 26.

The distribution plate 20 diffused the recycle gas through the particles at the base of the bed to keep them in a fluidized condition.

It is essential to operate the fluid bed reactor at a temperature sufficient to maintain the desired rate of polymerization but below the sintering temperature of the polymer particles. To insure that sintering will not occur, operating temperatures below the sintering temperature are desired. In methods according to the present invention an operating temperature of about 20-1 000C is preferred. While 400--900 is more preferred, a temperature of about 40 to 750C is most preferred.

The pressure in the reaction vessel can be from about atmospheric up to a pressure such that no condensate of monomers is formed at the temperature and pressure chosen. It is normally desired to run at the highest practical pressure to maximize polymerization rate. This could be about 500 psig.

The upper pressure limit will be determined primarily by the content of propylene in the gas entering the reactor.

The surface-impregnated carrier material is injected into the bed at a rate set by the desired polymerization rate at a point 30 which is above the distribution plate 20. Injection of the catalyst into the area below the distribution plate may cause polymerization to begin there and eventually cause plugging of the distribution plate. Injection into the viable bed instead, aids in distributing the catalyst throughout the bed and tends to preclude the formation of localized spots of high catalyst concentration which may result in the formation of "hot spots". The catalyst may be added to the bed by various known methods such as entrainment in an inert carrier gas (nitrogen).

The production rate of the bed is controlled by the rate of catalyst injection. The production rate may be increased by simply increasing the rate of catalyst injection and decreased by reducing the rate of catalyst injection.

Since any change in the rate of catalyst injection will change the rate of generation of the heat of reaction, the temperature of the recycle gas is adjusted upwards or downwards to accommodate the change in rate of heat generation. This insures the maintenance of an essentially constant temperature in the bed.

Under a given set of operating conditions, the fluidized bed is maintained at essentially a constant height by withdrawing a portion of the bed as product at a rate equal to the rate of formation of the particulate polymer product. Since the rate of heat generation is directly related to product formation, a measurement of the temperature rise of the gas across the reactor (the difference between inlet gas temperature and exit gas temperature) is determinative of the rate of particulate polymer formation at a constant gas velocity.

The particulate polymer product is preferably continuously withdrawn at a point 34 at or close to the distribution plate 20 and in suspension with a portion of the gas stream which is vented before the particles settle to preclude further polymerization and sintering when the particles reach their ultimate collection zone. The suspending gas may also be used to drive the product of one reactor to another reactor.

The particulate polymer product is conveniently withdrawn through the sequential operation of a pair of timed valves 36 and 38 defining a segregation zone 40. While valve 38 is closed, valve 36 is opened to emit a plug of gas and product to the zone 40 between it and valve 36 which is then closed.

Valve 38 is then opened to deliver the product to an external recovery zone. Valve 38 is then closed to await the next product recovery operation.

Finally, the fluidized bed reactor is equipped with an adequate venting system to allow venting the bed during start up and shut down.

In terms of weight of ethylene, the relative feed rates of the reactants to the fluidized bed is preferably no lower than about 10% ethylene based on the total weight of alpha-olefins being fed.

Below 10% ethylene, reactivity of the reaction mixture is greatly decreased. The more preferred lower limit is about 15% ethylene on the same basis. The upper limit Is preferably about 60% ethylene, since above that value elastic properties in the final product are lost. The most preferred upper limit is 50% ethylene. When additional monomers such as dienes are used in the reaction mixture, they are preferably added in amounts of 115% (weight) based on the total reaction mixture. The more preferred range is about 210%.

To control polymer molecular weight, hydrogen can also be fed to the reactor, either separately or, more preferably, mixed with monomer feed. Hydrogen feed rates equal to 0.1 to 10% of the monomers (volume basis) are typical.

Polymerization in accordance with the present invention could be performed in two or more reaction vessels disposed in parallel and/or series according to well-known techniques. Thus, for example, the unreacted monomers from a first reaction vessel could be fed to a second. Also, for example the unreacted monomer from a first reaction vessel could be fed to two or more downstream reaction vessels in parallel with each other.

The polymers produced by methods according to the present invention are elastomeric and have densities less than 0.9, preferably about 0.85 to 0.87. These products may contain about 30% to 90% ethylene (weight basis) and can be used for automotive radiator and heater hoses, vacuum tubing, weather stripping, etc.

The invention is illustrated by the following Examples, in which catalysts were evaluated in a fluidized bed polymerization reactor. The reactor consisted of a 1" dia. x 12" long glass tube containing a porous metal disc at the bottom to bubble the gas upwardly through the bed. Catalyst was charged batchwise to the reactor under an inert atmosphere. A solid catalyst diluent, usually additional inorganic oxide catalyst support not containing both catalyst components, was also charged to the reactor to provide a deep enough solid bed so that a fluidized bed would result at the start of a polymerization run before appreciable polymer has formed. The total supported catalyst charge to the reactor was normally 0.5-1 g, which contained 0.01--0.10 mmol of vanadium.

Monomers were fed through a purification system consisting of packed beds of heated cupric oxide to remove trace oxygen and 3A molecular sieves to remove trace water. The purified ethylene and propylene were metered into the reactor with calibrated rotometers. An automatic pressure relief valve vented part of the unreacted monomers leaving the reactor to maintain system pressure constant at 600-620 kPa. The remaining monomers were recycled back to the reactor via a compressor and mixed with the fresh feeds. The recycle rate was adjusted with a flow control valve to give an adequate level of fluidization and solids mixing in the reactor. Reactor temperature was set by passing the recycle stream thru either a heater or cooler in order to set the temperature at the reactor inlet.

Liquid reactants such as dienes or aluminum alkyls were added to the reactor by first preparing dilute solutions in dry isopentane which had been purified by passage over silica gel and 5A molecular sieves. These solutions were then pumped by calibrated metering pumps thru a coil in a heating bath in order to fully vaporize the solutions. The vapor stream was then injected into the monomer recycle.

At the start of the run all flows were started through a reactor bypass line with the reactor valved off. After the system reached steady state the bypass was closed and the reactor valves opened to begin a polymerization run. The length of a run was either 60 min. or until fluidization could no longer be maintained due to particle growth if this occurred first.

Example 1 Catalyst preparation: 1. 25 g of Grace Chemical grade #56 silica (SlO2), which had been heated to 5000C for 20 hours to remove water, was slurried in dry isopentane in a dry box. The surface hydroxyl content of this material is about 1 mmol/g.

2. 25 cc of 1 M solution of diethylaluminum chloride (DEAC) in hexane was added to the slurry and this mixture was agitated at room temperature for 30 min.

3. The diluent was evaporated from the slurry in a stream of nitrogen to give a dry, free flowing powder with an aluminum content of 1 mmol/g SiO2 based on the starting ingredients.

4. Five grams of the above material were reslurried in isopentane, and 1.25 cc of 0.1 M VOCI3 solution in isopentane was added. After 30 min. agitation, the diluent was evaporated in a stream of nitrogen to leave a free flowing powder. The reaction with VOCI3 was carried out at room temperature.

Based on the starting ingredients the VOCI3 content of the solid is 0.025 mmol per g of (SiO2+DEAC).

The Al/V ratio is approximately 40.

5. 5 g of SiO2 as used in step 1 was treated with triethyl aluminum (TEA) as described in steps 1-3 above to give a solid containing 1 mmol TEA/g SiO2.

Polymerization procedure: 1. A reactor was charged with 1 g of DEAC/SiO2-VOCI3 catalyst containing 0.025 mmol of vanadium; and 5 g of TEA/SiO2 were added to act as a diluent.

2. Monomers were fed into the system at rates of: ethylene=1.4 g/min.

propylene=7.0 g/min.

and the reactor pressure was set at 600 kPa. The recycle compressor was turned on to give a monomer recirculation rate of 53 g/min.

3. A solution of DEAC in isopentane was prepared containing 3.33 mmol/l isopentane. This solution was fed thru a vaporization coil and into the recycle monomers to give a DEAC addition rate of 0.1 mmol/hour. This was done to remove low levels of adventitious catalyst poisons from the system during polymerization.

4. After all the flows in the system were lined out, the monomer stream was valved into the reactor to begin polymerization. The monomers passed thru a heater to raise reactor temperature to 580C.

Results: Particle growth in the reactor was noted almost immediately after the introduction of monomers began. The bed was fluidized for 60 min., and then the monomer flow was terminated and the reactor depressurized. A total of 3.7 g of polymer was recovered which corresponds to a catalyst efficiency of 148,000 g polymer per mole of vanadium.

The polymeric product was separated from the catalyst support by adding a mixture of hot toluene to dissolve the polymer, filtering the solution to remove SiO2, and evaporating the toluene to leave the pure polymer. A solid, elastomeric material remained after the evaporation.

Exarnple 2 The procedure of Example 1 was repeated except that the SiO2 support was treated with ethylaluminum sesquichloride (EASC) instead of DEAC to produce an aluminum loading of 1 mmol per gram of SiO2.

After 60 min. of polymerization at 590C, 2.4 g of polymer were recovered corresponding to a catalyst efficiency of 46,000 g per mole V. The polymer was an elastomeric solid with an ethylene content of 43.3 wt.% as measured by infrared technique described by Gardner et al, Rubber Chem.

Tech., 44, 1015, (1971). The inherent viscosity was 3.63 as measured in decalin at 1 350C.

Inherent viscosity was calculated by the formula: 1 IV= In RV C where C=polymer concentration, g/dl RV=relative viscosity measured by ASTM D 2857 The catalyst used was prepared in an identical manner to that described in Example 1. The run procedure was also the same except the ethylene feed rate was varied to prepare copolymers with different ethylene contents.The results are indicated in Table 1: Table 1 Feed rates (g/min) Ethylene Polymer analysis In feed Wt. % Inherent Run Ethylene Propylene (wt. %J ethylene viscosity 1 1.6 7.0 18.6 54.2 3.05 2 4.0 7.0 36.4 63.0 4.18 3 7.0 7.0 50.0 81.7 Example 4 Catalyst preparation: 1. 10 g of Grace Chemical #56 silica, which had been dried for 20 hours at 5000 C, was slurried in isopentane. 2.5 cc of 0.1 M VOCI3 in isopentane was added, and the mixture was agitated for 30 min. at room temperature. After this time, the isopentane was evaporated in a stream of nitrogen to give a dry solid containing .025 mmol VOCI3/g SiO2 based on the initial charge weights.

2. Two grams of the material prepared in step 1 were re-slurried in isopentane, and 3 cc of 1 M DEAC solution was added. The mixture was agitated for 30 min. at room temperature and then the isopentane was evaporated to give a dry powder containing 1.5 mmol DEAC per gram of SiO2 plus VOCI2. The Al/V ratio is approximately 60.

3. SiO2 was impregnated with TEA as described in Example 1 to give a catalyst diluent containing 1 mmol TEA/'g SiO2.

Polymerization procedure: Identical to that described in Example 1 Results: After 60 min. of polymerization, 1.7 g of polymer was obtained.

Example 5 The procedure described in Example 1 was again used except in step 4 of the catalyst preparation, VCI4 was added to the DEAC-impregnated SiO2 support to give a catalyst containing 0.05 mmol VCl,/grnm (SiO2+DEAC). The Al/V ratio is approximately 20.

Polymerization with this catalyst at 580C yielded 2.5 g of an elastomeric polymer after 60 min.

Example 6 Vanadyldichloroethoxide (VOCl2(OEt)) was prepared by adding 0.05 mmol of VOCI3 and 0.05 mmol of ethanol to a flask containing 100 cc of dry isopentane and agitating the mixture for a short period. SiO2, previously calcined for 20..hours at 5000 C, was impregnated with DEAC by the procedure described in steps 1 to 3 of Example 1 to obtain an aluminum concentration on the silica of 1 mmol/g.

Two grams of this material was added to the VOCI2(OEt) solution, the mixture was agitated for 30 min.

at room temperature, and then the isopentane was evaporated in a stream of nitrogen to leave a dry, free flowing powder with a vanadium concentration of 0.025 mmol/g (SiO2+DEAC). All catalyst preparation operations were carried out under an inert atmosphere.

The fluid bed reactor was charged with 0.5 g of the supported catalyst and 5.5 g of SiO2 catalyst diluent containing 1 mmol TEA/g. Polymerization was carried out at 500C according to the procedure in Example 1. A yield of 2.9 g of solid, elastomeric polymer was obtained after 60 min. of polymerization.

Example 7 VOCI3 and tetrabutyltitanate (Ti(OBu)4) were reacted in a 2/1 molar ratio in isopentane solution to yield VOCI2(OBu) and TiCI2(OBu)2. The reaction was carried out by combining 1.0 cc of 0.1 M VOCI3 and 0.5 cc of 0.1 M Ti(OBu)4 solution in isopentane with 100 cc of dry isopentane and agitating the mixture for a short time at ambient temperature. Two grams of the DEAC-impregnated SiO2 prepared in Example 6 was then added to this solution. After agitating the slurry for 30 min. the isopentane was evaporated in a stream of nitrogen to produce a dry, free-flowing powder containing 0.05 mmol of vanadium per gram (SiO2+DEAC).

The fluid bed reactor was charged with 0.5 g of the catalyst and 5.5 g of SiO2 catalyst diluent containing 1 mmol of TEA per gram. Polymerization was carried out at 500C according to the procedure in Example 1. A yield of 3.2 g of solid, elastomeric polymer was obtained after 3.5 min.

Example 8 A supported catalyst containing ethylaluminum sesqui-chloride (EASC) and vanadium tris acetyl acetonate (V(AcAc)3) was prepared by the following procedure: 1. 5 g of Grace #56 silica which had been previously calcined for 20 hours at 500"C was slurried in 100 cc of dry isopentane. 5 cc of 1 M EASC solution was added and the mixture allowed to react for 30 min. This isopentane was then evaporated in a stream of N2 to yield a dry powder containing 1 mmol aluminum/g SiO2.

2. 0.2 mmol of V(AcAc)3 was dissolved in 100 cc of dry toluene and 4 g of the EASC/SiO2 preparation from step 1 was added. After stirring the mixture for 30 min. at ambient temperature, the toluene was evaporated in a stream of nitrogen to yield a dry, free-flowing powder containing 0.05 mmol of vanadium per gram (SiO2+EASC).

The fluid bed polymerization reactor was charged 0.5 g of supported catalyst and 5.5 g of SiO2 diluent containing 1 mmol TEA/g. Polymerization was conducted at 670C according to the procedure in Example 1. After 60 min. of reaction, a yield of 1.4 g of solid, elastomeric polymer was obtained.

Example 9 A polymerization was carried out to produce a terpolymer of ethylene, propylene and ethylidene norbornene (ENB).

Catalyst was prepared as described in Example 1 to give a supported catalyst on SiO2 containing 1 mmol of DEAC per gram of SiO2 and 0.025 mmol of VOCI3 per gram of SiO2 plus DEAC. The reactor was charged with 0.5 g of catalyst and 5.5 9 of SiO2 containing 1 mmol TEA/'g to act as a catalyst diluent.

ENB was fed to the polymerization system by introducing it as a vapor into the monomer recycle.

Vaporization was achieved by preparing a solution of ENB in isopentane (30 g/l concentration) which was pumped at a rate of 0.5 cc/min. thru a coil immersed in a hot oil bath. Polymerization conditions are the same as described in Example 1 except for the feed of 0.9 g/hour of ENB and 36 g/hour of isopentane into the reactor.

After a polymerization time of 40 min., 1.3 g of polymer was obtained which was analyzed to contain 2.07 wt.% ENB by refractive index measurement (I. J. Gardner and G. Ver Strate, Rubber Chem.

Tech., 46, 1 01 9 (1 973)). The ethylene content of the polymer was 48% and the inherent viscosity was 2.80.

Example 10 Ethylene-propylene copolymer with an inherent viscosity of 3.68 and a density of 0.865 g/cc, which was produced by the process described in Example 1, was compounded on a rubber mill according to the formulation below: Ingredient Wt./100 wt. rubber Polymer 100 HAF Carbon Black 30 Dicumylperoxide 2.8 Triallylcyanurate 1.5 A pad of the compound was cured for 20 min. at 320"F in a hot press, and then the stress-strain properties of the vulcanizate were measured on an Instron testing machine. The results are shown below: Tensile strength, psi Elongation, % 140 100 470 200 580 235 Example 11 Using catalyst preparation methods and the test apparatus as already described, a series of tests were conducted under the varying conditions, and with results, as shown in Table 2 below. The inert support material used in these tests was silica which had been heated to 500 C for 20 hours. The columns headed "M, On Support" and "M2 On Support" indicate, respectively, the first and second catalyst components added to the inert support material in accordance with certain aspects of the present invention. The "Alkyl to Reaction" column indicates those tests in which an alkyl was added to remove adventitious catalyst poisons from the reaction system during polymerization. The ethylene feed rate was 1 g/min., propylene feed was 4.5 g/min., monomer recirculation was 53 g/min. and pressure was 600 kPa. The results in Table 2 are a representative portion of the results obtained in the numerous tests conducted.

Table 2 Polymer M1 on support M2 on support Catalyst ization Alkyl to reactor Polymer yield Reaction Run Amount Amount Al/V on charge to tempera- Amount time no. Type (mmol/g) Type (mmol/g) support reactor (g) ture ( C) Type (mmol/g) (g) (g/mole V) (min) 1 VOCl3 .1 EASC 0.6 6 1.5 25 - - 2.75 19,700 30 2 VOCl3 .1 DEAC 1.0 10 1.7 51 - - 4.4 29,000 40 3 DEAC 1.0 V(AcAc)3 0.1 10 1.5 25 - - 1.7 11,330 25 4 EASC 1.0 V(AcAc)3 0.05 20 3.0 25 - - 2.1 14,000 60 5 DEAC 1.0 V(AcAc)3 0.05 20 3.0 25 - - 04 6 DEAC 1.0 VOCl3 0.05 20 3.0 25 - - 2.9 19,300 1 7 DEAC 1.0 VOCl3 0.025 40 6.0 25 - - 2.6 17,300 5 8 DEAC 1.0 VOCl3 0.0167 60 9.0 25 - - 2.9 19,300 3 9 DEAC 1.0 VOCl3 0.025 40 6.0 25 - - 2.1 14,000 2 10 DEAC .5 VOCl3 0.025 20 6.0 25 - - 2.5 17,000 not rcd.

11 VOCl3 .1 EASC 0.6 6 1.5 25 - - 2.2 14,670 25 12 EASC 1 VOCl3 0.05 20 2.8 25 - - 1.5 10,700 2 13 VOCl3 .1 DEAC 0.6 6 1.5 25 - - .8 5,330 5 14 VOCl3 .1 DEAC 1.0 10 1.5 25 - - 2.8 18,670 60 15 VOCl3 .025 DEAC 0.5 20 1 50 DEAC .13 .8 32,000 60 16 VOCl3 .025 DEAC 1.0 40 1 53 DEAC .13 1.5 60,000 60 17 VOCl3 .025 DEAC 1.5 60 1 53 DEAC .13 1.7 68,000 60 18 DEAC 1.0 VCl4 0.05 20 .5 53 DEAC .13 2.6 104,000 60 19 DEAC 1.0 VCl4 0.025 40 1 54 DEAC .13 2.0 80,000 60 20 DEAC 1.0 VCl4 0.013 80 2 55 DEAC .13 1.5 60,000 15 Footnotes: EASC=ethylaluminium sesqui-chloride.

Reaction was continued until fluidization of the bed was lost. This result was, to some extent, expected since polymer product was not withdrawn from reaction vessel during tests. Those catalyst systems which give longer runs would, of course, be preferred. Some shortened runs were anomalous.

DEAC=diethylaluminium chloride 4 Anomalous result believed to be due to contaminated catalyst system.

Some difficulties encountered during the tests included oxygen contamination which poisoned the catalyst system, giving poor yields (data not reported) and a few anomalous result, e.g., run 5 in Table 2, which are believed to have resulted from contamination of the catalyst system during preparation thereof. As is well recognized in the art, although activity is indeed demonstrated, variations in activity can be expected when experiments are conducted on a small scale utilizing small amounts of high activity catalyst. Despite the precautions taken to handle the catalyst only in an inert atmosphere and to rigorously purify all monomer streams, adventitous poisons were periodically present during some runs. Table 3 shows the reproducibility of catalyst activity for polymerizations carried out at standard sets of conditions with the catalysts formulated as described in Example 1.The ethylene feed rate was 1 g/min., propylene feed was 4.5 g/min., monomer recirculation was 53 g/min and pressure was 600 kPa.

Table 3 Polymer M1 on support M2 on support Catalyst ization Alkyl to reactor Polymer yield Reaction Run Amount Amount Al/V on charge to tempera- Amount time no. Type (mmol/g) Type (mmol/g) support reactor (g) ture ( C) Type (mmol/hr) (g) (g/mole V) (min) 1 VOCl3 .1 EASC 0.6 6 1.5 25 - - 2.45 17,500 35 2 VOCl3 .1 EASC 0.6 6 1.5 25 - - 3.50 25,000 30 3 VOCl3 .1 EASC 0.6 6 1.5 53 - - 2.4 17,200 10 4 DEAC 1.0 VOCl3 0.025 40 1 54 TEA4 .13 1.5 60,000 20 5 DEAC 1.0 VOCl3 0.025 40 1 55 DEAC .13 1.6 64,000 40 6 DEAC 1.0 VOCl3 0.025 40 1 57 DEAC .13 3.1 124,000 60 7 DEAC 1.0 VOCl3 0.025 40 1 55 DEAC .13 1.9 76,000 60 8 DEAC 1.0 VOCl3 0.025 40 1 56 DEAC .13 1.8 72,000 10 9 DEAC 1.0 VOCl3 0.025 40 1 55 DEAC .13 .5 20,000 60 10 DEAC 1.0 VOCl3 0.025 40 1 56 - - 3.6 144,000 60 11 DEAC 1.0 VOCl3 0.025 40 1 56 DEAC .12 3.4 136,000 60 12 DEAC 1.0 VOCl3 0.025 40 1 56 - - 3.6 144,000 60 13 DEAC 1.0 VOCl3 0.025 40 1 56 DEAC .12 3.4 136,000 60 14 DEAC 1.0 VOCl3 0.025 40 1 60 DEAC .11 4.2 168,000 60 15 DEAC 1.0 VOCl3 0.025 40 1 60 DEAC .11 4.1 164,000 34 16 DEAC 1.0 VOCl3 0.025 40 1 60 DEAC .9 5.3 212,000 48 Footnotes: EASC=ethylaluminium sesqui-chloride.

Reaction was continued until fluidization of the bed was lost. This result was, to some extent, expected since polymer product was not withdrawn from reaction vessel during tests. Those catalyst systems which give longer runs would, of course, be preferred. Some shortened runs were anomalous.

DEAC=diethylaluminium chloride 4 TEA=triethylaluminium Since different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the present invention is not limited to the embodiment(s) specifically disclosed in this specification.

Claims (43)

Claims

1. A gas phase method for producing an elastomeric ethylene/higher alpha-olefin copolymer (as hereinbefore defined) which comprises contacting a gaseous reaction mixture comprising ethylene monomer and higher alpha-olefin monomer, in the absence of liquid hydrocarbon solvent, with a fluidized bed comprising an inert support material that has been made catalytically active for copolymerization by sequential surface impregnation (as hereinbefore defined) with, as catalyst components, a hydrocarbon-soluble vanadium salt having a vanadium valence of 3 to 5, and an organo aluminum compound, at least one of which catalyst components contains a valence bonded halogen, to form the desired copolymer.

2. A method according to claim 1, wherein the vanadium salt has the general formula

where x is O to 3, y is 3 or 4 and R is a hydrocarbon radical.

3. A method according to claim 2, wherein R represents an aliphatic hydrocarbon radical having from 1 to 10 carbon atoms, or an aromatic hydrocarbon radical.

4. A method according to claim 2, wherein the vanadium salt is VOCI3 or '(Cl4.

5. A method according to claim 1, wherein the vanadium salt is

where (AcAc) represents an acetyl acetonate group.

6. A method according to claim 1, wherein the vanadium salt has the general formula VCl3. nB where n is 2 or 3 and B represents a Lewis base capable of forming a hydrocarbon-soluble complex with VCl3.

7. A method according to any one of the preceding claims wherein the organoaluminum compound is an aluminum alkyl, aluminum alkyl hydride or aluminum alkoxide.

8. A method according to any one of claims 1 to 6 wherein the organoaluminum compound has the general formula AICIx.R3~x,, RylAl(OR)3~yl or R2AIH where X' is O to 2, y' is 1 or 2 and R is a hydrocarbon radical.

9. A method according to claim 8, wherein R represents an aliphatic hydrocarbon radical having from 1 to 10 carbon atoms, or an aromatic hydrocarbon radical.

10. A method according to claim 7, 8 or 9 wherein the organoaluminum compound is Al(C2Hs)2CI, Al(C2H5)3 or Al(C2Hs)CI2 Al(C2Hs)2CI.

1 A method according to any one of the preceding claims wherein the mole ratio of aluminum to vanadium on the support material is from 10 to 200.

12. A method according to claim 11, wherein the mole ratio is from 1 5 to 100.

13. A method according to claim 12, wherein the mole ratio is from 20 to 60.

14. A method according to any one of the preceding claims wherein the concentration of vanadium on the support material is from 0.01 to 0.5 millimole per gram of support material.

1 5. A method according to claim 14, wherein the vanadium concentration is from 0.02 to 0.3 millimole per gram of support material.

1 6. A method according to any one of the preceding claims where sequential surfaceimpregnation of the inert support material is performed by first surface impregnating the support material with the organo-aluminum compound and then with the vanadium salt.

17. A method according to any one of the preceding claims wherein the support material is sequentially surface-impregnated with a liquid solution of each catalyst component.

1 8. A method according to any one of the preceding claims wherein the support material has surface hydroxyl groups and wherein the mole ratio of catalyst components to surface hydroxyl groups is at least 0.5.

1 9. A method according to claim 16, wherein the mole ratio is from 0.5 to 2.0.

20. A method according to any one of the preceding claims wherein the inert support material has a particle size of from 0.2 to 300 micron.

21. A method according to any one of the preceding claims wherein the inert support material has a surface area of from 10 to 1000 m2/g.

22. A method according to any one of the preceding claims wherein the inert support material has a porosity of from 0.2 to 1.0 cc/g.

23. A method according to any one of the preceding claims wherein the inert support material comprises an inorganic oxide or mixture of inorganic oxides.

24. A method according to claim 23, wherein the, or one of the, inorganic oxides is silica.

25. A method according to claim 23 or 24, wherein the, or one of the, inorganic oxides is alumina, magnesia, titania or aluminum silicate.

26. A method according to any one of the preceding claims which is performed at a temperature of from 20 to 1000C.

27. A method according to claim 26, when performed at a temperature of from 400C to 900 C.

28. A method according to claim 27, when performed at a temperature of from 40 to 750C.

29. A method according to any one of the preceding claims which is performed at a pressure of from atmospheric to 500 psig.

30. A method according to any one of the preceding claims wherein unreacted monomer mixture is recycled for additional contact with the fluidized bed.

31. A method according to any one of the preceding claims wherein an organoaluminum compound effective for removing catalyst poisons is added to the reaction mixture to remove catalyst poisons during copolymerization.

32. A method according to any one of the preceding claims wherein the higher alpha-olefin has from 3 to 10 carbon atoms.

33. A method according to claim 32, wherein the higher alpha-olefin is propylene.

34. A method according to any one of the preceding claims wherein the reaction mixture comprises more than one higher alpha-olefin and includes a non-conjugated diene.

35. A method according to claim 34, wherein the non-conjugated diene is ethylidene norbornene.

36. A method according to claim 35, when appendant to claim 33 wherein the gaseous reaction mixture comprises ethylene, propylene and ethylidene norbornene monomers and the copolymer produced is an ethylene-propylene-ethylidene norbornene terpolymer.

37. A method according to any one of the preceding claims wherein the copolymer produced has a density of from 0.85 to 0.87.

38. A method according to any one of the preceding claims, wherein hydrogen is included in the monomer mixture to control the molecular weight of the copolymer product.

39. A method according to any one of the preceding claims which includes the step of separating the desired copolymer from the product mixture.

40. A method according to claim 1, substantially as herein described in any one of Examples 1 to 9and 11.

41. A method according to claim 1 substantially as herein described with reference to the drawing.

42. A method according to claim 1 substantially as herein described.

43. An elastomeric copolymer whenever produced by the method according to any one of the preceding claims.