CA1174800A - Gas phase method for producing copolymers of ethylene and higher alpha-olefins - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A gas-phase fluid bed method is disclosed for making elasto-meric copolymers of ethylene and higher alphaolefins. A gaseous reac-tion mixture comprised of the monomers is contacted with a fluidized beo of inert support that has been sequentially surface-impregnated with liquid or gaseous catalyst components comprised of a vanadium compound and an aluminum alkyl.

Description

1 The present invention relates to a method for

2 preparing polymeric compositions. More specifically, it

3 relates to a novel, gas-phase method for preparing elasto-

4 meric copolymers of ethylene and higher alpha-olefins or

5 mixtures of higher alpha-olefins.

6 As is well known to those skilled in the art,

7 various processes exist for the homopolymerization or co-

8 polymerization of alpha-olefins. For example, processes

9 are known for polymerizing ethylene or propylene, either

10 alone or in the presence of small quantities of other 1l monomers, to produce plastics. These plastics are typi-12 cally used in such applications as blow and injection 13 molding, extrusion coating, film and sheeting, pipe, wire 14 and cable. Also for example, it is well known to copoly-15 merize ethylene and propylene, alone or with third monomers 16 such as non-conjugated dienes, to make elastomers. Ethyl-17 ene-propylene elastomers find many end-use applications 18 due to their resistance to weather, good heat aging pro-19 perties and their ability to be compounded with large 20 quantities of fillers and plasticizers. Typical automotive 21 uses are radiator and heater hose, vacuum tubing, weather 22 stripping and sponge doorseals. Typical industrial uses 23 are for sponge parts, gaskets and seals.
24 Due to their different properties and end uses, 25 it is important to distinguish between those factors 26 effecting elastomeric or plastic properties of alpha-olefin 27 polymers. While such factors are many and complex, a major 28 one of instant concern is that related to sequence distri-2g bution of the monomers throughout the polymer chain.
For polyolefin plastics, sequence distribution 31 is of little consequence in determining polymer properties 32 since primarily one monomer is present in the chain.
33 Accordingly, in plastic copolymers the majority monomer 34 will be~present in the form of long monomeric blocks.
While sequence distribution is thus of little 36 concern with respect to polymeric plastics, it is a criti-:
*

~ 174800 1 cal factor to be considered with respect to elastomers.
2 If the olefinic monomers tend to form long blocks which 3 can crystallize, elastic properties of the polymer are 4 poorer than in a polymer with short monomer sequences in the chain.
6 Titanium catalysts, which can produce stereo-7 régular propylene sequences, are particularly disadvanta-8 geous since creating blocks of either ethylene or propylene 9 will lead to crystallinity in the polymer.
At a given comonomer composition, sequence dis-

11 tribution is primarily a function of the catalyst compo-

12 nents chosen. It can thus be seen that the artisan must

13 exercise extreme care in selecting a catalyst system for making elastomers, with their critical dependency on se-quence distribution and stereoregularity. It can also be 16 seen that, on the other hand, no such restrictions apply 17 to the selection of a catalyst system for making plastic 18 polymer.
19 To avoid crystallinity in copolymers, it is also necessary to use a catalyst that produces a material with 21 a narrow compositional distribution so that fractions con-22 taining a high content of one monomer are not present.
23 It is primarily for the above-discussed reasons 24 that gas-phase techniques have been successfully used for making plastic polymers only. For example, titanium com-26 pounds, widely accepted catalyst components used in gas-27 phase polymerization techniques, are generally known to 28 make inferior eiastomers, because these compounds tend to29 make blocky copolymers. There have been few published attempts at developing gas-phase methods for making elasto-31 mers, particularly ethylene-propylene elastomers, and none 32 have gained wide acceptance.
33 The present invention concerns a method for mak-34 ing elastomeric ethylene-higher alpha-olefin copolymers by gas phase polymerization. It is particularly useful 36 for making copolymers of ethylene and propylene. Accord-37 ing to a method in accordance with the present invention, , . ~ .

- ` 117480~

1 at least one gaseous reaction mixture of the monomers, 2 e.g., ethylene-propylene or ethylene-propylene-non-conju-3 gated diene, is contacted with at least one fluidized bed 4 of inert support material that has been sequentially sur-face-impregnated with liquid or gaseous catalyst comprised 6 of (1) hydrocarbon-soluble vanadium compound in which the 7 vanadium valence is 3 to 5, and (2) aluminum alkyl. "Se-8 quential surface-impregnation with liquid or gaseous cata-9 lyst" refers to a method by which the inert support mate-rial is treated with the active catalyst components. "Se-11 quential", of course, refers to surface-impregnating with, 12 first, one of the two noted catalyst components, and, then, 13 with the other. "Liquid or gaseous" surface-impregnation

14 can be accomplished by either dispersing untreated inert solid support material in a liquid solution of the active 16 catalyst components or by suspending untreated inert solid 17 support material in a gaseous stream of active components, 18 e.g., fluidized bed process.
1'3 British Patent 907,579 discloses a gas-phase fluidized-bed method for making ethylene-propylene copoly-21 mer which "resembles" rubber. The specified catalyst com-22 ponents include titanium trihalide or vanadium trihalide 23 and an aluminum compound containing in the molecule alumi-24 num-alkyl and aluminum-alkoxy linkages. The vanadium tri-halide is a hydrocarbon-insoluble solid compound. This 26 reference refers to the use of inert solid "diluents", 27 such as silica, with the catalyst components, apparently 28 to control the rate of reaction between the aluminum alkyl 29 compound and the titanium-vanadium trihalide. As can be seen from the example presented in this reference, the 31 yield of polymer was very low, only 16.2 grams of copolymer 32 per mole of titanium.
33 British Patent 1,131,786 relates to an improved 34 catalys~ for polymerizing and copolymerizing olefins which 35 catalyst is a nitrogenous condensation polymer obtained by 36 treating an aminoplast carrier having free methylol groups ` 1174800 1 with a compound of a metal from Group IV-a, V-a or VI-a 2 of the Periodic Table and activated with a metal from 3 ~roup I, II or III of the Periodic Table. The Group IV-a, 4 V-a or VI-a metal compounds can be titanium or vanadium derivatives, e.g., TiC14, VOC13, ~C14. The Group I, II or 6 III activators can be alkyl aluminum compounds. While the 7 patent states that the polymerization reactions can be 8 carried out in either the liquid phase or gas-phase, all 9 examples appear to be in the liquid phase. In the examples which utilize a vanadium catalyst, a catalyst 11 mixture containing vanadium and titanium is used.
12 British Patent 1,286,867 discloses a titanium 13 tetrahalide-containing catalyst system for polymerizing 14 or copolymerizing olefins in either a liquid phase or a gas phase process. The catalyst comprises titanium tetrahalide 16 supported on anhydrous magnesium or zinc halide. The pre-17 ferred method for preparing the catalyst (although liquid 18 suspension treatment is disclosed) is to grind the support 19 in the presence of the titanium compound. All examples in this reference demonstrate the homopolymerization of ethyl-21 ene.
22 British Patent Application 2,033,911A published 5/29/80 relates to 23 the gas-phase copolymerization of ethylene and propylene 24 in a fluidized bed using a catalyst consisting of a~ organo-aluminum compound and a solid carrier containing a magne-26 sium-containing inorganic solid compound and a titanium/
27 vanadium compound. This reference, however, is specific 28 to making copolymers having densities of 0.910 to 0.945.
29 Since elastomers have densities below 0.9, and plastics above 0.9, it can be seen that this reference is specific 31 to making plastics. This is confirmed by t~le disclosed 3Z end uses for the products made, e.g., films, sheets, hollow 33 containers, extrusion molding, etc. In every example, 34 titanium tetrachloride catalyst is used, and this catalyst is attached to the suppor~ by ball milling.
36 British Patent Application 2,034,336 published 6/4/80 has a simi-37 lar disclosure, but for making ethylene-butene-l copolymer 1 17~800 1 having a melt index of 0.01 to 10 and a density of 0.850 2 to 0.910 which is "neither a crystalline plastic nor an 3 elastomer". The catalyst is attached to its solid carrier 4 by ball milling, according to this reference.
British Patent A~plication 2,034,337, published 6/4/80 likewise, 6 }las a similar disclosure, but for making ethylene-propylene 7 copolymer having a melt index of 0.01 to 10 and a density 8 of 0.850 to 0.910 which is "neither a crystalline plastic 9 nor an elastomer".
B~itish Patent Application 2,053,246A published V4/81 discloses 11 a gas-phase, fluidized-bed method for making ethylene-pro-12 pylene copolymers in which the proportion by weight of 13 units derived from propylene is from 33 to 66~, and in 4 which at least 60~ of the units derived from propylene are disposed in sequences of at least three successive units.
16 The catalyst system contains a titanium compound which can 17 either be added directly to the reaction vessel Qr on a 18 solid carrier.
19 British Patent Application 2,053,935A published 2/11/81 discloses a ga~-phase, fluidized bed method for making elastomeric 21 ethylene-propylene-diene terpolymers, but uses as catalyst 22 components organo-met~llic compounds and titanium compounds 23 produced by reducing titanium tetrachloride by means of an 4 organo-aluminum compound at a temperature of -10 to 80C
and then heating the resulting precipitate in the presence 26 of an excess of titanium tetrachloride at temperatures up 27 to 115C, these operations being carried out in the pre-28 sence of an electron donor or being associated with a 29 treatment by an electron donor compound, such as di-alipha-tic ether.
31 U.S. 3,634,384 relates to a catalyst system for 32 homo or co-polymerization of ethylene which comprises a 33 magnesium hydroxychloride reacted with the product of a 3~/ titanium or vanadium tetrahalide-alkyl aluminum hydrocar-bon~soluble complex reaction, the product of which is 36 treated with organo-metallic compound or hydride of a 37 Group I to III metal. While all examples demonstrate ''~3 `' 1 liquid phase processes, with all except one using TiC14, 2 the use of either liquid phase or gas-phase polymerization 3 methods is disclosed. The catalyst is specifically dis-4 closed as being made by, first, reacting the titanium or vanadium compound with the aluminum alkyl at very low tem-6 peratures, -30C to -78C, to form a soluble complex, and, 7 then, reacting the soluble complex with a solid magnesium 8 hydroxychloride solid also at very low temperatures, -30C
9 to -78C. Such low temperature methods of preparation add significantly to the overall costs for making the catalyst.
11 As already noted, in accordance with certain of 12 its aspects, the method of the present invention is useful 3 for producing elastomeric copolymer from ethylene and high-14 er alpha-olefins or mixtures of higher alpha-olefins. The higher alpha-olefins include those containing 3 to 10 car-16 bon atoms, e.g., propylene, butene-l, pentene-l, etc. Due 17 to the requirement, in accordance with certain aspects of 18 the present invention, that the olefinic monomers be gas-19 eous under the practical limits of temperature and pressure within the reaction vessel, higher alpha-olefins having 3 21 to 5 carbon atoms are preferred, i.e., propylene, butene-l 22 and pentene-l. While higher alpha-olefins having 3 to 4 23 carbon atoms are most preferred, methods in accordance with 24 the present invention are considered to be particularly suitable for making elastomeric copolymers of ethylene and 26 propylene. Accordingly, subsequent descriptions of methods 27 in accordance with the present invention will be directed, 28 but not limited, to ethylene-propylene systems.
29 As is well known to those skilled in the art, 30 Icopolynrers of ethylene and higher alpha-olefins such as 31 propylene often include other polymerizable monomers.
32 Typical of these other monomers may be non-conjugated dienes 33 such as the following:
34 A. straight chain acyclic dienes such as: 1, 4-hexadiene; 1, 6-octadiene;
36 B. branched chain acyclic dienes such as:
37 5-methyl-1, 4-hexadiene; 3,7-dimethyl-1,6-octa-1 diene 3,7-dimethyl-l,7 octadiene and the mixed 2 isomers of dihydro-myrcene and dihydro-ocinene;
3 C. single ring alicyclic dienes such as: l,4-4 cyclohexadiene; l,5-cyclooctadiene; and l,5-cyclododecadiene;
6 D. multi-ring alicyclic fused and bridged ring 7 dienes such as: tetrahydroindene; methyltetra-8 hydroindene; dicyclopentadiene; bicyclo-(2,2,l~
9 -hepta-2,5-diene; alkenyl, alkylidene, cyclo-alkenyl and cycloalkylidene norbornenes such as 11 5-methylene-2-norbornene (MNB), 5-ethylidene-2-12 norbornene (ENB), 5-propenyl-2-norbornene, 5-3 isopropylidene-2-norbornene, 5-(4-cyclopentenyl) 4 -2-norbornene; 5-cyclohexylidene-2-norbornene.
Of the non-conjugated dienes typically used to 16 prepare these copolymers, dienes containing at least one 17 of the double bonds in a strained ring are preferred. The 18 most preferred third monomer is 5-ethylidene-2-norbornene 19 (ENB). It should be kept in mind when practicing methods in accordance with the present invention that when another 21 monomer is used, it should preferably be chosen according 22 to its property of existing in the gaseous phase under the 23 practical limits of temperature and pressure within the 24 reaction vessel.
In accordance with certain other aspects of the 26 present invention, at least one fluidized bed of inert 27 support material is used. "Inert" is intended to mean that 28 the support material neither contains reactive surface 2g sites or adsorbed materials which prevent formation of active catalyst, nor reacts with the monomers.
31 The inert support material should contain suffi-32 cient ~uantities of sites on the surface to fix the catalyst 33 either by complexation or valence bonding. It should have 34 high surface area and porosity to allow free access of re-actants to the catalyst sites. Surface areas in the range 36 of lO - lOOO m /g and porosities in the range of 0.2 - 1.0 37 cc/g are believed to be useful.

, . ` , 1 17~800 1 Particle dimensions and shape are important ~rom 2 the standpoint of ease of handling in the particular poly-3 merization process in which they are used. Very large 4 particles will be difficult to transport and to suspend in a diluent during catalyst preparation, while very small 6 support particles may produce small polymer particles which 7 will be difficult to recover. Generally, it is believed 8 that the support particle size can range from about 0.2 to 9 300 microns. In a fluidized bed reaction, support parti-cles with an average size of about 25 to l50 microns give 11 good fluidization characteristics. Silica gel grades lD56 12 and lD952, produced by W.R. Grace and Company, are examples 3 of suitable materials. Fluidization is also enhanced by 4 particles that are roughly spherical in shape, as opposed, for example, to particles in the shape of long cylinders or 16 plates. Finally, the catalyst support should be resistant 17 to attrition.
18 Examples of supports meeting the above-described 19 criteria are:
A. inorganic oxides and mixed oxides such as 21 silica, alumina, magnesia, titania and aluminum 22 silicate.
23 B. carbon blacks 24 C. zeolites D. silicon carbide 26 E. magnesium-, aluminum- and silicon-containing 27 minerals such as talc and kaolin.
28 The inorganic oxides are preferred. The most 29 preferred support is silica.
It is well known that the inorganic oxides can 31 contain water adsorbed on the surface. Since water is a 32 catalyst poison, heat treatment of the oxide is necessary 33 to reduce water content to very low levels. The inorganic 34 oxides are known to contain a certain number of -OH groups chemically bound at the surface which groups are capable 36 of reacting with the catalyst components. Thus, the nature 37 of the final catalyst obtained will depend to some extent ~ 174800 1 upon the ratio of -OH groups to the amount of catalyst 2 added to the support. The mole ratio of catalyst compo-3 nents to surface hydroxyl groups on the inert support ma-4 terial should be at least about ~.5, preferably about 0.5 to 2Ø The concentration of -OH groups can be adjusted 6 by calcining the oxide to eliminate -OH as shown schemati-7 cally by:
OH O~
9 1 1 heat / \
~- M M - - > - M M - + H2O
11 According to further aspects of the present in-12 vention, the inert support material is sequentially sur-13 face-impregnated with liquid or gaseous catalyst components 14 before its use in the polymerization reaction. One advan-tage realized by this treatment of the inert support mate-16 rial, as opposed to prior art methods such as, but not 17 limited to, ball milling or precipitation methods, is that 18 the active catalyst species are highly and uniformly dis-19 persed on the support, in what approaches a mono-molecular layer, about the support particles. This greatly enhances 21 the catalyst activity, as well as, the ability of the 22 catalyst to yield the proper alternating sequence distri-23 bution of monomeric units in the polymer chain necessary 24 to impart elastomeric properties to the product made.
"Seqùential", of course, means that the catalyst is surface-26 impregnated with one of the vanadium and aluminum alkyl 27 co-catalysts at a time. If surface-impregnated with both 28 at the same time, a solid catalyst results which is not 29 highly and uniformly dispersed on the support material.
Surface-impregnation with the aluminum compound first is 31 preferred.
32 Surface-impregnation of the inert support with 33 liquid or gaseous catalyst components can be achieved in 34 various ways. Surface-impregnation with catalyst compo-nents in the liquid phase can be achieved, for example, by 36 mixing a dispersion of inert support material with liquid 1 1~4800 1 solution(s) of the catalyst components. Use of the vana-2 dium or aluminum compound in solution, rather than neat, 3 is preferred to avoid violent reactions. Surface-impreg-4 nation of the inert support material with gas-phase cata-lyst components could be achieved, for example, by suspend-6 ing a fluidized bed of support material in a flowing gas 7 stream of catalyst components, either neat or in gaseous 8 solution, e.g., mixed with nitrogen or another inert gas.
9 A preferred procedure for preparing a catalyst system in accordance with the present invention is as l follows:
12 1. An inorganic oxide support is heated to a 13 temperature of about 200-700C to drive off adsorbed water 14 and to adjust the surface hydroxyl concentration. Enough time is provided (4-24 hours) for the support to reach 16 equilibrium in regard to moisture and hydroxyl levels.
17 2. The support is then cooled to ambient temper-18 ature in a dry nitrogen atmosphere to avoid re-adsorption 19 of moisture, and is then evacuated and repressurized several times with nitrogen to eliminate oxygen, which is 21 a catalyst poison, from the pores of the support.
22 3. Under inert atmosphere, the support is slur-23 ried in a dry hydxocarbon diluent, essentially free of 24 impurities that could react with the catalyst components.
25 Suitable'diluents are aliphatic, alicyclic and aromatic 26 chlorinated and non-chlorinated hydrocarbons, e.g., iso-27 pentane.
28 4. To the agitated slurry, one of the catalyst 29 components, either the aluminum or vanadium compound (the aluminu~ is preferred), is added, preferably in solution, 31 e.g., in hexane, benzene, toluene, etc. Enough time (1/4 -32 4 hours) is allowed for essentially all of the catalyst 33 component to be completely adsorbed on the support surface.
34 Reaction temperature can be about 0-100C, but preferably about 10-30C.
36 5. The surface-impregnated support is removed 37 from contact with the original diluent, either by filtra-~ 174800 1 tion followed by washing with several portions of fresh 2 diluent or by diluent evaporation. The support plus cata-3 lyst component is then suspended in clean diluent by agi-4 tation, and the second component of the catalyst is added to the mixture, also preferably as a solution.
6 6. Enough time is allowed (1/4-4 hours) for the 7 second catalyst component to react with the first catalyst 8 component already present on the support and become fixed 9 to the support surface. Reaction temperatures of about 0-40C are preferred to avoid loss of catalyst activity 11 which occurs at higher temperatures.
12 7. The diluent is removed from the slurry either 13 by evaporation or filtration, as described in step S, and 4 the ormulated catalyst is completely freed of diluent by, for example, fluidization in an inert gas such as nitrogen.
16 Excessive heating (above about 40C) should be avoided 17 during this step. The dry, free-flowing powder finally 18 obtained is then added to the fluidized bed reactor.
19 The vanadium compound to be used in practicing methods in accordance with the present invention TS a hydro-21 carbon-soluble vanadium salt in which the vanadium valence ~2 is 3 to 5. Of course, mixtures of these vanadium compounds 23 can be used. Non-limiting, illustrative examples of these 24 compounds are as follows:
A. vanadyl trihalide, alkoxy halides and 26 alkoxides such as VOC13, VOC12(OBu) where Bu =
27 butyl and VO(OC2H5)3.
28 B. vanadium tetrahalide and vanadium alkoxy 29 halides such as VC14 and VC13 (OBu).
C. vanadium and vanadyl acetyl acetonates and 31 chloroacetyl acetonates such as V(AcAc)3 and 32 VOC12(AcAc) where (AcAc) is an acetyl acetonate.
33 D. Vanadium halide-Lewis base complexes such 34 as VC13-2THF where T~F i~ tetrahydrofuran.
The preferred vanadium compounds are VOC13, VC14 and VOC12-36 OR where R i9 a hydrocarbon radical, preferably a Cl to 37 C10 aliphatic or aromatic hydrocarbon radical such as ' 1 ethyl, phenyl, isopropyl, butyl, propyl, n-butyl, i-butyl, 2 t-butyl, hexyl, cyclohexyl, naphthyl, etc.
3 In terms of formulas, preferred vanadium com-4 pounds useful in practicing methods in accordance with the present invention would be at least one member selected 6 from the group consisting of:
7 ll (1) 89 VClx(OR)3-x where x = 0-3 and R = a hydrocarbon radical;
11 VC1y(OR)4_y (2) 12 . where y = 3-4 and R = a hydrocarbon radical;
13 (Il) 3-Z
V(ACAc)z (3) where z = 2-3 and (AcAc~ = acetyl acetonate group;
16 O O (4) 17 ll ll VC12(AcAc) or VCl(AcAc)2, 18 where (AcAc) - acetyl acetonate group; and 19 VC13 . nB, (5) where n = 2-3 and B = Lewis base, such as tetra-21 hydrofuran, which can form hydrocarbon-soluble 22 complexes with VC13.
23 In formulas 1 and 2 above, R preferably represents a Cl to 24 C10 aliphatic or aromatic hydrocarbon radical such as ethyl, 25 phenyl, isopropyl, butyl, propyl, n-butyl, i-butyl,-t-butyl, 26 ~hexyl, cyclohexyl, octyl, naphthyl, etc. The molar amount 27 of vanadium compound on the support (vanadium concentration) 28 can be about 0.01 to 0.5 millimole per gram of support, with about 0.02 29 to 0.3 being preferred.
The co-catalyst used in practicing methods accord-31 ing to the present invention is aluminum alkyl. Of course, 32 mixtures of these compounds can be used. Illustrative 33 examples of aluminum alkyls are as follows:
34 A. aluminum trialkyls such as Al(C2HS)3 and `- ~ 174800 1 Al (i-BU) 3, where i-BU = isobutyl.
2 B. aluminum alkyl chlorides such as Al(C2H5)2Cl, 3 Al (C2H5)Cl2, and Al(C2H5)Cl2 Al(C2H5)2Cl.
4 C. aluminum alkyl alkoxides such as AlOC2H5-(C2H5)2.
6 D. aluminum alkyl hydrides such as (C2H5)2AlH.
7 The preferred aluminum alkyl compounds are diethyl aluminum chloride and aluminum ethyl sesquichloride.
9 In terms of chemical formulas, these compounds are represented by at least one member selected from the 11 group consisting of:
12 AlClX R3_X ' ( 6 ) 13 where x' = O - 2 and R = a hydrocarbon radical;
14 RylAl(oR)3-yl (7) where y' = l - 2 and R - a hydrocarbon radical; and 16 R2AlH, (8) 17 where R = a hydrocarbon radical.
18 All R groups in formulas (6)-(8) are the same as described 19 above with respect to the vanadium compounds of formulas 20 (1) and (2).
21 For best catalyst performance, the molar amounts 22 of catalyst components added to the support surface should 23 provide an aluminum/vanadium (Al/V) ratio of about 10-200.
24 While an Al/V ratio of about l5-lOO is preferred, 20-60 is most preferred. Also, the vanadium salt/aluminum alkyl 26 pair selected for catalyst preparation must be chosen so 27 that at least one of the materials contains a valence 28 bonded halogen.-29 In addition to the vanadium salt and aluminum30 alkyl compounds, other compounds can be used for surface-31 impregnation of the inert support material. For example, 32 a Lewis base or a magnesium compound could be used to 33 modify the activity of the catalyst.

.

~ 1~4800 1 Polymerization is carried out in the absence of 2 liquid hydrocarbon solvents by directly contacting the 3 monomeric reaction mixture, e.g., ethylene-propylene or 4 ethylene-propylene-diene, in the gaseous phase with a fluidized bed of the inert support material surface-impreg-6 nated with the catalyst components. This process is ad-7 vantageously carried out in a fluidized bed reactor as, 8 for example, that illustrated in Figure 1. With reference g thereto, the reactor 10 consists of a gas dispersing plate 20, reaction zone 12 and velocity reduction zone 14.
11 The reaction zone 12 comprises a bed of growing 12 polymer particles, formed polymer particles and a minor 13 amount of catalyst particles fluidized by the continuous 14 flow of polymerizable and modifying gaseous components in the form of-make-up feed and recycle gas throuyh the re-16 action zone. To maintain a viable fluidized bed, the mass 17 gas flow rate through the bed must be above the minimum 18 flow required for fluidization.
19 }t is essential that the bed always contains par-ticles to prevent the formation of localized "hot spots"
21 and to entrap and distribute the particulate catalyst 22 throughout the reaction zone. On start up, the reaction 23 zone is usually charged with a base of particulate polymer 24 particles before gas flow is initiated. Such particles may be identical in nature to the polymer to be formed or 26 different therefrom. When different, they are withdrawn 27 with the desired formed polymer particles as the first pro-28 duct. Eventually, a fluidized bed of the desired p~lymer 29 particles supplants the start-up bed.
The catalyst system in the fluidized bed is pre-31 ferably stored for service in a reservoir 32 under a blan-32 ket of a gas which is inert to the stored material, such as 33 nitrogen or argon.
34 Fluidization is achieved by a high rate of gas recycle to and through the bed, typically in the order of 36 about 50 times the rate of feed of make-up gas. The pres-37 sure drop through the ~ed is dependent`on the geometry of .

.

1 17480~

, 5 1 the reactor.
2 Make-up gas is fed to the bed at a rate equal to 3 the rate at which it is consumed by polymerization and lost 4 from the bed with withdrawn product. The composition of the make-up gas is determined by analysis of the gas leav-6 ing the bed. A gas analyzer determines the composition of 7 the gas being recycled and the composition of the make-up 8 gas i8 adjusted accordingly to maintain an essentially 9 steady state gaseous composition within the reaction zone.
To insure complete fluidization, the recycle and 11 make-up gas are both returned to the reactor at point l8 12 below the bed. A gas distribution plate 20 above the point 3 of return aids in fluidizing the bed.
4 The portion of the gas stream which does not re-act in the bed constitutes the recycle gas which is removed 16 from the polymerization zone, preferably by passing it into 17 a velocity reduction zone 14 above the bed where entrained 18 particles are given an opportunity to drop back into the 19 bed. Particle return may be aided by a cyclone 22 which may be part of the velocity reduction zone or exterior 21 thereto. Where desired ,the recycle gas may then be passed 22 through a filter 24 designed to remove small particles at 3 high gas flow rates to prevent dust from contacting heat 24 transfer surfaces and compressor blades.
The recycle gas is compressed in a compressor 25 26 and then passed through a heat exchanger 26 wherein it is 27 stripped of heat of reaction before it is returned to the 28 bed. The compressor 25 can also be placed downstream of 29 the heat exchanger 26.
The distribution plate 20 diffuses thé recycle 31 gas through the particles at the base of the bed to ~eep 32 them in a fluidized condition.
33 It is essential to operate the fluid bed reactor 34 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 tempera-0 ~

1 ture are desired. In methods according to the present 2 invention an operating temperature of about 20-lO0C could 3 be used. While 40-90~C is preferred, a temperature of 4 about 40 to 75C is most preferred.
The pressure in the reaction vessel can be from 6 about atmospheric up to a pressure such that no condensate 7 of monomers is formed at the temperature and pressure 8 chosen. It is normally desired to run at the highest prac-9 tical pressure to maximize polymerization rate. This could be about 500 psig. The upper pressure limit will be deter-11 mined primarily by the content of propylene in the gas 12 entering the reactor.
3 The surface-impregnated carrier material is in-14 jected into the bed at a rate set by the desired polymeri-zation rate at a point 30 which is above the distribution 16 plate 20. Injection of the catalyst into the area below 7 the distribution plate may cause polymerization to begin 18 there and eventually cause plugging of the distribution 19 plate. Injection into the viable bed instead, aids in dis-tributing the catalyst throughout the bed and tends to pre-21 clude the formation of localized spots of high catalyst 22 concentration which may result in the formation of "hot 23 spots". The catalyst may be added to the bed by various 24 known methods such as entrainment in an inert carrier gas 25 (nitrogen).
26 The production rate of the bed is controlled by 27 the rate of catalyst injection. The production rate may 28 be increasad by simply increasing the rate of catalyst in-29 jection and decreased by reducing the rate of catalyst in-jection.
31 Since any change in the rate of catalyst injec-32 tion will change the rate of generation of the heat of 33 reaction, the temperature of the recycle gas is adjusted 34 upwards or downwards to acco~unodate the change in rate of heat generation. This insures the maintenance of an 36 essentially constant temperature in the bed.
37 Under a given set of operating conditions, the ~ 17~800 fluidized bed is maintained at essentially a constant 2 height by withdrawing a portion of the bed as product at 3 a rate equal to the rate of formation of the particulate 4 polymer product. Since the rate of heat generation is directly related to product formation, a measurement of 6 the temperature rise of the gas across the reactor (the 7 difference between inlet gas temperature and exit gas 8 temperature) is determinative of the rate of particulate 9 polymer formation at a constant gas velocity.
The particulate polymer product is preferably 11 continuously withdrawn at a point 34 at or close to the 12 distribution plate 20 and in suspension with a portion of 3 the gas stream which is vented before the particles settle 14 to preclude further polymerization and sintering when the particles reach their ultimate collection zone. The sus-16 pending gas may also be used to drive the product of one 17 reactor to another reactor.
18 The particulate polymer product is conveniently 19 withdrawn through the seguential operation of a pair of timed valves 36 and 38 defining a segregation zone 40.
21 While valve 38 is closed, valve 36 is opened to emit a 22 plug of gas and product to the zone 40 between it and valve 23 36 whïch is then closed. Valve 38 is then opened to de-24 liver the product to an external recovery zone. Valve 38 is then closed to await the next product recovery operation.
26 Finally, the fluidized bed reactor is equipped 27 with an adequate venting system to allow venting the bed 28 during start up and shut down.
29 In terms of weight of ethylene, the relative feed rates of the reactants to the fluidized bed should be no 31 lower than about lO~ ethylene based on the total weight 32 of alpha-olefins being fed. Below 10% ethylene, reactivity 33 of the reaction mixture is greatly decreased. The pre-34 ferred lower limit is about 15% ethylene on the same basis., The upper limit should be about 60% ethylene, since above 36 that value elastic properties in the final product are 37 lost. The preferred upper limit is 50% ethylene. When 8 ~ 0 1 additional monomers such as dienes are used in the reaction 2 mixture, they should be added in amounts of 1-15~ (weight) 3 ~ased on the total reaction mixture. The preferred range 4 i.s about 2-10~.
To control polymer molecular weight, hydrogen 6 can also be fed to the reactor, either separately or, more 7 preferably, mi~ed with monomer feed. Hydrogen feed rates 8 equal to 0.1 to 10% of the monomers (volume basis) are 9 typical.
Polymerization in accordance with the present 11 invention could be performed in two or more reaction 12 vessels disposed in parallel and/or series according to 3 well-known techniques. Thus, for example, the unreacted 4 monomers from a first reaction vessel could be fed to a second. Also, for example the unreacted monomer from a 16 first reaction vessel could be fed to two or more down-17 stream reaction vessels in parallel with each other.
18 The polymers produced by methods according to 19 the present invention are elastomeric and have densities less than O 9,preerably about 0.85 to 0.87. These products 21 contain about 303 to 90% ethylene (weight basis) and can 22 be used for automotive radiator and heater hoses, vacuum 23 tubing, weather stripping, etc.
24 Catalysts were evaluated in a fluidized bed poly-merization reactor. The reactor consisted of a 1~ dia.
26 x 12" long glass tube containing a porous metal disc at 27 the bottom to bubble the gas upwardly through the bed.
28 Catalyst was charged batchwise to the reactor under an 29 inert ~tmosphere. A solid catalyst diluent, usually additional inorganic oxide catalyst support not containing 31 both catalyst components, was also charged to the reactor 32 to provide a deep enough solid bed so that a fluidized bed 33 would result at the start of a polymerization run before 34 appreciable polymer has formed. The total supported cata-lyst charge to the reactor was normally 0.5-19, which con-36 tainedO.01-0.10 mmol of vanadium.
37 Monomers were fed through a purification system , g 1 consisting of packed beds of heated cupxic oxide to remove 2 trace oxygen and 3A molecular sieves to remove trace water.
3 The purified ethylene and propylene were metered into the 4 reactor with calibrated rotometers. An automatic pressure relief valve vented part of the unreacted monomers leaving 6 the reactor to maintain system pressure constant at 600-7 620 kPa. The remaining monomers were recycled back to the 8 reactor via a compressor and mixed with the fresh feeds.
9 The recycle rate was adjusted with a flow control valve to 0 give an adequate level of fluidization and solids mixing 11 in the reactor. Reactor temperature was set by passing the 12 recycle stream thru either a heater or cooler in order to 3 set the temperature at the reactor inlet.
14 Liquid reactants such as dienes or aluminum alkyls were added to the reactor by first preparing dilute solu-16 tions in dry isopentane which had been purified by passage 17 over silica gel and SA molecular sieves. These solu-18 tions were then pumped by calibrated metering pumps thru a 19 coil in a heating bath in order to fully vaporize the solu-tions. The vapor stream was then injected into the monomer 21 recycle.
22 At the start of the run all flows were started 23 through a reactor bypass line with the reactor valved off.
24 After the system reached steady state the bypass was closed and the reactor valves opened to begin a polymerization run.
26 The length of a run was either 60 min. or until fluidization 27 could no longer be maintained due to particle growth if 28 this occurred first.
29 EX~PLE 1 30 Catalyst preparation:
31 1. 25g of Grace Chemical grade #56 silica (SiO2), which 32 had been heated to 500C for 20 hours to remove water, 33 was slurried in dry isopentane in a dry box. The sur- , 34 face hydroxyl content of this material is about 1 mmol/g.
35 2. 25 cc o 1 M solution of diethylaluminum chloride 36 (DEAC) in hexane was added to the slurry and this mix-37 ture was agitated at room temperature for 30 min.
38 3. The diluent was evaporated from the slurry in a stream `` 1 174800 1 of nitrogen to give a dry, free flowing powder with an 2 aluminum content of 1 mmol/g SiO2 based on the starting 3 ingredients.
4 4~ Five grams of the above material were reslurried in isopentane, and 1.25 cc of 0.1 M VOC13 solution in 6 isopentane was added. After 30 min. agitation, the 7 diluent was evaporated in a stream of nitrogen to leave 8 a free flowing powder. The reaction with VOC13 was carried out at room temperature. Based on the starting ingredients the VOC13 content of the solid is 0.~
11 mmol per g of ~SiO2 + DEAC). The ~l/V ratio is approxi-12 mately 40.
13 S. 5g of SiO2 as used in step 1 was treated with triethyl 4 aluminum (TEA) as described in steps 1-3 above to give a solid containing 1 mmol TEA/g SiO2.
16 Polymerization proçedure:
17 1. A reactor was charged with lg of DEAC/SiO2-VOC13 cata-18 lyst containing 0.025 mmol of vanadium; and Sg of TEA/
lg SiO2 were added to act as a diluent.
2. Monomers were fed into the system at rates of:
21 ethylene = 1.4g/min.
22 propylene =7.Og/min.
23 and the reactor pressure was set at 600 kPa. The re-24 cycle compressor was turned on to give a monomer re-circulation rate of 53g/min.
26 3. A solution of DEAC in isopentane was prepared contain-27 ing 3.33 mmol/l isopentane. This solution was fed thru 28 a vaporization coil and into the recycle monomers to 29 give a DEAC addition rate of 0.1 mmol/hour. This was done to remove low levels of adventitious catalyst 31 poisons from the system during polymerization.
32 4. After all the flows in the system were lined out, the 33 monomer stream was valved into the reactor to begin poly-34 merization. The monomers passed thru a heater to raise reactor temperature to 58C.
36 Results:
37 Particle growth in the reactor was noted almost -1 ~74~0~

1 immediately after the introduction of monomers began. The 2 bed was fluidized for 60 min., and then the monomer ~low 3 was terminated and the reactor depressurized. A total of 4 3.7g o~ polymer was recovered which corresponds to a cata-lyst efficiency of 148,000g polymer per mole of vanadium.
6 The polymeric product was separated from the 7 catalyst support by adding a mixture of hot toluene to 8 dissolve the polymer, filtering the solution to remove 9 SiO2, and evaporating the toluene to leave the pure polymer.
A solid, elastomeric material remained after the evaporation.

12 The procedure of Example l was repeated except 3 that the SiO2 support was treated with ethylaluminum sesqui-4 chloride (EASC) instead of DEAC to produce an aluminum loading of 1 mmol per gram of SiO2.
16 After 60 min. of polymerization at 59C, 2.4g of 7 polymer were recovered corresponding to a catalyst effi-18 ciency of 46,000g per mole V. The polymer was an elasto-19 meric solid with an ethylene content of 43.3 wt. % as measured by infrared techni~ue described by Gardner et al, 21 Rubber Chem. Tech., 44, 1015, (1971). The inherent vis-22 cosity was 3.63 as measured in decalin at 135C.*

24 The catalyst used was prepared in an identical manner to that described in Example 1. The run procedure 26 was also the same except the ethylene feed rate was varied 27 to prepare copolymers with different ethylene contents.
28 The results are indicated below in Table 1:

29 * Inherent viscosity was calculated by the formula:
IV = 1 ln RV
31 whereCC = polymer concentration, g/dl ~2 ~V = relative viscosity measured by .

2 Feed Rates (g/min) Ethylene Polymer Analysis ,, In Feed Wt.~ Inherent 4 Run Ethylene Propylene (Wt%) Ethylene Viscosity 5 1 1.6 7.0 18.6 54.2 3.05 6 2 4.0 7.0 36.4 63.0 4.18 7 3 7,0 7.0 50.0 81.7 --'3 EXAMPLE 4 9 Catalyst Preparation:
0 1. 10g of Grace Chemical #56 silica, which had been dried 1l for 20 hours at 500C, was slurried in isopentane.
12 2.5 cc of 0.1 M VOC13 in isopentane was added, and the 13 mixture was agitated for 30 min. at room temperature.
4 After this time, the isopentane was evaporated in a stream of nitrogen to give a dry solid containing .025 16 mmol VOC13/g SiO2 based on the initial charge weights.
17 2. Two grams of the material prepared in step 1 were re-18 slurried in isopentane, and 3 cc of 1 M DEAC solution 19 was added. The mixture was agitated for 30 min. at room temperature and then the isopentane was evaporated 21 to give a dry powder containing 1.5 mmol DEAC per gram 22 of SiO2 plus VOC13. The Al/V ratio is approximately 23 60.
24 3. SiO2 was impregnated with TEA as described in Example 1 to give a catalyst diluent containing 1 mmol TEA/g 26 SiO2.
27 Polymerization procedure:
28 Identical to that described in Example 1 29 ReSults After 60 min. of polymerization, 1.7g of polymer was ob-31 tained.
32 ExAMæLErS
33 The procedure described in Example 1 was again 34 used except in step 4 of the catalyst preparation, VC14 3s was added to the DEAC-impregnated SiO2 support to give a 36 catalyst containing 0.05 mmol VC14/gram (SiO2+DEAC). The 37 Al/V ratio is approximately 20.

1 17480~ -1 Polymerization with this catalyst at 58C yielded 2 2.5g of an elastomeric polymer after 60 min.

4 Vanadyldichloroethoxide (VOC12(OEt)) was prepared by adding0.05 mmol of VOC13 and 0.05 mmol of ethanol to a 6 flask containing 100 cc of dry isopentane and agitating the 7 mixture for a short period. SiO2, previously calcined for 8 20 hours at 500C, was impregnated with DEAC by the proce-9 dure 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 VOC12tOEt) solu-tion, the mixture was agitated for 30 min. at room tempera-13 ture, and then the isopentane was evaporated in a stream 14 of nitrogen to leave a dry, free flowing powder with a vanaaium concentration of 0.025 mmol/g ~SiO2+DEAC). All 16 catalyst preparation operations were carried out under an 17 inert atmosphere.
18 The fluid bed reactor was charged with 0.5g of 19 the supported catalyst and 5.5g of SiO2 catalyst diluent containing 1 mmol TEA/g. Polymerization was carried out 21 at 50C according to the procedure in Example 1. A yield 22 of 2.9g of solid, elastomeric polymer was obtained after 23 60 min. of polymerization.

VOC13 and tetrabutyltitanate (Ti(OBu)4) were re-26 acted in a 2/1 molar ratio in isopentane solution to yield 27 VOC12(OBu) and TiC12(OBu)2. The reaction was carried out 28 by combining 1.0 cc of 0.1 M VOC13 and 0.5 cc of 0.1 M
29 Ti(OBu)4 solution in isopentane with 100 cc of dry isopen-tane and agitating the mixture for a short time at ambient 31 temperature. Two grams of the DEAC-impregnated SiO2 pre-32 pared i~ Example 6 was then added to this solution. After 33 agitating the slurry for 30 min. the isopentane was eva-34 porated in a stream of nitrogen to produce a dry, free-flowing powder containing 0.05 mmol of vanadium per gram36 (SiO2+DEAC).

- ~ 174800 1 The fluid bed reactor was charged with 0.5g of 2 the catalyst and 5.5g of SiO2 catalyst diluent containing 3 1 mmol of TEA per gram. Polymerization was carried out at 4 50C according to the procedure in Example 1. A yield of 3.2g of solid, elastomeric polymer was obtained after 3.5 6 min.

A supported catalyst containing ethylaluminu~
9 sesqui-chloride (EASC) and vanadium tris acetyl acetonate (V(AcAc)3) was prepared by the following procedure:
11 1. 5g of Grace #56 silica which had been previously cal-12 cined for 20 hours at 500C was slurried in 100 cc of 3 dry isopentane. 5 cc of 1 M EASC solution was added 4 and the mixture allowed to react for 30 min. This isopentane was then evaporated in a stream of N2 to 16 yield a dry powder containing 1 mmol aluminum/g SiO2.
7 2. 0.2 mmol of V~AcAc)3 was dissolved in 1~0 cc of dry 18 toluene and 4 g of the EASC/SiO2 preparation from step 19 1 was added. After stirring the mixture for 30 min.
at ambient temperature, the toluene was evaporated in 21 a stream of nitrogen to yield a dry, free-flowing pow-22 der containingQ.05 mmol of vanadium per gram (SiO2+
23 EASC).
24 The fluid bed polymerization reactor was charged 0.5g of supported catalyst and 5.5g of SiO2 diluent contain-26 ing 1 mmol TEA/g. Polymerization was conducted at 67C
27 according to the procedure in Example 1. After 60 min.
28 of reaction, a yield of 1.4g of solid, elastomeric 29 polymer was obtained.
EXAMPLE_9 31 A polymerization was carried out to produce a 32 terpolymer of ethylene, propylene and ethylidene norbornene 33 (ENB)-34 Catalyst was prepared as described in Example 1 to give a supported catalyst on SiO2 containing 1 mmol of 36 DEAC per gram of SiO2 and 0.02~ mmol of VOC13 per gram of 37 SiO2 plus DEAC. The reactor was charged with 0.5g of ~ 17~800 1 catalyst and 5.5g of SiO2 containing 1 mmol TEA/g to act 2 as a catalyst diluent.
3 ENB was fed to the polymerization system by in-4 troducing it as a vapor into the monomer recycle. Vapor-iæation was achieved by preparing a solution of ENB in 6 isopentane (30g/1 concentration) which was pumped at a rate 7 of 0. 5 cc/min. thru a coil immersed in a hot oil bath.
8 Polymerization conditions are the same as described in ~
9 Example 1 except for the feed of 0.9g/hour of ENB and 36g/
0 hour of isopentane into the reactor.
11 After a polymerization time of 40 min., 1.3g of 12 polymer was obtained which was analyzed to contain 2.07 13 wt% ENB by refractive index measurement (I.J. Gardner and 14 G. Ver Strate, Rubber Chem. Tech., 46, 1019 (1973)). The .
ethylene content of the polymer was 48% and the inherent 16 viscosity was 2.80.

18 Ethylene-propylene copolymer with an inherent 19 viscosity of 3.68 and a density of 0.865g/cc, which was pro-duced by the process described in Example 1, was compounded 2l on a rubber mill according to the formulation below:
22 IngredientWt./100 Wt. Rubber 23 Polymer 100 24 HAF Carbon Black30 Dicumylperoxide 2.8 26 Triallylcyanurate 1.5 27 . A pad of the compound was cured for 20 min. at 320F in a 28 hot press, and then the stress-strain properties of the 29 wlcanizate were measured on an Instron testing machine.
30The results are shown below:
31Tensile Strength, psi Elongation,%
32 .140 100 EX~MPLE ll 36 ; Using catalyst preparation methods and the test 37 apparatus as already described, a series of tests were 38 conducted under the varying conditions, and with results, 39 as shown in Table 2 below. The inert support material used .

1 in these tests was silica which had been heated to 500C
2 for 20 hours. The columns headed "Ml On Support" and 3 "M2 On Support" indicate, respectively, the first and 4 second catalyst components added to the inert support ma-terial in accordance with certain aspects of the present 6 invention. The "Alkyl to Reaction" column indicates those 7 tests in which an alkyl was added to remove adventitious 8 catalyst poisons from the reaction system during polymeri-9 zation. The ethylene feed rate was lg/min., propylene feed was 4 . 5g/min ., monomer recirculation was 53g/min. and 11 pressure was 600 kPa. The results in Table 2 are a repre-12 sentative portion of the results obtained in the numerous 3 tests conducted.

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Claims (37)

1. THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
   PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
   l. A gas-phase method for preparing elastomeric copolymer of ethylene and higher alpha-olefin comprising contacting, in the absence of liquid hydrocarbon solvent:
   (a) at least one gaseous reaction mixture comprised of ethylene and higher alpha-olefin monomers, and (b) at least one fluidized bed of inert support ma-terial that has been sequentially surface-impreg-nated with liquid or gaseous catalyst components comprised of:
   (1) hydrocarbon-soluble vanadium salt in which the vanadium valence is 3 to 5, and (2) aluminum alkyl, wherein the copolymer produced is an elastomeric copolymer having a density less than 0.9.
2. 2. A method according to Claim 1, wherein the temperature of reaction is about 20-100°C, and wherein the mole ratio of aluminum to vanadium in the catalyst is about 10-200.
3. 3. A method according to Claim 2, wherein the temperature of reaction is about 40-90°C, and wherein the mole ratio of the aluminum to vanadium in the catalyst is about 15-100.
4. 4. A method according to Claim 1, wherein the higher alpha-olefin is propylene.
5. 5. A method according to Claim 4, wherein the vanadium concentration is about 0.01 to 0.5 millimole per gram of inert support material.
6. 6. A method according to Claim 5, wherein the inert support material is an inorganic oxide or mixture of inorganic oxides.
7. 7. A method according to Claim 6 wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is at least about 0.5.
8. 8. A method according to Claim 7, wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is about 0.5 to 2.0, and the vanadium concentration is about 0.02 to 0.3 milli-mole per gram of inert support material.
9. 9. A method according to Claim 8, wherein the inert support material is at least one member selected from the group consisting of silica, alumina, magnesia, titania, and aluminum silicate.
10. 10. A method according to Claim 9, wherein the temperature of reaction is about 40-75°C, and wherein the mole ratio of aluminum to vanadium in the catalyst is about 20-60.
11. 11. A method according to Claim 9, wherein the inert support material is silica.
12. 12. A gas-phase method for preparing elastomeric copolymer of ethylene and higher alpha-olefin comprising contacting, in the absence of liquid hydrocarbon solvent:
    (a) at least one gaseous reaction mixture comprised of ethylene and higher alpha-olefin monomers, and (b) at least one fluidized bed of inert support ma-terial that has been sequentially surface-impreg-nated with catalyst comprised of:
    (1) at least one hydrocarbon-soluble vanadium salt compound selected from the group con-sisting of:
    where x = 0-3 and R = a hydrocarbon radical;
    VC1y(OR)4-y, where y = 3-4 and R = a hydrocarbon radical;
    where z = 2-3 and (AcAc) = acetyl acetonate group;
    ?C12(AcAc) or ?Cl(AcAc)2 where AcAc = acetyl acetonate group; and VCl3 nB
    where n = 2-3 and B = Lewis base capable of forming hydrocarbon-soluble complexes with VCl3; and (2) at least one aluminum alkyl compound selected from the group consisting of:
    AlClx'R3-x, where x' = 0-2 and R = a hydrocarbon radical;
    Ry'Al(OR)3-y' where y' = 1-2 and R a a hydrocarbon radical; and R2AlH, where R = a hydrocarbon radical, wherein the copolymer produced is an elastomeric copolymer having a density less than 0.9.
13. 13. A method according to Claim 12, wherein the temperature of reaction is about 20°-100°C, the mole ratio of aluminum to vanadium in the catalyst is about 10-200, and unreacted monomer is recycled for additional contact with said fluidized bed.
14. 14. A method according to Claim 13, wherein the vanadium concentration is about 0.01 to 0.5 millimole per gram of inert support material.
15. 15. A method according to Claim 12, wherein the higher alpha-olefin is propylene.
16. 16. A method according to Claim 15, wherein the hydrocarbon-soluble vanadium salt is selected from the group consisting of:
    
    ?Clx(OR)3-x, where x = 0-3 and R = C1 - C10 aliphatic or aromatic hydrocarbon radical;
    
    ?Cly(OR)4-y, where y = 3-4 and R = Cl - C10 aliphatic or aromatic hydrocarbon radical;
    where z = 2-3 and AcAc = acetyl acetonate group; and ?Cl2(AcAc) or ?Cl(AcAc)2 where AcAc = acetyI acetonate group; and wherein the aluminum alkyl has the formula:
    AlClx'R3-x' where x' = 0-2 and R = C1 to C10 aliphatic or aromatic hydrocarbon radical.
17. 17. A method according to Claim 15, wherein the inert support material is an inorganic oxide or mixture of inorganic oxides.
18. 18. A method according to Claim 17, wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is at least about 0.5.
19. 19. A method according to Claim 18, wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is about 0.5 to 2.0, and the vanadium concentration is about 0.02 to 0.3 milli-mole per gram of inert support material.
20. 20. A method according to Claim 16, wherein the inert support material is an inorganic oxide or mixture of inorganic oxides.
21. 21. A method according to Claim 20, wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is at least about 0.5.
22. 22. A method according to Claim 21, wherein the mole ratio of catalyst components to surface hydroxyl groups on the inert support material is about 0.5 to 2Ø
23. 23. A method according to Claim 19, wherein the reaction temperature is about 40°-75°C, and wherein the mole ratio of aluminum to vanadium in the catalyst is about 20-60.
24. 24. A method according to Claim 20, wherein the reaction temperature is about 40°-75°C, and wherein the mole ratio of aluminum to vanadium in the catalyst is about 20-60.
25. 25. A method according to Claim 22, wherein the inert support material is at least one member selected from the group consisting of silica, alumina, magnesia, titania and aluminum silicate.
26. 26. A method according to Claim 23, wherein the inert support material is at least one member selected from the group consisting of silica, alumina, magnesia, titania, and aluminum silicate.
27. 27. A method according to Claim 24, wherein the inert support material is at least one member selected from the group consisting of silica, alumina, magnesia, titania, and aluminum silicate.
28. 28. A method according to Claim 12, 13 or 14, wherein the inert support material is silica.
29. 29. A method according to Claim 15, wherein the inert support material is silica.
30. 30. A method according to Claim 16, wherein the inert support material is silica.
31. 31. A method according to Claim 22, wherein the inert support material is silica.
32. 32. A method according to Claim 30, wherein the hydrocarbon-soluble salt is selected from the group con-sisting of: VOCl3, VCl4, and V(AcAc)3 where AcAc = Acetyl acetonate, and wherein the aluminum alkyl is selected from the group con-sisting of: Al(C2H5)2Cl, Al(C2H5)3, and Al(C2H5)Cl2.Al(C2H5)2C1
33. 33. A method according to Claim 32, wherein the pressure of reaction is about atmospheric to 500 psig.
34. 34. A method according to claim 1, wherein the inert support material is surface-impregnated with the aluminum alkyl first followed by surface-impregnation with the vanadium compound.
35. 35. A method according to claim 12, wherein the inert support material is surface-impregnated with the aluminum alkyl first followed by surface-impregnation with the vanadium compound.
36. 36. A method according to claim 34 or 35, wherein both impregnations utilize liquid solutions of catalyst.
37. 37. A method according to claim 1, 3 or 12 wherein aluminum alkyl is added to remove catalyst poisons during polymerization.