SOLID CATALYST FOR THE (CO)POLYMERISATION OF ALPHA-OLEFINS AND PROCESS FOR THE PREPARATION THEREOF

Abstract

An improved solid Ziegler-Natta type catalyst for the (co)polymerisation of ethylene and α-olefins, particularly in high-temperature processes, such as for example adiabatic solution processes and high-pressure adiabatic processes with elevated productivity, is provided. Said catalyst is obtained by means of an original process comprising dissolving in hydrocarbons, compounds of titanium, magnesium and optionally a metal selected from hafnium and zirconium, and reprecipitating them in two steps in succession, the first of which is chlorination and the second reduction.

Claims

1. Process for the preparation of a solid catalyst for the (co)polymerisation of α-olefins, comprising titanium, magnesium, aluminium, chlorine and, optionally, at least one metal M selected from hafnium and zirconium, comprising the following steps in succession: (i) preparing a first mixture by heating in a hydrocarbon liquid medium to a temperature from 40 to 200° C., for at least one minute, at least one magnesium chloride, at least one titanium compound, at least one carboxylic acid R—COOH, wherein R is an organic group having from 2 to 30 carbon atoms, and, optionally, at least one compound of said metal M, in an amount such as to comply with the following ranges of atomic or molar ratios:
M/Ti=0.0-5.0; Mg/Ti=3.0-15.0; R—COOH/(Mg+M)=1.5-8 (ii) adding to the first mixture obtained in step (i), a chlorinating agent selected from a silicon chloride and an aluminium chloride which are soluble in said hydrocarbon liquid medium, in a sufficient quantity to cause at least 70%, of the magnesium and any metal M present in the solution to precipitate in the form of solid chlorides, so as to obtain a second mixture comprising a liquid phase and a solid phase; (iii) adding to the second mixture obtained in the previous step (ii) an organometallic compound of a metal M′ having the following formula (IV):
M′R″″.sub.nCl.sub.(p-n)  (IV) wherein: M′ is a metal selected from trivalent aluminium, trivalent gallium, tetravalent tin or divalent zinc; R″″ is a linear or branched alkyl radical containing from 1 to 20 carbon atoms, “n” is a decimal number having a value between 0.5 and p, where p is the valence of M′; and reacting until at least 70%, of the titanium present has precipitated in the form of a solid compound to obtain said solid catalyst.

2. Process according to claim 1, wherein said chlorinating agent in step (ii) is selected from soluble complexes of aluminium trichloride having one of the following general formulae (II) or (III):
AlCl.sub.3.OR″R′″  (II)
AlCl.sub.3.Ar.HX  (III) or from soluble Si chlorides and chlorosilanes having the following formula (I):
Si.sub.vCl.sub.(4v-m-r)H.sub.mR′.sub.r  (I) wherein: R′, R″ and R′″ each independently represent an organic group, having from 1 to 30 carbon atoms, Ar represents an optionally substituted aromatic hydrocarbon compound having from 6 to 20 carbon atoms, X represents a halogen atom, v is an integer between 1 and 4, m and r are two integers such that the sum m+r is between 0 and 2v.

3. Process according to claim 1, wherein said metal M′ in the compound of formula (IV) is trivalent aluminium.

4. Process according to claim 1, wherein, in said step (i), the total concentration of metals is between 0.1 and 1.0 mol/l.

5. Process according to claim 1, wherein, in said step (i), the compounds of Ti and M are selected from the chlorides and alcoholates of said metals.

6. Process according to claim 1, wherein, in step (i), the molar ratio M/Ti is between 0.2 and 5.0.

7. Process according to claim 1, wherein said step (i) is carried out in such a manner that there are no significant outward losses of material.

8. Process according to claim 1, wherein said step (ii) is carried out while maintaining a temperature between 30 and 50° C. during addition of the reactants to said first mixture, and then heating the suspension formed to a temperature between 50 and 70° C.

9. Process according to claim 1 wherein, in said step (iii), addition of the compound of formula (IV) to said second mixture is carried out at a temperature of 20 to 60° C., for a time of 10 minutes to 4 hours, and then the resultant suspension is heated and maintained at a temperature of 60 to 130° C. for a time of 5 to 180 minutes.

10. Process according to claim 1 wherein, in said step (iii), the amount in moles of the compound of formula (IV) is between 1.5 and 20 times the moles of titanium present in said second mixture.

11. Process according to claim 1 wherein, at the end of step (iii), said solid catalyst is separated from the reaction liquid and is obtained in the form of a suspension with concentrations between 150 and 500 g/l, in an aliphatic hydrocarbon having from 5 to 14 carbon atoms.

12. Process according to claim 1 wherein, at the end of step (iii), said solid catalyst is obtained in the form of a concentrated mixture or suspension comprising at least some, preferably up to 80%, of the reaction liquid.

13. Solid catalyst for the (co)polymerisation of α-olefins, comprising titanium, magnesium, chlorine, a metal M′, preferably aluminium and optionally a metal M selected from hafnium and zirconium, preferably zirconium, in the following molar ratio ranges:
M/Ti=0.0-4.0; Mg/Ti=3.0-15.0; M′/Ti=0.1-3.0;
Cl/Ti=15.0-50.0; (RCOO—)/Ti=0.05-2.0 where M, R and M′ have the meanings specified above and RCOO— denotes the carboxylate present in the solid, characterised that it is obtained by a process according to claim 1.

14. Catalyst according to claim 13, wherein the ratio M/Ti is between 0.5 and 4.0.

15. Catalyst according to claim 13, wherein at least 70% of the titanium is in oxidation state +3, the particle size has a narrow Gaussian distribution having a maximum between 2 and 15 μm, and dimensions of the granules such that 80% by weight thereof is in a range from 1 to 30 μm.

16. Catalyst according to claim 13, wherein the amount of titanium is between 1 and 10% by weight and at least 90% of the titanium is in oxidation state +3.

17. Catalytic system for the (co)polymerisation of α-olefins, comprising, in mutual contact, a cocatalyst consisting of a hydride or an organometallic compound of a metal of groups 1, 2 or 13 of the periodic table, and a solid catalyst in accordance with claim 13.

18. Catalytic system according to claim 17, wherein said cocatalyst is selected from trialkylaluminiums which contain from 1 to 10, carbon atoms in each alkyl radical.

19. Catalytic system according to claim 17, wherein the atomic ratio between aluminium (in the cocatalyst) and titanium (in the solid catalyst) is in the range from 3:1 to 500:1.

20. Process for the (co)polymerisation of α-olefins, comprising polymerising at least one α-olefin, whether continuously or batchwise, in one or more steps, at low (0.1-1.0 MPa), medium (1.0 to 10 MPa) or high (10-150 MPa) pressure, at temperatures between 20 and 300° C., optionally in the presence of an inert diluent, in the presence of a suitable catalytic system, characterised that said latter catalytic system is a catalytic system according to claim 17.

21. (Co)polymerisation process according to claim 20, wherein at least one α-olefin is ethylene.

22. (Co)polymerisation process according to claim 20, characterised that it is carried out in solution in an inert solvent, at temperatures between 150 and 250° C. and pressures between 1 and 25 MPa.

Description

EXAMPLES

[0116] Reactants and Materials

[0117] The following list shows the reactants and materials used in the subsequent examples of the invention and any optional pretreatments; manufacturers are indicated in brackets. [0118] Milli-Q water (Millipore): purity to standard ISO® 3696, type 1 [0119] n-Hexane (Carlo Erba, RPE): dried by distillation over NaH [0120] Diethylaluminium chloride (DEAC) (Chemtura, pure): used undiluted [0121] Triethylaluminium (TEA) (Akzo Nobel, pure): used undiluted [0122] Triisobutylaluminium (TIBA) (Akzo Nobel, pure): used undiluted [0123] n-Decane: pure, ≧95%, (Synthesis-Parma), treated on 4 Å and 10 Å molecular sieves from Grace. [0124] 1-Hexene: 97% (Aldrich) distilled over calcium hydride [0125] Ethylene: (Rivoira) Grade 3.5, purity ≧99.95% [0126] Anhydrous magnesium chloride (Cezus-Areva): >99%, grade T.202, used undiluted [0127] Titanium tetra-n-butylate [Ti(Bu.sup.nO).sub.4] (TNBT Tyzor): Dorf Ketal, purity >98% [0128] Hafnium tetrachloride (Cezus-Areva): >99%, used undiluted [0129] Zirconium tetrachloride (Cezus-Areva): >99%, used undiluted [0130] 2-Ethylhexanoic acid (2-EHA): (Gamma Chimica) dried for treatment with 4 Å molecular sieves [0131] Aluminium trichloride (99% anhydrous crystals, Fluka) [0132] Hydrochloric acid (99.9% gaseous, Rivoira) [0133] Dioctyl ether (Aldrich 99%) [0134] Toluene, xylene, mesitylene (Aldrich) >99% dried by passage over a battery of 4 Å and 10 Å molecular sieves.

[0135] Elemental Analysis

[0136] a) Determination of Mg, Al, Hf, Zr and Ti.

[0137] The quantity by weight of the metals Mg, Al, Hf, Zr and Ti in the precursors and solid catalysts of the present invention was determined, working in a dry box under a stream of nitrogen, by placing an accurately weighed aliquot of approx. 30-50 mg of sample in an approx. 30 ml platinum crucible together with a mixture of 1 ml of 40% HF, 0.25 ml of 96% H.sub.2SO.sub.4 and 1 ml of 70% HNO.sub.3. The crucible was then heated on a plate, increasing the temperature until white sulfuric fumes appeared (approx. 200° C.). The resultant mixture was cooled to room temperature, 1 ml of 70% HNO.sub.3 was added and then heated again until fumes appeared. Once the sequence had been repeated twice, a clear, almost colourless solution was obtained. 1 ml of HNO.sub.3 and approx. 15 ml of water were then added cold and the temperature was raised to 80° C. for approx. 30 minutes. The sample prepared in this matter was diluted with MilliQ purity water to an accurately weighed weight of approx. 50 g, in order to obtain a solution on which an instrumental analytical determination was performed by means of a Thermo Optek IRIS Advantage Duo ICP-OES spectrometer (plasma with optical detection) by comparison with solutions of known concentration. For this purpose, a calibration curve in the range from 0-10 ppm was prepared for each analyte by measuring solutions of known content obtained by weight dilution of certified solutions.

[0138] The solution of the sample prepared as above was again weight-diluted in such a manner as to obtain concentrations close to the reference concentrations prior to carrying out spectrophotometric detection. All samples were prepared in duplicate. The results were considered acceptable if the individual results of the duplicate tests differed by no more than 2% relative with respect to the mean value thereof.

[0139] b) Determination of Chlorine

[0140] A quantity of approx. 30-50 mg of the sample for analysis was transferred and accurately weighed into a 100 ml glass beaker which had been tared, working in a dry box under a stream of nitrogen. 2 g of Na.sub.2CO.sub.3 were added and then, outside the dry box, 50 ml of MilliQ water. The mixture was brought to the boil and stirred with a magnetic stirrer for approx. 30 minutes. After cooling, H.sub.2SO.sub.4 diluted 1/5 was added until an acidic reaction was obtained and titration was performed with 0.1 N AgNO.sub.3 with a potentiometric titrator.

[0141] c) Method for Quantitative Determination of Carboxylate

[0142] Quantitative determination of the organic carboxylate residue (in 2-ethylhexanoate examples) present in the catalyst was performed by a method developed by the present applicant and based FTIR spectroscopy measurements. An accurately weighed quantity of approx. 10 mg of solid catalyst was treated for 30 minutes at ambient temperature with approx. 10 ml of 5% HCl in water. The resultant suspension was extracted three times with a total of 20 ml of decane. The organic solution, adjusted to a volume of 30 ml, was analysed by transmission, subtracting the bands associated with decane. Quantitative IR determination of the carboxylate was carried out on the basis of a calibration curve obtained with solutions diluted to a known concentration of carboxylic acid by measuring the integrated area of the carbonyl bands from 1650 to 1775 cm.sup.−1. The measurement of the overall integrated intensity of the bands, on the basis of the calibration curve, was used to determine the molar concentrations of the carboxylic acid (2-ethylhexanoic acid in the examples) and, the volumes being known, also the total quantities. The liquid phases (organic and aqueous) were analysed by transmission using a stationary cuvette of a thickness equal to 0.0035 cm with CaF.sub.2 windows, a material which is sufficiently inert to hydrolysis and/or acid attack by the solutions in question. The spectra were acquired with Nicolet Nexus FTIR spectrophotometer in the range from 4000-1000 cm.sup.−1 with 64 scans and a resolution of 2 cm.sup.−1. The spectrum for pure decane was subtracted from the organic phase spectrum in order to reveal the 2-EHA bands more clearly.

[0143] The spectrum of the corresponding aqueous phase was in each case recorded, the absence of 2-EHA always being checked. Furthermore, in order to check that there is no partition of the 2-ethylhexanoic acid between the two phases, a blank test was also performed by treating a solution with a known content of 2-EHA in n-decane with acidic water and acquiring the spectra of both the initial solution and the final two phases (organic and aqueous). In confirmation of what had been assumed, no bands attributable to organic species were identified in the aqueous phase spectrum and the 2-EHA was recovered quantitatively in the organic phase.

[0144] All the operations associated with the preparation of the samples for analysis were carried out under a nitrogen atmosphere, taking those precautions which are necessary to avoid or at least minimise oxidation and/or hydrolysis phenomena.

[0145] The result of the analysis is stated formally in the examples as carboxylic acid (i.e. 2-EHA) content, although it may be considered that the acid is predominantly or completely bound as carboxylate in the catalyst.

[0146] Grain Size Analysis

[0147] The distribution and mean of the particle sizes of the catalytic solid were determined with an optical method using a series 2600 MALVERN Particle Sizer instrument with a 63 mm focusing lens and optical pathlength of the cell of 2 mm.

[0148] Characterisation of Polymers and Copolymers

[0149] The content of monomer units derived from 1-hexene in the ethylene/1-hexene copolymers was determined on samples in film form using the Nicolet Nexus FTIR spectrometer mentioned in a previous paragraph by measuring absorption of the bands at 4390 and 4255 cm.sup.−1 and on the basis of calibration curve obtained with copolymers of a known composition.

[0150] The melt flow index (MFI) of the polymers was measured according to standard ASTM D-1238E, with weight of 2.16 kg.

[0151] The density of the resultant polymeric products was measured by means of a gradient column in accordance with method ASTM D1505-68.

Preparative Example A: AlCl.SUB.3..Dioctyl Ether (1:1) Complex in n-Decane

[0152] 18.6 g of aluminium trichloride (139 mmol) and 48 ml of anhydrous n-decane were introduced into a glass flask which had previously been subjected to 3 vacuum/inert gas cycles. Once the suspension had been cooled with a water and ice bath, the anhydrous dioctyl ether (33.82 g, 139 mmol, 42 ml) was introduced dropwise with stirring. The aluminium trichloride passed slowly into solution. The mixture was allowed to return to room temperature to obtain a solution of a light yellowish colour.

[0153] Elemental analysis of the solution: Cl: 17.9%; Al: 4.3%.

[0154] [Al]=1.54 mmol/ml

[0155] FT-IR (Nujol): 938 cm.sup.−1 (v.sub.Al-OR).

Preparative Example B: AlCl.SUB.3..Dioctyl Ether (1:2) Complex in n-Decane

[0156] 20 g of aluminium trichloride (150 mmol) and 23 ml of anhydrous n-decane were introduced into a glass flask which had previously been subjected to 3 vacuum/inert gas cycles. Once the suspension had been cooled with a water and ice bath, the anhydrous dioctyl ether (72.7 g, 300 mmol, 91 ml) was introduced dropwise with stirring. The aluminium trichloride passed slowly into solution. The mixture was allowed to return to room temperature to obtain a solution of a light yellowish colour.

[0157] Elemental analysis of the solution: Cl: 15.9%; Al: 3.7%.

[0158] [Al]=1.32 mmol/ml

[0159] The solvent was removed from an aliquot of the solution by vacuum evaporation to obtain an oil which was characterised by elemental analysis and FT-IR and .sup.1H-NMR spectroscopy, confirming that the desired compound had been obtained.

[0160] Elemental analysis of the complex: (MW=618.23) [found (theoretical)] Cl: 17.3% (17.20); Al: 4.26% (4.36).

[0161] FT-IR (Nujol): 938 cm.sup.−1 (v.sub.Al-OR).

Preparative Example C: AlCl.SUB.3..Xylene.HCl Complex

[0162] Following the procedures set out in Example 1 of the cited patent application EP 412597, the complex of AlCl.sub.3 with hydrochloric acid and xylene was prepared by bubbling anhydrous hydrochloric acid (gas) into a suspension of anhydrous AlCl.sub.3 (51 g, 382 mmol) and anhydrous xylene (42.6 g, 401 mmol, 50 ml) until the aluminium trichloride had dissolved in the xylene, and leaving the mixture to react for three hours. A homogeneous oil of a brown-orange colour was obtained which was found to have the following composition: AlCl.sub.3 (51% wt./wt.), xylene (42.6% wt./wt.), HCl (6.4% wt./wt.), as determined on the basis of the above-stated elemental analysis methods and taking account of the organic proportion exclusively formed by xylene. The concentration of Al in the solution was equal to 6.75 mmol of AlCl.sub.3 per ml.

Preparative Example 1: Monometallic Mg/Ti Precursor

[0163] 280 ml of n-decane and 17.57 g (184.5 mmol) of magnesium chloride were introduced in succession under a blanket of anhydrous nitrogen into a stirred, jacketed glass reactor of a volume of 1 litre. Stirring was continued for 10 minutes to homogenise the mixture and 5.785 g (17 mmol) of titanium tetrabutylate and 72.49 g (502.7 mmol) of 2-ethylhexanoic acid were added. The nitrogen pressure was adjusted to 5 kPag at room temperature and the reactor was then sealed. Keeping the reactor sealed, the mixture was heated to 90° C. and maintained at this temperature for 2 hours with stirring. The pressure rose to 121 kPag.

[0164] A clear solution was obtained which became slightly opalescent once cooled to room temperature. The solution was transferred into an 800 ml glass bottle and stored under an inert nitrogen atmosphere at room temperature.

Preparative Example 2: Bimetallic Mg/Ti/Zr Precursor

[0165] 280 ml of n-decane, 17.57 g (184.5 mmol) of magnesium chloride and 5.1 g of zirconium tetrachloride (21.9 mmol) were introduced in succession under a blanket of anhydrous nitrogen into a stirred, jacketed glass reactor of a volume of 1 litre. Stirring was continued for 10 minutes to homogenise the mixture and 5.78 g (17 mmol) of titanium tetrabutylate and 89.7 g (622 mmol) of 2-ethylhexanoic acid were added.

[0166] The nitrogen pressure was adjusted to 5 kPag at room temperature and the reactor was then sealed. Keeping the reactor sealed, the mixture was heated to 90° C. for 2 hours with stirring. The pressure rose to 127 kPag. A clear solution was obtained which became slightly opalescent once cooled to room temperature.

[0167] The solution was transferred into an 800 ml glass bottle and stored under an inert nitrogen atmosphere at room temperature.

Preparative Example 3: Bimetallic Mg/Ti/Hf Precursor

[0168] The same procedure with the same molar quantities as in the preceding preparative Example 2 was repeated, with the only difference that 6.98 g (equal to 21.8 mmol) of hafnium tetrachloride were used instead of 5.1 g of zirconium tetrachloride (21.9 mmol). The pressure during heating rose to 127 kPag.

[0169] A clear solution was obtained which became slightly opalescent once cooled to room temperature. This solution was transferred into an 800 ml glass bottle and stored under an inert nitrogen atmosphere at room temperature.

Example 1: Monometallic Catalyst (C1)

[0170] 50 ml of the homogeneous monometallic solution prepared according to the preceding preparative Example 1 containing the following components was introduced into a 1 litre glass reaction flask equipped with a mechanical stirrer and thermostatically controlled by means of a silicone oil bath:

[0171] Ti=2.24 mmol

[0172] Mg=24.28 mmol

[0173] Cl=48.55 mmol

[0174] 2-ethylhexanoate=66.15 mmol

[0175] (O-butyl)=8.96 mmol

[0176] Approx. 200 ml of n-decane were added and stirring was continued with the temperature of the oil bath at 40° C. In total, 75.11 mmol of organic groups (O-butyl+C.sub.7H.sub.14COO—) were present. 24.39 ml of the solution in n-decane prepared using the method previously described in preparative Example A, containing 37.56 mmol of soluble AlCl.sub.3.dioctyl ether (1:1) complex, were further diluted to 50 ml with n-decane, and added dropwise to the solution in the flask thermostatically controlled to 40° C. to obtain an Al/(O-butyl+C.sub.7H.sub.14COO—) molar ratio of 0.5, based on the quantity of organic groups present in the initial precursor solution. Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition.

[0177] A white solid was observed to precipitate. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped. The clear supernatant liquid was sampled and analysed, yielding the following results:

[0178] Ti=7.47 mmol/litre (100% of introduced titanium)

[0179] Mg=absent

[0180] It could thus be concluded that the resultant solid was composed of all the magnesium chloride, while the entirety of the titanium had remained in soluble form.

[0181] For the purpose of then achieving reduction to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated by dropwise addition of a 50 vol. % strength solution containing 2.7 g of DEAC in n-decane, equal to 22.4 mmol, in such a manner as to obtain a molar Al/Ti ratio of 10.

[0182] Once addition at constant temperature was complete, the temperature of the thermostatic bath was adjusted to 90° C. and stirring was continued for a further 2 hours. The temperature was reduced to ambient, with stirring being continued, and an aliquot of suspension was taken and filtered on a G3 sintered glass filter, washed with n-decane, dried under a stream of anhydrous nitrogen and analysed in accordance with the previously stated elemental analysis method, with the following results (composition in % by weight):

[0183] Ti=2.48%.

[0184] Mg=15.7%

[0185] Al=3.48%

[0186] Cl=58.35%

[0187] 2-EHA=7.89%

[0188] corresponding to a formula of catalyst C1 which may be stated as follows:

Ti.sub.1Mg.sub.12.42Al.sub.2.48Cl.sub.31.65(C.sub.7H.sub.15COO—).sub.1.06

Example 2: Monometallic Catalyst (C2)

[0189] Exactly the same procedure described in the preceding Example 1 was used, but using an Al/(O-butyl+C.sub.7H.sub.15COO—) molar ratio of 0.33 based on the quantity of organic groups present in the initial precursor solution. 24.79 mmol of soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex, equal to 16.1 ml of the solution prepared using the method previously described in preparative Example A, further diluted to 50 ml with n-decane, were added dropwise. The temperature was maintained at 40° C. during addition.

[0190] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped, leaving the mixture to settle for a few minutes. The clear supernatant liquid was sampled and found to contain:

[0191] Ti=7.38 mmol/litre (approx. 100% of initial titanium)

[0192] Mg=8.0 mmol/litre (approx. 10% of initial magnesium).

[0193] It could thus be concluded that the resultant solid was composed of virtually all the introduced magnesium chloride, while the entirety of the titanium had remained in soluble form.

[0194] For the purpose of then achieving reduction to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated by dropwise addition of a 50% strength solution containing 1.34 g of DEAC in n-decane, equal to 11.1 mmol, in such a manner as to obtain a molar Al/Ti ratio of 5.

[0195] On completion, after filtration through a sintered filter and drying under a stream of nitrogen, a solid catalyst was obtained at a yield of greater than 90% relative to the initial titanium, which, after having been dried and analysed, was found to have following composition (% by weight):

[0196] Ti=2.8%.

[0197] Mg=15.24%

[0198] Al=2.65%

[0199] Cl=59.04%

[0200] 2-EHA=12.44%

[0201] corresponding to a formula of catalyst C2 which may be stated as follows:

Ti.sub.1Mg.sub.10.81Al.sub.1.69Cl.sub.28.67(C.sub.7H.sub.15COO—).sub.1.48

Example 3: Monometallic Catalyst (C3)

[0202] Exactly the same procedure as in Example 1 was followed, with the difference that the solution of the soluble AlCl.sub.3.dioctyl ether (1:2 mol/mol) compound in n-decane was used.

[0203] 28.5 ml of the solution in n-decane prepared using the method previously described in preparative Example B, having an Al concentration of 1.32 mmol/ml, corresponding to 37.56 mmol of soluble AlCl.sub.3.dioctyl ether (1:2) complex, were further diluted to 50 ml with n-decane, and added dropwise to the solution in the flask thermostatically controlled to 40° C. to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) molar ratio of 0.5, based on the quantity of organic groups present in the initial precursor solution. Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition.

[0204] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped, leaving the mixture to settle for a few minutes. The clear supernatant liquid was sampled and found to be composed of:

[0205] Ti=7.41 mmol (100% of introduced titanium)

[0206] Mg=(absent).

[0207] It could thus be concluded that the resultant solid was composed of all the magnesium chloride, while the entirety of the titanium had remained in soluble form.

[0208] The suspension, still being stirred at 40° C., was treated by dropwise addition of a 50% strength solution containing 4.02 g of DEAC in n-decane, equal to 33.35 mmol, in such a manner as to obtain a molar Al/Ti ratio of 15.

[0209] On completion, stirring of the suspension was continued for 2 hours at 90° C. The temperature was reduced and the solid separated as described in the preceding Example 2.

[0210] On elemental analysis, the solid catalyst C3 prepared in this manner was found to have the following composition:

[0211] Ti=4.0%.

[0212] Mg=15.4%

[0213] Al=3.8%

[0214] Cl=64.9%

[0215] 2-EHA=8.1%

[0216] corresponding to a formula of catalyst C3 which may be stated as follows:

Ti.sub.1Mg.sub.7.55Al.sub.1.68Cl.sub.21.76(C.sub.7H.sub.15COO—).sub.0.67

Example 4: Bimetallic Ti/Zr Catalyst (C4)

[0217] 50 ml of the homogeneous bimetallic Mg/Ti/Zr solution prepared according to the preceding preparative Example 2 containing the following components was introduced into a 1 litre glass reaction flask equipped with a mechanical stirrer and thermostatically controlled by means of a silicone oil bath:

[0218] Ti=2.21 mmol

[0219] Mg=23.96 mmol

[0220] Cl=59.3 mmol

[0221] Zr=2.84 mmol

[0222] 2-ethylhexanoate=80.78 mmol

[0223] (O-butyl)=8.84 mmol

[0224] Approx. 200 ml of n-decane were added and stirring was continued with the temperature of the oil bath at 40° C. In total, 89.62 mmol of organic groups (O-butyl+C.sub.7H.sub.15COO—) were present.

[0225] At this point, 89.62 mmol of soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex, equal to 58.19 ml of the solution prepared using the method previously described in preparative Example A, adjusted to a volume of 100 ml with n-decane prior to addition, were added dropwise in such a manner as to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1, based on the quantity of organic groups present in the initial precursor solution. Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition.

[0226] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped. The supernatant liquid was sampled and found to be composed of:

[0227] Ti=7.36 mM/l (100% of introduced titanium)

[0228] Mg=absent

[0229] Zr=absent

[0230] It could thus be concluded that the resultant solid was composed of all the magnesium chloride and the zirconium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0231] For the purpose of then achieving reduction to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated by dropwise addition of a 50 vol. % strength solution containing 2.66 g of DEAC in decane, equal to 22.1 mmol, in such a manner as to obtain a molar Al/Ti ratio of 10.

[0232] Once addition at constant temperature was complete, the temperature of the thermostatic bath was adjusted to 60° C. and stirring was continued for a further 1 hour. The temperature was reduced to ambient, stirring was stopped and, once approx. five minutes had elapsed, an aliquot of suspension was taken and filtered on a G3 sintered glass filter, washed with n-decane, dried under a stream of anhydrous nitrogen and analysed in accordance with the previously stated elemental analysis method, with the following results (% by weight).

[0233] Ti=4.43%.

[0234] Mg=15.75%

[0235] Zr=10.23%

[0236] Al=1.26%

[0237] Cl=58.51%

[0238] 2-EHA=6.56%

[0239] corresponding to a formula of catalyst C4 which may be stated as follows:

Ti.sub.1Mg.sub.7.04Zr.sub.1.22Al.sub.0.51Cl.sub.17.91(C.sub.7H.sub.15COO—).sub.0.49

Example 5: Bimetallic Ti/Zr Catalyst (C5)

[0240] The precipitation step with AlCl.sub.3.dioctyl ether 1/1 was repeated using the same procedures and quantities of reactants as in the preceding Example 4, with the difference that, at the end of addition of the soluble aluminium complex, the reaction mixture was adjusted to a temperature of 90° C. for 2 hours. At this point, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0241] Ti=7.26 mM/l (approx. 100% of introduced titanium)

[0242] Mg=absent.

[0243] Zr=absent.

[0244] The precipitated solid was thus composed of all the magnesium chloride and the zirconium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0245] The suspension, still being stirred at 40° C., was treated by dropwise addition of a 50 vol. % strength solution containing 1.31 g of DEAC in n-decane, equal to 10.89 mmol, in such a manner as to obtain a molar Al/Ti ratio of 5. On completion, the suspension was adjusted to a temperature of 90° C., and stirring was continued for 2 hours.

[0246] On completion, the mixture was filtered on a sintered glass filter, washing performed twice with 50 ml of n-decane, drying performed under a stream of anhydrous nitrogen, in order to obtain a solid catalyst having the following composition by weight, determined by means of elemental analysis using the previously described method:

[0247] Ti=3.4%

[0248] Mg=17.2%

[0249] Zr=9.6%

[0250] Al=3.31%

[0251] Cl=61.4%

[0252] 2-EHA=3.56%

[0253] corresponding to a formula of catalyst C5 which may be stated as follows:

Ti.sub.1Mg.sub.10.0Zr.sub.1.48Al.sub.1.73Cl.sub.24.36(C.sub.7H.sub.15COO—).sub.0.35

Example 6: Bimetallic Ti/Zr Catalyst (C6)

[0254] In a similar manner to the preceding Example 4, 50 ml of the homogeneous bimetallic Mg/Ti/Zr solution, prepared according to the preceding preparative Example 2, were introduced into a 1 litre glass flask and diluted with approx. 200 ml of anhydrous n-decane. Using the same procedures as in Example 4, 44.81 mmol of soluble AlCl.sub.3.dioctyl ether (1:2 mol/mol) complex, equal to 33.95 ml of the solution prepared using the method previously described in preparative Example B, adjusted to a volume of 50 ml with n-decane prior to addition, were added to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 0.5, based on the quantity of organic groups present in the initial precursor solution. Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition.

[0255] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped. The supernatant liquid was sampled and found to be composed of:

[0256] Ti=7.37 mM/l (100% of introduced titanium)

[0257] Mg=absent

[0258] Zr=absent

[0259] It could thus be concluded that the resultant solid was composed of all the magnesium chloride and the zirconium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0260] For the purpose of then achieving reduction to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated by dropwise addition of a 50 vol. % strength solution containing 6.57 g of TIBA in decane, equal to 33.17 mmol, in such a manner as to obtain a molar Al/Ti ratio of 15.

[0261] Once addition at constant temperature was complete, the temperature of the thermostatic bath was adjusted to 60° C. and stirring was continued for a further 1 hour. On completion, the mixture was filtered on a sintered glass filter, washing performed twice with 50 ml of n-decane, drying performed under a stream of anhydrous nitrogen, in order to obtain a solid catalyst having the following composition by weight, determined in accordance with the previously stated elemental analysis method.

[0262] Ti=3.29%

[0263] Mg=16.2%

[0264] Zr=8.91%

[0265] Al=0.5%

[0266] Cl=66.07%

[0267] 2-EHA=4.02%

[0268] corresponding to the following formula of catalyst C6:

Ti.sub.1Mg.sub.9.7Zr.sub.1.42Al.sub.0.28Cl.sub.27.23(C.sub.7H.sub.15COO—).sub.0.4

Example 7: Bimetallic Ti/Hf Catalyst (C7)

[0269] 50 ml of the homogeneous bimetallic Mg/Ti/Hf solution prepared according to the preceding preparative Example 3 were introduced, together with approx. 200 ml of n-decane, into a 1 litre glass flask equipped with a mechanical stirrer and thermostatically controlled by means of a silicone oil bath, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0270] The resultant solution contained, on the basis of the calculated quantities of preparative Example 3:

[0271] Ti=2.21 mmol

[0272] Mg=23.96 mmol

[0273] Cl=59.25 mmol

[0274] Hf=2.83 mmol

[0275] 2-ethylhexanoate=80.78 mmol

[0276] (O-butyl)=8.83 mmol

[0277] At this point, 58.19 (correct value) ml of soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex, (prepared as described previously in preparative Example A), adjusted to a volume of 50 ml with n-decane prior to addition, were added dropwise in such a manner as to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1, based on the quantity of organic groups present in the initial precursor solution.

[0278] Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition. A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature. At this point, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0279] Ti=7.35 mM/l (100% of input titanium)

[0280] Mg=absent

[0281] Hf=absent

[0282] It could thus be concluded that the resultant solid was composed of all the input magnesium chloride and hafnium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0283] For the purpose of then achieving chlorination and reduction to Ti(III), the suspension, still being stirred at 40° C., was treated with 50% DEAC in decane.

[0284] The quantity of pure DEAC was 2.66 g, equal to 22.05 mmol, in such a manner as to obtain a molar Al/Ti ratio of 10.

[0285] Once addition at constant temperature was complete, the temperature was raised to 60° C. by increasing the temperature of the thermostatic bath and stirring was continued for a further 1 hour.

[0286] The temperature was reduced to ambient, stirring was stopped and, on completion, an aliquot of suspension was filtered on a G3 sintered glass filter and dried under a stream of hot nitrogen. An accurately weighed quantity of the dry solid was analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0287] Ti=3.23%.

[0288] Mg=16.75%

[0289] Hf=16.42%

[0290] Al=1.26%

[0291] Cl=58.51%

[0292] 2-EHA=3.55%

[0293] corresponding to a formula of catalyst C7 which may be stated as follows:

Ti.sub.1Mg.sub.10.29H.sub.1.37Al.sub.0.7C.sub.24.6(C.sub.7H.sub.15COO—).sub.0.37

Example 8: Bimetallic Ti/Hf Catalyst (C8)

[0294] The same procedure and quantities as stated in Example 7 were used, with the sole difference that, once addition of the soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex was complete, the temperature was adjusted to 90° C. for 2 hours. On completion, the temperature was reduced to room temperature. At this point, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0295] Ti=7.33 mM/l (100% of input titanium)

[0296] Mg=absent

[0297] Hf=absent

[0298] It could thus be concluded that the resultant solid was composed of all the magnesium chloride and hafnium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0299] The same procedure and quantities as in Example 7 were then used for the subsequent addition of DEAC but, on completion, the suspension was adjusted to a temperature of 90° C. and stirring was continued for 2 hours. The quantity of pure DEAC was 2.66 g, equal to 22.05 mmol, in such a manner as to obtain a molar Al/Ti ratio of 10.

[0300] On completion, a dried solid catalyst was obtained having the following composition by weight, analysed in accordance with the previously stated elemental analysis method:

[0301] Ti=2.3%

[0302] Mg=12.09%

[0303] Hf=11.13%

[0304] Al=4.93%

[0305] Cl=54.7%

[0306] 2-EHA=7.77%

[0307] corresponding to a formula of catalyst C8 which may be stated as follows:

Ti.sub.1Mg.sub.10.38Hf.sub.1.29Al.sub.3.81Cl.sub.32.1(C.sub.7H.sub.15COO—).sub.1.12

Example 9: Bimetallic Ti/Hf Catalyst (C9)

[0308] Exactly the same procedure was followed as in Example 7, with the difference that a soluble AlCl.sub.3.dioctyl ether (1:2 mol/mol) compound was used, having an Al concentration (in n-decane) of 1.32 mmol/ml. Addition was carried out in such a manner as to achieve an Al/(O-butyl+C.sub.7H.sub.15COO—) molar ratio of 1.5 (60.44 ml of the solution of complex prepared in preparative Example B). Stirring was continued and the temperature of the mixture was maintained at 40° C. during addition.

[0309] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature.

[0310] At this point, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0311] Ti=6.30 mM/l (100% of input titanium)

[0312] Mg=absent

[0313] Hf=absent

[0314] It could thus be concluded that the resultant solid was composed of all the input magnesium chloride and hafnium tetrachloride and part of the input AlCl.sub.3, while the entirety of the titanium had remained in soluble form. The suspension was then treated with 5.47 g of pure EASC, equal to 22.1 mmol, diluted to 50% in n-decane, in such a manner as to achieve a molar Al/Ti ratio of 10. On completion of addition at a constant temperature of 40° C., the suspension was heated to 90° C. and stirring was continued for 2 hours.

[0315] Analysis of the dried catalyst yielded the following results by weight:

[0316] Ti=3.29%

[0317] Mg=17.2%

[0318] Hf=19.14%

[0319] Al=0.5%

[0320] Cl=56.07%

[0321] 2-EHA=3.03%

[0322] corresponding to a formula:

Ti.sub.1Mg.sub.10.26Hf.sub.1.55Al.sub.0.28Cl.sub.22.88(C.sub.7H.sub.15COO—).sub.0.31

Example 10: Monometallic Catalyst (C10)

[0323] 50 ml of the monometallic Mg/Ti solution, obtained as described above in accordance with preparative Example 1, together with approx. 200 ml of decane, were introduced into a 1 litre flask, stirred mechanically, immersed in a thermal bath filled with silicone oil for thermostatic control and maintained under an inert atmosphere with anhydrous nitrogen, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0324] The resultant solution contained, on the basis of the input weighed quantities in preparative Example 1:

[0325] Ti=2.24 mmol

[0326] Mg=24.28 mmol

[0327] Cl=48.55 mmol

[0328] 2-EHA=66.15 mmol

[0329] (O-butyl)=8.96 mmol

[0330] At this point, 37.56 mmol of soluble AlCl.sub.3.xylene.HCl complex, equal to 5.56 ml of the solution prepared using the method previously described in preparative Example C, were added dropwise to obtain a molar Al/(O-butyl+RCOO—) ratio of 0.5, based on the quantity of organic groups present in the initial precursor solution.

[0331] Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition. A white solid was observed to precipitate. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature. At this point, stirring was stopped and the clear supernatant liquid was sampled and analysed, yielding the following results:

[0332] Ti=8.52 mM/l (100% of input titanium)

[0333] Mg=absent

[0334] It could thus be concluded that the resultant solid contained all the initially introduced magnesium, while the entirety of the titanium had remained in soluble form.

[0335] For the purpose of then achieving reduction to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated with 2.53 g of 50% TEA in decane, equal to 22.15 mmol, in such a manner as to obtain a molar Al/Ti ratio of 10. Once addition at constant temperature was complete, the temperature was raised to 90° C. by increasing the temperature of the thermostatic bath and stirring was continued for 2 hours. The temperature was reduced to ambient and, on completion, an aliquot of suspension was filtered on a G3 sintered glass filter and dried under a stream of anhydrous nitrogen.

[0336] An accurately weighed quantity of the dry solid was analysed in accordance with the previously stated elemental analysis method to obtain the following results (composition in % by weight):

[0337] Ti=3.2%.

[0338] Mg=14.9%

[0339] Al=2.48%

[0340] Cl=68.35%

[0341] 2-EHA=7.67%

[0342] corresponding to a formula of catalyst C10 which may be stated as follows:

Ti.sub.1Mg.sub.9.15Al.sub.1.37Cl.sub.28.74(C.sub.7H.sub.15COO—).sub.0.79

Example 11: Bimetallic Ti/Zr Catalyst (C11)

[0343] 50 ml of the bimetallic Mg/Ti/Zr solution, obtained as described above in accordance with the preceding preparative Example 2, together with approx. 200 ml of n-decane, were introduced into a 1 litre glass flask, equipped with a mechanical stirrer, immersed in a thermal bath filled with silicone oil for thermostatic control and maintained under an inert atmosphere with nitrogen, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0344] The resultant solution contained, on the basis of the calculated weighed quantities of preparative Example 2:

[0345] Ti=2.21 mmol

[0346] Mg=23.96 mmol

[0347] Cl=59.3 mmol

[0348] Zr=2.84 mmol

[0349] 2-EHA=80.78 mmol

[0350] (O-butyl)=8.84 mmol

[0351] A total of 89.62 mmol of organic residue (O-butyl+C.sub.7H.sub.15COO—) were thus considered to be present. Over the course of approx. 40 minutes, 13.28 ml of soluble AlCl.sub.3.xylene.HCl complex, prepared as described in preparative Example C, equal to 89.61 mmol of soluble AlCl.sub.3.xylene.HCl complex, were added slowly to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1 based on the quantity of (O-butyl+C.sub.7H.sub.15COO—) groups present in the initial precursor solution. Stirring was continued and the temperature of the reaction mixture was maintained at 40° C. during addition. A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped. After a few minutes, the clear supernatant liquid was sampled and found to be composed of:

[0352] Ti=8.36 mM/l (100% of total)

[0353] Mg=absent

[0354] Zr=absent

[0355] It could thus be concluded that the resultant solid contained all the input magnesium and zirconium, while the entirety of the titanium had remained in soluble form.

[0356] For the purpose of achieving chlorination and reduction of the titanium to Ti(III), the suspension, still being stirred, was treated by slowly adding, at a constant temperature of 40° C., 6.58 g of TIBA (33.23 mmol) diluted to 50 vol. % in decane, in such a manner as to obtain a molar Al/Ti ratio of 15. Once addition was complete, the temperature was raised to 90° C. by increasing the temperature of the thermostatic bath and stirring was continued for 2 hours.

[0357] The temperature was then reduced to ambient and an aliquot of suspension was filtered on a G3 sintered glass filter. The solid separated in this manner was dried under a stream of hot nitrogen and analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0358] Ti=2.98%.

[0359] Mg=13.75%

[0360] Zr=8.23%

[0361] Al=2.26%

[0362] Cl=68.51%

[0363] 2-EHA=3.56%

[0364] corresponding to a formula of catalyst C11 which may be stated as follows:

Ti.sub.1Mg.sub.9.13Zr.sub.1.45Al.sub.1.36Cl.sub.31.14(C.sub.7H.sub.15COO—).sub.0.4

Example 12: Bimetallic Ti/Hf Catalyst (C12)

[0365] 50 ml of the bimetallic Mg/Ti/Hf solution, obtained as described above in accordance with the preceding preparative Example 3, together with approx. 200 ml of n-decane, were introduced into a 1 litre glass flask, equipped with a mechanical stirrer, immersed in a thermal bath filled with silicone oil for thermostatic control and maintained under an inert atmosphere with nitrogen, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0366] The resultant solution contained, on the basis of the calculated weighed quantities of preparative Example 3:

[0367] Ti=2.21 mmol

[0368] Mg=23.96 mmol

[0369] Cl=59.25 mmol

[0370] Hf=2.83 mmol

[0371] 2-EHA=80.78 mmol

[0372] (O-butyl)=8.83 mmol

[0373] A total of 89.61 mmol of organic residue (O-butyl+C.sub.7H.sub.15COO—) were thus considered to be present. Over the course of approx. 50 minutes, 13.28 ml of the solution prepared as described above in preparative Example C, equal to 89.61 mmol of soluble AlCl.sub.3.xylene.HCl complex, were added slowly to obtain an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1 based on the quantity of (O-butyl+RCOO—) groups present in the initial precursor solution. Stirring was continued and the temperature of the reaction mixture was maintained at 40° C. during addition. A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature and stirring was stopped. After a few minutes, the clear supernatant liquid was sampled and found to be composed of:

[0374] Ti=8.25 mM/l (100% of input titanium)

[0375] Mg=absent

[0376] Hf=absent

[0377] It could thus be concluded that the resultant solid contained all the input magnesium and hafnium, while the entirety of the titanium had remained in soluble form.

[0378] For the purpose of achieving chlorination and reduction of the titanium to Ti(III), the suspension, still being stirred, was treated by slowly adding, at a constant temperature of 40° C., 2.64 g of DEAC (21.86 mmol) diluted to 50 vol. % in decane, in such a manner as to obtain a molar Al/Ti ratio of 10. Once addition was complete, the temperature was raised to 90° C. by increasing the temperature of the thermostatic bath and stirring was continued for 2 hours.

[0379] The temperature was then reduced to ambient and an aliquot of suspension was filtered on a G3 sintered glass filter. The solid separated in this manner was dried under a stream of hot nitrogen and analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0380] Ti=2.75%.

[0381] Mg=14.71%

[0382] Hf=14.22%

[0383] Al=1.26%

[0384] Cl=65.51%

[0385] 2-EHA=1.26%

[0386] corresponding to a formula of catalyst C12 which may be stated as follows:

Ti.sub.1Mg.sub.10.61Hf.sub.14Al.sub.0.83Cl.sub.32.38(C.sub.7H.sub.15COO—).sub.0.15

Example 13: Bimetallic Ti/Zr Catalyst (C13)

[0387] The procedure of the preceding Example 11 was repeated with the same reactants and using the same conditions, with the sole difference that, in the titanium reduction and precipitation step, 2.73 g (22.65 mmol) of DEAC were added instead of 6.58 g of TIBA, in such a manner as to obtain a molar Al/Ti ratio of 10. On completion, the temperature was reduced to ambient and an aliquot of suspension was filtered on a G3 sintered glass filter. The solid separated in this manner was dried under a stream of hot nitrogen and analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0388] Ti=3.12%.

[0389] Mg=15.82%

[0390] Zr=8.43%

[0391] Al=2.36%

[0392] Cl=66.71%

[0393] 2-EHA=2.86%

[0394] corresponding to a formula of catalyst C13 which may be stated as follows:

Ti.sub.1Mg.sub.10.02Zr.sub.1.41Al.sub.1.34Cl.sub.28.91(C.sub.7H.sub.15COO—).sub.0.31

Example 14: Bimetallic Ti/Zr Catalyst (C14)

[0395] The procedure of the preceding Example 11 was repeated with the same reactants and using the same conditions, with the sole difference that, in the titanium reduction and precipitation step, 2.81 g (11.35 mmol) of EASC were added instead of 6.58 g of TIBA, in such a manner as to obtain a molar Al/Ti ratio of 5. On completion, the temperature was reduced to ambient and an aliquot of suspension was filtered on a G3 sintered glass filter. The solid separated in this manner was dried under a stream of hot nitrogen and analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0396] Ti=3.01%.

[0397] Mg=15.15%

[0398] Zr=8.44%

[0399] Al=1.95%

[0400] Cl=65.75%

[0401] 2-EHA=4.01%

[0402] corresponding to a formula of catalyst C14 which may be stated as follows:

Ti.sub.1Mg.sub.9.81Zr.sub.1.47Al.sub.1.14Cl.sub.29.40(C.sub.7H.sub.15COO—).sub.0.44

Example 15: Monometallic Ti Catalyst (C15)

[0403] 50 ml of the monometallic solution prepared according to the preceding preparative Example 1, and approx. 200 ml of n-decane were introduced into a 1 litre flask equipped with a mechanical stirrer, immersed in a silicone oil bath for thermostatic control and maintained under an inert atmosphere with anhydrous nitrogen. Stirring was continued stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0404] The resultant solution contained, on the basis of the input weighed quantities in preparative Example 1:

[0405] Ti=2.24 mmol

[0406] Mg=24.28 mmol

[0407] Cl=48.55 mmol

[0408] 2-ethylhexanoic acid=66.15 mmol

[0409] (O-butyl)=8.96 mmol

[0410] A total of 75.11 mmol of organic groups (O-butyl+C.sub.7H.sub.15COO—) were thus present.

[0411] Over a time of approx. 40 minutes, 50 ml of a solution in n-decane containing 24.79 mmol of soluble AlCl.sub.3.dioctyl ether (1:1) complex, obtained by diluting 16.1 ml of the solution prepared using the method previously described in preparative Example A, were added slowly to said solution. A molar Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 0.33, based on the quantity of organic groups present in the initial precursor solution, was obtained. Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition. The temperature of the reaction mixture varied from 40 to 42° C. over the course of addition. A white solid was observed to precipitate. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature.

[0412] At this point, stirring was stopped and, after a few minutes, the clear supernatant liquid was sampled and analysed, yielding the following results:

[0413] Ti=7.27 mM/l (100% of introduced titanium)

[0414] Mg=absent

[0415] It could thus be concluded that the resultant solid contained all the initially introduced magnesium, while the entirety of the titanium had remained in soluble form.

[0416] For the purpose of achieving chlorination and reduction of the titanium to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred, was treated by slowly adding, at a constant temperature of 40° C., 0.767 g of TEA (6.72 mmol) diluted to 50 vol. % in n-decane, in such a manner as to obtain a molar Al/Ti ratio of 3. Once addition was complete, the temperature was raised to 90° C. by increasing the temperature of the thermostatic bath and stirring was continued for 2 hours.

[0417] The temperature was reduced to ambient and, on completion, an aliquot of suspension was filtered on a G3 sintered glass filter and dried under a stream of anhydrous nitrogen. An accurately weighed quantity of the dried solid was analysed in accordance with the previously stated elemental analysis method to obtain the following results (composition in % by weight):

[0418] Ti=3.18%.

[0419] Mg=15.9%

[0420] Al=3.84%

[0421] Cl=61.70%

[0422] 2-EHA=10.27%

[0423] corresponding to a formula of catalyst C15 which may be stated as follows:

Ti.sub.1Mg.sub.9.85Al.sub.2.14Cl.sub.26.20(C.sub.7H.sub.15COO—).sub.1.08

Example 16: Bimetallic Ti/Zr Catalyst Supported on MgCl.SUB.2 .(C16)

[0424] 50 ml of the homogeneous bimetallic Mg/Ti/Zr solution described above in preparative Example 2, together with approx. 200 ml of n-decane, were introduced into a flask equipped with a mechanical stirrer, immersed in a silicone oil bath for thermostatic control and maintained under an inert atmosphere with nitrogen, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0425] The resultant solution contained, on the basis of the calculated quantities of preparative Example 2:

[0426] Ti=2.21 mmol

[0427] Mg=23.96 mmol

[0428] Cl=59.3 mmol

[0429] Zr=2.84 mmol

[0430] 2-EHA=80.78 mmol

[0431] (O-butyl)=8.84 mmol

[0432] A total 89.62 mmol of (O-butyl+C.sub.7H.sub.15COO—) were thus considered to be present.

[0433] At this point, 89.62 mmol of soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex, equal to 58.19 ml of the solution prepared using the method previously described in preparative Example A and further diluted to 50 ml with n-decane, were added dropwise in a time of approx. 40 minutes to obtain in this manner an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1, based on the quantity of organic groups present in the initial precursor solution.

[0434] Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition. The temperature of the reaction mixture was maintained between 39 and 41° C.

[0435] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0436] Ti=7.47 mM/l (100% of introduced titanium)

[0437] Mg=absent

[0438] Zr=absent

[0439] It could thus be concluded that the resultant solid contained all the initially introduced magnesium and zirconium, while the entirety of the titanium had remained in soluble form. For the purpose of then achieving reduction and chlorination of the titanium to Ti(III) and subsequent precipitation of TiCl.sub.3, the suspension, still being stirred at 40° C., was treated with 50% DEAC in decane.

[0440] The quantity of pure DEAC was 0.8 g, equal to 6.63 mmol, in such a manner as to obtain a molar Al/Ti ratio of 3.

[0441] Once addition at constant temperature was complete, the temperature was raised to 60° C. by increasing the temperature of the thermostatic bath and stirring was continued for a further 1 hour.

[0442] The temperature was reduced to ambient, stirring was stopped and, on completion, an aliquot of suspension was filtered on a G3 sintered glass filter and dried under a stream of hot nitrogen. An accurately weighed quantity of the dry solid was analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0443] Ti=4.03%.

[0444] Mg=16.62%

[0445] Zr=9.92%

[0446] Al=1.36%

[0447] Cl=56.48%

[0448] 2-EHA=7.26%

[0449] corresponding to a formula of catalyst C16 which may be stated as follows:

Ti.sub.1Mg.sub.8.12Zr.sub.1.29Al.sub.0.60Cl.sub.18.92(C.sub.7H.sub.15COO—).sub.0.60

Example 17: Bimetallic Ti/Hf Catalyst Supported on MgCl.SUB.2 .(C17)

[0450] 50 ml of the homogeneous bimetallic Mg/Ti/Hf solution described above in accordance with preparative Example 3, together with approx. 200 ml of n-decane, were introduced into a flask equipped with a mechanical stirrer, immersed in a silicone oil bath for thermostatic control and maintained under an inert atmosphere with nitrogen, and stirred with the temperature of the oil bath at 40° C. to homogenise the mixture.

[0451] The resultant solution contained, on the basis of the calculated quantities of preparative Example 3:

[0452] Ti=2.21 mmol

[0453] Mg=23.96 mmol

[0454] Cl=59.25 mmol

[0455] Hf=2.83 mmol

[0456] 2-EHA=80.78 mmol

[0457] (O-butyl)=8.83 mmol

[0458] A total 89.61 mmol of (O-butyl+C.sub.7H.sub.15COO—) were thus considered to be present.

[0459] At this point, 34.54 ml of the solution of the AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex, prepared as described in preparative Example A, and further diluted to 50 ml with n-decane, were added dropwise in a time of approx. 40 minutes. The input quantity permitted an Al/(O-butyl+C.sub.7H.sub.15COO—) ratio of 1, based on the quantity of organic groups present in the initial precursor solution.

[0460] Stirring was continued and the temperature of the thermal bath was maintained at 40° C. during addition. The temperature of the reaction mixture varied between 39 and 41° C.

[0461] A white precipitate was observed to form. The resultant suspension was adjusted to 60° C. by heating the thermal bath and stirred at this temperature for 1 hour. On completion, the temperature was reduced to room temperature. At this point, stirring was stopped for a few minutes, the supernatant liquid was sampled and found to be composed of:

[0462] Ti=7.43 mM/l (100% of input titanium)

[0463] Mg=absent

[0464] Hf=absent

[0465] It could thus be concluded that the resultant solid was composed of all the input magnesium chloride and hafnium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0466] For the purpose of then achieving reduction to Ti(III), the suspension, still being stirred at 40° C., was treated with 50% TEA in decane.

[0467] The quantity of pure TEA was 0.76 g, equal to 6.66 mmol, in such a manner as to obtain a molar Al/Ti ratio of 3.

[0468] Once addition at constant temperature was complete, the temperature was raised to 60° C. by increasing the temperature of the thermostatic bath and stirring was continued for a further 1 hour. The temperature was reduced to ambient, stirring was stopped and, on completion, an aliquot of suspension was filtered on a G3 sintered glass filter and dried under a stream of hot nitrogen.

[0469] An accurately weighed quantity of the dry solid was analysed in accordance with the previously stated elemental analysis method to obtain the following results by weight:

[0470] Ti=3.33%.

[0471] Mg=16.95%

[0472] Hf=16.23%

[0473] Al=1.36%

[0474] Cl=56.51%

[0475] 2-EHA=4.32%

[0476] corresponding to a formula of catalyst C17 which may be stated as follows:

Ti.sub.1Mg.sub.10.02Hf.sub.1.31Al.sub.0.72Cl.sub.22.91(C.sub.7H.sub.15COO—).sub.0.43

Example 18: Bimetallic Ti/Hf Catalyst Supported on MgCl.SUB.2 .(C18)

[0477] The same procedure and quantities as stated in Example 17 were used, with the sole difference that, once addition of the soluble AlCl.sub.3.dioctyl ether (1:1 mol/mol) complex was complete, the temperature was adjusted to 90° C. for 2 hours.

[0478] On completion, the temperature was reduced to room temperature.

[0479] At this point, stirring was stopped and the supernatant liquid was sampled and found to be composed of:

[0480] Ti=7.52 mM/l (100% of input titanium)

[0481] Mg=absent

[0482] Hf=absent

[0483] It could thus be concluded that the resultant solid was composed of all the magnesium chloride and hafnium tetrachloride, while the entirety of the titanium had remained in soluble form.

[0484] For the purpose of then achieving chlorination and reduction of the titanium to Ti(III), the suspension, still being stirred at 40° C., was treated with 0.82 g, equal to 6.80 mmol of DEAC diluted to 50% in decane, in such a manner as to obtain an Al/Ti ratio of 3.

[0485] On completion, the suspension was adjusted to a temperature of 90° C., and stirring was continued for 2 hours. On completion, a dried solid catalyst was obtained having the following composition:

[0486] Ti=2.63%

[0487] Mg=14.21%

[0488] Hf=11.28%

[0489] Al=5.12%

[0490] Cl=52.7%

[0491] 2-EHA=7.92%

[0492] corresponding to a formula of catalyst C18 which may be stated as follows:

Ti.sub.1Mg.sub.10.64Hf.sub.1.15Al.sub.3.45Cl.sub.27.05(C.sub.7H.sub.15COO—).sub.1.00

Example 19: copolymerisation of ethylene and 1-hexene with catalyst (C1)

[0493] At least three vacuum-nitrogen cycles were performed for an overall duration of approx. 2 hours in a Brignole type 5 litre steel autoclave equipped with a burette for adding the catalyst, a propeller stirrer and a heating element connected to a thermostat for temperature control. A solution containing 1900 ml of decane, 75 ml of 1-hexene and 1.0 ml of a 1 M solution of triisobutylaluminium (TIBA; 1.0 mmol) in n-decane as cocatalyst (molar Al/Ti ratio=106) was introduced into the autoclave. The internal temperature of the reactor was adjusted to 190° C. and 18.15 mg of catalyst C1, obtained in accordance with the preceding Example 1 (9.40 μmol of Ti), as a suspension in approx. 10 ml of n-decane were introduced by means of the burette under a slight ethylene overpressure. Pressurisation was performed with ethylene, stirring being continued, until a total pressure in the autoclave of 15 barg was achieved. Heating by the element was stopped and an increase in temperature due to the exothermic nature of the polymerisation reaction was observed. The amount of the variation in enthalpy (DH) may be directly correlated to the activity of the converted ethylene and was proportional to the catalytic activity obtained; the flow rate of ethylene required to replenish that converted into polymer was also recorded by means of calibrated ASA flowmeters with an analogue volumetric meter. Polymerisation was continued for 5 minutes while maintaining the system at a constant pressure of 15 bar. The reaction was finally brought to an end by introducing approx. 10 ml of ethanol into the autoclave. The temperature was allowed to drop and the reactor contents were then discharged into approx. 3 litres of ethanol. The polymer was separated by means of filtration, washed with acetone and dried in an oven under a vacuum (approx. 100 Pa) at 90° C. for approx. 12 hours. On completion, 84 g of ethylene/1-hexene copolymer were obtained and characterised by measuring the content of 1-hexene, the melt flow index and density. The results are shown in Table 1 below.

Example 20: copolymerisation of ethylene and 1-hexene with catalyst C2

[0494] The same procedures as previously described in Example 19 were used, with the difference that 23.93 mg of the catalyst prepared in the preceding Example 2 (C2) (13.99 μmol Ti) as a suspension in approx. 15 ml of n-decane, and 1 ml of a 1 M solution of TIBA (1 mmol) in n-decane as cocatalyst (molar Al/Ti ratio=71) were introduced into the autoclave. On completion, 89 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 1.

Example 21: copolymerisation of ethylene and 1-hexene with catalyst C3

[0495] The same procedures as previously described in Example 19 were used, with the difference that 16.50 mg of the catalyst prepared in the preceding Example 3 (C3) (13.78 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=73) were respectively introduced into the autoclave. On completion, 73 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 1.

TABLE-US-00001 TABLE 1 Copolymerisation of ethylene/1-hexene with monometallic Ti catalysts supported on MgCl.sub.2; initial temperature 190° C.; cocatalyst TIBA; P.sub.total = 15 bar. Ti AI.sub.TIBA/ 1-Hexene Yield Activity MFI 2.16 Density Example Cat. (mg) Ti (ml) (g) (kg/g.sub.Ti) g/10′ g/cm.sup.3 19 C1 0.45 106 75 84 187 0.63 0.928 Mg/Ti 20 C2 0.67 71 75 89 132 0.76 0.931 Mg/Ti 21 C3 0.66 73 75 73 110 0.60 0.933 Mg/Ti

Example 22: copolymerisation of ethylene and 1-hexene with catalyst C4

[0496] The same procedures as previously described in Example 19 were used, with the difference that 14.22 mg of catalyst C4, obtained in accordance with Example 4 (13.15 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=76) were respectively introduced into the autoclave. On completion, 94 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 2.

Example 23: copolymerisation of ethylene and 1-hexene with catalyst C5

[0497] The same procedures as previously described in Example 19 were used, with the difference that 19.41 mg of catalyst C5, obtained in accordance with Example 5 (13.78 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=73) were respectively introduced into the autoclave. On completion, 73 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 2.

Example 24: copolymerisation of ethylene and 1-hexene with catalyst C6

[0498] The same procedures as previously described in Example 19 were used, with the difference that 28.27 mg of catalyst C6, obtained in accordance with Example 6 (19.42 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=51) were respectively introduced into the autoclave. On completion, 107 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 2.

TABLE-US-00002 TABLE 2 Copolymerisation of ethylene/1-hexene with bimetallic Ti/Zr catalysts supported on MgCl.sub.2; initial temperature 190° C.; cocatalyst TIBA; P.sub.total = 15 bar. Ti AI.sub.TIBA/ 1-Hexene Yield Activity MFI 2.16 Density Example Cat. (mg) Ti (ml) (g) (kg/g.sub.Ti) g/10′ g/cm.sup.3 22 C4 0.63 76 75 94 150 0.17 0.925 Mg/Ti/Zr 23 C5 0.66 73 75 73 110 0.09 0.924 Mg/Ti/Zr 24 C6 0.93 51 75 107 115 0.33 0.929 Mg/Ti/Zr

Example 25: copolymerisation of ethylene and 1-hexene with catalyst C7

[0499] The same procedures as previously described in Example 19 were used, with the difference that 15.79 mg of catalyst C7, obtained in accordance with Example 7 (10.65 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=94) were respectively introduced into the autoclave. On completion, 64 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 3.

Example 26: copolymerisation of ethylene and 1-hexene with catalyst C8

[0500] The same procedures as previously described in Example 19 were used, with the difference that 22.61 mg of catalyst C8, obtained in accordance with Example 8 (18.86 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=92) were respectively introduced into the autoclave. On completion, 59 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 3.

Example 27: copolymerisation of ethylene and 1-hexene with catalyst C9

[0501] The same procedures as previously described in Example 19 were used, with the difference that 25.84 mg of catalyst C9, obtained in accordance with Example 9 (17.75 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=56) were respectively introduced into the autoclave. On completion, 114 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 3.

TABLE-US-00003 TABLE 3 Copolymerisation of ethylene/1-hexene with bimetallic Ti/Hf catalysts supported on MgCl.sub.2; initial temperature 190° C.; cocatalyst TIBA; P.sub.total = 15 bar. Ti AI.sub.TIBA/ 1-Hexene Yield Activity MFI 2.16 Density Example Cat. (mg) Ti (ml) (g) (kg/g.sub.Ti) g/10′ g/cm.sup.3 25 C7 0.51 94 75 64 126 0.27 0.928 Mg/Ti/Hf 26 C8 0.52 92 75 59 114 0.19 0.926 Mg/Ti/Hf 27 C9 0.85 56 75 114 134 0.43 0.927 Mg/Ti/Hf

Example 28: copolymerisation of ethylene and 1-hexene with catalyst C10

[0502] The same procedures as previously described in Example 19 were used, with the difference that 17.50 mg of catalyst 010, obtained in accordance with Example 10 (11.69 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=86) were respectively introduced into the autoclave. On completion, 184 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 4.

Example 29: copolymerisation of ethylene and 1-hexene with catalyst C11

[0503] The same procedures as previously described in Example 19 were used, with the difference that 17.79 mg of catalyst C11, obtained in accordance with Example 11 (11.07 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=90) were respectively introduced into the autoclave. On completion, 149 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 4.

Example 30: copolymerisation of ethylene and 1-hexene with catalyst C12

[0504] The same procedures as previously described in Example 19 were used, with the difference that 20 mg of catalyst C12, obtained in accordance with Example 12 (11.42 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=88) were respectively introduced into the autoclave. On completion, 124 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 4.

Example 31: copolymerisation of ethylene and 1-hexene with catalyst C13

[0505] The same procedures as previously described in Example 19 were used, with the difference that 13.46 mg of catalyst C13, obtained in accordance with Example 13 (8.77 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=114) were respectively introduced into the autoclave. On completion, 85 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 4.

Example 32: copolymerisation of ethylene and 1-hexene with catalyst C14

[0506] The same procedures as previously described in Example 19 were used, with the difference that 14.95 mg of catalyst C14, obtained in accordance with Example 14 (9.40 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=106) were respectively introduced into the autoclave. On completion, 99 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 4.

TABLE-US-00004 TABLE 4 Copolymerisation of ethylene/1-hexene with bimetallic Ti/Hf and Ti/Zr catalysts supported on MgCl.sub.2; initial temperature 190° C.; cocatalyst TIBA; P.sub.total = 15 bar. Ti AI.sub.TIBA/ 1-Hexene Yield Activity MFI 2.16 Density Example Cat. (mg) Ti (ml) (g) (kg/g.sub.Ti) g/10′ g/cm.sup.3 28 C10 0.56 86 75 184 329 0.87 0.925 Mg/Ti 29 C11 0.53 90 75 149 281 0.07 0.924 Mg/Ti/Zr 30 C12 0.55 88 75 124 225 0.13 0.927 Mg/Ti/Hf 31 C13 0.42 114 75 85 203 0.10 0.925 Mg/Ti/Zr 32 C14 0.45 106 75 99 220 0.08 0.924 Mg/Ti/Zr

Example 33: copolymerisation of ethylene and 1-hexene with catalyst C15

[0507] The same procedures as previously described in Example 19 were used, with the difference that 24.31 mg of catalyst C15 prepared in accordance with Example 15 (16 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (1 mmol) in n-decane as cocatalyst (molar Al/Ti ratio=58.8) were introduced into the autoclave. On completion, 92 g of ethylene/1-hexene copolymer were obtained and characterised by measuring the content of 1-hexene, the melt flow index and density. The results are shown in Table 5 below.

Example 34: copolymerisation of ethylene and 1-hexene with catalyst C16

[0508] The same procedures as previously described in Example 19 were used, with the difference that 20.00 mg of catalyst C16 prepared in accordance with Example 16 (16 μmol Ti) as a suspension in approx. 15 ml of n-decane, and 1 ml of a 1 M solution of TIBA (1 mmol) in n-decane as cocatalyst (molar Al/Ti ratio=58.8) were introduced into the autoclave. On completion, 87 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 5.

Example 35: copolymerisation of ethylene and 1-hexene with catalyst C17

[0509] The same procedures as previously described in Example 19 were used, with the difference that 17.75 mg of catalyst C17 prepared in accordance with Example 17 (12 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=83.3) were respectively introduced into the autoclave. On completion, 65 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 5.

Example 36: copolymerisation of ethylene and 1-hexene with catalyst C18

[0510] The same procedures as previously described in Example 19 were used, with the difference that 22.62 mg of catalyst C18 prepared in accordance with Example 18 (12 μmol Ti) as a suspension in approx. 10 ml of n-decane, and 1 ml of a 1 M solution of TIBA (molar Al/Ti ratio=83.36) were respectively introduced into the autoclave. On completion, 69 g of ethylene/1-hexene copolymer were obtained having the characteristics stated in Table 5.

TABLE-US-00005 TABLE 5 Copolymerisation of ethylene/1-hexene with catalysts supported on MgCl.sub.2; initial temperature 190° C.; cocatalyst TIBA; P.sub.total = 15 bar. Ti AI.sub.TIBA/ 1-Hexene Yield Activity MFI 2.16 Density Example Cat. (mg) Ti (ml) (g) (kg/g.sub.Ti) g/10′ g/cm.sup.3 33 C15 0.41 58.8 75 92 224 0.85 0.929 Mg/Ti 34 C16 0.64 58.8 75 87 136 0.12 0.926 Mg/Ti/Zr 35 C17 0.61 83.3 75 65 107 0.20 0.927 Mg/Ti/Hf 36 C18 0.75 83.4 75 69 92 0.18 0.925 Mg/Ti/Hf