SOLID SUPPORT MATERIAL

Abstract

Solid support materials are described for use as supports for olefin polymerisation catalysts. Also described is a process for the preparation of the solid support materials and the use of the solid support materials as supports in olefin polymerisation reactions.

Claims

1. A solid support material suitable for supporting an olefin polymerisation catalyst, the solid support material comprising: a) a layered double hydroxide; b) a methylaluminoxane associated with the layered double hydroxide; and c) a compound or moiety having a structure according to formula (I) and/or (II) shown below: ##STR00038## wherein X represents a portion of the layered double hydroxide or the methylaluminoxane, or X is hydrogen, halo, hydroxyl or aryl optionally substituted with one or more groups selected from halo, hydroxyl, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl and (1-4C)haloalkyl; Y is O, B(Q) or Al(Q) wherein Q is halo, hydroxyl or aryl optionally substituted with one or more groups selected from halo, hydroxyl, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl and (1-4C)haloalkyl; each R.sup.x is independently selected from halo, hydroxyl, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl and (1-4C)haloalkyl, and/or two adjacent groups R.sup.x are linked, such that, when taken in combination with the atoms to which they are attached, they form a 6-membered aromatic ring that is optionally substituted with one or more groups selected from halo, hydroxyl, (1-4C)alkyl, (2-4C)alkenyl, (2-4C)alkynyl and (1-4C)haloalkyl; and q is 0 to 5; ##STR00039## wherein X.sup.1 and X.sup.2 are independently selected from OH, COOH, SH, PR.sup.vR.sup.wH and NR.sup.vH, or their deprotonated forms; rings A.sup.1 and A.sup.2 are independently aromatic or heteroaromatic, and are optionally substituted with one or more groups R.sup.1 selected from OH, COOH, NR.sup.vR.sup.w, halo, (1-5C)alkyl, (2-5C)alkenyl, (2-5C)alkynyl, (1-5C)alkoxy, aryl and heteroaryl; L.sup.1, L.sup.2 and L.sup.3 are independently selected from (1-5C)alkylene and phenylene, and are optionally substituted with one or more groups selected from OH, halo, (1-3C)alkyl and (1-3C)haloalkyl; R.sup.v and R.sup.w are independently selected from hydrogen and (1-4C)alkyl; m is 0 or 1; n is 0 or 1; o is 0 or 1; and p is 0 or 1.

2. The solid support material of claim 1 or 2, wherein X represents a portion of the layered double hydroxide or the methylaluminoxane, or X is perfluorophenyl or hydrogen.

3. The solid support material of claim 1, 2 or 3, wherein Y is O or B(Q).

4. The solid support material of any preceding claim, wherein Q is selected from chloro, hydroxyl or phenyl optionally substituted with one or more groups selected from chloro, fluoro, hydroxyl, (1-4C)alkyl and (1-4C)haloalkyl.

5. The solid support material of any preceding claim, wherein Q is perfluorophenyl.

6. The solid support material of any preceding claim, wherein each R.sup.x is independently selected from chloro, fluoro, hydroxyl, (1-4C)alkyl and (1-4C)fluoroalkyl.

7. The solid support material of any preceding claim, wherein all R.sup.x groups are identical.

8. The solid support material of any preceding claim, wherein all R.sup.x groups are fluoro.

9. The solid support material of any preceding claim, wherein q is 1, 2 or 5.

10. The solid support material of any preceding claim, wherein X represents a portion of the layered double hydroxide or the methylaluminoxane, or X is perfluorophenyl or hydrogen; Y is O or B(Q); Q is phenyl substituted with one or more groups selected from chloro and fluoro; each R.sup.x is independently selected from chloro and fluoro; and q is 1, 2 or 5.

11. The solid support material of any preceding claim, wherein the modifying compound or moiety having a structure according to formula (I) has any one or more of the following structures: ##STR00040##

12. The solid support material of any preceding claim, wherein the modifying compound or moiety having a structure according to formula (I) has any one or more of the following structures: ##STR00041## wherein X.sup.a represents a portion of the layered double hydroxide or the methylaluminoxane, or X.sup.a is hydrogen; X.sup.b represents a portion of the layered double hydroxide or the methylaluminoxane, or X.sup.b is perfluorophenyl; and Q is perfluorophenyl.

13. The solid support material of any preceding claim, wherein the modifying compound or moiety of formula (II) has any one or more of the following structures: ##STR00042## wherein X.sup.1 and X.sup.2 are OH, or its deprotonated form.

14. The solid support material of any preceding claim, wherein the modifying compound or moiety of formula (II) has any one or more of the following structures: ##STR00043## wherein X.sup.1 and X.sup.2 are OH, or its deprotonated form.

15. The solid support material of any preceding claim, wherein the solid support material comprises 50-70 wt % of layered double hydroxide and 30-50 wt % of methylaluminoxane relative to the total mass of the solid support material.

16. The solid support material of any preceding claim, wherein the solid support material comprises 0.1-12.0 mol % of the compound of formula (I) and/or formula (II) relative to the number of moles of aluminium in the methylaluminoxane.

17. The solid support material of any preceding claim, wherein the layered double hydroxide is a Mg/Al, Ca/Al, Ni/Al, Cu/Al or a Zn/Al layered double hydroxide.

18. The solid support material of any preceding claim, wherein the layered double hydroxide comprises at least one anion selected from carbonate, nitrate, nitrite and sulphate.

19. The solid support material of any preceding claim, wherein the layered double hydroxide is a magnesium aluminium carbonate layered double hydroxide.

20. A process for the preparation of a solid support material as defined in any preceding claim, the process comprising the steps of: a) thermally treating a layered double hydroxide at a temperature of 100-500 C.; b) in a suitable solvent, combining, in a single or multiple steps, the thermally-treated layered double hydroxide, a methylaluminoxane and a compound having a structure according to formula (I) and/or formula (II) as defined in any preceding claim, c) isolating the product resulting from step b).

21. The process of claim 20, wherein step b) comprises the sub-steps: bi) contacting, in a first solvent, the thermally-treated layered double hydroxide and the methylaluminoxane (optionally under sonication), and bii) contacting, in a second solvent, the product resulting from step b)i) with the compound of formula (I) and/or formula (II).

22. The process of claim 21, wherein the first and second solvents are identical or different.

23. The process of claim 21 or 22, wherein the first and second solvents are independently selected from toluene, hexane, benzene, pentane and a mixture of two or more thereof.

24. The process of any one of claim 21, 22 or 23, wherein any one or more of the sub-steps of step b) is conducted at a temperature of 18-120 C.

25. The process of claim 24, wherein any one or more of the sub-steps of step b) is conducted at a temperature of 50-100 C.

26. The process of any one of claims 20 to 25, wherein the amount of MAO used in step b) is 30-70 wt % based on the mass of the layered double hydroxide pre-thermal treatment.

27. The process of any one of claims 20 to 26, wherein the amount of MAO used in step b) is 35-45 wt % based on the mass of the layered double hydroxide pre-thermal treatment.

28. The process of any one of claims 20 to 27, wherein the amount of the compound of formula (I) and/or formula (II) used in step b) is 0.1-12.0 mol % relative to the number of moles of aluminium in the methylaluminoxane.

29. The process of any one of claims 20 to 28, wherein the amount of the compound of formula (I) and/or formula (II) used in step b) is 0.1-7.5 mol % relative to the number of moles of aluminium in the methylaluminoxane.

30. The process of any one of claims 20 to 29, wherein step a) comprises thermally treating a layered double hydroxide at a temperature of 120-200 C.

31. A solid support material obtainable by the process of any one of claims 20 to 30.

32. A catalytic composition comprising an olefin polymerisation catalyst supported on a solid support material as defined in any one of claims 1 to 10 and 31.

33. The catalytic composition of claim 32, wherein the olefin polymerisation catalyst has any of the structures shown below: ##STR00044##

34. The catalytic composition of claim 32 or 33, wherein the olefin polymerisation catalyst has any of the structures shown below: ##STR00045##

35. The catalytic composition of claim 33 or 34, wherein [Al.sub.MAO]/[Zr] (i.e. the number of moles of Al in the methylaluminoxane of the solid support material divided by the number of moles of Zr in the olefin polymerisation catalyst) is 50-250.

36. The catalytic composition of claim 35, wherein [Al.sub.MAO]/[Zr] is 75-225.

37. A process for the preparation of a polyolefin, the process comprising the step of: a) contacting olefin monomers with a catalytic composition as defined in any one of claims 32 to 36.

38. The process of claim 37, wherein the polyolefin is polyethylene and the olefin monomers are ethene molecules.

Description

EXAMPLES

[0459] One or more examples of the invention will now be described, for the purpose of illustration only, with reference to the accompanying figure, in which:

[0460] FIG. 1 shows the effect of the temperature of LDH thermal treatment under vacuum of Mg.sub.3AlCO.sub.3-EtOH AMO-LDH on the polymerisation activity of LDHMMAO-(.sup.n BuCp).sub.2ZrCl.sub.2. Error bars shown as the root mean square standard deviation.

[0461] FIG. 2 shows the effect of the temperature of thermal treatment under vacuum of Mg.sub.3AlCO.sub.3-EtOH AMO-LDH on the polymerisation activity of LDHMAO-(.sup.nBuCp).sub.2ZrCl.sub.2 and LDHMAO-rac-(EBI)ZrCl.sub.2. Error bars shown as the root mean square standard deviation.

[0462] FIG. 3 shows SEM imaging of LDHMAO particles formed by swirling (left) or sonicating (right) Mg.sub.3AlCO.sub.3-acetone AMO-LDH pre-treated at 150 C. under vacuum and MAO (40 wt % based on initial LDH mass) in toluene at 80 C. for 2 hours.

[0463] FIG. 4 shows the effect of the synthetic method on the polymerisation activity for catalysts based on Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally pre-treated at 150 C. under vacuum, MAO (dried, 40 wt % based on initial LDH mass) and rac-(EBI)ZrCl.sub.2 (Al/Zr=100) prepared by methods 5, 6 and 7 (Scheme 4). Error bars shown as the root mean square standard deviation.

[0464] FIG. 5 shows the effect of increasing the MAO loading from 40 to 60 wt % based on the initial LDH mass and varying the Al:Zr ratio on the polymerisation activity for LDHMAO-rac-(EBI)ZrCl.sub.2 catalyst, where LDHMAO was formed by sonication (Method 6). LDH=Mg.sub.3AlCO.sub.3-acetone thermally pre-treated at 150 C. under vacuum for 6 hours. Error bars shown as the root mean square standard deviation.

[0465] FIG. 6 shows SEM imaging of Mg.sub.3AlCO.sub.3-acetone AMO-LDH particles pre-treated at 150 C. under vacuum either untreated (left) or having been sonicated for 1 hour in toluene (right).

[0466] FIG. 7 shows the effect of the synthesis method with untreated or sonicated LDH particles on the polymerisation activity for LDHMAO-rac-(EBI)ZrCl.sub.2 catalysts formed from Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally pre-treated at 150 C. under vacuum for 6 hours, 60 wt % MAO and rac-(EBI)ZrCl.sub.2 (Al/Zr=100). Error bars shown as the root mean square standard deviation.

[0467] FIG. 8 shows the ethylene polymerisation activity of LDHMAOBCF based catalysts as a function of BCF loading (mol %). Error bars shown as the root mean square standard deviation.

[0468] FIG. 9 shows the molecular weight distribution of the polymer produced by LDHMAOBCF-(.sup.nBuCp).sub.2ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading).

[0469] FIG. 10 shows the molecular weight distribution of the polymer produced by LDHMAOBCF-rac-(EBI)ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading).

[0470] FIG. 11 shows the ethylene polymerisation activity of LDHMAOBCF based catalysts formed by heating at 80 C. during the modification as a function of BCF loading (mol %). Error bars shown as the root mean square standard deviation.

[0471] FIG. 12 shows the molecular weight distribution of the polymer produced by LDHMAOBCF-(.sup.nBuCp).sub.2ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading).

[0472] FIG. 13 shows the molecular weight distribution of the polymer produced by LDHMAOBCF-rac-(EBI)ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading).

[0473] FIG. 14 shows a comparison between the ethylene polymerisation activity of LDHMAOBF-rac-(EBI)ZrCl.sub.2 where the modification was performed either by sonicating or heating at 80 C. as a function of modifier loading (mol %). %). Error bars shown as the root mean square standard deviation.

[0474] FIG. 15 shows the ethylene polymerisation activity of LDHMAOTFHQ-rac-(EBI)ZrCl.sub.2 as a function of TFHQ loading (mol %). Error bars shown as the root mean squared standard deviation.

[0475] FIG. 16 shows a comparison between the ethylene polymerisation activity of TFHQ modified supports formed by swirling or sonication with their unmodified analogues for both (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 based catalyst systems. Error bars shown as the root mean squared standard deviation.

PART A

Example 1Preparation of Solid Support Materials

1.1 Preparation of LDH Precursors

[0476] Following the procedure outlined in Chen, C.; Yang, M.; Wang, Q.; Buffet, J.-C.; O'Hare, D. Synthesis and Characterisation of Aqueous Miscible Organic-Layered Double Hydroxides. J. Mater. Chem. A 2014, 2 (36), 15102-15110, layered double hydroxides (LDHs) were synthesised by co-precipitation followed by AMO washing (acetone or ethanol). For the results presented here Mg.sub.3AlCO.sub.3 and Mg.sub.3Al-504 LDHs were utilised.

[0477] The LDH precursor (1 g) was loaded into a crucible and place inside a quartz tube that was sealed at one end. This was then connected to a vacuum/nitrogen manifold at the other and placed under dynamic vacuum (10.sup.3 mbar). By utilising a tube furnace the sample could be heated to a desired temperature (100-500 C.) at a controlled ramp rate of 5 C. min.sup.1 at which it was held for six hours. After cooling, the tube was transferred to a nitrogen filled glovebox under static vacuum, where the dehydroxylated samples were stored in sealed vials.

1.2 Modification of LDH Precursors

[0478] The solid support materials were prepared by modification of the LDH precursors with methylaluminoxane (MAO) and an organic/organometallic modifier (namely B(C.sub.6F.sub.5).sub.3 or C.sub.6F.sub.5OH). The three reagents can be combined in multiple ways: prior reaction of the modifier with the LDH surface followed by treatment with MAO (Method 1), one-pot combined reaction with modifier, MAO and the LDH (Method 2), prior modification of the MAO followed by impregnation on the LDH surface (Method 3), or finally, post modification of the LDHMAO support (Method 4).

[0479] The different synthetic protocols are outlined below in more detail:

##STR00035##

[0480] Reaction with the modifiers can be achieved by reaction in toluene utilising sonication, swirling, or heating and swirling usually over the course of 1 hour.

Example 2Preparation of Catalytic Compositions

[0481] The isolated solid support materials from Example 1 were reacted with (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (shown below) in toluene at 60 C. for 1 hours. Addition of the solvent to the Schlenk flask yielded a pale yellow solution. Swirling with heating led to a gradual discolouration of the solution which ultimately became clear and colourless, indicative of complete immobilisation of the metallocene precursor. The resulting powders after drying were pale yellow

##STR00036##

Example 3Polymerisation Studies

3.1 General Protocol for Polymerisation Experiments

[0482] TIBA (150 mg, 0.76 mmol) was dissolved in hexane (10 mL), added to a 100 mL Rotaflo ampoule and swirled to ensure no contaminants were present. Catalytic compositions of Example 2 (10 mg) were added and washed down with hexane (40 mL), after which the ampoule was sealed. Polymerisations were conducted on a specially designed vacuum/nitrogen manifold, with a separate ethylene feed that was dried through a column of activated molecular sieves. Prior to ethylene addition, all the tubing and headspace were cycled between vacuum and N2 three times, after which the internal atmosphere of the ampoule was evacuated and the tubing cycled between vacuum and ethylene 3 times. Polymerisations were conducted at 70 C., 2 bar ethylene with a stirring speed of 1000 rpm for 30 minutes. The resulting polyethylene was collected on a frit and washed with pentane (325 mL), before being dried under vacuum overnight at room temperature.

3.2 Effect of LDH Thermal Treatment on Polymerisation Activity

[0483] Using the procedure outlined in Example 1.1, Mg.sub.3AlCO.sub.3-EtOH AMO-LDH was thermally treated for 6 hours under vacuum at 100, 200, 300, 400 and 500 C. and stored in a glovebox prior to use. Analysis of the materials shows an increase in the BET surface area and a decrease in the surface hydroxyl concentration with increased treatment temperature.

[0484] To see the effect of varying the pre-treatment temperature on the polymerisation activity, a commercially-available (Sigma Aldrich) modified MAO (termed MMAO), modified by replacement of some methyl groups with isobutyl or octyl groups, was grafted (at 40 wt %) onto the thermally treated Mg.sub.3AlCO.sub.3-EtOH AMO-LDH surfaces at 80 C. in toluene for 2 hours, followed by (.sup.nBuCp).sub.2ZrCl.sub.2 (Al/Zr=50) at 60 C. for 1 hour in toluene. Polymerisations were conducted in duplicate in hexane at 70 C. utilising triisobutylaluminium (TIBA) as a scavenger, the results are shown in (FIG. 1 and Table 1).

TABLE-US-00001 TABLE 1 Effect of the temperature of LDH thermal treatment under vacuum of Mg.sub.3AlCO.sub.3EtOH AMO-LDH on the polymer yield and polymerisation activity of LDHMMAO-(.sup.nBuCp).sub.2ZrCl.sub.2. Treatment PE Activity temperature ( C.) (mg) (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) 100 239 271 25 200 461 522 13 300 217 246 6 400 302 342 9 500 252 286 14 Mg.sub.3AlCO.sub.3-EtOH AMO-LDH thermally treated under vacuum (6 hours) impregnated with 40 wt % MMAO, (.sup.nBuCp).sub.2ZrCl.sub.2 Al/Zr = 50, 10 mg catalyst loading (0.88 mol.sub.Zr), 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0485] The activities of polymerisation range between 246 and 522 kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1, with a peak in activity observed at 200 C. A slight increase is observed at 400 C. compared to 300 and 500 C., which may be due to the increase in BET surface area between 300 and 400 C. (300 vs 361 m.sup.2g.sup.1) after loss of the layered LDH structure is seen to occur. Increase in surface area means the active sites are better dispersed and can lead to higher activity.

3.3 Effect of MAO Reagent on Polymerisation Activity

[0486] When compared with the use of the Sigma Aldrich MMAO (Example 3.2), employing unmodified MAOs supplied by Sigma Aldrich and Chemtura demonstrated an improvement in ethylene polymerisation activity. For example, the polymerisation activity of the LDHMAO-(.sup.nBuCp).sub.2ZrCl.sub.2 system (Mg.sub.3AlCO.sub.3-EtOH AMO-LDH treated at 150 C., 40 wt % unmodified MAO, Al/Zr=50) was 1,271 kg.sub.PEmol.sub.Zr.sup.1h.sup.1 bar.sup.1 (Chemtura MAO) and 671 kg.sub.PEmol.sub.Zr.sup.1h.sup.1 bar.sup.1 (Sigma Aldrich MAO), whereas the activity of the analogous composition Sigma Aldrich MMAO (Example 3.2) was 497 kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1.

3.4 Effect of Modifier on Polymerisation Activity

[0487] The impact of modifiers on the activity was also tested for both (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 complexes immobilised on MAO (Sigma Aldrich) (Table 2). In both cases addition of 2.5 mol % of modifier (B(C.sub.6F.sub.5).sub.3 or C.sub.6F.sub.5OH) to LDHMAO at room temperature with sonication resulted in a solid support material exhibiting lower ethylene polymerisation activity when compared to the corresponding unmodified control (LDHMAO). For the (.sup.nBuCp).sub.2ZrCl.sub.2 catalyst, two modification methods with B(C.sub.6F.sub.5).sub.3 were employed; one where both the B(C.sub.6F.sub.5).sub.3 and MAO where mixed with LDH in toluene and heated at 80 C., so called LDH-(MAO+BCF) (Method 2 of Example 1.2), and one where B(C.sub.6F.sub.5).sub.3 was first reacted with the LDH surface at 80 C. for 2 hours in toluene and then MAO was impregnated under the same conditions, called LDHBCF-MAO (Method 1 of Example 1.1). For the former, a small increase in ethylene polymerisation activity within the error was observed.

TABLE-US-00002 TABLE 2 Effect on the polymer yield and polymerisation activity of (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 supported on LDHMAO modified with B(C.sub.6F.sub.5).sub.3 or C.sub.6F.sub.5OH. PE Activity Support Zirconocene (mg) (kg.sub.PEmol.sub.Zr.sup.-1h.sup.-1bar.sup.-1) LDHMAO (.sup.nBuCp).sub.2ZrCl.sub.2 473 497 31 rac-(EBI)ZrCl.sub.2 541 569 25 LDHMAO-BCF (.sup.nBuCp).sub.2ZrCl.sub.2 417 438 18 rac-(EBI)ZrCl.sub.2 160 168 12 LDH-(MAO + BCF) (.sup.nBuCp).sub.2ZrCl.sub.2 480 505 20 LDHBCF-MAO (.sup.nBuCp).sub.2ZrCl.sub.2 323 339 12 LDHMAO-C.sub.6F.sub.5OH (.sup.nBuCp).sub.2ZrCl.sub.2 104 110 5 rac-(EBI)ZrCl.sub.2 76 80 7 Mg.sub.3AlCO.sub.3EtOH AMO-LDH thermally treated under vacuum (6 hours) at 150 C. impregnated with 40 wt % MAO (Sigma Aldrich), 2.5 mol % loading of modifier based on mol % aluminium from MAO, Al/Zr = 50, 10 mg catalyst loading (0.88 mol.sub.Zr), 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

PART B

Example 4Polymerisation Studies

4.1 Effect of LDH Thermal Treatment on Polymerisation Activity

[0488] Using the procedure outlined in Example 1.1, Mg.sub.3AlCO.sub.3-EtOH AMO-LDH was thermally treated for 6 hours under vacuum at 100, 200, 300, 400 and 500 C. and stored in a glovebox prior to use. Analysis of the materials shows an increase in the BET surface area and a decrease in the surface hydroxyl concentration with increased treatment temperature.

[0489] To see the effect of varying the pre-treatment temperature on the polymerisation activity, MAO (Chemtura, 40 wt % based on initial LDH mass) was grafted onto the thermally treated Mg.sub.3AlCO.sub.3-EtOH AMO-LDH surfaces at 80 C. in toluene for 2 hours, followed by either (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr=100) at 60 C. for 1 hour in toluene. Polymerisations were conducted in duplicate in hexane (50 mL) at 70 C. for 30 minutes utilising triisobutylaluminium (TIBA, 150 mg) as a scavenger, the results are shown in (FIG. 2 and Table 3).

TABLE-US-00003 TABLE 3 Effect of the temperature of thermal treatment under vacuum of Mg.sub.3AlCO.sub.3EtOH AMO-LDH on the polymer yield and polymerisation activity of LDHMAO-(.sup.nBuCp).sub.2ZrCl.sub.2 and LDHMAO-rac-(EBI)ZrCl.sub.2. Treatment PE (g) Activity (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) temperature ( C.) (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 100 1.26 0.76 2601 165 1582 18 200 1.16 0.94 2403 32 1945 28 300 1.02 1.22 2122 56 2519 91 400 1.13 1.31 2347 10 2715 98 500 0.93 0.60 1928 70 1246 56 Mg.sub.3AlCO.sub.3EtOH AMO-LDH thermally treated under vacuum (6 hours) impregnated with 40 wt % MAO, (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr = 100), 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0490] The two complexes supported on LDHMAO show differing trends in activity with respect to thermal pre-treatment temperature of the LDH precursor. For (.sup.nBuCp).sub.2ZrCl.sub.2, the activity slightly decreases across the temperature range but maintains fairly constant. In contrast, rac-(EBI)ZrCl.sub.2 displays a steady increase in activity between 100 and 400 C., however a sharp drop in activity is observed at 500 C. This suggests that rac-(EBI)ZrCl.sub.2 is more sensitive to changes in the support than (.sup.nBuCp).sub.2ZrCl.sub.2 appearing to favour a more dehydroxylated layered oxide based support.

4.2 Effect of Catalyst Synthesis Method on Polymerisation Activity

[0491] The catalyst preparation process was varied in an attempt to optimise the properties of the catalyst (Scheme 4).

##STR00037##

[0492] From SEM imaging of the LDHMAO particles formed from swirling LDH and MAO at 80 C. for 2 hours (Scheme 4, Method 5) it was seen that aggregation of particles occurred leading to a broad particle size distribution (FIG. 3). To see if a narrower size range and more even MAO coating of the particles could be obtained, sonication during the LDHMAO synthesis at 80 C. was attempted (Scheme 4, Method 6). From this method much smaller LDHMAO particles were obtained, suggesting that the MAO coating of sonicated particles inhibits particle aggregation.

[0493] In order to form the solid catalysts LDHMAO formed by swirling or sonicating was reacted with a metallocene pre-catalyst (Al/Zr=100) in toluene at 60 C. for 1 hour (Scheme 4, Methods 5 and 6). Alternatively, the solid catalyst was formed by incipient wetness impregnation whereby a mixture of LDH, MAO (40 wt % based on mass of LDH) and metallocenes pre-catalyst (Al/Zr=100) were heated at 60 C. for 1 hour with regular swirling (Scheme 4, Method 7). The resulting solid catalysts were tested for their slurry-phase ethylene polymerisation activity (Table 4 and FIG. 4).

TABLE-US-00004 TABLE 4 Effect of the synthetic method on the polymerisation activity for catalysts based on Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally pre-treated at 150 C. under vacuum, MAO (dried, 40 wt % based on initial LDH mass) and rac-(EBI)ZrCl.sub.2 (Al/Zr = 100) prepared by methods 5, 6 and 7 (Scheme 4). Synthesis method PE (g) Activity (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) 5 1.41 2846 49 6 1.66 3431 75 7 0.94 1944 7 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours) impregnated with 40 wt % MAO, rac-(EBI)ZrCl.sub.2 (Al/Zr = 100), 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0494] From the activity data, the most active system is formed when the LDHMAO was sonicated during synthesis. This is believed to be due to the reduction in aggregation of particles, leading to a more even MAO coating and a greater particle surface area.

[0495] To further try and enhance the activity of the LDHMAO system formed by sonication (Method 6), the MAO loading was increased to 60 wt % based on the initial based of LDH. Two different metallocene pre-catalyst loadings were utilised and compared to the solid catalyst formed with 40 wt % MAO. The first loading maintained an Al:Zr of 100, whilst the second compared the activity when the molar loading of zirconium in the final catalyst was the same (0.48 pmolz.sub.r in 10 mg of catalyst). Increasing the MAO loading to 60 wt % leads to an increase in the activity of the system (FIG. 5 and Table 5). Moreover, maintaining the same zirconium loading in the same final catalyst (Al/Zr=130 for 60 wt % MAO support), leads to a greater enhancement in activity, 1.42 times that of the 40 wt % support.

TABLE-US-00005 TABLE 5 Effect of increasing the MAO loading from 40 to 60 wt % based on the initial LDH mass and varying the Al:Zr ratio on the polymerisation activity for LDHMAO-rac-(EBI)ZrCl.sub.2 catalyst, where LDHMAO was formed by sonication (Method 6). MAO loading Activity (wt %) Al/Zr PE (g) (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) 40 100 1.66 3431 75 60 100 2.51 3964 49 60 130 2.36 4873 61 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours) impregnated by sonication with either 40 or 60 wt % MAO, rac-(EBI)ZrCl.sub.2 (Al/Zr = 100 or 130), 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0496] As controls, the LDHMAO-rac-(EBI)ZrCl.sub.2 systems with 60 wt % MAO were also synthesised by swirling during the LDHMAO synthesis (Method 5) using the thermally pre-treated LDH either as is or having sonicated it for 1 hour in toluene to see if this would reduce particle aggregation. SEM imaging of the thermally pre-treated LDH with and without sonication showed that particle aggregation was reduced to some extent by sonication but a broad particle size distribution was still observed (FIG. 6).

[0497] For the catalysts synthesised by swirling during the LDHMAO synthesis (Method 5) with 60 wt % MAO, the activities increased (FIG. 7 and Table 6) compared to the 40 wt % MAO catalyst formed from method 5 (FIG. 4 and Table 4). There is very little difference in activity between the sonicated and untreated LDH, however both are lower than the catalyst formed by method 6. This could be due to aggregation of the sonicated LDH particles after drying, which may be inhibited by method 6 due to the MAO coating on the surface.

TABLE-US-00006 TABLE 6 Effect of the synthesis method with untreated or sonicated LDH particles on the polymerisation activity for LDHMAO-rac-(EBI)ZrCl.sub.2 catalysts formed from Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally pre-treated at 150 C. under vacuum for 6 hours, 60 wt % MAO and rac-(EBI)ZrCl.sub.2 (Al/Zr = 100). Synthesis Activity LDH method PE (g) (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) Untreated 5 2.14 3382 89 Sonicated 5 2.09 3303 76 Untreated 6 2.51 3964 49 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours) either untreated or sonicated for 1 hour in toluene, impregnated by either with swirling or sonication with 60 wt % MAO, rac-(EBI)ZrCl.sub.2 (Al/Zr = 100), 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

4.2 Effect of Modifier on Polymerisation Activity

[0498] LDHMAO was synthesised by swirling (Method 5) Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally pre-treated at 150 C. under vacuum for 6 hours and Chemtura MAO (40 wt % based on the initial mass of LDH).

4.2.1 Tris-pentafluorophenyl Borane (B(C.sub.6F.sub.5).sub.3 or BCF)

[0499] Tris-pentafluorophenyl borane (B(C.sub.6F.sub.5).sub.3 or BCF) was reacted with the LDHMAO by room temperature sonication in toluene for 1 hour. The solid was filtered, washed with toluene (220 mL) followed by hexane (220 mL) and dried. The BCF loading was varied from 5 to 10 mol % based on the aluminium present in the MAO. The resulting LDHMAOBCF was reacted with either (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr=100) at 60 C. for 1 hour in toluene. Solid catalysts were isolated by filtration of the clear and colourless toluene solution followed by drying under vacuum. The ethylene polymerisation activities of the catalysts are shown in FIG. 8 and Table 7. The rac-(EBI)ZrCl.sub.2 system shows an increase in activity at 5 and 10 mol % BCF loading compared to the control.

TABLE-US-00007 TABLE 7 Ethylene polymerisation activity of LDHMAOBCF based catalysts as a function of BCF loading (mol %). BCF loading PE (g) Activity (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) (mol %) (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 0 1.77 1.14 3653 98 2342 25 5 1.52 1.81 3130 22 3703 155 10 1.24 1.29 2567 54 2650 49 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours), impregnated with 40 wt % MAO, BCF (0, 5 or 10 mol %) and (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr = 100), 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0500] Gel permeation chromatography (GPC) traces of the polymer produced showed a marked difference between the (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 based systems (FIGS. 9 and 10 and Tables 8 and 9). For the (.sup.nBuCp).sub.2ZrCl.sub.2 a small increase is observed in the number average molecular weights for the polymer as the BCF loading is increased whilst maintaining narrow polydispersity. For the rac-(EBI)ZrCl.sub.2 based catalysts an increase in molecular weight is observed with increased BCF loading, however the GPC trace appears to be bimodal, with broad PDI values suggesting the catalyst is no longer single-site in nature.

TABLE-US-00008 TABLE 8 Number average molecular weight (Mw), number average molecular number (Mn) and polydispersity (PDI) values for the polymer produced by LDHMAOBCF-(.sup.nBuCp).sub.2ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading). BCF loading (%) Mw (gmol.sup.1) Mn (gmol.sup.1) PDI (Mw/Mn) 0 176300 66900 2.6 5 203100 71100 2.9 10 225100 80900 2.8

TABLE-US-00009 TABLE 9 Number average molecular weight (Mw), number average molecular number (Mn) and polydispersity (PDI) values for the polymer produced by LDHMAOBCF-rac-(EBI)ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading). BCF loading (%) Mw (gmol.sup.1) Mn (gmol.sup.1) PDI (Mw/Mn) 0 174200 64700 2.7 5 187500 37200 5.0 10 213300 41000 5.2

[0501] To try and quantify the BCF loading in each case the rac-(EBI)ZrCl.sub.2 based catalysts were analysed by ICP-MS (Table 10). With increased BCF loading the aluminium weight percent in the LDHMAO and final catalysts are expected to decrease. A theoretical Al wt % can be calculated by assuming transfer of one C.sub.6F.sub.5 group per mole of BCF. From the results it can be seen that the Al wt % does decrease with increased BCF loadings, however the results suggest that either more than one equivalent of C.sub.6F.sub.5 is transferred per mole of BCF or that some of the borane may immobilise on the surface.

TABLE-US-00010 TABLE 10 ICP-MS analysis of AMO-LDH, thermally treated AMO-LDH, LDHMAO, BCF modified LDHMAOs (5 and 10 mol %) and the catalysts formed with rac-(EBI)ZrCl.sub.2. BCF Theoretical loading Calculated Material MAO wt % Al (mol %) Mg/Al MAO wt % Al Al/Zr Mg.sub.2.87AlCO.sub.3-acetone N/A N/A 2.87 N/A N/A AMO-LDH (Mg.sub.2.98AlCO.sub.3-acetone)150 C. N/A N/A 2.98 N/A N/A LDHMAO 13.3 0 1.13 13.2 N/A LDHMAOBCF 12.8 5 1.16 11.5 N/A LDHMAOBCF 12.4 10 1.16 11.9 N/A LDHMAO-rac-(EBI)ZrCl.sub.2 13.1 0 1.14 10.1 82.0 LDHMAOBCF-rac-(EBI)ZrCl.sub.2 12.7 5 1.15 11.8 94.7 LDHMAOBCF-rac-(EBI)ZrCl.sub.2 12.2 10 1.15 12.1 119.3 Digestions performed in 2.5 mL conc. HNO.sub.3 at 60 C. for 2 hours, followed by two 100-fold dilutions with DI water.

[0502] Catalysts were synthesised by reaction of LDHMAO and BCF (0, 5 and 10 mol %) in toluene at 80 C. for 1 hour with regular swirling followed by immobilisation of either (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr=100) at 60 C. for 1 hour in toluene. In analogy to the sonicated support, the rac-(EBI)ZrCl.sub.2 based catalysts activity is again seen to increase with increased loading (FIG. 11 and Table 11), and this increase is maintained at 10 mol % BCF loading. The peak activity at 5 mol % is 1.9 times more active than the control.

TABLE-US-00011 TABLE 11 Ethylene polymerisation activity of LDHMAOBCF based catalysts formed by heating at 80 C. during the modification as a function of BCF loading (mol %). BCF loading PE (g) Activity (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) (mol %) (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 (.sup.nBuCp).sub.2ZrCl.sub.2 rac-(EBI)ZrCl.sub.2 0 1.77 1.14 3653 98 2342 25 5 1.44 2.19 2972 106 4475 86 10 1.44 2.06 2980 11 4217 251 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours), impregnated with 40 wt % MAO, BCF (0, 5 or 10 mol %) and (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr = 100). 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0503] Gel permeation chromatography (GPC) traces of the polymer produced by the (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 based systems are analogous to those observed when the LDHMAOBCF support was sonicated during modification (FIGS. 12 and 13 and Tables 12 and 13). For the (.sup.nBuCp).sub.2ZrCl.sub.2 a small increase is observed in the number average molecular weights for the polymer as the BCF loading is increased whilst maintaining narrow polydispersity. For the rac-(EBI)ZrCl.sub.2 based catalysts an increase in molecular weight is observed with increased BCF loading, however the GPC trace appears to be bimodal, with broad PDI values suggesting the catalyst is no longer single-site in nature.

TABLE-US-00012 TABLE 12 Number average molecular weight (Mw), number average molecular number (Mn) and polydispersity (PDI) values for the polymer produced by LDHMAOBCF-(.sup.nBuCp).sub.2ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading). BCF loading (%) Mw (gmol.sup.1) Mn (gmol.sup.1) PDI (Mw/Mn) 0 176300 66900 2.6 5 197300 71400 2.8 10 195300 68900 2.8

TABLE-US-00013 TABLE 13 Number average molecular weight (Mw), number average molecular number (Mn) and polydispersity (PDI) values for the polymer produced by LDHMAOBCF-rac-(EBI)ZrCl.sub.2 catalysts (0, 5, 10 mol % BCF loading). BCF loading (%) Mw (gmol.sup.1) Mn (gmol.sup.1) PDI (Mw/Mn) 0 174200 64700 2.7 5 179000 33300 5.4 10 171900 31800 5.4

[0504] Comparison of the activity between the LDHMAOBCF-rac-(EBI)ZrCl.sub.2 catalysts formed either by sonicating or swirling during the modification step (FIG. 14), shows that the heated sample displays increased activity at both 5 and 10 mol % BCF loading compared to the sonicated support. The peak activity at 5 mol % BCF loading is 1.2 times more active than the sonicated analogue.

4.2.2 Tetrafluorohydroquinone (TFHQ)

[0505] LDHMAO and tetrafluorohydroquinone (TFHQ) (0, 1, 2, 5, 10 and 20 mol %) were sonicated in toluene at room temperature for 1 hour followed by filtration, washing with toluene (220 mL) and drying in vacuo. The resulting LDHMAOTFHQ supports were reacted with rac-(EBI)ZrCl.sub.2 (Al/Zr=100) in toluene at 60 C. for 1 hour after which the supernatant was removed by filtration and the solid dried. The activity towards ethylene polymerisation of the resulting catalysts are shown in FIG. 15 and Table 14. As the amount of modifier in the system is increased the ethylene polymerisation activity is seen to decrease.

TABLE-US-00014 TABLE 14 Ethylene polymerisation activity of LDHMAOTFHQ-rac- (EBI)ZrCl.sub.2 as a function of TFHQ loading (mol %). TFHQ loading (mol %) PE (mg) Activity (kg.sub.PEmol.sub.Zr.sup.1h.sup.1bar.sup.1) 0 960 1989 32 1 808 1687 62 2 823 1729 41 5 466 1000 31 10 119 263 4 20 59 139 3 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours), impregnated with 40 wt % MAO, TFHQ (0, 1, 2, 5, 10, 20 mol %) and rac-(EBI)ZrCl.sub.2 (Al/Zr = 100). 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0506] To see if sonication during the modification system was detrimental to the system the modification was also performed with 5 mol % TFHQ by regular swirling at room temperature. Catalyst systems based on (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 were synthesised and compared to the unmodified systems (FIG. 16 and Table 15). The activity of the modified support formed by swirling is much higher than when sonication was employed, which may be due to sonication breaking up LDHMAO aggregates exposing unreacted hydroxyl groups which then deactivate the metallocenes pre-catalyst. However, for both (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 the TFHQ modified supports are less active than the unmodified analogue.

TABLE-US-00015 TABLE 15 Comparison between the ethylene polymerisation activity of TFHQ modified supports formed by swirling or sonication with their unmodified analogues for both (.sup.nBuCp).sub.2ZrCl.sub.2 and rac-(EBI)ZrCl.sub.2 based catalyst systems. Modification TFHQ loading Metallocene Activity method (mol %) pre-catalsyt PE (g) (kg.sub.PEmolz.sub.r.sup.1h.sup.1bar.sup.1) Swirled 0 (.sup.nBuCp).sub.2ZrCl.sub.2 0.94 1951 21 Swirled 5 (.sup.nBuCp).sub.2ZrCl.sub.2 0.62 1331 33 Swirled 0 rac-(EBI)ZrCl.sub.2 1.08 2233 14 Swirled 5 rac-(EBI)ZrCl.sub.2 0.99 2134 25 Sonicated 0 rac-(EBI)ZrCl.sub.2 0.96 1989 32 Sonicated 5 rac-(EBI)ZrCl.sub.2 0.47 1000 31 Mg.sub.3AlCO.sub.3-acetone AMO-LDH thermally treated at 150 C. under vacuum (6 hours), impregnated with 40 wt % MAO, TFHQ (0 or 5 mol %) and (.sup.nBuCp).sub.2ZrCl.sub.2 or rac-(EBI)ZrCl.sub.2 (Al/Zr = 100). 10 mg catalyst loading, 2 bar ethylene, 50 mL hexane, 150 mg TIBA, 1000 rpm, 70 C., 0.5 hours. Error calculated as the root mean square standard deviation.

[0507] While specific embodiments of the invention have been described herein for the purpose of reference and illustration, various modifications will be apparent to a person skilled in the art without departing from the scope of the invention as defined by the appended claims.