METHOD FOR PREPARING A CATALYST

Abstract

The present invention relates to a method for preparing a catalyst, and in particular provides a method for preparing a catalyst suitable for the polymerisation of ethylene and/or propylene, said catalyst comprising a compound of yttrium, neodymium or scandium supported on a silica support, and wherein the method comprises: a) Treating a silica support by heating at a temperature of at least 550° C., b) Contacting the treated silica support with a complex of the following formula: D.sub.mMX.sup.1X.sup.2R wherein M is selected from Y, Sc and Nd, R is a hydrocarbyl group, X.sup.1 and X.sup.2 are anionic groups, D is a neutral donor group, and m is 0 or greater.

Claims

1. A method for preparing a catalyst suitable for the polymerisation of ethylene and/or propylene, said catalyst comprising a compound of yttrium, neodymium or scandium supported on a silica support, and wherein the method comprises: a) Treating a silica support by heating at a temperature of at least 550° C. to at least partially hydroxylate the silica support but leave silanol groups on the surface, b) Contacting the treated silica support with a complex of the following formula:
D.sub.mMX.sup.1X.sup.2R wherein M is selected from Y, Sc and Nd, R is a hydrocarbyl group or a substituted hydrocarbyl group, X.sup.1 and X.sup.2 are anionic groups, D is a neutral donor group, and m is 0 or greater, such that the complex reacts with a silanol and the metal (M) of the complex becomes bound to the surface through the formation of a M-O—Si bond.

2. A method for preparing a catalyst suitable for the polymerisation of ethylene and/or propylene, said catalyst comprising a compound of yttrium, neodymium or scandium supported on a silica support, and wherein the method comprises: a) Treating a silica support by heating at a temperature of at least 550° C., b) Contacting the treated silica support with a complex of the following formula:
D.sub.mMX.sup.1X.sup.2R wherein M is selected from Y, Sc and Nd, R is a hydrocarbyl group or a substituted hydrocarbyl group, X.sup.1 and X.sup.2 are anionic groups, D is a neutral donor group, and m is 0 or greater, characterised in that the silica support is not contacted with an alumoxane prior to the treatment of step (a) or the contact with the complex of step (b).

3. A method according to claim 1 wherein the silica support is not contacted with any compounds which may react with the treated silica between the treatment of step (a) and the contact with the complex of step (b), and preferably also not contacted with any such compounds prior to the treatment of step (a).

4. A method according to claim 1, wherein at least one of X.sup.1 and X.sup.2 is selected from hydride, hydrocarbyl and substituted hydrocarbyl groups.

5. A method according to claim 1, wherein both of X.sup.1 and X.sup.2 are selected from hydride, hydrocarbyl and substituted hydrocarbyl groups.

6. A method according to claim 1, wherein each of X.sup.1, X.sup.2 and R are hydrocarbyl or substituted hydrocarbyl groups.

7. A method according to claim 1 wherein at least R is an allyl or substituted allyl group, and preferably each of X.sup.1, X.sup.2 and R are allyl or substituted allyl groups.

8. A method according to claim 7 wherein the group(s) are silicon substituted allyl groups, especially trialkylsilanes.

9. A method according to claim 8 wherein the allyl group(s) are each a 1,3-C.sub.3H.sub.3(SiR′.sub.3).sub.2 group where R′ is a linear, branched or cyclic alkyl group, such as methyl, ethyl, n-propyl, tert-butyl, cyclohexyl, etc.

10. A method according to claim 1 wherein m equals 0.

11. A method according to claim 1 wherein the metal (M) content of the supported catalyst is in range 0.5 to 10 wt % metal compared to the mass of catalyst, preferably within a range of 1 to 5 wt %.

12. A method according to claim 1 wherein the metal is yttrium (Y).

13. A catalyst suitable for the polymerisation of ethylene and/or propylene, said catalyst being prepared by the method of claim 1.

14. A process for polymerisation of ethylene or propylene, which process comprises: (i) preparing a catalyst for the polymerisation of ethylene and/or propylene, said catalyst comprising a compound of yttrium, neodymium or scandium supported on a silica support, and wherein the method comprises: a) Treating a silica support by heating at a temperature of at least 550° C., b) Contacting the treated silica support with a complex of the following formula:
D.sub.mMX.sup.1X.sup.2R wherein M is selected from Y, Sc and Nd, R is a hydrocarbyl group or a substituted hydrocarbyl group, X.sup.1 and X.sup.2 are anionic groups, D is a neutral donor group, and m is 0 or greater, and (ii) contacting said catalyst with ethylene or propylene, and optionally comonomers, in a polymerisation reactor, wherein during step (ii) alkyl aluminium or other alkylating agent is either not used or is used in an amount of less than 5 moles of alkylating agent per mole of metal (M) in the catalyst.

15. A process according to claim 14 wherein the catalyst is prepared by the method of claim 1.

16. (canceled)

17. A method according to claim 2 wherein each of X.sup.1, X.sup.2 and R are hydrocarbyl or substituted hydrocarbyl groups.

18. A method according to claim 2 wherein at least R is an allyl or substituted allyl group, and preferably each of X.sup.1, X.sup.2 and R are allyl or substituted allyl groups.

19. A method according to claim 18 wherein the allyl group(s) are each a 1,3-C.sub.3H.sub.3(SiR′.sub.3).sub.2 group where R′ is a linear, branched or cyclic alkyl group, such as methyl, ethyl, n-propyl, tert-butyl, cyclohexyl, etc.

20. A method according to claim 2 wherein the metal is yttrium (Y).

21. A process according to claim 14 wherein the catalyst is prepared by the method of claim 2.

Description

EXAMPLES

Catalyst Preparation

Catalyst 1: Y Containing Catalyst, Silica Treated at 700° C.

[0089] Sylopol 2408 silica (WR Grace) was heated at 700° C. for 12 hours under a dynamic vacuum.

[0090] Y{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 was prepared according to the method described by White and Hanusa in Organometallics 2006, 25, p. 5621-5630.

[0091] The treated support was then contacted with Y{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 in hexane at room temperature. On contact the support turned rapidly yellow. After two hours the reaction was interrupted and the product dried. A bright yellow support was obtained.

[0092] The catalyst was analysed by DRIFT, which showed that all silanols on the silica surface had reacted. Based on a mass balance the composition of the catalyst is calculated as in Table 1.

TABLE-US-00001 TABLE 1 Elemental analysis results and olefin quantification. wt % wt % wt % Y C H C/Y H/Y Y mmol .Math. g.sup.−1 3.7 8.54 1.6 17.1 38.1 0.42

[0093] The 8.54 wt % of carbon found on the surface corresponds to a 17.1 C/Y ratio, which is very close to the theoretical value for (≡SiO)Y{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.2, 18 C/Y. The amount of olefin C.sub.3H.sub.4(SiMe.sub.3).sub.2 released during the grafting matches that expected for “loss” of one of the original allyl groups.

Catalyst 2: Nd Containing Catalyst, Silica Treated at 700° C.

[0094] Sylopol 2408 silica (WR Grace) was heated at 700° C. for 12 hours under a dynamic vacuum. Nd{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 was prepared in an equivalent manner to the preparation of Y{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 but using NdCl.sub.3.

[0095] The treated support was then contacted with Nd{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 in hexane at room temperature. After 24 hours the reaction the product was filtered and washed 3 times with 6 mL of toluene and 3 times with hexane (6 mL). The powder was then dried under high vacuum.

Comparative Catalyst A: Y-Containing Catalyst, Silica Treated at 200° C.

[0096] Sylopol 2408 silica (WR Grace) was heated at 200° C. for 12 hours under a dynamic vacuum.

[0097] The treated support was then contacted with Y{1,3-C.sub.3H.sub.3(SiMe.sub.3).sub.2}.sub.3 in hexane at room temperature. On contact the support turned rapidly yellow. After two hours the reaction was interrupted and the product dried. A bright yellow support was obtained.

TABLE-US-00002 wt % wt % wt % Y C H C/Y H/Y Y mmol .Math. g.sup.−1 4.92 5.15 1.11 7.75 19.9 0.55 (th.9) (th.21)

Ethylene Polymerization

[0098] 1) Small Scale Autoclave

[0099] Polymerization tests were conducted in 80 ml autoclave, with 50 ml of heptane as solvent. The reactor was pressurised with ethylene to a pressure of 10 bar. In selected experiments 1-hexene was added as comonomer. The reaction temperature was 80° C. No hydrogen was used during the polymerization.

[0100] Catalyst was injected in the reactor to initiate the reaction, and reaction was performed for 30 minutes before the reaction was stopped.

Table 1 shows the results obtained from Catalyst 1

TABLE-US-00003 TABLE 1 1- Activity Activity m.sub.support Y.sub.surface [TiBA] hexene Yield g g.sub.cat.sup.−1 Kg mol.sub.Y.sup.−1 Run mg μmol mM mol % g h.sup.−1 h.sup.−1 bar.sup.−1 1 16.5 6.9 — — 6.19  752 180 2  9.0 3.8 — 21 5.76 1280 305 3 11.2 4.7 1 21 4.77  855 203

[0101] The results from Run 1 show that the catalyst is active without the addition of TIBAL or other activating agent. The results from Run 2 show that activity is increased in the presence of 21 mol % of 1-hexene, whilst comparison of Run 3 with Run 2 shows that the addition of 1 mM of TIBAL, which is a well-known activating agent, is actually detrimental to the activity.

[0102] Table 2 shows the result obtained from Comparative Catalyst A also in the presence of TIBAL and 1-hexene:

TABLE-US-00004 TABLE 2 1- Activity Activity m.sub.support Y.sub.surface [TiBA] hexene Yield g g.sub.cat.sup.−1 Kg mol.sub.Y.sup.−1 Run mg μmol mM mol % g h.sup.−1 h.sup.−1 bar.sup.−1 4 18.7 10.3 1 21 5.91 633 115

[0103] Comparison of Run 4 with Run 3 shows that the activity of the Comparative Catalyst A, where the silica is activated at 200° C. is much lower than that seen under the equivalent conditions for Catalyst 1, where the silica is activated at 700° C.

Table 3 shows the result obtained from Catalyst 2:

TABLE-US-00005 TABLE 3 1- Activity Activity m.sub.support Nd.sub.surface [TiBA] hexene Yield g g.sub.cat.sup.−1 Kg mol.sub.Y.sup.−1 Run mg μmol mM mol % g h.sup.−1 h.sup.−1 bar.sup.−1 5 32.3 6.9 1 9.6 4.36 270 100 6 36.4 3.8 1 — 5.19 285 106

[0104] These results show that the Nd containing catalyst was also active for polymerisation.

[0105] 2) 5 L autoclave

[0106] Polymerization tests were conducted in 5 L autoclave, with 1.5 L of isobutane as solvent. The reactor was pressurised with ethylene to a pressure of 10 bar. 2.6 mol % relative to ethylene of hydrogen was added, along with 30 g of 1-hexene as comonomer. The reactor was then heated to the reaction temperature of 80° C. The total equilibrium pressure of the system was of 24.4 bars.

[0107] 100 mg of the catalyst (Catalyst 1) was injected in the reactor as a 10 wt % suspension in oil to initiate the reaction, and reaction was performed for 1 hour before the reaction was stopped.

[0108] FIG. 1 shows the results obtained as a function of TIBAL addition for Catalyst 1. It can be seen that highest activity is obtained at the lowest level of TIBAL, consistent with the results shown in the small scale autoclaves.