High activity polyethylene catalyst prepared from an alcohol and silicon tetrachloride

• US 5,561,091 A
• Filed: 05/02/1995
• Issued: 10/01/1996
• Est. Priority Date: 11/18/1993
• Status: Expired due to Term

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Nowlin, Thomas E., Mink, Robert I.
• Primary Examiner(s): Delmendo, Romulo H.
• Application Number:
  US08/432,879
• Time in Patent Office: 518 Days
• Field of Search: 502/115, 502/119, 502/120, 502/125, 526/124.3, 526/124.5, 526/124.6, 526/129, 526/127, 526/124.9
• US Class Current: 502/115
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 4/6565 and magnesium or compounds thereof
• CPC Class Codes: Y02P 20/52 using catalysts, e.g. selective catalysts

Abstract

A catalyst composition for producing linear low density polyethylene with relatively narrower molecular weight distributions is described. The catalyst is formed by treating silica having reactive OH groups with a dialkylmagnesium in a solvent for said dialkylmagnesium; then adding to said magnesium-containing support a mixture of ROH and SiCl₄ to form an intermediate which is subsequently treated with a transition metal to form a transition metal-containing intermediate, the catalyst precursor. The catalyst precursor is activated with a trialkylaluminum compound.

Claims

1. A catalyst composition for copolymerization of ethylene with an alpha-olefin, to produce a resin product of narrow molecular weight distribution, and having a density of less than 0.94 g/cc;

wherein the catalyst composition is prepared by a process which comprises the steps of;

(i) contacting a solid, porous carrier having reactive OH groups in a non-polar liquid with dibutylmagnesium to form a product of step (i) which contains said carrier and incorporated therein a source of magnesium, wherein said dibutylmagnesium is soluble in said non-polar liquid;

wherein, the ratio of the number of moles of said dibutylmagnesium to the number of moles of said OH groups is from about 1.1 to about 2.5;

(ii) introducing into the liquid containing said product of step (i) a mixture of SiCl₄ and an alcohol R"OH in which R" is selected from the group consisting of methyl, ethyl, propyl, n-butyl, pentyl, and n-octyl, thereby to form a slurry of step (ii) wherein the mixture has a molar ratio of R"OH to SiCl₄ of 2.00 to 6.00;

wherein the molar ratio of SiCl₄ to Mg is 0.40 to 1.40; and

wherein the molar ratio of R"OH to Mg is at least about 1.32.

(iii) contacting said slurry of step (ii) with at least one transition metal compound in a non-polar liquid medium, the number of moles of said transition metal compound being in excess of the number of moles of OH groups on said carrier prior to reaction with said dibutylmagnesium in step (i), said transition metal compound being soluble in said non-polar liquid, and said dibutylmagnesium contacted carrier being substantially insoluble in said liquid medium, whereby a reacted form of the transition metal becomes supported on said carrier to form a step (iii) precursor; and

(iv) contacting the step (iii) precursor with an activating amount of trialkylaluminum R'"'"'₃ Al, in which R'"'"' is an alkyl group of 1 to 10 carbon atoms.

2. The catalyst composition of claim 1, wherein the carrier is silica.

3. The catalyst of claim 2, wherein the trialkylaluminum is trimethylaluminum.

4. A catalyst composition of claim 2, wherein the trialkylaluminum is triethylaluminum.

5. The catalyst of claim 4, wherein the molar ratio of the triethylaluminum to transition metal ranges from 1 to 500.

6. The catalyst of claim 5, wherein the transition metal is titanium.

7. The catalyst of claim 6, wherein the transition metal is provided as tetravalent titanium compound.

8. The catalyst of claim 7, wherein the tetravalant titanium compound is titanium tetrachloride.

9. A catalyst which is formed by the steps consisting essentially of (i)-(iv) of claim 1.

10. A catalyst which is formed by the steps consisting of (i)-(iv) of claim 1.

11. A catalyst which is formed by the steps consisting essentially of (i)-(iv) of claim 8.

25. The catalyst of claim 1, wherein R"OH is n-butanol or n-octanol.

26. The catalyst of claim 1, wherein R"OH is n-butanol.

30. The catalyst of claim 6, wherein the R"OH is n-butanol or n-octanol.

31. The catalyst of claim 3, wherein the transition metal is titanium.

32. The catalyst of claim 31, wherein the R"OH is n-butanol or n-octanol.

33. The catalyst of claim 32, wherein the R"OH is n-butanol.

35. The catalyst of claim 3, wherein the R"OH is n-butanol or n-octanol.

36. The catalyst of claim 35, wherein the R"OH is n-butanol.

12. A catalyst composition for copolymerization of ethylene with an alpha-olefin, to produce a resin product of narrow molecular weight distribution, wherein the catalyst is prepared by a process which comprises the steps of:

contacting a solid, porous carrier having reactive OH groups in a non-polar liquid with an organomagnesium compound which has the empirical formula

space="preserve" listing-type="equation">R.sub.m MgR'"'"'.sub.n

where R and R'"'"' are the same or different C₄ -C₈ alkyl groups, and m and n are each 0, 1 or 2, providing that m+n=2, to form a product of step (i) which contains said carrier and incorporated therein a source of magnesium, wherein said organomagnesium compound is soluble in said non-polar liquid;

wherein, the ratio of the number of moles of said organomagnesium compound to the number of moles said OH groups is from about 1.1 to about 2.5

(ii) introducing into the liquid containing said product of step (i) a mixture of R"OH wherein R" is selected from the group consisting of methyl, ethyl, propyl, n-butyl, pentyl, and n-octyl, and SiCl₄ to form a slurry of step (ii)

wherein the mixture is characterized by a molar ratio of R"OH to SiCl₄ ranging from 2.00 to 6.00;

wherein the molar ratio of SiCl₄ to Mg is 0.40 to 1.40; and

wherein the molar ratio of R"OH to Mg is at least about 1.32

(iii) contacting said slurry of step (ii) with at least one transition metal compound in a non-polar liquid medium, the number of moles of said transition metal compound being in excess of the number of moles of OH groups on said carrier prior to reaction with said organomagnesium compound in step (i), said transition metal compound being soluble in said non-polar liquid, and said organomagnesium compound contacted carrier being substantially insoluble in said liquid medium, whereby a reacted form of the transition metal becomes supported on said carrier to form a step (iii) precursor; and

(iv) contacting the step (iii) precursor with an activating amount of trialkylaluminum.

13. The catalyst composition of claim 12, wherein the carrier is silica.

14. The catalyst of claim 13, wherein the trialkylaluminum is trimethylaluminum.

15. A catalyst composition of claim 13, wherein the trialkylaluminum is triethylaluminum.

16. The catalyst of claim 15, wherein the molar ratio of the triethylaluminum to transition metal ranges from 1 to 500.

17. The catalyst of claim 16, wherein the transition metal is titanium.

18. The catalyst of claim 17, wherein the transition metal is provided as tetravalent titanium compound.

19. The catalyst of claim 18, wherein the tetravalent titanium compound is titanium tetrachloride.

20. A catalyst which is formed by the steps consisting essentially of (i)-(iv) of claim 12.

21. A catalyst which is formed by the steps consisting of (i)-(iv) of claim 12.

22. A catalyst which is formed by the steps consisting essentially of (i)-(iv) of claim 18.

23. A catalyst which is formed by the steps consisting essentially of (i)-(iv) of claim 19.

24. The catalyst of claim 13, wherein the molar ratio of R"OH to SiCl₄ is 3 to 4.

27. The catalyst of claim 12, wherein R"OH is n-butanol or n-octanol.

28. The catalyst of claim 12, wherein R"OH is n-butanol.

29. The catalyst of claim 12, wherein the molar ratio of R"OH to SiCl₄ is 3 to 4.

34. The catalyst of claim 14, wherein the transition metal is titanium.

37. The catalyst of claim 17, wherein the R"OH is n-butanol or n-octanol.

38. The catalyst of claim 37, wherein the R"OH is n-butanol.