Catalyst composition for polymerizing alpha-olefins and alpha-olefins polymerization therewith

• US 5,096,868 A
• Filed: 04/27/1990
• Issued: 03/17/1992
• Est. Priority Date: 10/21/1987
• Status: Expired due to Term

• Current Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Original Assignee: Mobil Oil Corporation (Exxon Mobil Corporation)
• Inventors: Simondsen, Jeanne C., Hsieh, John T. T.
• Primary Examiner(s): GARVIN, PATRICK
• Application Number:
  US07/517,952
• Time in Patent Office: 690 Days
• Field of Search: 502/107, 502/113, 502/242, 502/309, 502/256, 502/305
• US Class Current: 502/107
• CPC Class Codes: C08F 10/00 Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
• CPC Class Codes: C08F 210/08 Butenes
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/07 High density, i.e. > 0.95 g/cm3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 4/025 Metal oxides
• CPC Class Codes: C08F 4/24 Oxides
• CPC Class Codes: C08F 4/6232 Component of C08F4/62 containing at least two different metals
• CPC Class Codes: C08F 4/69 Chromium, molybdenum, tungsten or compounds thereof

Abstract

A supported catalyst for polymerizing 1-olefins, for example, ethylene, is prepared by depositing a chromium compound and a titanium compound on a refractory oxide support which is substantially non-spherical, and which has a relatively broad particle size distribution range. The catalyst is preferably combined, either outside of the polymerization vessel or in situ, with a sufficient amount of at least one magnesium composition of the formula RMgR'"'"', where R and R'"'"' are the same or different and they are C₁ to C₁₂ hydrocarbyl groups, to provide a molar ratio of magnesium to chromium in the catalyst composition of about 0.01:1 to about 25:1. The resulting catalyst composition has good feedability and fluidization characteristics, and it produces resins of relatively high HLMI at relatively low temperatures.

There is also disclosed a process for polymerizing 1-olefins, at relatively lower temperatures than was heretofore possible, to obtain resins of relatively high HLMI, using the above-identified catalyst composition. The resulting polymers can be used for the fabrication of blow-molded products, e.g., household and industrial containers.

Claims

1. In an alpha-olefin polymerization catalyst composition comprising a chromium compound and a titanium compound deposited on a refractory oxide support,

an improvement comprising a catalyst which is substantially non-spherical and irregular in shape, wherein the refractory oxide support has at least 75% of its pore volume in the pore size range of about 200 to about 500 Angstrom diameter, thereby producing a catalyst which produces a polymer having a higher flow index (HLMI) than a polymer produced under comparable conditions with a catalyst having a broader pore size distribution.

2. A catalyst composition of claim 1 which is a fluidized bed catalyst composition.

3. A catalyst composition of claim 2 which has the particle diameter of about 5 to about 250μ

.

4. A catalyst composition of claim 3 which has the particle diameter of about 10 to about 200μ

.

5. A catalyst composition of claim 4 which has the following particle size distribution:

cumulative volume distribution--10 to 90% of the catalyst particles have diameters of from about 37 to about 117μ

, as determined by volume distribution.

6. A catalyst composition of claim 5 which has a median particle diameter of about 75μ

, as determined by volume distribution.

7. A catalyst composition of claim 6 wherein CrO₃ or any compound of chromium calcinable to CrO₃ under the catalyst activation conditions is used as the chromium compound.

8. A catalyst composition of claim 7 wherein it is activated for at least about 10 hours at a temperature of at least about 800°

C.

9. A catalyst composition of claim 8 wherein the refractory oxide support is silica having at least 80% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

10. A catalyst composition of claim 9 wherein the refractory oxide support is silica having at least 85% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

11. A catalyst composition of claim 10 containing about 0.05 to about 3.0% by weight of chromium, calculated as elemental chromium.

12. A catalyst composition of claim 11 containing about 0.10 to about 0.25% by weight of chromium, calculated as elemental chromium.

13. A catalyst composition of claim 12 containing about 0.13 to about 0.18% by weight of chromium, calculated as elemental chromium.

14. A catalyst composition of claim 13 containing about 0.15 to about 0.18% by weight of chromium, calculated as elemental chromium.

15. A catalyst composition of claim 14 wherein the refractory oxide support is silica containing 0.18% by weight of CrO₃ and having about 88% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

16. A catalyst composition of claim 15 wherein, prior to the activation thereof, it is dehydrated at a temperature of about 100°

to about 500°

C. for at least about 14 hours in a nitrogen atmosphere.

17. A catalyst composition of claim 16 wherein it is dehydrated at a temperature of about 150°

to about 300°

C. for at least about 16 hours.

18. A catalyst composition of claim 17 wherein it is dehydrated at a temperature of about 200°

C. for about 16 hours.

19. A catalyst composition of claim 18 wherein after the dehydration is completed, the titanium compound is deposited thereon.

20. A catalyst composition of claim 19 wherein, after the titanium compound deposition is completed, it is activated at a temperature of at least about 820°

C. for at least about 16 hours.

21. A catalyst composition of claim 20 wherein it is activated at a temperature of about 820°

to about 870°

C.

22. A catalyst composition of claim 21 wherein it is activated at a temperature of about 825°

C. for about 16 hours.

23. A catalyst composition of claim 22 further comprising a sufficient amount of a magnesium composition of the formula RMgR'"'"', where R and R'"'"' are the same or different and they are C₁ to C₁₂ hydrocarbyl groups, to provide a molar ratio of magnesium to chromium in the catalyst composition of about 0.01:

1 to about 25;

1.

24. A catalyst composition of claim 23 wherein R and R'"'"' are C₁ to C₈ alkyl groups.

25. A catalyst composition of claim 24 wherein R and R'"'"' are C₂ to C₄ normal alkyl groups.

26. A catalyst composition of claim 25 wherein R and R'"'"' are the same and they are n-butyl.

27. A catalyst composition of claim 26 comprising such an amount of the magnesium composition as to provide a molar ratio of magnesium to chromium in the catalyst composition of about 0.1:

1 to about 15;

1.

28. A catalyst composition of claim 27 wherein the polymerization catalyst is combined with the magnesium composition outside of a polymerization reaction vessel.

29. A catalyst composition of claim 27 wherein the polymerization catalyst is combined with the magnesium composition inside of a polymerization reaction vessel.

30. A method of preparing a supported alpha-olefin polymerization catalyst composition comprising the steps of:

(a) depositing a chromium compound on a refractory oxide support having at least 75% of its pore volume in the pores of about 200 to about 500 Angstrom diameter;

(b) dehydrating the product of step (a) at about 100°

to about 500°

C. for at least about 16 hours;

(c) contacting the product of step (b) with a titanium compound; and

(d) activating the product of step (c) at at least about 820°

C. for at least about 16 hours, thereby producing the catalyst composition which is substantially non-spherical and irregular in shape and which has a relatively broad particle size distribution range.

31. A method of claim 30 wherein the catalyst composition is a fluidized bed catalyst composition.

32. A method of claim 31 wherein the catalyst composition particles have the particle diameter of about 5 to about 250μ

.

33. A method of claim 32 wherein the catalyst composition particles have the particle diameter of about 10 to about 200μ

.

34. A method of claim 33 wherein the catalyst composition particles have the following particle size distribution:

cumulative volume distribution--10 to 90% of the particles have diameters from about 37 to about 117μ

as determined by volume distribution.

35. A method of claim 34 wherein the catalyst composition particles have a median particle diameter of about 75μ

, as determined by volume distribution.

36. A method of claim 35 wherein the chromium compound is CrO₃ or any compound of chromium calcinable to CrO₃ under the catalyst activation conditions.

37. A method of claim 36 wherein the refractory oxide support is silica having at least 80% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

38. A method of claim 37 wherein the refractory oxide support is silica having at least 85% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

39. A method of claim 38 wherein the catalyst composition contains about 0.05 to about 3.0% by weight of chromium, calculated as elemental chromium.

40. A method of claim 39 wherein the catalyst composition contains about 0.10 to about 0.25% by weight of chromium, calculated as elemental chromium.

41. A method of claim 40 wherein the catalyst composition contains about 0.13 to about 0.18% by weight of CrO₃, calculated as elemental chromium.

42. A method of claim 41 wherein the catalyst composition contains about 0.15 to about 0.18% by weight of CrO₃, calculated as elemental chromium.

43. A method of claim 42 wherein the refractory oxide support is silica containing 0.18% by weight of CrO₃ and having about 88% of its pore volume in the pores of about 250 to about 450 Angstrom diameter.

44. A method of claim 43 wherein the product of step (a) is dehydrated at a temperature of about 150°

to about 300°

C. for at least about 16 hours in a nitrogen atmosphere.

45. A method of claim 44 wherein the product of step (a) is dehydrated at a temperature of about 200°

C. for about 16 hours.

46. A method of claim 45 wherein the product of step (c) is activated at a temperature of at least about 820°

C. for at least about 16 hours.

47. A method of claim 46 wherein the product of step (c) is activated at a temperature of about 820°

to about 870°

C.

48. A method of claim 47 wherein the product of step (c) is activated at a temperature of about 825°

C. for about 16 hours.

49. A method of claim 48 wherein the catalyst composition is combined with a sufficient amount of a magnesium composition of the formula RMgR'"'"' where R and R'"'"' are the same or different and they are C₁ to C₁₂ hydrocarbyl groups to provide a molar ratio of magnesium to chromium in the catalyst composition of about 0.01:

1 to about 25;

1.

50. A method of claim 49 wherein R and R'"'"' are C₁ to C₈ alkyl groups.

51. A method of claim 50 wherein R and R'"'"' are C₂ to C₄ normal alkyl groups.

52. A method of claim 51 wherein R and R'"'"' are the same and they are n-butyl.

53. A method of claim 52 wherein a sufficient amount of the magnesium composition is used to provide a molar ratio of magnesium to chromium in the catalyst composition of about 0.1:

1 to about 15;

1.

54. A method of claim 53 wherein the polymerization catalyst is combined with the magnesium composition outside of a polymerization reaction vessel.

55. A method of claim 54 wherein the polymerization catalyst is combined with the magnesium composition inside of a polymerization reaction vessel.