Preparation of large pore silicas and uses thereof in chromium catalysts for olefin polymerization
Silica composites and supported chromium catalysts having a bulk density of 0.08 to 0.4 g/mL, a total pore volume of 0.4 to 2.5 mL/g, a BET surface area of 175 to 375 m 2 /g, and a peak pore diameter of 10 to 80 nm are disclosed herein. These silica composites and supported chromium catalysts can be formed by combining two silica components. The first silica component can be irregularly shaped, such as fumed silica, and the second silica component can be a colloidal silica or a silicon-containing compound, and the second silica component can act as a glue to bind the silica composite together.
1. A silica composite characterized by:
a bulk density from about 0.08 to about 0.4 g/mL;
a total pore volume from about 0.4 to about 2.5 mL/g;
a BET surface area from about 175 to about 375 m 2 /g; and
a peak pore diameter from about 10 to about 80 nm;
wherein from about 0.5 to about 40% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
2. The silica composite of claim 1 , wherein the silica composite has an average pore diameter from about 10 to about 50 nm.
3. The silica composite of claim 1 , wherein:
the bulk density is from about 0.1 to about 0.35 g/mL;
the total pore volume is from about 0.5 to about 2 mL/g;
the BET surface area is from about 200 to about 375 m 2 /g; and
the peak pore diameter is from about 15 to about 50 nm.
4. The silica composite of claim 1 , wherein:
from about 40 to about 85% of the total pore volume of the silica composite is in pores with diameters in the 10-50 nm range;
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
5. The silica composite of claim 1 , wherein from about 1 to about 35% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
6. The silica composite of claim 1 , wherein from about 2 to about 35% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
7. The silica composite of claim 1 , wherein the silica composite has an average pore diameter from about 9 to about 30 nm.
8. The silica composite of claim 1 , wherein from about 40 to about 85% of the total pore volume of the silica composite is in pores with diameters in the 10-50 nm range.
9. The silica composite of claim 1 , wherein:
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
10. The silica composite of claim 1 , wherein:
the silica composite has an average pore diameter from about 10 to about 50 nm;
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
11. The silica composite of claim 3 , wherein:
from about 40 to about 85% of the total pore volume of the silica composite is in pores with diameters in the 10-50 nm range;
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
12. The silica composite of claim 3 , wherein the silica composite has an average pore diameter from about 10 to about 50 nm.
13. The silica composite of claim 12 , wherein from about 1 to about 35% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
14. The silica composite of claim 3 , wherein from about 40 to about 85% of the total pore volume of the silica composite is in pores with diameters in the 10-50 nm range.
15. The silica composite of claim 3 , wherein:
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
16. The silica composite of claim 3 , wherein:
the silica composite has an average pore diameter from about 10 to about 50 nm;
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
17. The silica composite of claim 3 , wherein from about 2 to about 35% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
18. The silica composite of claim 3 , wherein the silica composite has an average pore diameter from about 9 to about 30 nm.
19. A silica composite characterized by:
a bulk density from about 0.08 to about 0.4 g/mL;
a total pore volume from about 0.4 to about 2.5 mL/g;
a BET surface area from about 175 to about 375 m 2 /g; and
a peak pore diameter from about 10 to about 80 nm;
wherein from about 40 to about 85% of the total pore volume of the silica composite is in pores with diameters in the 10-50 nm range.
20. The silica composite of claim 19 , wherein the silica composite has an average pore diameter from about 10 to about 50 nm.
21. The silica composite of claim 19 , wherein the silica composite has an average pore diameter from about 9 to about 30 nm.
22. The silica composite of claim 19 , wherein from about 2 to about 35% of the total pore volume of the silica composite is in pores with diameters in the 30-100 nm range.
23. The silica composite of claim 19 , wherein:
the bulk density is from about 0.1 to about 0.35 g/mL;
the total pore volume is from about 0.5 to about 2 mL/g;
the BET surface area is from about 200 to about 375 m 2 /g; and
the peak pore diameter is from about 15 to about 50 nm.
24. The silica composite of claim 23 , wherein less than or equal to about 20% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm.
25. The silica composite of claim 19 , wherein:
the bulk density is from about 0.12 to about 0.34 g/mL;
the total pore volume is from about 0.4 to about 1.5 mL/g;
the BET surface area is from about 190 to about 375 m 2 /g; and
the peak pore diameter is from about 17 to about 40 nm.
26. The silica composite of claim 25 , wherein less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
27. A silica composite characterized by:
a bulk density from about 0.08 to about 0.4 g/mL;
a total pore volume from about 0.4 to about 2.5 mL/g;
a BET surface area from about 175 to about 375 m 2 /g; and
a peak pore diameter from about 10 to about 80 nm; wherein:
from about 1 to about 25% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 5 nm; and
less than or equal to about 4% of the total pore volume of the silica composite is in pores with diameters of less than or equal to 3 nm.
28. The silica composite of claim 27 , wherein the silica composite has an average pore diameter from about 9 to about 30 nm.
29. The silica composite of claim 27 , wherein:
the bulk density is from about 0.1 to about 0.35 g/mL;
the total pore volume is from about 0.5 to about 2 mL/g;
the BET surface area is from about 200 to about 375 m 2 /g; and
the peak pore diameter is from about 15 to about 50 nm.