Silica-alumina catalyst support with bimodal pore distribution, catalysts, methods of making and using same
View Patent ↗An effective catalyst includes an amorphous silica-alumina support having a bimodal pore size-distribution. The support may be prepared by a method that includes the physical mixing of two silica-alumina gels prepared so as to have two different average pore sizes. The catalyst has the advantage that both metal dispersion on the support and product diffusion in the pores are optimized. Further, the catalyst has improved performance in the production of hydrocarbons from synthesis gas.
1. A process for producing hydrocarbons, comprising contacting a feed stream comprising carbon monoxide and hydrogen with a catalyst so as to convert at least a portion of the carbon monoxide to the hydrocarbons comprising hydrocarbons with at least 5 carbon atoms per hydrocarbon molecule (C 5+ hydrocarbons), wherein the catalyst comprises a Fischer-Tropsch catalytic metal and a support comprising an amorphous silica-alumina having a bimodal pore size-distribution comprising a first mode between about 4 nm and about 10 nm and a second mode between about 10 nm and about 20 nm, and further wherein the productivity in C 5+ hydrocarbons is from 370 g C 5+ /hr/kg cat to 660 g C 5+ /hr/kg cat .
2. The process according to claim 1 wherein the distribution has a first mode between about 5 nm and about 9 nm, and a second mode between about 12 nm and about 17 nm.
3. The process according to claim 1 wherein the first mode and the second mode differ by at least about 2 nm.
4. The process according to claim 1 wherein the bimodal pore size-distribution has a range of pore sizes from about 4 nm to about 20 nm.
5. The process according to claim 1 wherein the bimodal pore size-distribution has a first range of pores with an average pore size from about 4 nm to about 10 nm, said first range comprising the first mode, and further wherein the bimodal pore size-distribution has a second range of pores with an average pore size from about 10 nm to about 20 nm, said second range comprising the second mode.
6. The process according to claim 5 wherein the first mode and the second mode differ by at least about 2 nm.
7. The process according to claim 1 wherein the bimodal pore size-distribution has a first range of pores comprising the first mode and a second range of pores comprising the second mode, said first range comprising from about 70% to about 90% of the pores and an average pore size between about 4 nm and about 10 nm, and said second range comprising from about 10% to about 30% of the pores and an average pore size between about 10 nm and about 20 nm.
8. The process according to claim 1 wherein the support has a pore volume of at least about 0.7 cc/g.
9. The process according to claim 1 wherein the support has a surface area of at least about 260 m 2 /g.
10. The process according to claim 1 wherein the support has a surface area of at least about 300 m 2 /g.
11. The process according to claim 1 wherein the support has a molar ratio of silica to alumina between about 3:1 and about 1,000:1.
12. The process according to claim 1 wherein the support has a molar ratio of silica to alumina between about 30:1 and about 500:1.
13. The process according to claim 1 wherein the support has a molar ratio of silica to alumina between about 40:1 and about 400:1.
14. The process according to claim 1 wherein the support has a surface area greater than 260 m 2 /g.
15. The process according to claim 1 wherein the support comprises less than about 0.05 cc/g of pore volume in pores having a diameter less than about 4 nm.
16. The process according to claim 1 wherein the support comprises at least about 0.7 cc/g of pore volume in pores having a diameter from about 4 nm to about 20 nm.
17. The process according to claim 1 wherein the catalytic metal is selected from the group consisting of cobalt, iron, ruthenium, and combinations thereof.
18. The process according to claim 1 wherein the catalytic metal is cobalt.
19. The process according to claim 1 wherein the hydrocarbons comprise a fuel selected from the list consisting of gasoline, heating oil, jet fuel, diesel fuel, and kerosene.
20. The process according to claim 1 wherein the carbon monoxide conversion is between 31.9% and 62.5%.
21. The process according to claim 1 wherein the process comprises a Schultz-Flory probability (α value) between 0.88 and 0.92.
22. A process for producing hydrocarbons, comprising contacting a feed stream comprising carbon monoxide and hydrogen with a catalyst so as to convert at least a portion of the carbon monoxide to the hydrocarbons comprising hydrocarbons with at least 5 carbon atoms per hydrocarbon molecule (C 5+ hydrocarbons) wherein the catalyst comprises a Fiseher-Tropsch catalytic metal dispersed on an amorphous silica-alumina having a bimodal pore size-distribution comprising a first mode between about 4 nm and about 10 nm and a second mode between about 10 nm and about 20 nm, said amorphous silica-alumina comprising a pore volume greater than about 0.7 cc/g and further wherein the productivity in C 5+ hydrocarbons is from 370 g C 5+ /hr/kg cat to 660 g C 5+ /hr/kg cat .
23. The process according to claim 22 wherein the support has a surface area greater than 260 m 2 /g.
24. The process according to claim 22 wherein the first mode and the second mode differ by at least about 2 nm.
25. The process according to claim 22 wherein the distribution has a first mode between about 5 nm and about 9 nm, and a second mode between about 12 nm and about 17 nm.
26. The process according to claim 22 wherein the bimodal pore size-distribution has a first range of pores comprising the first mode and a second range of pores comprising the second mode, said first range comprising from about 70% to about 90% of the pores and an average pore size between about 4 nm and about 10 nm, and said second range comprising from about 10% to about 30% of the pores and an average pore size between about 10 nm and about 20 nm.
27. The process according to claim 22 wherein the support comprises less than about 0.05 cc/g of pore volume in pores having a diameter less than about 4 nm.
28. The process according to claim 22 wherein the support comprises at least about 0.7 cc/g of pore volume in pores having a diameter from about 4 nm to about 20 nm.
29. The process according to claim 22 wherein the hydrocarbons comprise a fuel selected from the list consisting of gasoline, heating oil, jet fuel, diesel fuel, and kerosene.
30. The process according to claim 22 wherein the support has a molar ratio of silica to alumina between about 3:1 and about 1,000:1.