Carrier for ethylene oxide catalysts
An improved carrier for an ethylene epoxidation catalyst is provided. The carrier includes an alumina component containing a first portion of alumina particles having a mean primary particle size of, or greater than, 2 μm and up to 6 μm, and a second portion of alumina particles having a particle size less than 2 μm. An improved catalyst containing the above-described carrier, as well as an improved process for the epoxidation of ethylene using the catalyst are also provided.
1. A carrier for an ethylene epoxidation catalyst, the carrier comprising alumina containing a first portion of alumina particles having a mean primary particle size (D50) of, or greater than, 2 μm and up to 6 μm, and a second portion of alumina particles having a mean primary particle size (D50) less than 2 μm.
2. The carrier according to claim 1 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 5 μm.
3. The carrier according to claim 1 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.5 μm.
4. The carrier according to claim 1 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1 μm.
5. The carrier according to claim 1 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.5 μm.
6. The carrier according to claim 1 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1 μm.
7. The carrier according to claim 1 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 4 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1 μm.
8. The carrier according to claim 1 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 3 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.0 μm.
9. The carrier according to claim 1 , wherein at least 10 wt % but less than 100 wt % of the carrier particles have a size (D50) less than 2 μm, wherein said wt % is relative to the weight of alumina in the carrier.
10. The carrier according to claim 1 , wherein at least 10 wt % but less than 100 wt % of the carrier particles have a size (D50) of, or less than, 1 μm, wherein said wt % is relative to the weight of alumina in the carrier.
11. The carrier according to claim 1 , wherein the alumina component is α-alumina.
12. The carrier according to claim 1 , further comprising a stability-enhancing amount of mullite.
13. The carrier according to claim 12 , wherein the stability-enhancing amount of mullite is about 0.5-20 wt % mullite by total weight of the carrier.
14. The carrier according to claim 12 , wherein the stability-enhancing amount of mullite is about 1-15% mullite by total weight of the carrier.
15. The carrier according to claim 12 , wherein the stability-enhancing amount of mullite is about 3-12% mullite by total weight of the carrier.
16. The carrier according to claim 1 , further comprising a promoting amount of rhenium.
17. The carrier according to claim 1 , further comprising a promoting amount of an alkali or alkaline earth metal.
18. The carrier according to claim 1 , further comprising a promoting amount of cesium.
19. The carrier according to claim 1 , wherein the carrier possesses a pore size distribution characterized by a peak pore size of, or less than, 2 μm.
20. The carrier according to claim 1 , wherein no more than 45% of the pores have a pore size of or less than 1 μm.
21. An ethylene epoxidation catalyst comprising:
a) a carrier comprising alumina containing a first portion of alumina particles having a mean primary particle size (D50) of, or greater than, 2 μm and up to 6 μm, and a second portion of alumina particles having a mean primary particle size (D50) less than 2 μm;
b) a catalytic amount of silver deposited on and/or in said carrier; and
c) a promoting amount of rhenium deposited on and/or in said carrier.
22. The catalyst according to claim 21 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 5 μm.
23. The catalyst according to claim 21 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.5 μm.
24. The catalyst according to claim 21 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1 μm.
25. The catalyst according to claim 21 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.5 μm.
26. The catalyst according to claim 21 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles have a mean primary particle size (D50) of, or less than, 1 μm.
27. The catalyst according to claim 21 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 4 μm, and the second portion of alumina particles have a mean primary particle size (D50) of, or less than, 1 μm.
28. The catalyst according to claim 21 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 3 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.0 μm.
29. The catalyst according to claim 21 , wherein at least 10 wt % but less than 100 wt % of the first portion of alumina particles have a size (D50) less than 2 μm, wherein said wt % is relative to the weight of alumina in the carrier.
30. The catalyst according to claim 21 , wherein at least 10 wt % but less than 100 wt % of the first portion of alumina particles have a size (D50) of, or less than, 1 μm, wherein said wt % is relative to the weight of alumina in the carrier.
31. The catalyst according to claim 21 , wherein the carrier possesses a pore size distribution characterized by a peak pore size of, or less than, 2 μm.
32. The catalyst according to claim 21 , wherein no more than 45% of the pores have a pore size of or less than 1 μm.
33. A method for the vapor phase conversion of ethylene to ethylene oxide in the presence of oxygen, the method comprising reacting a reaction mixture comprising ethylene and oxygen in the presence of a catalyst comprising:
a) a carrier comprising alumina containing a first portion of alumina particles having a mean primary particle size (D50) of, or greater than, 2 μm and up to 6 μm, and a second portion of alumina particles having a mean primary particle size (D50) less than 2 μm;
b) a catalytic amount of silver deposited on and/or in said carrier; and
c) a promoting amount of rhenium deposited on and/or in said carrier.
34. The method according to claim 33 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 5 μm.
35. The method according to claim 33 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.5 μm.
36. The method according to claim 33 , wherein the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1 μm.
37. The method according to claim 33 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles has a mean primary particle size of, or less than, 1.5 μm.
38. The method according to claim 33 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 3 μm and up to 5 μm, and the second portion of alumina particles has a mean primary particle size of, or less than, 1 μm.
39. The method according to claim 33 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 4 μm, and the second portion of alumina particles has a mean primary particle size of, or less than, 1 μm.
40. The method according to claim 33 , wherein the first portion of alumina particles has a mean primary particle size (D50) of, or greater than, 2 μm and up to 3 μm, and the second portion of alumina particles has a mean primary particle size (D50) of, or less than, 1.0 μm.
41. The method according to claim 33 , wherein at least 10 wt % but less than 100 wt % of the first portion of alumina particles have a size (D50) less than 2 μm, wherein said wt % is relative to the weight of alumina in the carrier.
42. The method according to claim 33 , wherein at least 10 wt % but less than 100 wt % of the first portion of alumina particles have a size (D50) of, or less than, 1 μm, wherein said wt % is relative to the weight of alumina in the carrier.
43. The method according to claim 33 , wherein the carrier possesses a pore size distribution characterized by a peak pore size of, or less than, 2 μm.
44. The method according to claim 33 , wherein no more than 45% of the pores have a pore size of or less than 1 μm.