Epoxidation catalyst, a process for preparing the catalyst, and a process for the production of an olefin oxide

1. A catalyst for the epoxidation of an olefin comprising a carrier and, deposited on the carrier, silver, a rhenium promoter, a first co-promoter, and a second co-promoter; wherein:

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst;

e) wherein the carrier has a monomodal, bimodal or multimodal pore size distribution, with a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

f) wherein a fluoride-containing species and a strength-enhancing additive are incorporated into the carrier.

2. The catalyst as claimed in claim 1 , wherein the quantity of the rhenium promoter is at least 1.25 mmole/kg, relative to the weight of the catalyst.

3. The catalyst as claimed in claim 2 , wherein the quantity of the rhenium promoter is in the range of from 1.25 to 50 mmole/kg, relative to the weight of the catalyst.

4. The catalyst as claimed in claim 1 , wherein the fluoride-containing species is ammonium fluoride.

5. The catalyst as claimed in claim 1 , wherein the strength-enhancing additive is selected from the group consisting of a zirconium species, a lanthanide Group species, a calcium species, a magnesium species, inorganic glass, and mixtures thereof.

6. The catalyst as claimed in claim 1 , wherein the catalyst further comprises a further element selected from nitrogen, fluorine, alkali metals, alkaline earth metals, titanium, hafnium, zirconium, vanadium, thallium, thorium, tantalum, niobium, gallium and germanium and mixtures thereof.

7. The catalyst as claimed in claim 1 , wherein the catalyst has a water extractable quantity of potassium in the range of from 1.25 to 10 mmole/kg, relative to the weight of the catalyst.

8. The catalyst as claimed in claim 1 , wherein the carrier has a surface area of at least 1 m 2 /g, and a pore size distribution such that pores with diameters in the range of from 0.2 to 10 μm represent at least 70% of the total pore volume and such pores together provide a pore volume of at least 0.27 ml/g, relative to the weight of the carrier.

9. The catalyst as claimed in claim 1 , wherein the carrier has a median pore diameter of more than 0.5 μm, and a pore size distribution wherein at least 80% of the total pore volume is contained in pores with diameters in the range of from 0.1 to 10 μm and at least 80% of the pore volume contained in the pores with diameters in the range of from 0.1 to 10 μm is contained in pores with diameters in the range of from 0.3 to 10 μm.

10. A catalyst for the epoxidation of an olefin comprising a carrier and, deposited on the carrier, silver, a rhenium promoter, a first co-promoter, and a second co-promoter; wherein:

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst;

e) wherein the carrier has a bimodal or multimodal pore size distribution, with a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

(f) wherein the carrier has at least two log differential pore volume distribution peaks in a pore diameter range of 0.01-100 μm and at least one the peaks is present in a pore diameter range of 0.01-1.0 μm in the pore size distribution as measured by mercury porosimetry, wherein each peak is a maximum value of the log differential pore volume distribution of 0.2 cm 3 /g or larger.

11. A catalyst for the epoxidation of an olefin comprising a carrier and, deposited on the carrier, silver, a rhenium promoter, a first co-promoter, and a second co-promoter; wherein:

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst; and

e) wherein the carrier has a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

(f) wherein the carrier has a bimodal pore size distribution, with a first mode of pores which has a mean diameter ranging from about 0.01 m to about 5 μm, and a second mode of pores which has a mean diameter ranging from about 5 μm to about 30 μm.

12. The catalyst as claimed in claim 1 , wherein the carrier has a monomodal pore size distribution, a pore volume from pores with less than 1 micron in diameter of less than 0.20 ml/g, a pore volume from pores with greater than 5 micron in diameter of less than 0.20 ml/g, and at least 40 percent of pore volume from pores between 1 micron in diameter and 5 microns in diameter.

13. A process for preparing a catalyst for the epoxidation of an olefin comprising depositing silver, a rhenium promoter, a first co-promoter, and a second co-promoter on a carrier; wherein

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst; and

e) wherein the carrier has a monomodal, bimodal or multimodal pore size distribution, with a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

f) wherein a fluoride-containing species and a strength-enhancing additive are incorporated into the carrier.

14. A process for preparing ethylene oxide by reacting a feed comprising ethylene and oxygen in the presence of a catalyst that comprises a carrier and, deposited on the carrier, silver, a rhenium promoter, a first co-promoter, and a second co-promoter; wherein:

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst;

e) wherein the carrier has a monomodal, bimodal or multimodal pore size distribution, with a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

f) wherein a fluoride-containing species and a strength-enhancing additive are incorporated into the carrier.

15. A process for preparing a 1,2-diol, a 1,2-diol ether, a 1,2-carbonate, or an alkanolamine comprising:

preparing ethylene oxide by reacting a feed comprising ethylene and oxygen in the presence of a catalyst that comprises a carrier and, deposited on the carrier, silver, a rhenium promoter, a first co-promoter, and a second co-promoter; wherein:

a) the quantity of the rhenium promoter deposited on the carrier is greater than 1 mmole/kg, relative to the weight of the catalyst;

b) the first co-promoter is selected from sulfur, phosphorus, boron, and mixtures thereof;

c) the second co-promoter is selected from tungsten, molybdenum, chromium, and mixtures thereof;

d) the total quantity of the first co-promoter and the second co-promoter deposited on the carrier is at most 5.0 mmole/kg, relative to the weight of the catalyst;

e) wherein the carrier has a monomodal, bimodal or multimodal pore size distribution, with a pore diameter range of 0.01-200 μm, a specific surface area of 0.03-10 m 2 /g, a pore volume of 0.2-0.7 cm 3 /g, wherein the median pore diameter of the carrier is 0.1-100 μm and has a water absorption of 10-80%; and

f) wherein a fluoride-containing species and a strength-enhancing additive are incorporated into the carrier; and

converting the ethylene oxide into the 1,2-diol, the 1,2-diol ether, the 1,2-carbonate, or the alkanolamine.

16. The process as claimed in claim 13 , wherein the strength-enhancing additive is selected from the group consisting of a zirconium species, a lanthanide Group species, a calcium species, a magnesium species, inorganic glass, and mixtures thereof.

17. The process as claimed in claim 13 , wherein the strength-enhancing additive is selected from the group consisting of a zirconium species, a lanthanide Group species, a calcium species, a magnesium species, inorganic glass, and mixtures thereof.

18. The process as claimed in claim 15 , wherein the strength-enhancing additive is selected from the group consisting of a zirconium species, a lanthanide Group species, a calcium species, a magnesium species, inorganic glass, and mixtures thereof.