Catalyst, a process for preparing the catalyst and a process for the production of an olefin oxide, a 1,2-diol, a 1,2 diol ether, or an alkanolamine

1. A catalyst comprising a carrier and silver deposited on the carrier, which carrier comprises at least 85 weight percent α-alumina and has a surface area of at least 1.3 m 2 /g, a median pore diameter of more than 0.8 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.

2. A catalyst as claimed in claim 1 wherein the carrier has a pore size distribution such that at least 90% of the total pore volume is contained in the pores with diameters in the range of from 0.1 to 10 μm; at least 90% 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; the pores with diameters greater than 10 μm represent less than 10% of the total pore volume; and the pores with diameters less than 0.3 μm represent less than 10% of the total pore volume.

3. A catalyst as claimed in claim 2 wherein the pores with diameters greater than 10 μm represent at most 8% of the total pore volume; and the pores with diameters less than 0.3 μm represent at most 3% of the total pore volume.

4. A catalyst as claimed in claim 1 wherein the carrier has a median pore diameter of at most 2 μm, a total pore volume in the range of from 0.25 to 0.8 ml/g and a surface area of at most 5 m 2 /g, a total pore volume in the range of from 0.3 to 0.7 ml/g and a surface area in the range of from 1.3 to 3 m 2 /g.

5. A catalyst as claimed in claim 1 wherein the carrier has a total pore volume of at most 0.6 ml/g.

6. A catalyst as claimed in claim 1 wherein the carrier comprises at least 95 weight percent α-alumina and the carrier has a median pore diameter in the range of from 0.9 to 1.8 μm, a water absorption in the range of from 0.3 to 0.7 g/g and a surface area in the range of from 1.4 m 2 /g to 2.5 m 2 /g.

7. A catalyst as claimed in claim 1 wherein the carrier has a water absorption of at most 0.6 g/g.

8. A catalyst as claimed in claim 1 wherein silver is deposited on the carrier in a quantity of from 10 to 500 g/kg, relative to the weight of the catalyst.

9. A catalyst as claimed in claim 1 wherein the carrier comprises alumina and a bond material.

10. A catalyst as claimed in claim 9 wherein the carrier has an α-alumina content of at least 95 weight percent, and wherein the bond material comprises an alkaline earth metal silicate bond material.

11. A catalyst as claimed in claim 10 wherein the bond material further comprises one or more additional components selected from the group consisting of a hydrated alumina, a zirconium component and a titanium component.

12. A catalyst as claimed in claim 1 which comprises, deposited on the carrier in addition to silver, one or more further elements selected from the group consisting of nitrogen, sulfur, phosphorus, boron, fluorine, Group IA metals, Group IIA metals, rhenium, molybdenum, tungsten, chromium, titanium, hafnium, zirconium, vanadium, manganese, thallium, thorium, tantalum, niobium, gallium and germanium and mixtures thereof.

13. A catalyst as claimed in claim 12 wherein the Group IA metals are selected from the group consisting of lithium, potassium, rubidium and cesium.

14. A catalyst as claimed in claim 1 which comprises, deposited on the carrier in addition to silver, one or more of rhenium, molybdenum, tungsten, Group IA metals, and nitrate- or nitrite-forming compounds.

15. A catalyst as claimed in claim 1 which comprises rhenium deposited on the carrier in addition to silver, and optionally a rhenium co-promoter selected from the group consisting of sulfur, phosphorus, boron, and compounds thereof.

16. A catalyst as claimed in claim 1 wherein the carrier has a pore size distribution such that at least 75%, of the pore volume contained in pores with diameters in the range of from 0.1 to 10 μm is contained in pores with diameters in the range of from 0.4 to 10 μm.

17. A catalyst as claimed in claim 1 wherein the carrier has a pore size distribution such that the pores with diameters in the range of from 0.1 to 10 μm represent more than 90% of the total pore volume and at least 15% of the pore volume contained in pores with diameters in the range of from 0.1 to 10 μm is contained in pores with diameters in the range of from 5 to 10 μm.

18. A catalyst as claimed in claim 1 wherein the carrier is in the form of formed bodies fired at a temperature of at least 1250° C.

19. A catalyst comprising a carrier and silver deposited on the carrier, which carrier comprises a bond material and at least 85 weight percent α-alumina, and has a surface area of at least 1 m 2 /g, a median pore diameter of more than 0.8 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.

20. A catalyst as claimed in claim 19 wherein the surface area is at least 1.3 m 2 /g.

21. A catalyst comprising a carrier and silver deposited on the carrier, which carrier is in the form of formed bodies fired at a temperature of at least 1250° C. comprising at least 85 weight percent α-alumina, and has a surface area of at least 1 m 2 /g, a median pore diameter of more than 0.8 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.

22. A catalyst comprising a carrier and silver deposited on the carrier, which carrier comprises at least 85 weight percent α-alumina and has a non-platelet morphology, a surface area of at least 1 m 2 /g, a median pore diameter of more than 0.8 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.

23. A catalyst comprising a carrier and silver deposited on the carrier, which carrier has a surface area of at least 1 m 2 /g, a water absorption of at most 0.6 g/g, a median pore diameter of more than 0.8 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.

24. A process for the preparation of a catalyst, which process comprises:

a) selecting a carrier which has a surface area of at least 1.3 m 2 /g, a median pore diameter of more than 0.8 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, and

b) depositing silver on the carrier.

25. A process as claimed in claim 24 , wherein the carrier has been obtained by a method which comprises forming a mixture comprising:

a) from 50 to 95 weight percent of a first particulate α-alumina having a median particle size (d 50 ) of from 5 to 100 μm;

b) from 5 to 50 weight percent of a second particulate α-alumina having a d 50 which is less than the d 50 of the first particulate α-alumina and which is in the range of from 1 to 10 μm; and

c) an alkaline earth metal silicate bond material;

weight percent being based on the total weight of α-alumina in the mixture; and

firing the mixture to form the carrier.

26. A process as claimed in claim 25 , wherein

the carrier has an α-alumina content of at least 95 weight percent,

the mixture comprises:

a) from 60 to 90 weight percent, relative to the total weight of α-alumina in the mixture, of a first particulate α-alumina having a median particle size (d 50 ) of from 10 to 40 μm;

b) from 10 to 40 weight percent, relative to the total weight of α-alumina in the mixture, of a second particulate α-alumina having a median particle size (d 50 ) of from 2 to 8 μm;

c) from 0.2 to 2 weight percent, calculated as the total weight of alkaline earth metal oxide and silicate, as SiO 2 , relative to the total weight of α-alumina in the mixture, of an alkaline earth metal silicate bond material; and

d) from 0.5 to 5 weight percent of an alumina hydrate, calculated as Al 2 O 3 , relative to the total weight of α-alumina in the mixture, and

the process comprises shaping the mixture into formed bodies and firing the formed bodies at a temperature of from 1250 to 1550° C.

27. A process as claimed in claim 25 wherein the alkaline earth metal bond material comprises magnesium silicate.

28. A process as claimed in claim 25 wherein the alkaline earth metal bond material comprises a magnesium compound and a silica compound such that the atomic ratio of magnesium to silicon is in the range of 0.9 to 1.2.