Process for producing geometric shaped catalyst bodies

1. A process for producing geometric shaped catalyst bodies K which comprise, as an active material, a multielement oxide I of the general stoichiometry I

[Bi a Z 1 b O x ] p [Bi c Mo 12 Fe d Z 2 e Z 3 f Z 4 g Z 5 h Z 6 i O y ] 1   (I),

where

Z 1 =tungsten or tungsten and molybdenum, with the proviso that at least 10 mol % of the molar total amount of Z 1 is tungsten,

Z 2 =one element or more than one element from the group consisting of nickel and cobalt,

Z 3 =one element or more than one element from the group consisting of the alkali metals, the alkaline earth metals and thallium,

Z 4 =one element or more than one element from the group consisting of zinc, phosphorus, arsenic, boron, antimony, tin, cerium, vanadium and chromium,

Z 5 =one element or more than one element from the group consisting of silicon, aluminum, titanium, tungsten and zirconium,

Z 6 =one element or more than one element from the group consisting of copper, silver, gold, yttrium, lanthanum and the lanthanides,

a=0.1 to 3,

b=0.1 to 10,

d=0.01 to 5,

e=1 to 10,

f=0.01 to 2,

g=0 to 5,

h=0 to 10,

i=0 to 1,

p=0.05 to 6, and

x, y=numbers determined by the valency and frequency of the elements in I other than oxygen,

in which

a finely divided mixed oxide Bi a Z 1 b O x with a particle diameter d 50 A1 , as starting material A1, is preformed with the proviso that 1 μm≦d 50 A1 ≦100 μm;

sources of the elements other than oxygen in the component T=[Bi c Mo 12 Fe d Z 2 e Z 3 f Z 4 g Z 5 h Z 6 i O y ] 1 of the multielement oxide I are used in an aqueous medium to obtain an intimate aqueous mixture M, with the proviso that

each of the sources used, in the course of preparation of the aqueous mixture M, passes through a degree of division Q for which its diameter d 90 Q is ≦5 μm, and

the aqueous mixture M comprises the elements Bi, Mo, Fe, Z 2 , Z 3 , Z 4 , Z 5 and Z 6 in the stoichiometry I*

Bi c Mo 12 Fe d Z 2 e Z 3 f Z 4 g Z 5 h Z 6 i   (I*);

the aqueous mixture M, by means of drying and adjusting the degree of division d 90 A2 , is used to obtain a finely divided starting material A2 with a particle diameter d 90 A2 , with the proviso that 400 μm≧d 90 A2 ≧10 μm;

starting material A1 and starting material A2, or starting material A1, starting material A2 and finely divided shaping assistant, are mixed with one another to form a finely divided starting material A3, with the proviso that the starting material A3 comprises the elements other than oxygen introduced into the starting material A3 via starting materials A1 and A2 in the multielement oxide I in the stoichiometry I**

[Bi a Z 1 b ] p [Bi c Mo 12 Fe d Z 2 e Z 3 f Z 4 g Z 5 h Z 6 i ] 1   (I**),

finely divided starting material A3 is used to form geometric shaped bodies V, and

the shaped bodies V are treated thermally at elevated temperature to obtain the geometric shaped catalyst bodies K,

wherein the stoichiometric coefficient c satisfies the condition 0<c≦0.8, and

wherein all particle diameters are base on volume-based particle diameter distribution determined according to ISO 13320 at a dispersion pressure of 2 bar absolute.

2. The process according to claim 1 , wherein c is ≧0.001.

3. The process according to claim 1 , wherein c is ≧0.002.

4. The process according to claim 1 , wherein c is ≧0.005.

5. The process according to any one of claims 1 to 4 , wherein c is ≦0.7.

6. The process according to any one of claims 1 to 4 , wherein c is ≦0.6.

7. The process according to claim 1 , wherein 0.007≦c≦0.5.

8. The process according to claim 1 , wherein 0.01≦c≦0.4.

9. The process according to claim 1 , wherein 0.02≦c≦0.3.

10. The process according to claim 1 , wherein 0.03≦c≦0.2.

11. The process according to claim 1 , wherein 0.04≦c≦0.1.

12. The process according to claim 1 , wherein 0.005≦c≦0.08.

13. The process according to claim 1 , wherein 0.01≦c≦0.06.

14. The process according to claim 1 , wherein p is 0.1 to 4.

15. The process according to claim 1 , wherein p is 0.2 to 3.

16. The process according to claim 1 , wherein p is 0.3 to 1.

17. The process according to claim 1 , wherein the n Bi :n Mo ratio of the total molar amount of Bi present in the multielement oxide I, n Bi , to the total molar amount of Mo present in the multielement oxide I, n Mo , is 0.3 to 2:12.

18. The process according to claim 17 , wherein n Bi :n Mo is 0.4 to 1.8:12.

19. The process according to claim 17 , wherein n Bi :n Mo is 0.5 to 1.6:12.

20. The process according to claim 1 , wherein 1 μm≦d 50 A1 ≦50 μm.

21. The process according to claim 1 , wherein 1 μm≦d 50 A1 ≦10 μm.

22. The process according to claim 1 , wherein 1.5 μm≦d 50 A1 ≦6 μm.

23. The process according to claim 1 , wherein 2 μm≦d 50 A1 ≦3 μm.

24. The process according to claim 1 , wherein 200 μm≧d 90 A2 ≧20 μm.

25. The process according to claim 1 , wherein 150 μm≧d 90 A2 ≧40 μm.

26. The process according to claim 1 , wherein 100 μm≧d 90 A2 ≧50 μm.

27. The process according to claim 1 , wherein the particle diameter d 50 A2 of the finely divided starting material A2 satisfies the condition 10 μm≦d 50 A2 ≦100 μm.

28. The process according to claim 1 , wherein the particle diameter d 50 A2 of the finely divided starting material A2 satisfies the condition 20 μm≦d 50 A2 ≦60 μm.

29. The process according to claim 1 , wherein the ratio of the particle diameter d 90 A2 of the finely divided starting material A2 to the particle diameter d 10 A2 of the finely divided starting material A2 is in the range from 5 to 20.

30. The process according to claim 1 , wherein d 90 Q for each of the sources used is ≦3 μm.

31. The process according to claim 1 , wherein d 90 Q for each of the sources used is ≦1 μm.

32. The process according to claim 1 , wherein d 90 Q for each of the sources used is ≦0.5 μm.

33. The process according to claim 1 , wherein each of the sources used, in the course of preparation of the aqueous mixture M, passes through the state of a colloidal solution or of a true solution.

34. The process according to claim 1 , wherein the component T comprises the element Si and each of the sources of the elements other than silicon used, in the course of preparation of the aqueous mixture M, passes through the state of a true solution and the source of the element Si used is a silica sol.

35. The process according to claim 1 , wherein the finely divided starting material A2 is obtained by spray-drying the aqueous mixture M.

36. The process according to claim 1 , wherein Z 2 =Co.

37. The process according to claim 1 , wherein Z 3 =K, Cs and/or Sr.

38. The process according to claim 1 , wherein Z 5 =Si.

39. The process according to claim 1 , wherein a is from 0.5 to 3.

40. The process according to claim 1 , wherein a is from 1.5 to 2.5.

41. The process according to claim 1 , wherein b is from 2 to 5.

42. The process according to claim 1 , wherein b is from 3 to 5.

43. The process according to claim 1 , wherein at least 20 mol % of the molar total amount of Z 1 is tungsten.

44. The process according to claim 1 , wherein at least 80 mol % of the molar total amount of Z 1 is tungsten.

45. The process according to claim 1 , wherein the molar total amount of Z 1 is tungsten.

46. The process according to claim 1 , wherein e is from 3 to 8.

47. The process according to claim 1 , wherein e is from 4 to 7.

48. The process according to claim 1 , wherein f is from 0.03 to 1.

49. The process according to claim 1 , wherein d is from 1 to 4.

50. The process according to claim 1 , wherein h is from 0.1 to 8.

51. The process according to claim 1 , wherein h is from 0.5 to 3.

52. The process according to claim 1 , wherein the finely divided mixed oxide Bi a Z 1 b O x is the mixed oxide Bi 2 W 4 O 15 .

53. The process according to claim 1 , wherein the product

(d 50 A1 ) 0.7 ·(d 90 A2 ) 1.5 ·(p/2) −1

defined as F, has a value ≧820, where the two particle diameters d 50 A1 and d 90 A2 are in μm.

54. The process according to claim 53 , wherein 1000≦F≦5000.

55. The process according to claim 53 , wherein 2000≦F≦4000.

56. The process according to claim 1 , wherein the product

(d 50 A1 ) 0.7 ·(d 90 A2 ) 0.7 ·(p/2) −1

defined as F*, has a magnitude ≧15, where the two particle diameters d 50 A1 and d 90 A2 are in μm.

57. The process according to claim 56 , wherein 35≧F*≧18.

58. The process according to claim 1 , wherein finely divided starting material A1, finely divided starting material A2 and shaping assistant comprising finely divided hydrophobized silica are mixed with one another to give the finely divided starting material A3.

59. The process according to claim 1 , wherein finely divided starting material A1, finely divided starting material A2 and shaping assistant comprising finely divided graphite are mixed with one another to give the finely divided starting material A3.

60. The process according to claim 1 , wherein geometric shaped bodies V are formed with finely divided starting material A3 by compacting the finely divided starting material A3.

61. The process according to claim 60 , wherein the compaction is effected by extrusion or tableting.

62. The process according to claim 1 , wherein the geometric shaped body V is a ring.

63. The process according to claim 62 , wherein the side crushing strength SCS of the annular shaped body V satisfies the condition 12 N≦SCS≦25 N.

64. The process according to claim 1 , wherein the geometric shaped body V is a sphere.

65. The process according to claim 1 , wherein the geometric shaped body V is a solid cylinder.

66. The process according to claim 62 or 63 , wherein the external diameter=from 2 to 10 mm, the height=from 2 to 10 mm and the wall thickness of the ring is from 1 to 3 mm.

67. The process according to claim 64 , wherein the sphere diameter is from 2 to 10 mm.

68. The process according to claim 65 , wherein the external diameter=from 1 to 10 mm and the height of the solid cylinder is from 2 to 10 mm.

69. The process according to claim 1 , wherein geometric shaped bodies V are formed with finely divided starting material A3 by applying the finely divided starting material A3 to the surface of a geometric shaped support body with the aid of a liquid binder.

70. The process according to claim 1 , wherein the temperature of 350° C. is exceeded and the temperature of 600° C. is not exceeded in the course of thermal treatment of the shaped bodies V.

71. The process according to claim 1 , wherein the temperature of 420° C. is exceeded and the temperature of 500° C. is not exceeded in the course of thermal treatment of the shaped bodies V.

72. The process according to claim 1 , wherein the thermal treatment is effected in the presence of air.

73. The process according to claim 1 , wherein the shaped catalyst body K is a shaped unsupported catalyst body K and the process for preparing it is followed by a process for grinding to give finely divided material and the finely divided material is applied to the surface of a geometric shaped support body with the aid of a liquid binder.