Method for producing catalyst for ammoxidation, and method for producing acrylonitrile

1. A method for producing a catalyst for ammoxidation, comprising steps of:

preparing a catalyst precursor slurry comprising a liquid phase and a solid phase;

drying the catalyst precursor slurry to obtain a dry particle; and

calcining the dry particle to obtain a catalyst for ammoxidation,

wherein the solid phase of the catalyst precursor slurry comprises an aggregate containing a metal and a support, metal primary particles constituting the aggregate have a particle size of 1 μm or smaller, and an average particle size of the metal primary particles is 40 nm or larger and 200 nm or smaller, wherein the catalyst for ammoxidation comprises a composite metal oxide having composition represented by the following general formula (1): Mo 12 Bi a Fe b X c Y d Z e O f (1) wherein X represents one or more elements selected from the group consisting of nickel, cobalt, magnesium, calcium, zinc, strontium, and barium; Y represents one or more elements selected from the group consisting of cerium, chromium, lanthanum, neodymium, yttrium, praseodymium, samarium, aluminum, gallium, and indium; Z represents one or more elements selected from the group consisting of potassium, rubidium and cesium; a represents the atomic ratio of bismuth to the 12 atoms of molybdenum and satisfies 0.1<a<2.0; b represents the atomic ratio of iron to the 12 atoms of molybdenum and satisfies 0.1<b<3.0; c represents the atomic ratio of X to the 12 atoms of molybdenum and satisfies 0.1<c<10.0; d represents the atomic ratio of Y to the 12 atoms of molybdenum and satisfies 0.1<d<3.0; e represents the atomic ratio of Z to the 12 atoms of molybdenum and satisfies 0.01<e<2.0; and f represents the atomic ratio of oxygen to the 12 atoms of molybdenum and is the number of atoms of oxygen necessary for satisfying valence requirements of other elements present.

2. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, a free acid concentration in the slurry is 0.1% or more and 1.2% or less.

3. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, the free acid concentration in the slurry is 0.8% or more and 1.2% or less.

4. The method for producing the catalyst for ammoxidation according to claim 1 , wherein the catalyst for ammoxidation comprises a support, and a content of the support in the catalyst for ammoxidation is 35 to 45% by mass.

5. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, a proportion of a total mass of the metal component and the support as starting materials to a mass of the whole catalyst precursor slurry is 10% by mass or more and 40% by mass or less.

6. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, the proportion of the total mass of the metal component and the support as starting materials to the mass of the whole catalyst precursor slurry is 20% by mass or more and 35% by mass or less.

7. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of drying the catalyst precursor slurry to obtain the dry particle, a dryer is kept at an inlet air temperature of 180 to 250° C. and at an outlet temperature of 100 to 150° C.

8. The method for producing the catalyst for ammoxidation according to claim 1 , wherein the step of calcining the dry particle to obtain the catalyst for ammoxidation comprises denitration treatment before the calcination, and the denitration treatment involves performing heating at 150 to 450° C. for 1.5 to 3 hours.

9. The method for producing the catalyst for ammoxidation according to claim 1 , wherein in the step of calcining the dry particle to obtain the catalyst for ammoxidation, a calcination temperature is 550 to 650° C.

10. A method for producing acrylonitrile, comprising steps of:

preparing a catalyst for ammoxidation by the method of claim 1 ; and

supplying the catalyst for ammoxidation to a fluidized reaction vessel in advance, and while circulating the catalyst in the fluidized reaction vessel, reacting propylene, molecular oxygen, and ammonia to obtain acrylonitrile,

wherein the solid phase of the catalyst precursor slurry comprises an aggregate containing a metal and a support, metal primary particles constituting the aggregate have a particle size of 1 μm or smaller, and an average particle size of the metal primary particles is 40 nm or larger and 200 nm or smaller.

11. The method for producing acrylonitrile according to claim 10 , wherein

a source of the molecular oxygen is air, and

a molar ratio of ammonia and air to propylene is in the range of 1/(0.8 to 1.4)/(7 to 12) in terms of a ratio of propylene/ammonia/air.

12. The method for producing acrylonitrile according to claim 10 , wherein

a source of the molecular oxygen is air, and

a molar ratio of ammonia and air to propylene is in the range of 1/(0.9 to 1.3)/(8 to 11) in terms of a ratio of propylene/ammonia/air.

13. The method for producing acrylonitrile according to claim 10 , wherein a temperature at which propylene, molecular oxygen, and ammonia are reacted in the presence of the catalyst for ammoxidation is in the range of 350 to 550° C.

14. The method for producing acrylonitrile according to claim 10 , wherein a temperature at which propylene, molecular oxygen, and ammonia are reacted in the presence of the catalyst for ammoxidation is in the range of 400 to 500° C.

15. The method for producing acrylonitrile according to claim 10 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, a free acid concentration in the slurry is 0.1% or more and 1.2% or less.

16. The method for producing acrylonitrile according to claim 10 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, the free acid concentration in the slurry is 0.8% or more and 1.2% or less.

17. The method for producing acrylonitrile according to claim 10 , wherein the catalyst for ammoxidation comprises a support, and a content of the support in the catalyst for ammoxidation is 35 to 45% by mass.

18. The method for producing acrylonitrile according to claim 10 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, a proportion of a total mass of the metal component and the support as starting materials to a mass of the whole catalyst precursor slurry is 10% by mass or more and 40% by mass or less.

19. The method for producing acrylonitrile according to claim 10 , wherein in the step of preparing the catalyst precursor slurry comprising the liquid phase and the solid phase, the proportion of the total mass of the metal component and the support as starting materials to the mass of the whole catalyst precursor slurry is 20% by mass or more and 35% by mass or less.

20. The method for producing acrylonitrile according to claim 10 , wherein in the step of drying the catalyst precursor slurry to obtain the dry particle, a dryer is kept at an inlet air temperature of 180 to 250° C. and at an outlet temperature of 100 to 150° C.

21. The method for producing acrylonitrile according to claim 10 , wherein the step of calcining the dry particle to obtain the catalyst for ammoxidation comprises denitration treatment before the calcination, and the denitration treatment involves performing heating at 150 to 450° C. for 1.5 to 3 hours.

22. The method for producing acrylonitrile according to claim 10 , wherein in the step of calcining the dry particle to obtain the catalyst for ammoxidation, a calcination temperature is 550 to 650° C.