Method for producing acrylonitrile

1. A method for producing acrylonitrile, the method comprising performing a vapor phase catalytic ammoxidation process by bringing a source gas containing propylene, molecular oxygen, and ammonia into contact with a fluidized bed catalyst to obtain acrylonitrile,

wherein the fluidized bed catalyst comprises particles containing Fe, Sb, and Te, and

the vapor phase catalytic ammoxidation process is performed while maintaining a B/A ratio in the range of 2.4 to 4.6, where A denotes an atomic ratio of Te/Sb in a bulk composition of the fluidized bed catalyst and B denotes an atomic ratio of Te/Sb in a surface composition of the particles of the fluidized bed catalyst.

2. The method for producing acrylonitrile according to claim 1 , wherein the bulk composition of the fluidized bed catalyst is represented by the following Formula (1)

Fe 10 Sb a A b Te c D d E e O x. (SiO 2 ) y   (1)

(wherein Fe, Sb, Te, O, and SiO 2 represent iron, antimony, tellurium, oxygen, and silica, respectively;

A represents at least one element selected from the group consisting of vanadium, molybdenum, and tungsten;

D represents at least one element selected from the group consisting of magnesium, calcium, strontium, barium, titanium, zirconium, niobium, chromium, manganese, cobalt, nickel, copper, silver, zinc, boron, aluminum, gallium, indium, thallium, germanium, tin, lead, phosphorus, arsenic, and bismuth;

E represents at least one element selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium; and

a, b, c, d, e, x, and y represent an atomic ratio and a is 3 to 100, b is 0.1 to 5, c is 0.1 to 10, d is 0 to 50, e is 0 to 5, y is 10 to 200, and x is a number of oxygen atom required to satisfy a valence of each of the components except silica provided that b, d, and e represent a sum of an atomic ratio of each element where A, D, and E contain two or more elements.

3. The method according to claim 1 , wherein the fluidized bed catalyst consists of particles containing Fe, Sb, and Te.

4. The method according to claim 1 , wherein the source gas has a molar ratio of propylene/ammonia/oxygen in the range of 1/1.0 to 2.0/1.0 to 5.0.

5. The method according to claim 1 , wherein the vapor phase ammoxidation reaction is conducted at a temperature of 350 to 500° C, at a pressure of 100 kPa to 500 kPa, and the contact time of the fluidized bed catalyst with the reaction gas is 0.1 to 20 seconds.

6. The method according to claim 1 , wherein the particles are from 1 to 200μm in size.

7. The method according to claim 1 , wherein the particles are from 5 to 150 μm in size.

8. The method according to claim 2 , wherein the source gas has a molar ratio of propylene/ammonia/oxygen in the range of 1/1.0 to 2.0/1.0 to 5.0.

9. The method according to claim 2 , wherein the vapor phase ammoxidation reaction is conducted at a temperature of 350 to 500° C, at a pressure of 100 kPa to 500 kPa, and the contact time of the fluidized bed catalyst with the reaction gas is 0.1 to 20 seconds.

10. The method according to claim 2 , wherein the particles are from 1 to 200 μm in size.

11. The method according to claim 2 , wherein the particles are from 5 to 150 μm in size.