Oxide catalyst and method for producing same, and method for producing unsaturated nitrile

1. A method for producing an oxide catalyst, the method comprising:

a step (a) of obtaining an aqueous mixed liquid A comprising Mo, V and Sb;

a step (b) of mixing a Nb raw material which is one or more selected from the group consisting of niobic acid, and inorganic niobate and an organic niobate, water and an organic acid to obtain a Nb aqueous solution;

a step (c) of mixing the Nb aqueous solution and a silica raw material to obtain an aqueous mixed liquid B;

a step (d) of mixing the aqueous mixed liquid A and the aqueous mixed liquid B to obtain an aqueous mixed liquid C;

a step (e) of drying the aqueous mixed liquid C to obtain a dried powder D; and

a step (f) of calcining the dried powder D to obtain the oxide catalyst,

wherein the oxide catalyst consists of a metal component represented by formula (1):

Mo 1 V a Sb b Nb c W d Z e O n   (1),

wherein Z is at least one element selected from the group consisting of La, Ce, Pr, Yb, Y, Sc, Sr and Ba; a, b, c, d, e and n represent atomic ratios of each element and satisfy 0.1≤a≤0.3, 0.15≤b≤0.5, 0.01≤c≤0.5, 0≤d≤0.4, and 0≤e≤0.2, and n is a number determined by a, b, c, d and e.

2. The method for producing the oxide catalyst according to claim 1 , wherein a molar ratio (Nb/Si) of Nb to 1 mol of Si in the aqueous mixed liquid B is 0.02 to 0.7.

3. The method for producing the oxide catalyst according to claim 1 , wherein in the step (c), a mixing time of the Nb aqueous solution and the silica raw material is 1 minute to 6 hours.

4. The method for producing the oxide catalyst according to claim 1 , comprising, after the step (d) and before the step (e), a step (d′) of mixing the aqueous mixed liquid C and powder silica and/or silica sol.

5. The method for producing the oxide catalyst according to claim 1 , wherein a content of silica in the oxide catalyst is 20 to 70% by mass in terms of SiO 2 .