Silica-supported catalyst

A method for producing a silica-supported catalyst, comprising the steps of:

• (I) preparing a raw material-prepared solution containing Mo, V, Nb, X, T, and Z, wherein an atomic ratio a of V to one Mo atom is 0.05≦a≦0.5, an atomic ratio b of Nb to one Mo atom is 0.01≦b≦0.5, an atomic ratio c of X to one Mo atom is 0.001≦c≦0.5, an atomic ratio d of T to one Mo atom is 0≦d≦1, and an atomic ratio e of Z to one Mo atom is 0≦e≦1;
• (II) drying the raw material-prepared solution to obtain a dry powder;
• (III) pre-stage calcining the dry powder at 200 to 400° C. to obtain a pre-stage calcined body;
• and
• (IV) main-calcining the pre-stage calcined body at 600 to 750° C. to obtain a calcined body,
• wherein the raw material-prepared solution comprises 0 to 30% by mass based on total mass of silica raw materials of (i) a silica sol having an average primary particle size of 3 nm or more and less than 20 nm, 30 to 70% by mass based on total mass of the silica raw materials of (ii) a silica sol having an average primary particle size of 20 nm or more and 100 nm or less, and 30 to 70% by mass based on total mass of the silica raw materials of a silica powder having an average primary particle size of 50 nm or less, and wherein a total of the silica sol (i), the silica sol (ii), and the silica powder is 100% by mass based on silica.