Patent ID: 7632777

Claim:
A process for producing a composite oxide catalyst expressed by the following formula (1): Mo a Bi b Co c Ni d Fe e X f Y g Z h Si i O j (1) wherein X is at least one element selected from the group consisting of magnesium (Mg), calcium (Ca), zinc (Zn), cerium (Ce), samarium (Sm) and halogen, Y is at least one element selected from the group consisting of sodium (Na), potassium (K), rubidium (Rb), cesium (Cs) and thallium (Tl), Z is at least one element selected from the group consisting of boron (B), phosphorus (P), arsenic (As) and tungsten (W), the letters a to j are atomic ratios of the respective elements, where if a=12, then b=0.5-7, c=0-10, d=0-10 (where c−d=1-10), e=0.05-3, f=0-2, g=0.04-2, h=0-3 and i=5-48, and j is a numeral which satisfies the oxidation state of the other elements, by a process comprising incorporating supply source compounds of the respective elements into a composite in an aqueous solution, and subjecting the composite to heat treatment, comprising a pre-step for producing a catalyst precursor by mixing, while stirring, respective aqueous salt solutions of molybdenum equivalent to partial atomic ratio (a 1 ) of the entire atomic ratio (a) of molybdenum, iron, nickel and cobalt to obtain a first mixture, adding silica to the first mixture, stirring the first mixture, drying the first mixture and subjecting the first mixture to heat treatment, and an after-step in which said catalyst precursor is dispersed in an aqueous salt solution of molybdenum equivalent to the remaining atomic ratio (a 2 ) after subtracting said a 1 from the entire atomic ratio (a) of molybdenum, thereafter a bismuth compound is added and stirred to obtain a second mixture, and the second mixture is dried and calcined, wherein the ignition loss of said catalyst precursor is 0.5-5 wt % Ignition loss (%)=[W 0 -W 1 )/W 0 ]×100 W 0 : weight (g) of said catalyst precursor after drying for three hours at 150° to remove adhering water content W 1 : weight (g) of said catalyst precursor after the adhering water content has been removed and after it has further been heat-treated for two hours at 500°.