Composite oxide catalyst and method for preparation thereof

A process for producing a composite oxide catalyst expressed by the following formula (1):

• MoaBibCocNidFeeXfYgZhSiiOj (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 (a1) 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 (a2) after subtracting said a1 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 (%)=[W0-W1)/W0]×100
• W0:
• weight (g) of said catalyst precursor after drying for three hours at 150° to remove adhering water content
• W1:
• 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°.