Patent ID: 7262148

Claim:
A process for producing a composite oxide catalyst, comprising: conducting cooling of a calcined dried product of a mixed solution or aqueous slurry containing catalyst components under a gaseous atmosphere having a relative humidity, as calculated at 25° C., of at most 30%; wherein said composite oxide catalyst comprises molybdenum, bismuth and iron, for the production of an unsaturated aldehyde and an unsaturated carboxylic acid, for use in the gas phase catalytic oxidation of an olefin with a molecular oxygen-containing gas to produce the corresponding unsaturated aldehyde and unsaturated carboxylic acid, whereupon, having prepared the composite oxide catalyst, having calcined the catalyst in a furnace under an atmosphere having a relative humidity, as determined at 25° C., of at most 30% and having withdrawn and recovered the calcined catalyst from the furnace and having stored the calcined catalyst, all under an atmosphere of a relative humidity of at most 30%, and then upon drying the stored catalyst, the loss of moisture upon drying is at most 0.5 wt % as determined by the equation (1): Loss on drying=(W2-W1)/W2×100 (1) wherein W1 represents the weight when the catalyst is heated for two hours at 110±5° C., and W2 represents the weight of the catalyst prior to said heating.