Method for preparing mixed metal oxide catalysts containing molybdenum and bismuth

The present invention relates to a process for producing mixed oxide catalysts on the basis of molybdenum and bismuth oxides in which the precursor compounds of the components of mixed oxide catalysts provided in the form of a solution and/or suspension are subjected to a spray-drying with a specific temperature regime and the spray particles obtained in this way are then calcined to yield a catalytic active mass, and to the mixed oxide catalysts obtainable by this process and to the use of these catalysts in the partial oxidation of olefins, in particular in the partial gas phase oxidation of propene to acrolein and acrylic acid. The spray drying of the precursor compounds containing solution or suspension is performed in concurrent with a gas stream having a specific entrance temperature. Alternatively, when the main gas stream has a higher entrance temperature, an additional colder gas stream can be fed in downstream. The thus obtained mixed oxide catalysts give lower a maximum temperature in the hot spot of catalyst fixed bed when they are used in the partial gas phase oxidation of olefins.