| abstract |
An improved catalyst is provided for use in the vapor phase oxidation of at least one compound selected from the group consisting of propylene, isobutylene, t-butanol and methyl-t-butyl ether, which is with molecular oxygen or a gas containing molecular oxygen to produce the corresponding unsaturated carboxylic acid and unsaturated aldehyde. The improved catalysts are compositions comprising (A) an oxide complex containing as essential components, molybdenum, bismuth and iron, which are known to be catalysts for said reaction and (B) an oxide complex containing cerium and zirconium as The essential components. When the improved catalysts are used, the production operation of the unsaturated carboxylic acid and unsaturated aldehyde can be stably continued for prolonged periods. |