Patent ID: 7553986

Claim:
A process for producing unsaturated carboxylic acids or unsaturated nitriles by vapor phase oxidation reaction of their corresponding C 3 to C 5 alkanes, C 3 to C 5 alkenes, and mixtures thereof, using a reaction system having at least two reaction zones arranged in series with one another and at least one catalyst capable of catalyzing the vapor phase oxidation reaction disposed in each of the at least two reaction zones, wherein at least one intermediate effluent stream exits a preceding one of the at least two reaction zones and is at least partially fed to a subsequent one of the at least two reaction zones, said process comprising the steps of: separating the at least one intermediate effluent stream into at least an intermediate product stream comprising an oxidation product selected from the group consisting of an unsaturated carboxylic acid and an unsaturated nitrile, and an intermediate feed stream comprising starting materials selected from the group consisting of an unreacted C 3 to C 5 alkane, an unreacted C 3 to C 5 alkene, and mixtures thereof; feeding the intermediate feed stream to the subsequent reaction zone; and feeding an oxygen-containing gas to the subsequent reaction zone.