Patent ID: 6984749

Claim:
A process for manufacturing an unsaturated mononitrile which process comprises: reacting at least one feed compound selected from the group consisting of propane, propylene, isobutane and isobutylene, with ammonia and a source comprising dioxygen in the presence of a catalyst in a reactor to produce a reactor effluent containing the corresponding unsaturated mononitrile; transferring the reactor effluent containing the unsaturated mononitrile to a quench/absorption section wherein the reactor effluent containing the unsaturated mononitrile is contacted with at least a first aqueous stream to cool the reactor effluent, and thereafter the cool effluent is contacted with at least a second aqueous stream in an absorption column to separate and recover the unsaturated mononitrile in an aqueous solution; transferring the aqueous solution containing the unsaturated mononitrile to a recovery and purification section where the unsaturated mononitrile is recovered and purified in at least a first distillation column and a second distillation column; and maintaining within one or more of the distillation columns an effective polymerization inhibiting amount of at least one phenylenediamine compound represented by the formula: wherein Ph is a phenylene group, and R 1 and R 2 are the same or different and are hydroxyl free organic moieties having about 2 to about 10 carbon atoms with the proviso that neither R 1 nor R 2 is a phenyl group.