Improvements in and relating to the production of acrylonitrile

Acrylonitrile is recovered from gaseous mixtures containing it together with free ammonia, such mixtures being produced by the vapour phase catalytic oxidation of propylene in the presence of ammonia and molecular oxygen, by volatilizing into the gaseous mixture, while still at a temperature above its dew point, formic acid in amount at least sufficient for the neutralization of the free ammonia, washing the gaseous mixture with water to absorb acrylonitrile and other soluble products and distilling the resulting solution to recover the acrylonitrile. The formic acid may be volatilized in the gaseous mixture as it leaves the reactor by injecting a spray of aqueous acid into the hot gas stream. The washing with water is generally effected at 0-26 DEG C. and it may be effected in two stages, i.e. in a preliminary stage in which ammonium formate is dissolved out and a second stage for removing acrylonitrile and other components.