The Standard Oil Company

Hsin C Wu

William O Fitzgibbons

A process is described for the recovery and purification of an olefinic nitrile, such as methacrylonitrile, from mixtures of said olefinic nitrile with hydrogen cyanide, acetonitrile, acrylonitrile, and carbonyl compounds, which result from the ammoxidation of an olefin, such as isobutylene. The mixtures of olefinic nitrile are fed to an extractive distillation column at a point above the middle of the column, a vapor sidestream is removed at a point below the middle of the extractive distillation column said sidestream containing substantially all of the hydrogen cyanide, acetonitrile and carbonyl compounds and then concentrating the hydrogen cyanide, acetonitrile and carbonyl compounds in a stripping pot.

Recovery and purification of olefinic nitriles

Acrylonitrile or methacrylonitrile found in the reactor effluent of the ammoxidation reaction of propylene or isobutylene is recovered by cooling the reactor effluent to a temperature of about 40.degree. to about 100.degree. C. using direct contacting cooling, preferably with an aqueous stream, to obtain a gaseous stream containing acrylonitrile or methacrylonitrile and cooling the gaseous stream using indirect contact cooling to condense at least some of the acrylonitrile or methacrylonitrile from the gaseous stream.

Recovery of acrylonitrile or methacrylonitrile by condensation

In the recovery and purification of acrylonitrile or methacrylonitrile obtained by the ammoxidation reaction of propylene or isobutylene, the bottoms stream associated with the column for extractively distilling acrylonitrile or methacrylonitrile is both reduced in size and increased in polymer concentration by removing a vapor stream containing water from the lower fourth of said column, thus reducing the amount of solids-containing waste streams to be treated.

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Parma, OH, United States of America

Hsin C Wu