(Meth)acrylonitrile recovery and purificn from ammoxidn effluent - with recycle of prod column bottoms to form quench liq in quench system

摘要

In the recovery and purification of acrylonitrile produced by the reaction of propylene, O2 and NH3 in the presence of an ammoxidation catalyst, which consists of (a) contacting the ammoxidation reactor effluent with an aq. quench liquid in a quench system to produce a gaseous quench effluent having a temp. of 90-230 degrees F, (b) removing this effluent and absorbing it in water to form a soln., (c) distilling most of the by-products of the ammoxidation reaction and most of the water from the soln. to obtain a liquid stream contg. crude acrylonitrile, and (d) distilling the crude acrylonitrile to obtain a gaseous overhead stream of product quality acrylonitrile and a bottoms stream contg. acrylonitrile and impurities and having a pH of 3-5, the improvement comprises recycling part of the liq. bottoms stream obtd. in step(d) as at least part of the quench liquid in step (a). This improvement may also be applied to the recovery and purification of methacylonitrile by ammoxidation of isobutylene. There is no need for the fractional distillation column of prior art. and the efficiency of the recovery and purification system is improved.