GB603823A - Improvements in or relating to the manufacture of acetonitrile - Google Patents

Abstract

Aqueous acetonitrile containing acetone is distilled in a column still, acetone vapour <PICT:0603823/III/1> being led off from the top and aqueous acetonitrile as a sidestream, part of which is returned at a lower point, and the residue is azeotropically dehydrated as described in Specification 540,799. In case the acetonitrile is produced by catalytic dehydration of ammonium acetate, the crude product may be fed to a stripping column (which may be the lower part of a combined stripping and acetone-removal column) to remove ammonia (by means of dilute acid, e.g. sulphuric acid), acetic acid and some water. In one embodiment of the invention, crude acetonitrile vapour is fed into the stripping column 2 at 12 and dilute sulphuric or other acid at 13, while the boiler 1 is heated by introduction of steam at 10. Acetone and water-acetonitrile binary azeotrope pass into the acetone-removal column 3 and acetone vapour is led off at 7 and condensed at 8, part of the liquid being refluxed via 9 and the remainder removed by 15. Water-acetonitrile binary azeotrope (containing only a small proportion of acetone) is led off at 4, part being refluxed at 6 and the remainder passing via 16 to a dehydrating apparatus as described in Specification 540,799, from which the aqueous layer is returned to column 2 at 14. In a modification (Fig. 2, not shown), the liquid passing out at 16 is led to a stripping column, residual acetone being removed as vapour and fed back to column 3 slightly above 4 and acetone-free binary being led to the dehydrating apparatus as above. Specification 603,824 also is referred to.