Process for finishing vinyl chloride monomer

Abstract

This process stems from the discovery that the solubility of water in vinyl chloride monomer ('VCM') is so low in a cold aqueous caustic solution at a temperature below 0.degree. C., that the aqueous solution will remove water dissolved in the monomer, and at the same time, will neutralize the HCl associated with the monomer and prevent the formation of acetylene. This discovery makes it possible to dry and neutralize a HCl and water-containing vinyl chloride ('VCl') stream, by intimately contacting the stream with a cold aqueous 2 to 30 wt % caustic soda solution at a temperature below 25.degree. F. and above the freezing point of the caustic solution. In a commercial VCM producing facility, VCl can be 'finished' in a 'stand-alone' processing facility with greater economy than in a conventional VCM plant, yet avoid the hazards of operating a conventional VCl stripping column and scrubbers packed with solid caustic pellets. The process allows simultaneously drying and neutralizing a VCl stream containing from about 1 part per million (ppm) to about 500 ppm HCl, and from about 10 ppm to about 300 ppm of water by contacting it with a 10% to 25% aqueous cold caustic solution, and separating dry and neutralized VCM monomer containing no more than 100 ppm water.