GB712376A - Improvements in or relating to the manufacture of vinyl chloride - Google Patents

Abstract

Vinyl chloride is obtained by reacting acetylene and ammonium chloride at 250-500 DEG C. in the presence of a hydrochlorination catalyst and recovering vinyl chloride and ammonia from the reaction mixture. It is preferred to operate at 250 DEG to 350 DEG C. and to use a molar ratio of acetylene to ammonium chloride of at least 2 : 1 and preferably of about 3 : 1 and the excess acetylene may be separated and recycled continuously to the reaction. Steam, nitrogen, or other inert gaseous diluents may be used with the acetylene and ammonium chloride vapours. The catalyst may comprise mercury in which case the acetylene is advantageously used as a carrier for the ammonium chloride vapour and for the mercury vapour and the reaction is completed over a contact mass such as activated carbon. Alternatively, activated carbon may be impregnated with mercuric chloride or barium chloride or both. Other catalysts specified are chlorides of bismuth, lead, barium, magnesium, vanadium, aluminium, zinc and iron. The catalyst may be handled as a body of finely divided material which is maintained in a fluidized state by regulating the vapour velocity through the reaction zone, or it may be handled in pelleted form as a compact bed which is moved through the reaction zone in concurrent or countercurrent contact with the preheated acetylene. The reaction may also be conducted by adding ammonium chloride to a melt of metal chloride hydrochlorination catalysts and contacting the mixture with acetylene. Also the ammonium chloride may be mixed with inert, stable, organic liquids which act as heat transfer media. The vaporized ammonium chloride may then be contacted with acetylene in a reaction zone containing the catalyst in bed form or the reaction may be conducted in the organic heat transfer medium by forming a slurry of the catalyst and the ammonium chloride charge which is contacted with a stream of preheated acetylene gas. Specified organic liquids are chlorinated diphenyl, diphenyl, diphenyl oxide, mixtures of diphenyl and diphenyl oxide, ditolyl ethane, terphenyl, and highly aromatic petroleum oils. Examples are given, the acetylene used in each case being diluted with nitrogen. In one of the examples the catalyst used comprises activated carbon impregnated with barium chloride and a small amount of mercuric chloride.