process for the preparation of highly pure vinyl chloride free from hydrogen chloride, from 1

摘要

1283028 Vinyl chloride KNAPSACK AG 24 Feb 1970 [4 March 1969] 8819/70 Heading C2C Vinyl chloride is produced by incomplete thermal cracking of 1,2-dichloroethane at 450‹ to 650‹ C. in the absence of a catalyst, the gas mixture leaving the cracking zone, consisting of vinyl chloride, hydrogen chloride, unreacted 1,2 - dichloroethane and by - products, being passed in a partially condensed state into a first distillation zone wherein hydrogen chloride is distilled off and then into a second distillation zone wherein the vinyl chloride is distilled off, whereupon the sump product of the second distillation zone is treated so as to recycle the unreacted 1,2-dichloroethane to the cracking zone as described in Specification 1,124,874, the vinyl chloride removed at the top of the second distillation zone being condensed and a part of it pumped back to an intermediate point in the first distillation zone, the remaining vinyl chloride removed as product, which still contains traces of hydrogen chloride, being fed to the top of a degasification zone from which a part of the'vinyl chloride, together with all the hydrogen chloride associated therewith, is evaporated by a recirculating evaporator, condensed, and pumped back to an intermediate point in the original hydrogen chloride distillation zone, pure vinyl chloride being removed from the bottom of the degasification zone.