GB801663A - Improved process for the production of vinyl chloride from 1,2-dichlorethane and acetylene - Google Patents

Abstract

A dehydrochlorination catalyst consisting of an active carbon base impregnated with a metal salt (e.g. barium chloride) is regenerated by treatment with inert gases (e.g. nitrogen) containing water vapour and only traces of oxygen at elevated temperature (e.g. 900 DEG C.).ALSO:Vinyl chloride is produced partly by catalytic dehydrochlorination of 1 : 2-dichlorethane and partly by catalytic synthesis from the hydrochloric acid so produced and acetylene, by a process wherein the catalytic dehydrochlorination is effected in a first substantially upright reaction zone and the catalytic synthesis in a second such zone, the catalyst in each zone being in the form of a powder having a particle size of 40-200 microns in diameter, 95 per cent of the particles being of 50-150 microns diameter, and wherein the reactants and reaction products in each zone are in the gaseous state, the amount of catalyst and rate of flow of reactants and reaction products through each zone being such that the catalyst is maintained in fluidized suspension throughout substantially the entire length of each reaction zone, and that in each reaction zone the upper level of said suspension is adjacent to the upper limit of the reaction zone. Preferably the dehydrochlorination is effected at 350-450 DEG C. in the presence of a catalyst consisting of a base (e.g. silica gel, clay or active carbon) impregnated with a metal salt (e.g. barium chloride), which may be regenerated by continuously extracting it from the upper part of the reaction zone and recycling it to the lower part after burning off the tar deposited thereon or (in the case of a catalyst with an active carbon base) treating it with inert gases (e.g. nitrogen) containing water vapour and only traces of oxygen at elevated temperatures (e.g. 900 DEG C.). The synthesis step is preferably carried out at 120-160 DEG C. in the presence of powdered active carbon impregnated with mercuric chloride, using acetylene substantially free from catalyst poisons. A suitable apparatus, described with the aid of a drawing, comprises a double-column vertical dehydrochlorination reactor and a double-column vertical synthesis reactor, there being an injector at the foot of each reactor for supplying the fluidized catalyst suspensions thereto and a cyclone device at the top of each reactor and connected to the top of each lower column for receiving product gases therefrom, a dichlorethane distillation unit for receiving excess dichlorethane liquefied from the products leaving the dehydrochlorination reactor and for returning part of said excess dichlorethane to said reaction as a recycle food, a product distillation unit for separating the products leaving the synthesis reactor into recycle acetylene and dichlorethane and product vinyl chloride, and a regenerator for the dehydrochlorination catalyst. The latter preferably comprises cyclone means for collecting the powdered catalyst, conduit means for causing hot gases to suspend said catalyst during the regeneration and to deposit the regenerated catalyst in said cyclone means, further conduit means connecting said cyclone means to the supply mains for the dichlorethane feed to the dehydrochlorination reactor, and blower means in said supply mains to entrain the regenerated catalyst with the gases fed to the foot of said reactor. A jacket may surround at least part of the lower column of the dehydrochlorination reactor, there being conduit means for causing hot fluid to enter said jacket near the top and leave the bottom thereof. A numerical example describes the production of 5 tons a day of pure vinyl chloride.