Deacon process vinyl chloride

In oxychlorination, ethylene reacts with dry HCl and either air or pure oxygen to produce EDC and water. Various commercial oxychlorination processes differ from one another to some extent because they were developed independentiy by several different vinyl chloride producers (78,83), but in each case the reaction is carried out in the vapor phase in either a fixed- or fluidized-bed reactor containing a modified Deacon catalyst. Unlike the Deacon process for chlorine production, oxychlorination of ethylene occurs readily at temperatures weU below those requited for HCl oxidation. 

Alternatives to oxychlorination have also been proposed as part of a balanced VCM plant. In the past, many vinyl chloride manufacturers used a balanced ethylene—acetylene process for a brief period prior to the commercialization of oxychlorination technology. Addition of HCl to acetylene was used instead of ethylene oxychlorination to consume the HCl made in EDC pyrolysis. Since the 1950s, the relative costs of ethylene and acetylene have made this route economically unattractive. Another alternative is HCl oxidation to chlorine, which can subsequently be used in dkect chlorination (131). The SheU-Deacon (132), Kel-Chlor (133), and MT-Chlor (134) processes, as well as a process recently developed at the University of Southern California (135) are among the available commercial HCl oxidation technologies. Each has had very limited industrial appHcation, perhaps because the equiHbrium reaction is incomplete and the mixture of HCl, O2, CI2, and water presents very challenging separation, purification, and handling requkements. HCl oxidation does not compare favorably with oxychlorination because it also requkes twice the dkect chlorination capacity for a balanced vinyl chloride plant. Consequently, it is doubtful that it will ever displace oxychlorination in the production of vinyl chloride by the balanced ethylene process. 

Chlorine and sodium hydroxide are the main products of the industrial chlor-alkali electrolysis that is described as a process example in Section 6.19. Hydrochloric acid is produced by reaction from the elements H2 and CI2 or by the reaction of chloride salts such as, for example, NaCl or CaCl2, with sulfuric acid. Other important sources of HCl are industrial chlorination processes using CI2 as chlorination agent (e.g., chlorination of benzene to form chlorobenzene and HCl or the chlorination of methane to give chloromethane and HCl) or industrial dehydrochlorination processes (e.g., production of vinyl chloride and HCl from 1,2-dichloroethane). The main uses of hydrochloric acid are addition reactions to unsaturated compounds (by hydrochlorination or oxychlorination), formation of chlorine in the Deacon process, production of chloride salts from amines and other organic bases, dissolution of metals, regeneration of ion exchange resins, and the neutralization of alkaline products. 

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