Vinyl chloride single-step manufacture

If the production of vinyl chloride could be reduced to a single step, such as dkect chlorine substitution for hydrogen in ethylene or oxychlorination/cracking of ethylene to vinyl chloride, a major improvement over the traditional balanced process would be realized. The Hterature is filled with a variety of catalysts and processes for single-step manufacture of vinyl chloride (136—138). None has been commercialized because of the high temperatures, corrosive environments, and insufficient reaction selectivities so far encountered. Substitution of lower cost ethane or methane for ethylene in the manufacture of vinyl chloride has also been investigated. The Lummus-Transcat process (139), for instance, proposes a molten oxychlorination catalyst at 450—500°C to react ethane with chlorine to make vinyl chloride dkecfly. However, ethane conversion and selectivity to vinyl chloride are too low (30% and less than 40%, respectively) to make this process competitive. Numerous other catalysts and processes have been patented as weU, but none has been commercialized owing to problems with temperature, corrosion, and/or product selectivity (140—144). Because of the potential payback, however, this is a very active area of research. 

A number of syntheses using acetylene, by thrir very nature (simplicity of the reaction in a single step, high yield and selectivity etc.), were favored over their counterparts employing ethylene. These included, for example, the manufacture of vinyl chloride or acetate. Inasmuch as resources became available to fund the corresponding investments, such a substitution could be considered in the long term. 

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