ABSTRACT
Hydrogen chloride, generated as a by-product from the cracking of ethylene dichloride to vinyl chloride, is used in the oxychlorination process. Excess hydrogen chloride generated by other processes, such as the production of perchloroethylene or carbon tetrachloride, can be utilized. Low-temperature chlorination reduces the quantity of by-product formation, but energy consumption is high due to steam requirements for ethylene dichloride recovery. In the high-temperature process, the heat of reaction is utilized for ethylene dichloride distillation leading to considerable energy savings. Ethylene dichloride is produced as a by-product of the oxychlorination route to ethylene oxide, but this process is no longer of any importance. In the low-temperature process, ethylene chlorination proceeds at 20–70°C in ethylene dichloride as the solvent for temperature control. In the high-temperature process a gaseous mixture of ethylene and chlorine, together with recycled ethylene dichloride, are reacted at a temperature of 100–150°C. Liquids from the base of the azeotropic distillation column are fed to the direct chlorination process.
