| 摘要 |
Vinyl chloride is prepared by thermal decomposition of dichlorethane in the vapour phase, the decomposition being carried out in the presence of dry ash-free carbon obtained by washing active carbon firstly with 2N nitric acid at 50-75 DEG C., and then with water, and thereafter drying the carbon. The carbon so obtained is free from metallic salts, e.g. iron salts, which catalyse the formation of undesired by-products such as tar. In an example, 1,2-dichlorethane vapours, at a gauge pressure of 8 atm., are passed through a stainless steel tube containing ash-free active carbon heated to a temperature of 400 DEG C. The condensed reaction products are subjected to fractional distillation to separate pure vinyl chloride from untransformed dichlorethane. The latter is recycled to the pyrolysis zone. A yield of 99% of vinyl chloride is obtained with a conversion rate of 65 to 70% per pass. The pyrolysis of 1,1-dichlorethane is referred to. |
