COKE PRODUCED IN THE COMMERCIAL PYROLYSIS OF ETHYLENE DICHLORIDE INTOVINYL-CHLORIDE

A variety of cokes formed in the reactor and transfer lines of a comme rcial ethylene dichloride pyrolysis process producing a vinyl chloride monomer were characterized by optical and electron scanning microscop ies to determine the mechanism by which they were formed and to find m eans for suppressing this coke formation. Typical columnar pyrolytic c arbon was found on the reactor wall, which was anisotropic carbon of g ranular appearance. Deposits of carbon found in the transfer lines of product and feed varied in amount and composition, depending on the lo cation of the deposition. The latter carbon appeared to be formed thro ugh a mechanism similar to refluxing carbonization of reactive species such as chloroprene and acetylene, which are easily oligomerized, can precipitate on the wall, and finally yield carbon after the repeated dissolution and precipitation. The temperature and kinds of reactive s pecies in the product and feed may define the extent of adhesion, coal escence, and growth of carbon primary granules and may induce their so ftening during carbonization.