Mechanism of Carbonaceous Deposition in the Ethylene Dichloride Pyrolytic Process

The particular morphological features of the carbonaceous material deposited on the shell wall of heat-exchangers in the commercial pyrolytic process converting ethylene dichloride (EDC) into vinyl chloride monomer were reproduced to study the mechanism and factors affecting the deposition. The effects of time and temperature in the heat-treatment were examined in a stainless steel reactor at 220°-250°C using pure EDC and commercial EDC in the process. The yield of carbonaceous material from pure EDC increased almost proportionally with the period of heat-treatment from 0.12 wt % at 6 hr to 0.73 wt % at 48 hr. Addition of 1% benzene to pure EDC at 250°C reduced the yield and particle size of deposited carbonaceous material. Biphenyl and tetralin slightly reduced the yield. Small but significant amounts of 1,1-dichloroethylene, dichlorobutene, and ethylchloride were observed in addition to vinyl chloride, even at 250°C if the heat-treatment time was extended.