| 摘要 |
PURPOSE:To industrially and advantageously remove chloroprene in 1,2- dichloroethane without consuming chlorine gas by making the 1,2-dichloroethane containing the chloroprene stay at a specific temperature for >= a specified time while heating. CONSTITUTION:1,2-Dichloroethane (EDC) containing chloroprene is made to stay at 100-250 deg.C, preferably 100-150 deg.C temperature for >=30min, preferably 1-10hr by heating to advantageously remove the chloroprene in the EDC without consuming chlorine gas while avoiding an increase in high-boiling residues due to chlorination. Thereby, the above-mentioned EDC is mostly recovered as the EDC. The unreacted raw material is recycled through a purification step composed of a dehydration column 1, a separation column 2 for low-boiling substances and a separation column 3 for high-boiling substances according to the above-mentioned method to produce vinyl chloride monomer from the high-purity EDC by a thermal decomposition method. In the process, an increase in chloroprene concentration in the separation column 2 for the low boiling substances can be suppressed to prevent trouble by polymerization of the chloroprene.
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