Ethylene dichloride is the first intermediate in the manufacturing of the versatile plastic from raw materials. While useful on its own as a strong solvent, 90% of the EDC produced is dedicated to making vinyl chloride monomer the chemical precursor to PVC.
Heated to 500 °C in a cracking furnace, EDC splits into VCM and recyclable HCl; the products are quickly cooled to avoid recombination, after which unreacted EDC is returned to the furnace. Sometimes the EDC entering the furnace contains a bit of ferric chloride (FeCl3), a catalyst used to chlorinate ethylene in the making of EDC; this contamination is far from trivial, as trace FeCl3 is known to clog the cracking furnace and foul various mechanisms. Additionally, PVC made from EDC with impurities-typically low levels of FeCl3 and chlorine-is less useful than high-quality PVC and fails to meet customer needs.
