4.2 Process Description 4.2.1 Process Description

Figure ?? Block Flow Diagram
Shown in Figure ?? is the block flow diagram of the manufacturing process of VCM Industries for production of VCM from ethylene and chlorine through the balanced Ethylene Process.
C2H4+Cl2→C2H4Cl2
The first reaction is direct chlorination. Pure chlorine gas and ethylene is feed to the reactor at 65C and yields almost 100% conversion into ethylene dichloride. The reaction is exothermic thus it requires cooling afterwards.
C2H4Cl2→C2H3Cl+HCl
The EDC produced is then sent for thermal cracking. Also known as pyrolysis, reaction is carried out at 530C and 4atm. Pyrolysis product is then condensed prior distillation. The products are a mix of HCl, and VCM.
C2H4+2HCl+12O2→C2H4Cl2+H2O
The HCl byproduct is then sent to a conversion reactor with ethylene and oxygen for oxychlorination. The product of the oxychlorination are sent to a three phase separator to isolate the EDC from the excess air and water. The EDC is then sent back to the pyrolysis for recycling. The product of the oxy-chlorination are sent to a three phase separator to isolate the EDC from the excess air and water. The EDC is then sent back to the pyrolysis for recycling.

Catalyst used (Direct Chlorination)

Ethylene and chlorine combine in a homogeneous catalytic reaction to form EDC. Normally, the reaction rate is controlled by mass transfer, with absorption of ethylene as the limiting factor. Due to high selectivity, ferric chloride is the common catalyst of choice for chlorination of ethylene. The catalytic reaction utilizes an electrophilic addition mechanism. The catalyst polarizes chlorine and then the polarized chlorine molecule acts as an electrophilic reagent to add Cl- to the double bond of ethylene.
FeCl3 + Cl2↔ FeCl4-Cl
FeCl4-Cl + CH2CH2 FeCl3 + ClCH2CH2Cl

Catalyst used (Oxychlorination)
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