VCM from Ethane Becomes Profitable

     Vinyl chloride monomer (VCM) is the building block for the popular polyvinyl chloride polymer (PVC).  The first industrial process used to manufacture VCM utilized the reaction between acetylene and hydrogen chloride.   This route was replaced by the thermal cleavage of 1,2-dichloroethane which is formed by the oxychlorination of ethylene with hydrogen chloride and oxygen.  This route changed the major feedstock from acetylene to ethylene.

     The conventional route to VCM via ethylene takes place at temperatures ranging from 200 ⁰C to 250 ⁰C.  The reaction temperature in the production of VCM is very important due to its impact on corrosion rates within the plants.  The easiest (chemically) route to VCM has long bee known to be the direct chlorination of ethane.  However, companies have been unable to keep the reaction temperature below 500 ⁰C where corrosion becomes unmanageable and the ethylene process is more economically feasible. EVC International has been able to achieve this goal with a catalyst derived from Ziegler-Natia chemistry.   EVC claims a reaction temperature of 450-470 ⁰C.  They have operated a 1000 m.t./year pilot plant in Germany with excellent results.  Catalyst life is very good and corrosion has been controlled well. Licensing efforts are underway and Bechtel has been contracted to market the technology.  With ethane costs being about one third of those of ethylene, the new technology should be able to lower the cost of VCM from $415/m.t. to $255/m.t.  Most expect the technology (if successful) will displace the ethylene process in about 20 years, the same amount of time it took for the ethylene process to replace the acetylene process.