New process technology from Chemetry (Moss Landing, Calif.; www.chemetrycorp.com) aims to revitalize the chlor-alkali product chain by manufacturing ethylene dichloride (EDC) and caustic using much less power than conventional processes. Through an exclusive licensing and engineering agreement, Technip (Paris, France; www.technip.com) is helping to commercialize Chemetry’s eShuttle technology. The company has operated a continuous pilot plant since 2014, and is now scouting operating partner sites to construct a full-size demonstration plant.
Combining a specialized three-compartment electrochemical cell and an aqueous catalysis step, eShuttle uses the same raw materials as typical chlor-alkali processes while eliminating the chlorine gas intermediate. In addition to saving power, removing chlorine makes the process inherently safer and allows for longer membrane life and simpler startup and shutdown, as no chlorine purge or disposal is required. Furthermore, since no chlorine gas is present in the system, eShuttle’s electrochemical cell is much thinner than those used in traditional chlor-alkali processes, which can provide for increased production rates within the same footprint, explains Chemetry CEO Ryan Gilliam. This makes eShuttle very attractive in the retrofit market.
In the eShuttle process, copper chloride is used as a carrier for chloride ions. The copper chloride is oxidized as it picks up chloride ions and flows in a closed loop between the electrochemical cell’s anode and the reaction step (diagram). “Using this copper-chloride shuttle reaction allowed us to fundamentally lower the energy,” says Gilliam, because the voltage required for copper oxidation is much lower than that of the chlorine evolution reaction that takes place within traditional chlor-alkali systems. This difference amounts to a 30% reduction in power per ton of caustic, says Gilliam. The power consumption can be further reduced by as much as 53% through integration of oxygen depolarized cathode (ODC) technology, with which eShuttle is compatible.
