Multi-layer electrode membrane-assembly and electrolysis process using same

摘要

A unitary membrane-electrode assembly includes an electrode structure with multiple layers having different overvoltages for the desired electrochemical reaction. In the preferred arrangement the layer attached to the membrane has the higher overvoltage thereby preferentially locating the reaction zone a small but controlled distance away from the electrode membraneinterface. In a NaCl brine electrolysis process the use of a dual layer electrode as the cathode is particularly useful because it eliminates formation of concentrated caustic at the membrane surface. As a result, back migration of OH- ions is reduced and cathodic current efficiency is increased.