Patent ID: 9150970
Filing Date: 2015-10-06
Classification: C25B

Abstract:
1. Process for chloralkali electrolysis with an electrolysis cell in a micro-gap arrangement, with a distance of 0.01 mm to 2 mm between ion exchange membrane and oxygen-consuming electrode, the cell having at least one anode space with anode and an anolyte comprising alkali metal chloride, an ion exchange membrane, a cathode space at least comprising an oxygen-consuming electrode as the cathode, the cathode comprising a silver-containing catalyst, and comprising a flat, porous element arranged between the oxygen-consuming electrode and membrane, which porous element has a thickness of 0.01 mm to 2 mm and through which catholyte flows, and further comprising a gas space for an oxygen containing gas wherein application of the electrolysis voltage between anode and cathode is preceded, in a first step, by wetting of the oxygen-consuming electrode with an aqueous alkali metal hydroxide solution having a content of chloride ions of not more than 1000 ppm, and, after subsequent introduction of the anolyte into the anode space and of an oxygenous gas into the gas space of the cathode space, the electrolysis voltage is applied.