Process and apparatus for the electrolysis of an aqueous solution of hydrogen chloride or alkali chloride in an electrolytic cell

摘要

In a process for chlorine-alkali electrolysis, use is made of an oxygen depletion cathode. The process is run with a high excess of oxygen. The oxygen needed for this is provided for a device of the gas separation, for example a VPSA plant or an air fractionation plant. The large quantities of oxygen produced lead to considerable costs of the process. According to the invention, the oxygen-rich atmosphere remaining after passing through the process is fed back into the device for gas separation as input gas. The device the gas separation is therefore operated with an oxygen-rich input gas and therefore produces a larger quantity of oxygen-rich gas, which in turn is fed to the oxygen depletion cathode. As a result of the circulation of the gas, the economy of the overall process is increased considerably.

主权项

1. A process for the electrolysis of an aqueous solution of hydrogen chloride or alkali metal chloride in an electrolysis cell, which comprises:
providing an anode half element having an anode, a cathode half element having a gas diffusion electrode as a cathode and a cation-exchange membrane for electrolytically separating the anode half element and the cathode half element, feeding an oxygen-containing gas to the cathode half element and discharging gas containing excess oxygen from the cathode half element, and at least partly feeding the gas containing excess oxygen taken off from the cathode half element to a gas separation apparatus in which the gas containing excess oxygen is separated into an oxygen-rich fraction and a low-oxygen fraction and the oxygen-rich fraction is subsequently fed to the cathode half element.