PROCESS FOR PRODUCING A PLASTIC-BOUND GAS DIFFUSION ELECTRODE CONTAINING A MANGANESE OXIDE CATALYST WITH A PREDOMINANT COMPOSITION OF DIMANGANESE TRIOXIDE AND PENTAMANGANESE OCTOXIDE

摘要

In an electrically heated vibratory screw conveyor, manganese carbonate (MnCO3. x H2O) is thermally decomposed at about 500 DEG C to give the abovementioned manganese oxide catalyst which is then processed by dry, intensive mixing with a carbon-containing conductivity agent (carbon black, graphite, activated carbon) and PTFE as binder to give a highly active electrode mass which can be rolled into a carrier net of Ni or Ag. A two-stage mixing process is particularly advantageous in which the catalyst powder is initially premixed with only a little conductivity agent and binder, compacted and granulated. In a second mixing step, the granules are combined with the larger remainder of the intended quantity of conductivity agent and binder. The finished gas diffusion electrode has a biporous structure of hydrophilic and hydrophobic pore channels, which structure is highly advantageous for transport processes and the electrochemical conversion. The electrode can be used in fuel cells, chloro-alkali electrolysis cells and atmospheric oxygen cells.