Palladium-based hollow cathode electrolysers for hydrogen production.

Abstract : Ultra-pure hydrogen can be obtained through the use of water electrolysers with dense metal cathodes. In this chapter, the theory of hydrogen evolution over Pd-based cathodes and its permeation through dense metal walls is introduced, and the Damköhler − Peclet analysis for these membrane reactors is described. Optimization of the electrolysis process is considered, based on the relationship of DaPe number with the cell overpotential and the apparent activation energy of permeation. Literature studies on hollow cathode water electrolysers are discussed, as are new prototypes using thin-wall Pd–Ag permeator tubes, and the efficient operation of cell effi ciency and surface activation/deactivation phenomena. The main applications of cells with Pd-based hollow cathodes are the production of ultra-pure hydrogen at high pressure for small scale laboratory electrolysers and the treatment of tritiated water. The results of tests on prototypes are examined in detail, and attention is given to future trends in material development.