Dense Ceramic Membranes for Hydrogen Separation

This chapter contains sections titled: Introduction Applications and Principles of Operation Simple Cases Examples of More Complex Applications Defect Chemistry of Dense Hydrogen-Permeable Ceramics Materials Classes Neutral and Ionised Hydrogen Species in Oxides Protonic Defects and Their Transport Defect Structures of Proton-Conducting Oxides Diffusivity, Mobility and Conductivity: The Nernst–Einstein Relation Wagner Transport Theory for Dense Ceramic Hydrogen-Separation Membranes General Expressions From Charged to Well-Defined Species: The Electrochemical Equilibrium The Voltage Over a Sample Flux of a Particular Species Fluxes in a Mixed Proton, Oxygen Ion, and Electron Conductor Fluxes in a Mixed Proton and Electron Conductor Fluxes in a Mixed Proton and Oxygen Ion Conductor Fluxes in a Mixed Proton, Oxygen Ion, and Electron Conductor Revisited Permeation of Neutral Hydrogen Species What About Hydride Ions? Surface Kinetics of Hydrogen Permeation in Mixed Proton-Electron Conductors Issues Regarding Metal Cation Transport in Hydrogen-Permeable Membrane Materials Modeling Approaches Experimental Techniques and Challenges Investigation of Fundamental Materials Properties Concentration Diffusion Conductivity Transport Numbers Other Properties Investigation of Surface Kinetics Measurements and Interpretation of Hydrogen Permeation Hydrogen Permeation in Selected Systems A Few Words on Flux and Permeability Classes of Membranes Mixed Proton–Electron Conducting Oxides Cermets Permeation in Other Oxide Classes and the Possibility of Neutral Hydrogen Species Comparison with Metals Summary