Hydrogen separation and stability study of ceramic membranes based on the system Nd5LnWO12

This contribution presents the preparation, permeation and stability study of mixed protonic-electronic conducting membranes based on the system Nd5LnWO12. The tungstates Ln6WO12 are proton conducting crystalline materials, which show sufficient protonic and electronic mixed conductivity and stability in moist CO2 environments to consider them as potential candidates for the separation of hydrogen at high temperatures. Hydrogen separation properties of A-substoichiometric Nd6WO12 and Nd5LaWO12 were systematically analyzed, i.e. the influence of the H2 concentration in feed stream, humidification degree and operating temperature on the hydrogen separation was studied. Finally, the stability of these materials at different temperatures and CO2-rich and sulfur-containing environments was evaluated.

► Nd6WO12 membranes allowed the selective hydrogen separation at high temperature.
► The feed and/or sweep gas must be humidified in order to activate proton transport.
► Above 800 °C and wet conditions, oxide-ion strongly contributes to separation.
► Nd6WO12 is stable at high temperature in CO2- and S-bearing atmospheres.