Studies of interactions oxygen-BIMEVOX membrane materials by transient techniques

A study of the influence of different dopant cations and of a surface modification on the oxygen uptake of BIMEVOX materials is reported. An advanced EDTA complexing route for rapid dense membrane materials preparation is described. In addition, this gel-based procedure allows the coating of thin porous layers on dense membrane disks. This top layer modification was used to increase the surface area on top of membrane materials while keeping the same composition than the bulk. The uptake of gas-phase oxygen by the membrane material was directly studied using the highly time resolved temporal-analysis-of-products (TAP) transient technique. It is shown that the easily applicable surface modification led to an enhanced uptake of gas-phase oxygen. An investigation using differently doped BIMEVOX samples indicated that the activation process of oxygen does not directly dependent on the dopant. This suggests that in all these cases the observed oxygen uptake proceeds via a similar surface site. On the other hand, the amount of oxygen taken up depends on the dopant, allowing to conclude, however, that the number of available surface sites is influenced by the dopant.