Promising NiO–30 wt % Ag–40 wt % Bi2O3 Membrane Material for Separation of Oxygen from Air

Abstract

Composite NiO–30 wt % Ag–40 wt % Bi2O3 material was synthesized and studied. The microstructure of this material cooled from 800°C was studied, and the presence of a percolative network of silver in the bulk of composite was shown. The transport properties of this composite (electrical conductivity, oxygen ion transport number, and oxygen fluxes) in the temperature range of 725–800°C were investigated. The oxygen permeability of a membrane based on the NiO–30 wt % Ag–40 wt % Bi2O3 material was calculated and the selectivity of transferred oxygen over nitrogen in the process of separation from air was evaluated. At 800°C, the electrical conductivity was ~50 Ω–1 cm–1, the oxygen ion transport number was 0.02, the oxygen permeability was 2.1 × 10–8 mol cm–1 s–1, and the selectivity of oxygen (over nitrogen) was above 1000. The oxygen permeabilities of some ceramic and cermet membranes and the membrane material fabricated in this work were compared. Composite NiO–30 wt % Ag–40 wt % Bi2O3 shows a high selective oxygen permeability compared to the state-of-the-art analogs and can be used as an ion transport membrane for separation of oxygen from air.