A new CO₂-resistant Ruddlesden-Popper oxide with superior oxygen transport: A-site deficient (Pr₀.₉La₀.₁)₁.₉(Ni₀.₇₄Cu₀.₂₁Ga₀.₀₅)O₄₊ổ

Abstract

A-site deficient (Pr₀.₉La₀.₁)₁.₉Ni₀.₇₄Cu₀.₂₁Ga₀.₀₅O₄₊ổ ((PL)₁.₉NCG), with the K₂NiF₄ structure, is found to exhibit higher oxygen transport rates compared with its cation-stoichiometric parent phase. A stable oxygen permeation flux of 4.6 × 10⁻⁷ mol cm⁻² s⁻¹ at 900 °C at a membrane thickness of 0.6 mm is measured, using either helium or pure CO₂ as sweep gas at a flow rate of 30 mL min⁻¹ The oxygen flux is more than two times higher than that observed through A-site stoichiometric (PL)₂.₀NCG membranes operated under similar conditions. The high oxygen transport rates found for (PL)₁.₉NCG are attributed to highly mobile oxygen vacancies, compensating A-site deficiency. The high stability against carbonation gives (PL)₁.₉NCG potential for use, e.g., as a membrane in oxy-fuel combustion processes with CO₂ capture