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

Abstract

A-site deficient (Pr_0.9La_0.1)_1.9Ni_0.74Cu_0.21Ga_0.05O_4+δ ((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.