Efficient pure oxygen separation with the unique graded porous supported symmetric flat mixed conductor ceramic membrane

A graded porous supported symmetric (GPSS) flat ceramic membrane made of a K2NiF4+δ type oxide (Pr0.9La0.1)2(Ni0.74Cu0.21Ga0.05)O4+δ (PLNCG) is fabricated by aqueous tape casting. This membrane design stands out for its unique structure, consisting of a thin dense layer at its core and two graded porous substrates that adhere symmetrically to this middle layer. In comparison to previously reported PLNCG hollow fiber membranes, the GPSS membrane offers superior oxygen permeation flux, exceeding that of the hollow fiber membrane by more than four times. When using air as the feed gas and even when introducing CO2 into the feed gas or sweep gas, the membrane maintains a consistent oxygen permeation flux of 4.41 mL min-1 cm-2 (STP). This work demonstrates that by paying close attention to membrane structure, the oxygen permeation flux of flat membranes can surpass that of hollow fiber membranes. Given its exceptional oxygen separation performance, the PLNCG-GPSS membrane holds great potential for practical applications such as high-purity oxygen production, pure hydrogen production, oxygen-involved catalytical reactions, and CO2 capture and storage.