Highly Stable Dual-Phase Membrane Based on Ce 0.9 Gd 0.1 O 2–δ —La 2 NiO 4+δ for Oxygen Permeation under Pure CO 2 Atmosphere

Abstract

Dense oxygen ion–conducting ceramic membranes with CO 2 resistance can promote many advanced applications such as membrane reactors for green chemical synthesis and oxy-fuel combustion for clean energy delivery. The state-of-the-art perovskite oxide membranes are characterized by their high O 2 flux but low stability in a CO 2 -containing atmosphere. To solve this problem, dual-phase membranes have captured the imagination of researchers. Herein, a novel dual-phase hollow fiber membrane with a composition of 40 wt% Ce 0.9 Gd 0.1 O 2–δ (GDC)–60 wt% La 2 NiO 4+δ (LNO) is developed via a combined phase inversion sintering process. During the high temperature treatment, La-doping behavior is observed with La leaching out from the LNO phase and diffusing into the GDC phase. This dual phase membrane displays the O 2 flux of 1.47 at 950 °C, which is reduced by 10% to 1.31 mL min −1  cm −2 when the sweep gas is switched from helium to pure CO 2 . Such minor O 2 flux reduction is due to the strong CO 2 adsorption on membrane surface occupying the O 2 vacancies without permanent membrane damage, which is fully eliminated by an inert gas purge. Such a robust dual-phase membrane exhibits the potential to overcome the low stability problem under the CO 2 -containing atmosphere.