Maximizing oxygen permeation via catalytic functionalization under oxyfuel conditions

Abstract

Oxygen transport membranes (OTMs) offer a promising route for high-efficiency, cost-effective oxygen supply in energy and chemical industries, with the potential to significantly reduce CO2 and NOx emissions when integrated into oxy-combustion processes. However, conventional OTMs suffer from poor chemical stability in CO2-rich environments, prompting the development of dual-phase membranes that, while more stable, typically exhibit lower oxygen permeation rates. In this study, we address this limitation by enhancing the surface exchange kinetics of Fe2NiO4-Ce0.8Tb0.2O2-delta (NFO-CTO) membranes by surface modification with various oxygen oxidation-reduction reaction (OORR) catalysts, including Ce, Pr, Sm, Tb, Co, Nb, Zr, and Al oxides, and Pr-based binary oxides. Comprehensive characterization using electrochemical impedance spectroscopy, oxygen isotopic exchange, and gas permeation measurements revealed a substantial improvement in surface reaction kinetics. Catalyst activation led to a six-fold increase in oxygen flux under standard conditions and up to a 2.5-fold enhancement under harsh environments containing CO2 and SO2 at 850 degrees C, mimicking oxyfuel combustion conditions. This work demonstrates that rational catalyst selection and integration can overcome fundamental surface limitations in dual-phase membranes, offering a viable strategy to advance oxygen separation technologies for sustainable energy applications.