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 NO_x 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–Ce_0.8Tb_0.2O_2–δ (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 °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.