Exceptional performance of water splitting coupled with methane partial oxidation by oxygen-permeable membrane reactor

Abstract

An oxygen-permeable membrane reactor, capable of high-performance water splitting and simultaneous methane conversion while maintaining the syngas ratio (H2/CO) close to 2, is reported in this study. Most coupling studies of water splitting and partial oxidation of methane (POM) using oxygen-conducting ceramic membranes have so far focused on the application in high-temperature (>900 °C) conditions that can accelerate the kinetics of surface exchange reactions. Considerable hydrogen production through the coupling reaction is possible below 800 °C by adopting Ruddlesden-Popper oxide for water reduction and a Ni/perovskite/fluorite composite for POM. The membrane composition was optimized to maximize the oxygen ionic conductivity and ensure the stability. Using a chemically stable dual-phase membrane with highly active coating layers, the production of 4.5 mL·cm−2·min−1 of hydrogen from water splitting and 14 mL·cm−2·min−1 of syngas from methane were stably secured at 800 °C. In addition, coupling reaction was confirmed to be possible even at 700 °C.