Hydrogen Purification through a Highly Stable Dual‐Phase Oxygen‐Permeable Membrane

Abstract

Using oxygen permeable membranes (OPMs) to upgrade low-purity hydrogen is a promising concept for highpurity H 2 production. At high temperatures, water dissociates into hydrogen and oxygen. The oxygen permeates through OPM and oxidizes hydrogen in a waste stream on the other side of the membrane. Pure hydrogen can be obtained on the water-splitting side after condensation. However, the existing Co-and Fe-based OPMs are chemically instable as a result of the over-reduction of Co and Fe ions under reducing atmospheres. Herein, a dual-phase membrane Ce 0.9 Pr 0.1 O 2Àd-Pr 0.1 Sr 0.9 Mg 0.1 Ti 0.9 O 3Àd (CPO-PSM-Ti) with excellent chemical stability and mixed oxygen ionic-electronic conductivity under reducing atmospheres was developed for H 2 purification. An acceptable H 2 production rate of 0.52 mL min À1 cm À2 is achieved at 940 8C. No obvious degradation during 180 h of operation indicates the robust stability of CPO-PSM-Ti membrane. The proven mixed conductivity and excellent stability of CPO-PSM-Ti give prospective advantages over existing OPMs for upgrading low-purity hydrogen.

Tuning the two phases ratio by nonmetal ion doping in dual‐phase mixed‐conductive ceramic membranes

“…37 Unfortunately, the electron-conducting phase of BaCe 0.15 Fe 0.85 O 3−δ is easily reduced to form the additional Fe 2 O 3 impurity during the H 2 separation process, leading to the poor chemical stability of this dual-phase membrane, which seriously hinders its practical application. 38 Therefore, the development of an efficient MPEC membrane with high H 2 permeability and good chemical stability is urgently needed.…”

“…first reported a perovskite membrane of BaCe 0.5 Fe 0.5 O 3− δ , which could automatically decompose into two thermodynamically stable phases with a protonic conductor of BaCe 0.85 Fe 0.15 O 3− δ and an electronic conductor of BaCe 0.15 Fe 0.85 O 3− δ , respectively 37 . Unfortunately, the electron‐conducting phase of BaCe 0.15 Fe 0.85 O 3− δ is easily reduced to form the additional Fe 2 O 3 impurity during the H 2 separation process, leading to the poor chemical stability of this dual‐phase membrane, which seriously hinders its practical application 38 . Therefore, the development of an efficient MPEC membrane with high H 2 permeability and good chemical stability is urgently needed.…”

Oxygen activation on Ba-containing perovskite materials

“…Oxygen exchange reactions, including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), occurring at gas-solid interfaces are vital to the process of energy conversion in metal-air batteries (1), solid oxide cells (SOCs) (2)(3)(4)(5), water splitting (6), and catalytic membrane reactors (7). The activation mechanism of oxygen at gas-solid interfaces is still unclear, because the complex four-electron transfer process is related to various oxygen species, evolving with the material composition and structure, as well as the reaction conditions (8)(9)(10)(11)(12).…”

Coupling of dielectric barrier discharge plasma with oxygen permeable membrane for highly efficient low-temperature permeation

“…The typical operating temperatures of the current state of the art OPMs are 800-1000 o C; this provides important advantages including high oxygen flux, highly efficient integration with combustion processes (such as IGCC) without significant energy penalty [4], and high catalytic activity and reaction kinetics in catalytic membrane reactors (CMRs), e.g., partial oxidation of methane [5][6][7][8][9], methane coupling [10][11][12], methane aromatization [13,14], hydrogen production by water splitting [15,16], decompositions of carbon dioxide [17,18] and nitrogen oxides [19][20][21]. However, high operating temperatures also result in high system costs, and high performance-degradation rates.…”