Rational design via tailoring Mo content in La2Ni1-xMoxO4+δ to improve oxygen permeation properties in CO2 atmosphere

Perovskite (ABO(3)) and ruddlesden-popper (A(2)BO(4)) oxides are typical mixed conducting ceramic membrane materials for oxygen separation from air. In particular, ruddlesden-popper (RP) membrane display high CO2 resistance despite their relative low oxygen permeation flux compared to perovskite oxide membranes. Element-doping is an important method to improve the oxygen permeability. In this work, the mechanism of oxygen transfer process through one RP ceramic La(2)Ni(1-x)MoxO(4+delta) (x = 0, 0.025, 0.05, 0.1, 0.2) membranes was investigated. An optimum doping level (x = 0.05) in La2Ni1-xMoxO4+delta was found. The optimized composition of La2Ni0.95Mo0.05O4+delta membrane could not only improve surface oxygen exchange reactions, but also promote oxygen ion bulk diffusion through the dense layer. The maximum oxygen flux of La2Ni0.95Mo0.05O4+delta membrane reached 3.27mL min(-1) cm(-2) at 1000 degrees C. Furthermore, La2Ni0.95Mo0.05O4+delta membrane high stability in CO2 atmosphere. When sweeping gas was switched from helium to pure CO2, the oxygen fluxes were only reduced by 5% and stabilized at 2.75 mL min(-1) cm(-2) at 950 degrees C. Our results highlight the efficiency of Mo-doping strategy to simultaneously improve the oxygen permeability and stability of A(2)BO(4+delta)-type oxide membranes. (C) 2019 Elsevier B.V. All rights reserved.