Influence of the preparation methods on the microstructure and oxygen permeability of a CO2‐stable dual phase membrane

Abstract

AbstractA CO2‐stable dual phase membrane of the composition 40 wt % NiFe2O4‐60 wt % Ce0.9Gd0.1O2‐δ (40NFO‐60CGO) was synthesized in three different ways: mixing of the starting powders (1) in a mortar and (2) in a ball‐mill as well as by (3) direct in situ one‐pot sol–gel powder synthesis. Backscattered scanning electron microscopy revealed that the direct one‐pot synthesis of 40NFO‐60CGO gives the smallest grains in a homogeneous distribution, compared with powder homogenization in the mortar or the ball‐mill. The smaller is the grains, the higher is the oxygen permeability. The permeation of the membrane can be improved by coating a porous La0.6Sr0.4CoO3‐δ (LSC) layer on the surface of the air side. The dual phase membrane of 40NFO‐60CGO prepared by in situ synthesis shows a steady oxygen flux of 0.30 ml/(min cm2) over more than 100 h when pure CO2 was used as sweep gas, which indicated that the dual phases membrane is CO2‐resistant at least over this 5 days testing period. © 2010 American Institute of Chemical Engineers AIChE J, 2011