Feasibility study of LSCF5582 membrane integration into a nitrogen based chemical looping air separation process

Abstract

This study investigates the suitability and effectiveness of La0.5Sr0.5Co0.8Fe0.2O3-δ (LSCF5582) membrane for integration into the reduction reactor of a Nitrogen based chemical looping air separation (CLAS) process for exclusive separation of oxygen. First, the structural and chemical characteristics as well as the oxygen separation properties of LSCF5582 membranes, prepared at sintering temperatures of 1050–1350°C, were examined to obtain the optimum range of sintering temperatures resulting in membranes with enhanced oxygen separation from air. This was achieved by determining the oxygen permeation properties of LSCF5582 membranes under the reducing environment of the Nitrogen based CLAS process, whereby oxygen is liberated from CuO oxygen carriers on the feed side of the membrane using nitrogen as a reducing gas. Membrane characterisation results showed that a single phase dense LSCF5582 membrane was formed at the sintering temperature range of 1200–1225°C obtaining a maximum oxygen permeation flux of 0.67mlmin−1cm−2 and oxygen recovery of 27% at the sintering and operating temperatures of 1200°C and 900°C, respectively. At the same operating temperature, under the reducing environment of nitrogen, the LSCF5582 membrane sintered at 1225°C was found to perform best achieving an oxygen permeation flux and oxygen recovery of 0.77mlmin−1cm−2 and 76%, respectively.