Exploring the performance of dual-phase oxygen transport membranes for carbon capture purposes

Abstract

There is a rising pressure on industry to meet the steady climb of energy demand while concurrently reducing harmful emissions exhausted into the atmosphere. For the past decade, oxygen transport membrane reactors (OTMs), have been receiving growing attention due to their ability to provide high volumes of pure oxygen that react with incoming fuel at minimal energy costs. However, one significant concern is the OTM's stability when exposed to high concentrations of CO2, a potentially harmful acidic gas. To preserve the integrity of the OTM in acidic environments, many have adapted dual-phase OTMs, combining the advantages of the perovskite-type material's high oxygen permeation performance with a stable additive material's tolerance of CO2. In this study, dual-phase OTMs comprised of varying weight ratios between SrSc0.1Co0.9O3-δ (SSC) and Sm0.2Ce0.8O1.9 (SDC) were successfully prepared and studied. Specifically, the dual-phase OTMs' oxygen permeation flux and combustion performance are reported. The results show that the oxygen permeation flux through dual-phase OTMs decreases with the increase in SDC wt.% in the composition using a helium or methane sweeping gas. The highest oxygen permeation flux is found to be a pure SSC OTM at 5.27 ml.min-1.cm-2 using methane sweeping gas with a flow rate of 80 ml.min-1. Additionally, a pure SSC OTM exhibits a CO2 selectivity of 97.7% with a methane sweeping gas flow rate of 5 ml.min-1. Despite the SSC OTM's higher oxygen permeation flux and CO2 selectivity, a dual-phase OTM exhibited a higher oxygen permeation flux and membrane stability compared to a pure SSC membrane after exposed to a CO2 sweeping gas for 60 hours. This suggests the potential for a highly stable dual-phase OTM design that can maintain an oxygen permeation performance in any environment and be potentially implemented in future carbon capture technologies.