Investigation of oxygen transport membrane reactors for oxy-fuel combustion and carbon capture purposes

There is an increasing pressure for industry to reduce carbon dioxide (CO₂) emissions from combustion processes, resulting in an increased interest in the development of methods to sequester and recycle CO₂ from flue gases. Current methods available to separate nitrogen and CO₂ for environmental benefits, such as chemical looping combustion (CLC), are expensive at the high flow rates encountered in industry. One potential alternative is a ceramic membrane catalytic reactor, which produces pure oxygen and simultaneously conducts oxy-fuel combustion, thus, CO₂ in the product stream can successfully be separated from the nitrogen in air. This work investigates the performance of a perovskite-type SrSc_0.1Co_0.9O_3-δ(SSC) and La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ(LSCF) membrane reactors for the combustion of methane in various configurations. The ceramic membranes exploited here are oxygen semi-permeable, dense ceramic membranes based on the composite oxides with a high mixed oxygen ionic and electronic conductivity at high temperatures. The prepared SSC and LSCF hollow fibre membranes with catalysts were used to perform reactions with a methane fuel. The oxygen permeability feasibility of the membrane reactors were studied and confirmed. The CO₂ selectivity at various test conditions were also reported with the maximum selectivity achieved for SSC membrane to be 85.4% while LSCF membrane achieved 87.1% CO₂ selectivity.