Catalytic Membrane Reactors: Next Generation Mixed Conducting Membranes

75164-This project will develop technology to improve mechanical properties and enhance the oxygen anion conductivity for the next generation of ceramic oxygen anion conducting membranes, which provide pure oxygen for the spontaneous conversion of natural gas to synthesis gas. The mechanical properties will be improved by controlling the expansion characteristics, leading to a decrease in fabrication time and improvement in production yield. Furthermore, the ruggedness of the ceramic parts under reactor conditions will be increased. Enhancing the oxygen anion conductivity will increase oxygen separation rates, thereby reducing the active ceramic surface area required and the amount of ceramic material used, lowering the overall costs of the reactors. The strategy involves controlled doping of the mixed conductor (isovalent doping of lanthanides on the A-site and aliovalent doping on the B-site) to yield a desired oxidation state and redox couple. (Available data suggests that the chemical expansion of this class of ceramics is related to the oxidation state and redox couple of the B-site transition metal.) Phase I will address the synthesis and characterization of the new materials. Materials testing will characterize nonstoichiometry and expansion properties, and permeation testing will be used to evaluate the transport properties of selected materials under reactor conditions. Commercial Applications and Other Benefits as described by the awardee: The technology should find use as a key step in the economical conversion of natural gas to liquids, providing a transitional resource as the use of fossil fuels is gradually phased out and renewable sources of hydrogen are developed. The intermediate formation of synthesis gas also can serve as a source of hydrogen.