Studying the Possibility of Applying Barium-Strontium Cobaltite in Hydrogen Energy

Abstract

Anion-deficient structures based on \({\text{S}}{{{\text{r}}}_{{0.5}}}{\text{B}}{{{\text{a}}}_{{0.5}}}{\text{C}}{{{\text{o}}}_{{1 - x}}}{\text{F}}{{{\text{e}}}_{x}}{{{\text{O}}}_{{3 - \delta }}}\) synthesized from a melt in a stream of concentrated solar radiation with a density of 100–200 W/cm² created in a large solar furnace (LSF) were studied. Briquettes in the form of tablets made on the basis of a stoichiometric mixture of carbonates and metal oxides (\({\text{SrC}}{{{\text{O}}}_{3}}\) + \({\text{BaC}}{{{\text{O}}}_{3}}\) + \({\text{C}}{{{\text{o}}}_{2}}{{{\text{O}}}_{3}}\) + \({\text{F}}{{{\text{e}}}_{2}}{{{\text{O}}}_{3}}\)) were melted in a water-cooled melting unit in the LSF focal zone. Drops of the melt flowed into the water in a container located 40 cm below the melting unit. Such conditions contributed to the cooling of the melt at a rate of 10³ K/s. The castings were ground to a grinding fineness of 63 microns, dried at 673 K, and samples were molded from the resulting powder using semidry pressing (at a pressure of 100 MPa) in the form of tablets with a diameter of 20 mm and a height of 10 mm. The tablets were sintered in air at a temperature of 1050–1250°C. The structure, water absorption, and electrical properties of the finished samples were studied. The crystal lattice of the material had a perovskite structure with a unit cell parameter A = 4.04 × \({{10}^{{ - 10}}}\) m of space group Рm3m. The area of homogeneity of compositions \({\text{S}}{{{\text{r}}}_{{0.5}}}{\text{B}}{{{\text{a}}}_{{0.5}}}{\text{C}}{{{\text{o}}}_{{1 - x}}}{\text{F}}{{{\text{e}}}_{x}}{{{\text{O}}}_{{3 - \delta }}}\) corresponded to the interval x = [0; 0.7], where x is the amount of element introduced instead of the main one. The most optimal composition in terms of stability of structure and properties was \({\text{S}}{{{\text{r}}}_{{0.5}}}{\text{B}}{{{\text{a}}}_{{0.5}}}{\text{C}}{{{\text{o}}}_{{0.8}}}{\text{F}}{{{\text{e}}}_{{0.2}}}{{{\text{O}}}_{{2.78}}}\). The average crystallite size of the obtained materials is 30–40 μm. The grains are predominantly in the form of spherulites and curved cylinders. Samples of the material showed high resistance to water vapor. The values of structural parameters indicate that the material made from \({\text{S}}{{{\text{r}}}_{{0.5}}}{\text{B}}{{{\text{a}}}_{{0.5}}}{\text{C}}{{{\text{o}}}_{{0.8}}}{\text{F}}{{{\text{e}}}_{{0.2}}}{{{\text{O}}}_{{2.78}}}\) can be used as a catalyst in the generation of hydrogen and synthesis gas through reforming and oxidation of methane.