New mixed perovskite-type Gd2–x Sr1+x Fe2O7 catalysts for dry reforming of methane, and production of light olefins

The catalytic properties of complex perovskite-type gadolinium and strontium oxides in carbon dioxide reforming of methane and the production of gaseous olefins by carbon monoxide hydrogenation have been studied. Samples of Gd2SrFe2O7 and Gd2–xSr1+xFe2O7 (х = 0.1; 0.2; 0.3; and 0.4) have been obtained by the sol–gel method and ceramic technology, and have been characterized by means of X-ray diffraction, scanning electron microscopy, photon correlation spectroscopy, Mössbauer spectroscopy, and N2 adsorption–desorption analysis. It has been shown that the sol–gel method allows us to produce samples with better catalytic characteristics than ceramic systems. The nonisovalent substitution of Gd3+ for Sr2+ distorts the structure of complex oxide, resulting in the emergence of the heterovalent state of iron atoms (Fe3+ and Fe4+) reflected in the values of reactant conversion and selectivity for the target products. A sample of Gd2–xSr1+xFe2O7 with х = 0.3 displays the highest catalytic activity in dry reforming of methane reforming, along with the highest selectivity for unsaturated hydrocarbons (ethylene and propylene) in hydrogenation of carbon monoxide.