New mixed perovskite-type Gd2–xSr1+xFe2O7 catalysts for dry reforming of methane, and production of light olefins

Resumo

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 Gd_2–xSr_1+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 Gd_2–xSr_1+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.