New mixed perovskite-type Gd2–xSr1+xFe2O7 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. © 2017, Pleiades Publishing, Ltd

New mixed perovskite-type Gd2–xSr1+xFe2O7 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. © 2017, Pleiades Publishing, Ltd

Catalytic hydrogenation of carbon monoxide over nanostructured perovskite-like gadolinium and strontium ferrites

The catalytic properties of perovskite-like ferrites (An + 1BnO3n + 1, where n = 1, 2, 3, …, ∞; A = Gd, Sr; and B = Fe) synthesized via ceramic and sol-gel technology in the hydrogenation of carbon monoxide are studied. The interrelation between catalytic activity, selectivity to olefins and synthetic methods for complex oxide preparation, the number of perovskite layers, crystallite size, composition, and the valence state of iron is established. © 2016, Pleiades Publishing, Ltd

Interaction between carbon oxides, hydrogen and Fe2O3 and An + 1FenO3n + 1 (A = Gd, Sr, n = 1, 2, …, ∞)

The interaction between carbon oxides and hydrogen and surfaces of iron(III) oxide and An + 1FenO3n + 1 (where A = Gd, Sr, and n = 1, 2, …, ∞ is the number of perovskite layers) complex oxides is studied for the first time by means of thermal programmed desorption. It is shown that carbon oxides are adsorbed in molecular form with the formation of carbonate–carboxylate complexes, and in dissociative form. The ratios of the adsorption forms of both oxides are determined by the structure of ferrites, the number of perovskite layers, and the valence state and coordinative saturation of iron. The presence of weakly and strongly bonded hydrogen forms is established, and it is suggested that hydrogen dissolves in the bulk of a perovskite. © 2016, Pleiades Publishing, Ltd

Sol–gel synthesis and investigation of catalysts on the basis of perovskite-type oxides GdMO 3 (M = Fe, Co)

The perovskite-type oxides GdCo x Fe 1−x O 3 (x = 0; 0.2; 0.5; 0.8; 1) synthesized by the sol–gel method were tested as catalysts in the dry reforming of methane to syngas between 500 and 950 °С at atmospheric pressure. Thermal analysis (TG and DSC coupled with MS) and phase analysis (X-ray diffraction) were used for the synthesis parameters control. The morphology and surface area were determined by BET and SEM methods. The highly crystalline, homogeneous and pure solids with well-defined structures were prepared. The mixed GdCo x Fe 1−x O 3 (x = 0; 0.2; 0.5; 0.8; 1) structure belongs to an orthorhombic crystal system with a space group of Pnma (62). The partial substitution of Fe by Co leads to the increase of the catalytic activity. in the row: GdFeO 3 < GdFe 0.5 Co 0.5 O 3 < GdCoO 3 ⩽ GdFe 0.8 Co 0.2 O 3 ≈ GdFe 0.2 Co 0.8 O 3 . An additional point is that the presence of Co in B-site suppresses secondary reactions such as reverse water gas-shift without slowing the dry reforming reaction, which produces syngas in a ratio close to 1. [Figure not available: see fulltext.]. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

Effect of Cobalt in GdFeO3 Catalyst Systems on Their Activity in the Dry Reforming of Methane to Synthesis Gas

Abstract: Perovskite-type complex oxides GdFeO3 and GdCo0.5Fe0.5O3 synthesized by the sol–gel method and gadolinium ferrite modified with cobalt oxide (5 wt %) are studied as catalysts for the dry reforming of methane. Single-phase catalysts with the perovskite orthorhombic crystal structure and an average particle size of 100–200 nm are synthesized. Catalytic activity testing shows that the surface modification of gadolinium ferrite with cobalt, as well as the introduction of Co directly into the crystal structure to form a GdCo0.5Fe0.5O3 solid solution, leads to the formation of new catalytically active sites and provides an increase in the activity of GdFeO3. The sample with cobalt oxide deposited on the surface is highly resistant to coking. © 2020, Pleiades Publishing, Ltd