Sol-gel synthesis and investigation of catalysts on the basis of perovskite-type oxides GdMO3 (M = Fe, Co)

The perovskite-type oxides GdCoxFe1-xO3 (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 degrees C 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 GdCoxFe1-xO3 (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: GdFeO3 < GdFe0.5Co0.5O3 < GdCoO3 <= GdFe0.8Co0.2O3 approximate to GdFe0.2Co0.8O3. 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.