Óxidos estruturados do tipo perovsquita para geração de gás de síntese via reforma a seco de metano

Abstract

High-performance catalysts have been widely researched in order to increase the yield in methane dry reforming processes (DRM). Some transition metals, especially nickel, are largely studied for this purpose. Due to its catalysts’ properties, thermal and chemical stability, perovskite-type oxides ABO3 are promising materials as catalytic precursors in DRM processes. The objective of this study is to evaluate the efficiency of perovskite type oxides as catalysts and as supports in dry reforming of methane (DRM). Perovskite-type oxides ABO3 were synthesized by microwave assisted combustion using urea as fuel and calcinated at 900 ºC for 2h. After the calcination, all the prepared oxides were impregnated with 20% (w/w) of nickel and calcinated again at 600ºC for 2h. The samples were characterized by the following techniques: x-ray diffraction (XRD), temperature programmed reduction (TPR), and dispersive energy scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Methane reforming tests with CO2 were performed for evaluation of these materials as catalysts in the production of syngas. After the reforming tests, the catalysts were submitted once again to characterizations for the evaluation of the existence of carbon in the oxides’ surface. According to the X-ray diffractograms, secondary phases of nickel oxides were formed after the nickel impregnation in the powders. The mapping by EDS showed that the impregnation methodology resulted in a homogeneous dispersion of the nickel oxide particles on the perovskite’s surface. The catalytic tests were performed at 750 ° C for 10 hours. The catalysts showed better performances, conversions and stability, after nickel impregnation, showing that the perovskites may be potential catalytic supports for dry reforming methane.