Materiais estruturados para reforma a seco de metano

Abstract

The implementations of new technologies that act to reduce emissions of the gases responsible for increased greenhouse effect are often searched. The improvement of these technologies depends mainly on the availability of materials with essential properties for this purpose (abrasion resistance, toughness and high reactivity with oxygen). The metal oxides that exhibit structure type inverted spinel and normal spinel are materials that exhibit these properties. This study evaluates the synthesis method based on combustion assisted by microwave to obtain the following synthetic oxides MgAl2O4, ZnAl2O4, and CaAl2O4 LaNi2O4 using urea as fuel. It is also aims to produce synthesis gas from methane using dry reforming reaction over nickel catalysts supported on oxides previously synthesized. Samples of the synthesized oxides were calcined at 800 °C for 2 hours and impregnated with 5% nickel after calcination. The impregnated samples were calcined at 850 °C for 4 hours to obtain the desired phases. The materials were chemically characterized by X-ray fluorescence, X-ray diffraction, spectroscopy in the infrared Fourier transform (FTIR), Thermogravimetric analysis, specific surface area measurements and scanning electron microscopy. The results of X-ray diffraction showed that all samples exhibited crystalline peaks with or without impregnation of nickel. Observing the results of scanning electron microscopy, we note that in all the samples impregnated, are evident the presence of small amounts of NiO. The morphology observed is compatible with the synthesis methodology, ie combustion reaction assisted by microwave. The nickel oxide present in the samples is importance in the reaction of steam reforming or dry reforming because it is responsible by active sites actuation. The results of the catalytic tests showed that the catalysts are active for the methane dry reforming, but the catalyst that got the best performance relating methane conversion and oxygen transfer capacity was 5% Ni/MgAl2O4 850 °C/4h.