Synthesis and characterization of Ir-containing alumina catalysts for ammonia decomposition to satellite attitude control

OSCAR A. ANUNZIATA; MARCOS B. GÓMEZ COSTA

Seul

Congreso; 14th International Congress on Catalysis; 2008

IACS

Ir/γ-alumina catalysts for decomposition of ammonia were synthesized by a sol-gel method. In order to determine the physical and chemical characteristics we used X ray diffraction (XRD) analysis, Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR-MAS). The designed method was effective for the synthesis Ir/γ-alumina catalysts. The surface area was 250m2/g.The samples displayed the characteristic bands of NH3-OH bond and the characterization by pyridine adsorption and desorption to determine the presence of Lewis acid sites showing higher acid strength than commercial sample. The analysis of particle size and morphology reveal uniformity, with tendency to a spheroid aspect and smaller to 3 µm. The NMR-MAS test, allowed determining the tetrahedral and octahedral aluminum presence in both samples, where the greater proportion of octahedral aluminum of γ-alumina synthesized by us, is related to the greater acid force of its Lewis sites. XRD analyses show the absence of maximums at 28 and 34.7º corresponding to iridium oxide, indicating a high efficiency of the reduction treatment, increasing the active sites for the specific reaction of ammonia decomposition to N2 and H2.