NiMo/Al2O3–MgO (x) catalysts: the effect of the prolonged exposure to ambient air on the textural and catalytic properties

In the search to obtain stable catalysts for selective elimination of sulfur from gasoline, maintaining octane number, NiMo catalysts supported on Al–Mg mixed oxides were prepared by the sol–gel method and evaluated after 6-month storage in contact with ambient air, the results were compared with the freshly prepared samples. Both, freshly prepared and aged samples were characterized by nitrogen physisorption measurements (SBET), infrared spectroscopy (FT-IR) and X-ray powder diffraction (XRD) and high-resolution electron microscopy (HREM), they were tested in the thiophene hydrodesulfurization reaction. The results indicate that the incorporation of small amounts of magnesia (5 mol%) into the alumina support, leads to the catalyst with low hydrogenation function and appropriate stability during prolonged contact with ambient conditions.