EFFECT OF CALCINATION TEMPERATURE ON THE PROPERTIES AND CATALYTIC PERFORMANCE OF NICKEL OXIDE IN THE ETHANE OXIDATIVE DEHYDROGENATION REACTION

In this paper, the catalytic behavior of nonstoichiometric nickel oxides was investigated in the ethane oxidative dehydrogenation reaction (ODH). The oxide was obtained by heat treatment in the range 250 - 400 degrees C of ss-Ni(OH)(2) synthesized by precipitation-oxidation. The structural properties of the catalysts were characterized by XRD, FTIR, UVvis, and SEM. The selective ODH reaction was quantified by gas chromatography. The samples showed pure NiO cubic structure with different degrees of crystallinity, crystallite size, and specific surface area. The increase of calcination temperature caused an increase in the average crystallite size from 28 angstrom at 250 degrees C to 104 angstrom at 400 degrees C, whereas the shape of the particles showed no significant differences; pore diameter increased from 35 angstrom to 69 angstrom and specific surface area decreased from 245 to 82 m(2)/g. The test carried out at 240 degrees C showed a decrease in conversion, from 8.75% to 4.25%; the more crystalline samples displayed the highest intrinsic activity with selectivity to ethene close to 60%. No influence of band-gap energy on catalytic properties was observed.