Bibliographic citations
Baldeón, I., (2020). Síntesis y caracterización de catalizadores basados en óxidos de Ni-Ti másicos y soportados en γ-alúmina para la deshidrogenación oxidativa del etano [Tesis, Universidad Nacional de Ingeniería]. http://hdl.handle.net/20.500.14076/22458
Baldeón, I., Síntesis y caracterización de catalizadores basados en óxidos de Ni-Ti másicos y soportados en γ-alúmina para la deshidrogenación oxidativa del etano [Tesis]. PE: Universidad Nacional de Ingeniería; 2020. http://hdl.handle.net/20.500.14076/22458
@mastersthesis{renati/267546,
title = "Síntesis y caracterización de catalizadores basados en óxidos de Ni-Ti másicos y soportados en γ-alúmina para la deshidrogenación oxidativa del etano",
author = "Baldeón Ortíz, Iván Wimple",
publisher = "Universidad Nacional de Ingeniería",
year = "2020"
}
Commercial ethylene production is primarity by steam cracking of ethane and thermal cracking, but it requires high operating temperatures (T>700°C) to produce side reactions. The use of catalytic technology to obtain ethylene by reactions of oxidative dehydrogenation (ODH) of ethane permit to obtain high selectivity, lower operating temperatures (~400°C) and additionally, energy saving. In this work, some bulk and alumina-supported catalysts based on nickel oxides (NiO) and mixed nickel-titanium oxides (Ni-Ti) were prepared for the oxidative dehydrogenation (ODH) of ethane toward ethylene. Before the test experiments, the preparation conditions were studied in order to obtain some catalysts with the highest specific surface area. The catalysts prepared were synthesized through methods of sol-gel and solvent evaporation with water, ethanol and 2-propanol as a solvent. Then, the effect of polymerizing agent and the calcination temperature were studied, finding the highest specific surface area with the sol-gel procedure in ethanol as a solvent and the ratio of 1:3 particularly for citric acid and ethylene glycol respectively as polymerizing agents. The effect of the calcination temperature was evaluated, being 500 °C calcination temperature optimum for obtaining catalysts oxides with high surface area. The results of thermogravimetric analysis (TGA) show that 500 °C the catalysts become thermally stable. In mixed nickel-titanium oxide catalysts, the insertion of titanium into the crystal lattice of nickel oxide results in a decrease in crystallite size, which was determined by X-ray diffraction analysis (XRD). This interaction can be observed by appearance of new vibrations modes in the Laser Raman Spectroscopy. That modes observed at 583 cm-1, 701 cm-1 and 756 cm-1 evidencing the formation of a different crystalline phase to NiO. The low reducibility of Ti4+ ions redistributed in the nickel crystal lattice inhibits the reduction of Ni2+ species causing a widening of the band towards lower temperatures in the graphics of TPR-H2. The spectra XPS analysis of the mixed Ni-Ti catalysts shows the modifications in deconvolution peaks of species Ni2p and Ti2p at the mixed catalysts. The mass catalysts were supported on γ-Al2O3 (20 wt. %) by the mechano-synthesis method. The XRD pattern shows the characteristic peak of nickel oxide around 2θ = 37.2° more intense than peaks detected at 43.3°, the highest peak in bulk NiO. This change in intensities is being caused by the formation of surface nickel aluminates (NiAl2O4) as a result of a strong interaction between the active phase (nickel oxide) and the catalytic support. The TPR of H2 analysis shown some differences in supported catalysts, the hardly reducibility of the nickel species which are forming aluminates decreasing on the value of the ratio between H/Ni as a certain amount of nickel is not reduced. The catalytic tests shown that the mass catalyst with 15% of Ti (NiTi15) reached an activation energy of 88.01KJ/mol, and a selectivity of almost 86.9% at a reaction temperature of 400 ° C and it was the most selective mass catalyst. Its equivalent alumina supported with the same surface density (the number of charged metal atoms per nm2 of specific surface=8.3 atoms/nm2) increases its selectivity toward ethylene to 93.3%, turning out to be the best catalyst for this work. The activation energy determined for this supported catalyst by measuring the reaction rate at different temperatures has caused the increase in nucleophilic oxygen in relation to electrophilic oxygen (determined by the XPS technique) this resulted in the increase in selectivity an ethylene.
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