Obtenção de catalisadores suportados para dessulfurização do óleo diesel

Abstract

The more important purpose of this work was prepare supported γ-Al2O3 catalysts, by conformation of the aluminum hydroxide Versal, using as active phases precursors, commercial salts of the metals Ni, Nb e Mo, resulting in the catalysts NbMo/γ-Al2O3, NiNb/γ-Al2O3 e NiMo/γ-Al2O3. This were evaluated about the catalytic performance in the Hydrodessulfurization (HDS), principal process in the oil diesel refining. The work specific purpose was evaluated the influence in the properties of the supports and catalysts, diversified some parameters in peptizer and calcination. The studied variables were: the type of peptizer agente (acetic acid, oxalic acid and ammonium hydroxide), the peptizer agent concentration (2% e 3%) and the calcinations temperature (550°C e 650°C). Matching up this different parameters, were make nine supports with different characteristics. Initially, using X-Ray Diffraction, was evaluated the influence of the peptization, the concentration of peptizer agent and the calcination temperature in the supports crystalline structure. The results demonstrated that the peptizated samples with the superior peptizer concentration, show more crystalline. The supports were analyzed by Nitrogen Adsorption, that determine the textural properties (superficial specific area, specific volume of pore and medium diameter of pore) and Mechanical Resistance. The results allowed to select three supports (acetic acid 3%/650°C, oxalic acid 3%/650°C and ammonium hydroxide 3%/650°C) to impregnation. Was made incipient impregnation, in two to two combinations (NbMo, NiNb e NiMo) and the final catalysts were also evaluated with the supports tests, as result, just the three catalysts by supports peptizated with acetic acid 3%/650°C, were selected to catalytic tests. The Hydrodessulfuruzations were made in a high pressure unit of H2 (30 bar) and high temperature (280°C), simulating the industrial refining conditions, using as initial sufured compost the Dibenzothiophene (DBT). The results indicated that the catalysts NiMo/γ-Al2O3 was the only one to had a good performance.