NOVEL METHOD OF COATING OF MAGNESIUM SPINEL ON ALFA ALUMINA SPHERES

LIC. GRACIELA MABEL BAEZ; ING. OSVALDO SCELZA; DR. SERGIO DE MIGUEL; DRA. SONIA BOCANEGRA

Congreso; XXIII INTERNATIONAL MATERIALS RESEARCH CONGRESS; 2014

A structured material composed of spherical nuclei of α-Al2O3 covered with a thin layer of magnesium spinel was synthesized. The coating method consists in the deposition of a primer of bohemite suspension on the alumina spheres, and then the impregnation of them with solutions of Mg(NO3)2.6H2O, followed by drying and calcination in air at high temperature in order to form the MgAl2O4 spinel. The original method was submitted to two modifications for improving both the thickness and purity of the MgAl2O4 layer. The first change consisted in the use of successive suspensions of bohemite of increasing concentrations to obtain a primer of higher thickness. The second change included the use of (NH4)2CO3 solution to purify the material of the layer, which contained residues of MgO. The coated spheres were studied by scanning electron microscopy (SEM), thus showing the formation of a uniform layer of spinel on the nuclei. The analysis of the layer material by X-ray diffraction (XRD) showed the MgAl2O4 formation. The synthesized materials were used as a support to prepare Pt(0.3 wt%) catalysts, which were evaluated in the n-butane dehydrogenation reaction. Results showed good yields to the desired products (butenes).