Estudio preliminar de la síntesis de ferritas de cobalto cubiertas por una capa mesoporosa de silicalita de titanio con potencial aplicación para reacciones de oxidación selectiva : Estudio preliminar de la influencia de la relación molar de hidróxido de tetrapropilamonio (TPAOH) TPAOH/(Ti+Si) en la síntesis de ferritas de cobalto cubiertas por una capa densa de sílice y una capa mesoporosa de silicalita de titanio.

Abstract

The present work studies the influence of the molar ratio of tetrapropylammonium hydroxide (TPAOH) TPAOH/(Ti+Si) on the synthesis of cobalt ferrites (CoFe2O4) covered by a dense layer of silica and a mesoporous layer of titanium silicalite with application in selective oxidation reactions. Titanium silicalites are heterogeneous catalysts difficult to recover due to their particle size. For this reason, the synthesis of catalysts consisting of a magnetic core covered by a mesoporous layer with titanium active sites in which the olefin oxidation occurs is proposed in this work. The cobalt ferrite was synthesized by the hydrothermal method. The coating was carried out by sol-gel, where tetraethoxysilane (TEOS) and titanium butoxide (TBOT) were used as Si and Ti precursors, in addition to TPAOH (structure directing agent), and cetyltrimethylammonium bromide (CTAB, surfactant). Two catalysts FCR_TPAOH_0,48 and FCR_TPAOH_0,73 were obtained. X-Ray Diffraction analysis determined the presence of CoFe2O4. Scanning Electron Microscopy confirmed the presence of the mesoporous layer. Nitrogen Physisorption analysis determined specific surface areas of 411 m2g-1 and 399 m2g-1. The Ti content determined by ICP-OES analysis was 38.60 mg Ti g-1catalyst and 41.20 mg Ti g-1catalyst, respectively. FTIR confirmed the presence of the Si-O-Ti band in both samples, but FCR_TPAOH_0,48 displayed the highest intensity. Finally, the conversion reached was 20 % with FCR_TPAOH_0,48 and 14 % with FCR_TPAOH_0,73. An excess of TPAOH was not beneficial for the catalytic performance of the samples.