Óxido de tântalo: estudos relativos à sua obtenção, caracterização e uso como suporte de catalisadores comparativamente ao óxido de nióbio.

Abstract

The catalysts of selective oxidation of gaseous hidrocarbons has been under research in last years as an alternative technology for some conventional processes. In this work the obtention of propene from the propane and the phythalic anhydride from the o-xylene are pointed out Two supports are used: the niobium oxide (V) and the tantalum oxide (V) prepared from the niobic acid (CBMM) and by means of complexation with tanine respectively. The catalysts are prepared by the impregnation and grafting techniques whose imobilized active phase is vanadium live VOx species. The characterization of the solids is done by thermal analysis, X-ray diffraction, specific area, sweep eletronic miscroscope, isoelectric point, temperature-programmed reduction, spectrografic emission otic, chemical analysis and catalystic tests to the selective oxidation reaction from o-xylene to ptythalic anhydride and oxidative dehydrogenation from propane to propene in temperatures of 325 and 450°C recpectively. The results of the characterization present similarities in the texture of the supports that are maintained mainly by the catalysts. To the reactions of selective oxidation of o-xylene and oxidative dehydrogenation of propane, the supported solids in niobium oxide present themselves more favourable to the referred reactions. Complementary essays, basically of the surface characterization to all the solids referred here were proposed in addition to the redirection of the study of these supports, the tantalum and niobium oxides.