Catalizadores de manganeso sintetizados por autocombustión y coprecipitación y su empleo en la oxidación del 2-propanol

Abstract

ResumenSe sintetizaron óxidos mixtos de manganeso a través de las metodologías de autocombustión y coprecipitación manteniendo constantes las relaciones Mn 2+ /Mg 2+ =1 y M 2+ /M 3+ =3, las cuales son características de los óxidos obtenidos a través de la descomposición térmica de precursores del tipo de la hidrotalcita. Los catalizadores se caracterizaron mediante las técnicas de fluorescencia de rayos X (FRX), difracción de rayos X (DRX), microscopía electrónica de barrido (SEM), adsorción de N 2 , reducción a temperatura programada y se evaluaron en la oxidación catalítica del 2-propanol. Los resultados evidenciaron que el empleo de la autocombustión como método de síntesis permite generar óxidos con propiedades estructurales, texturales, de reducción-oxidación (redox) y catalíticas similares a las obtenidas para el óxido preparado a través del precursor tipo hidrotalcita. El desempeño catalítico de los óxidos mixtos se asoció directamente con sus propiedades redox. El óxido de manganeso obtenido por autocombustión se depositó sobre monolitos metálicos de FeCrAlloy y se evaluó el efecto de la adherencia de la fase activa por medio del recubrimiento previo de los materiales con alúmina coloidal. La oxidación del 2-propanol sobre el monolito evidenció que no hay pérdida de actividad cuando el catalizador está sobre un material estructurado.Palabras clave: hidrotalcita, autocombustión, coprecipitación, monolito, COV. Self-combustion and Co-precipitation manganese catalysts and their use in the oxidation of 2-propanol AbstractManganese mixed oxides were synthesized by self-combustion and co-precipitation, maintaining constant the relationship Mn 2 + / Mg 2 + = 1 and M 2 + / M 3 + = 3, which are characteristic of the oxides obtained by thermal decomposition of hydrotalcite-like precursors. The catalysts were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), N 2 adsorption, and temperature-programmed reduction, and they were evaluated in the catalytic oxidation of 2 -propanol. The results showed that the use of such self-combustion synthesis method allows generating oxides with structural, textural, redox and catalytic properties similar to those obtained for the oxide prepared via a hydrotalcite-like precursor. The catalytic performance of mixed oxides was directly related to their redox properties. We evaluated the manganese oxide obtained by self-combustion deposited on Fecralloy metal monoliths, as well as the effect of the adhesion of the active phase of the precoat materials using colloidal alumina. The oxidation of 2-propanol over the monolith showed that there is no loss of activity when a catalyst is on a structured material.

Degradation of Crystal Violet by Catalytic Wet Peroxide Oxidation (CWPO) with Mixed Mn/Cu Oxides

“…In addition, signals were related with spinel-type phases, which were preferential due to the high temperatures reached during the synthesis and subsequent calcination. This result showed the effectiveness of autocombustion as a novel method when compared with similar phases with traditional methods, such as co-precipitation [25]. The diffraction signals of the mixed catalyst of Mn-Cu (x:y) displayed the periclase phase and the formation of spinels, as occurred with the oxides separately.…”