ALUMINAS MESOPOROSAS OBTENIDAS POR LA RUTA DE LOS ATRANOS PARA SU APLICACIÓN COMO MATRICES EN CRAQUEO CATALITICO
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Rev. Bol. Quim
Abstract
La ruta de los atranos fue utilizada para sintetizar alúminas que mostraron un área superficial específica en el rango de 150 - 275 m²/g y tamaño de poro medio en el rango de 60 - 180 Å después de calcinarse. Las alúminas fueron caracterizadas por IR, XRD, 27Al MAS-NMR, N2 adsorsión. Microdiminios cristalinos de AlOOH de tipo bohemita se formaron en las muestras no calcinadas. El tratamiento por calcinación provoco una reestructuración desde estructuras tipo bohemita hacia γ - alúmina. Las actividades de las alúminas preparadas por la ruta de los atranos, para la conversión de TIPB a 500 °C y tiempos cortos de reacción de 12 a 30 s fueron ligeramente inferiores que aquellas observadas en alúminas convencionales. Los parámetros cinéticos aparentes en un modelo simple de primer orden resultaron ser similares, lo que sugiere que no existen limitaciones por accesibilidad en el sistema de poros. Las propiedades mostradas por estas alúminas sintetizadas por la ruta de los atranos indicaron condiciones preliminares apropiadas para su uso como matrices de catalizadores en procesos FCC
The atrane route was used to synthesize aluminas that showed specific surface areas in the 150 - 275 m²/g range and average pore sizes in the 60 - 180 Å range after calcination. Different techniques were used to characterize the aluminas (IR, XRD, 27Al MAS-NMR, N2 adsorption). Crystalline micro domains of AlOOH boehmite type were formed in the uncalcined samples that increased their size as a function of the proportion of water in the synthesis, because water favors the hydrolysis and condensation of the Al[N(CH2-CH2-O)3]2H3 complex. The calcination treatment induced the crystalline restructuration from boehmite-type to γ - alumina-type structures. The activities of the aluminas prepared by the atrane route, as indicated by the TIPB conversion at 500 °C and short reaction times from 12 to 30 s, were somewhat smaller than those observed in conventional aluminas. The apparent kinetic parameters in a simple, first order model were similar, suggesting that accessibility limitations from the pore systems were not present. The properties shown by these aluminas synthesized by the atrane route indicated a preliminary appropriate condition for being used as FCC catalyst matrices. Corresponding author: gustavogarcia@correo.umsa.bo
The atrane route was used to synthesize aluminas that showed specific surface areas in the 150 - 275 m²/g range and average pore sizes in the 60 - 180 Å range after calcination. Different techniques were used to characterize the aluminas (IR, XRD, 27Al MAS-NMR, N2 adsorption). Crystalline micro domains of AlOOH boehmite type were formed in the uncalcined samples that increased their size as a function of the proportion of water in the synthesis, because water favors the hydrolysis and condensation of the Al[N(CH2-CH2-O)3]2H3 complex. The calcination treatment induced the crystalline restructuration from boehmite-type to γ - alumina-type structures. The activities of the aluminas prepared by the atrane route, as indicated by the TIPB conversion at 500 °C and short reaction times from 12 to 30 s, were somewhat smaller than those observed in conventional aluminas. The apparent kinetic parameters in a simple, first order model were similar, suggesting that accessibility limitations from the pore systems were not present. The properties shown by these aluminas synthesized by the atrane route indicated a preliminary appropriate condition for being used as FCC catalyst matrices. Corresponding author: gustavogarcia@correo.umsa.bo
Description
Vol. 27, No. 1