The activity of Ni/Al 2 O 3 -La 2 O 3 catalysts prepared by sol-gel process for hydrogen production using ethanol steam reforming was studied. The effect of Ni and La loading in the reaction activity and hydrogen selectivity was analyzed. The catalytic measurements were performed on a fixed-bed microreactor for a 6 h period; within this time, the catalysts showed partial deactivation. The catalyst containing 12 wt % La showed the highest yield to H 2 , but it also presented the highest deactivation. The other catalysts with the same Ni loading showed a decrease in H 2 yield over time. The increase of Ni loading from 5 to 10 wt % caused an increase in H 2 and CO yields in all La containing catalysts. The catalyst supported on sol-gel synthesized alumina showed the highest activity after 6 h on stream. This catalyst showed the lowest deactivation from all the systems that were studied. Polymeric and graphitic carbon were identified by DTA analysis of the spent catalysts. TGA analysis showed that the total coke deposited after reaction followed the trend: Ni/Al > Ni/12La ≈ Ni/8La > Ni/5La. However, less graphitic coke was identified on the catalysts as the lantana loading increased in the supports. Additionally, TEM results indicate that the radius of the graphite tubes decreased as the concentration of La in the support increased. A slight increase of H 2 and CO 2 yields was obtained when the water to ethanol mole ratio increased from 3 to 6. Higher deactivation was observed when more steam was fed to the reaction, even when lower carbon contents were determined by DTA-TGA analysis.
In this paper, layered double hydroxides (LDH) were synthesized and characterized using techniques of Physisorption of Nitrogen, Infrared, Temperature Programmed Desorption, X-Ray Diffraction, TGA and Immersion Microcalorimetry, in order to determine the basic properties of the adsorbent. The methyl orange (MO) is used as a dye and as a result, it is frequently found in effluents from textile industries. The dye adsorption isotherms on LDH were studied as function of pH and temperature. The maximum adsorption capacity of methyl orange on LDH was carried out at pH 5, and the minimum adsorption capacity at pH 11, being 40.2 mg/g and 22.1 mg/g, respectively. Furthermore, the suitable temperature to promote the adsorption of methyl orange on LDH was at 25 °C, as at 35 °C shows a significant decrease.
Se investigó la producción de biodiesel usando un reactor intermitente, se utilizó la metacaolinita como un catalizador sólido ácido que presentó una alta actividad para la producción de biodiesel a partir de aceite de maíz usado en freidora. El área superficial de la metacaolinita, diámetro de poro y volumen de poro fueron 10 m2/g, 13.0 nm y 30 mm3/g, respectivamente. Las condiciones óptimas para la reacción de transesterificación fueron: una relación molar aceite/metanol 1:31, temperatura de 160 ºC, presión manométrica de 1.65 MPa y una cantidad de catalizador de 3 (% peso). El rendimiento de ésteres metílicos de ácidos grasos (biodiesel) fue de 92.4 % para 2 h de reacción. Este método de preparación de biodiesel puede ser una buena alternativa para la utilización de aceite de maíz usado en freidora como una fuente muy barata para la producción de biodiesel combinado con un catalizador barato y además amigable con el medio ambiente.
En este trabajo se presenta el estudio de síntesis, caracterización y aplicación catalítica de hidróxidos doble laminares y Iodo en la obtención de benzopiran-2-onas. En esta metodología de síntesis se analizó la ventaja de utilizar la radiación infrarroja como fuente de energía comparándola con el calentamiento convencional. Otro punto descrito, es el estudio de los derivados de benzopiran-2-onas como moléculas con actividad antifúngica utilizando como modelo el hongo fitopatógeno Sclerotium cepivorum. El hidróxido doble laminar con una proporción molar X = 0.36 (X = Al/Al+Mg) fue el más eficiente en la reacción de Knoevenagel, mientras que el Iodo (0.4 mmol) fue un catalizador eficiente en la reacción de Pechmann. Al comparar los análisis de las diferentes fuentes de calentamiento utilizadas, se observó que la radiación infrarroja requiere menor tiempo de reacción en comparación con el calentamiento convencional. Los derivados de benzopiran-2-onas 3a-d presentaron efecto antifúngico a concentraciones mayores a 1.33 μg/μL hasta por 30 días.
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