Síntesis y caracterización estructural de hidrotalcitas de Cu-Zn-Al
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Meza Fuentes, Edgardo
Rodríguez Ruiz, Johana
Pájaro Payares, Adolfo
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2016-09-01
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Las hidrotalcitas pueden ser usadas en áreas como catálisis, medicina, química ambiental, entre otras. Dependiendo de los metales presentes, los sólidos derivados de la calcinación de hidrotalcitas también son usados debido a su carácter básico, efecto de memoria y alta área superficial especifica. En este estudio se evaluaron características de hidrotalcitas a base de Cu-Zn-Al. Los análisis se realizaron usando AAS, DRX, FTIR, TGA y DSC. Se observó que, en los sólidos con mayor cantidad de cobre, la banda del estiramiento O••H (M••OH, H••OH) se desplaza a valores más bajos de número de onda, debido a que la densidad electrónica de los grupos OH se orienta hacia el centro metálico de cobre. En todos los sólidos se observó la formación de la fase hidrotalcita, y de la fase Cu(OH)2 en los sólidos con mayor contenido de cobre, lo que puede ser atribuido al efecto Jahn-Teller. Los resultados mostraron que los sólidos con mayor contenido de cobre colapsan en temperaturas menores. En todas las muestras se observaron eventos como: descomposición de la estructura HTLc, formación de óxidos metálicos y descomposición de carbonatos que quedaron ocluidos en los poros de los sólidos debido al colapso de la estructura laminar.
Hydrotalcite-like compounds have been used in catalysis, medicine, environmental chemistry, and other applications. Depending on the metals present, the solids obtained by calcinations can be used due to their basicity, memory effect and high specific surface area. This study describes some characteristics of hydrotalcites based on Cu-Zn-Al. The solids were characterized by AAS, XRD, FTIR, DSC and TGA. Was observed in the FTIR spectra of the solids with higher copper contents, that the band signed to O••H stretching (M••OH, H••OH) was moved to lower wave number values, because electron density of hydroxide groups orients toward the metallic copper center. In all material was observed hydrotalcite phase, and the Cu(OH)2 phase in solids with higher copper content was detected, fact attributed to the Jahn-Teller effect. Results indicate that the collapse of the structure occurs at lower temperatures in the case of solids with higher copper content. In all the materials was observed the decomposition of the HTLc structure and the formation of metal oxides, as well as decomposition of carbonate ions occluded in the solid due to the collapse of the lamellar structure.
Hydrotalcite-like compounds have been used in catalysis, medicine, environmental chemistry, and other applications. Depending on the metals present, the solids obtained by calcinations can be used due to their basicity, memory effect and high specific surface area. This study describes some characteristics of hydrotalcites based on Cu-Zn-Al. The solids were characterized by AAS, XRD, FTIR, DSC and TGA. Was observed in the FTIR spectra of the solids with higher copper contents, that the band signed to O••H stretching (M••OH, H••OH) was moved to lower wave number values, because electron density of hydroxide groups orients toward the metallic copper center. In all material was observed hydrotalcite phase, and the Cu(OH)2 phase in solids with higher copper content was detected, fact attributed to the Jahn-Teller effect. Results indicate that the collapse of the structure occurs at lower temperatures in the case of solids with higher copper content. In all the materials was observed the decomposition of the HTLc structure and the formation of metal oxides, as well as decomposition of carbonate ions occluded in the solid due to the collapse of the lamellar structure.