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Consejo Nacional de Ciencia y Tecnología, CONACYT: CB-2006 61856
Adsorption and dehydrogenation of 2-propanol on the surface of γ-Al 2O 3-supported gold
The adsorption and reactions of 2-propanol on γ-Al 2O 3 and γ-Al 2O 3-supported gold samples were investigated by infrared (IR) spectroscopy, modulated differential scanning calorimetry (MDSC) and mass spectrometry. Adsorption of the alcohol on the samples at room temperature led to formation of molecularly adsorbed 2-propanol and 2-propoxide species bonded to Al 3%2b sites. Treatment of γ-Al 2O 3 after alcohol adsorption in flowing He from 25 to 300°C led to 2-propanol desorption, without evidence of surface reactions. In contrast, when supported gold samples were exposed to the same thermal treatment, formation of acetone and H 2 was observed by mass spectra of the effluent gases from the flow reactor. Concomitantly, IR spectra of the samples showed the appearance of a band at 1698 cm - 1, assigned to ν CO vibrations of adsorbed acetone. The formation of acetone occurred by the dehydrogenation of 2-propoxide species bonded to Al 3%2b sites, as evidenced by (a) the decrease in the intensities of their IR bands and (b) the presence of a MDSC peak at approximately the same temperature as that at which acetone was formed and the 2-propoxide species were consumed. It is proposed that gold particles on the γ-Al 2O 3 surface facilitate breaking of the β-CH bond of neighboring surface 2-propoxide species to give acetone. Our results emphasize the bifunctional character of supported gold catalysts for the dehydrogenation of alcohols. © 2012 Elsevier B.V. All rights reserved.
2-propanol dehydrogenation; Infrared spectroscopy; Modulated differential scanning calorimetry; Supported gold catalysts 2-propanol; Adsorption and reactions; Bifunctional; C-H bond; Dehydrogenation of alcohols; Effluent gas; Flow reactors; Gold particles; IR bands; IR spectrum; Mass spectra; Modulated differential scanning calorimetry; Room temperature; Supported gold; Supported gold catalysts; Acetone; Adsorption; Catalysts; Dehydrogenation; Desorption; Differential scanning calorimetry; Gold; Infrared spectroscopy; Mass spectrometry; Propanol; Surface reactions; Aluminum
The adsorption and reactions of 2-propanol on γ-Al 2O 3 and γ-Al 2O 3-supported gold samples were investigated by infrared (IR) spectroscopy, modulated differential scanning calorimetry (MDSC) and mass spectrometry. Adsorption of the alcohol on the samples at room temperature led to formation of molecularly adsorbed 2-propanol and 2-propoxide species bonded to Al 3 sites. Treatment of γ-Al 2O 3 after alcohol adsorption in flowing He from 25 to 300°C led to 2-propanol desorption, without evidence of surface reactions. In contrast, when supported gold samples were exposed to the same thermal treatment, formation of acetone and H 2 was observed by mass spectra of the effluent gases from the flow reactor. Concomitantly, IR spectra of the samples showed the appearance of a band at 1698 cm - 1, assigned to ν CO vibrations of adsorbed acetone. The formation of acetone occurred by the dehydrogenation of 2-propoxide species bonded to Al 3 sites, as evidenced by (a) the decrease in the intensities of their IR bands and (b) the presence of a MDSC peak at approximately the same temperature as that at which acetone was formed and the 2-propoxide species were consumed. It is proposed that gold particles on the γ-Al 2O 3 surface facilitate breaking of the β-CH bond of neighboring surface 2-propoxide species to give acetone. Our results emphasize the bifunctional character of supported gold catalysts for the dehydrogenation of alcohols. © 2012 Elsevier B.V. All rights reserved.
Consejo de Ciencia y Tecnología del Estado de Guanajuato, CONCYTEG: FOMIX-GTO2007
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