Adsorption and dehydrogenation of 2-propanol on the surface of γ-Al2O3-supported gold

The adsorption and reactions of 2-propanol on γ-Al₂O₃ and γ-Al₂O₃-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 Al³⁺ sites. Treatment of γ-Al₂O₃ 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 H₂ 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 Al³⁺ 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-Al₂O₃ 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.     

Silanization of di-n-octyldichlorosilane as a route to improve the integration of titanium dioxide in polypropylene

Journal of Thermal Analysis and Calorimetry - This paper experimentally investigates the effects of constant magnetic field on the average Nusselt number variation when the water-based ferrofluid...