Metal oxides materials have been employed in a wide range of applications from electronics and optoelectronics, paints and coatings, food science, cosmetics and catalysis. Aluminum oxide is one of the more prominent materials used in heterogeneous catalysis. The commercial usage of alumina as a catalyst is significant as exemplified by the broad range of applications from petroleum refining to automotive emission control. Interestingly, alumina has been used both as an active catalyst and as a support for a variety of catalytically active phases (metals and oxides). Many attempts have been made to understand the nature of alumina catalysts and alumina surfaces, especially the various Brønsted and Lewis acid sites that are considered active centers in acid catalyzed reactions. We present preliminary results using inelastic neutron scattering (INS) techniques to investigate the microscopic behavior of and inter relationship of Q-Al2O3 and g-Al2O3 by tracking the changes in INS spectrum as a function of thermal treatment and exposure to calibrated amounts of ethanol and after ramps in temperature consistent with the TPD ramps performed by Peden and coworkers. By using the same parent boehmite as the starting material both Q-Al2O3 and g-Al2O3 materials were characterized using XRD, SSNMR and desorption measurements. Changes in the INS signal as a function of calcining temperature, ethanol adsorbate exposure and subsequent adsorbate desorption are made. INS is well suited for such explorations, because they allow for tracking of the internal modes of remnant ethanol, ethylene and chemically decomposed species on the surface (i.e. evolution of hydroxyl, methyl groups and for the potential presence of water). The VISION spectrometer at the Spallation Neutron Source was used for these preliminary investigations.

Inelastic neutron studies of ethanol interaction with transition aluminas

253rd National Meeting (2017)

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