cl145(10)_1904.pdf 809 KB
Suganuma, Satoshi Center for Research on Green Sustainable Chemistry, Graduate School of Engineering, Tottori University Researchers DB KAKEN
Murakami, Yuta Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University
Ohyama, Jota Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University
Torikai, Tatsuya MicrotracBEL Corp.
Okumura, Kazu Department of Applied Chemistry, Faculty of Engineering, Kogakuin University
Spectroscopy and General Characterisation
Bending vibrations in the infrared (IR) spectra of ammonia adsorbed on Lewis acidic metal oxides, i.e., Al2O3, ZrO2 and TiO2, and zeolite were analyzed with an aid of density functional theory (DFT) calculations. The results by DFT methods reveal the wavenumbers of the vibration modes (ν4 and ν2) of NH4 bonded to Brønsted acid site and the vibration modes (δs and δd) of NH3 species coordinated to a Lewis acidic metal center (M = Al, Zr or Ti). The wavenumbers calculated based on DFT were reasonably in agreement with the experimentally observed values. The estimation of wavenumbers suggests that the δs vibration of NH3 hydrogen-bonded is invisible on a zeolite, because it is hidden by an intense absorption due to skeletal vibration. On the other hand, multiple bands of asymmetric bending modes (δd and ν2) observed on a zeolite were assigned. A quantification method of Brønsted and Lewis acid sites, and hydrogen-bonded NH3 is provided based on the peak assignments.
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© Springer Science+Business Media New York 2015
Suganuma, S., Murakami, Y., Ohyama, J. et al. Assignments of Bending Vibrations of Ammonia Adsorbed on Solid Surfaces. Catalysis letters. 2015, 145, 1904-1912. / This is a post-peer-review, pre-copyedit version of an article published in "Catalysis letters". The final authenticated version is available online at: http://doi.org/10.1007/s10562-015-1592-6.
Faculty of Engineering/Graduate School of Engineering