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Quantitative Analysis of Lewis Acid Centers of γ‑Alumina by Using EPR of the Adsorbed Anthraquinone as a Probe Molecule: Comparison with the Pyridine, Carbon Monoxide IR, and TPD of Ammonia
journal contribution
posted on 2015-12-10, 00:00 authored by Marat R. Gafurov, Ildar
N. Mukhambetov, Boris
V. Yavkin, Georgy V. Mamin, Alexander A. Lamberov, Sergei B. OrlinskiiQuantitative
electron paramagnetic resonance (EPR) measurements
were done on the alumina oxide surface by using 9,10-anthraquinone
probe (AQ) with the AQ amount in the range of (0.5–20) wt %.
The nature of three paramagnetic centers observed simultaneously is
ascribed to the strong, medium, and weak Al Lewis acid sites on the
basis of combined EPR study/infrared (IR) spectroscopy of the adsorbed
CO and pyridine/temperature-programmed desorption (TPD) of ammonia.
It is shown how the optimal concentration of AQ probe molecule for
the exhaustive quantitative examination of alumina surface can be
determined directly from EPR. A possibility to characterize the surface
distribution of Lewis acid centers by AQ molecules is discussed.