Quantitative
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.
The rate of the endothermic process of kaolinite transformation into metakaolinite was examined by X-ray phase and thermogravimetric analyses, as well as by means of differential scanning calorimetry, in relation to the particle size distribution and crystal structure characteristics of kaolinite in kaolin clays from different deposits.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.