Magnetite surface area titration using nitric oxide, II. Pretreatment effects and silica-supported samples |
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| Authors: | J. E. Kubsh C. R. F. Lund Yi Chen J. A. Dumesic |
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| Affiliation: | (1) Department of Chemical Engineering, University of Wisconsin, 53706 Madison, Wisconsin, USA;(2) Present address: Department of Chemistry, Nanking University, People's Republic of China |
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| Abstract: | The use of NO adsorption for determination of Fe3O4 surface areas has been examined and extended, from earlier work on unsupported samples, to silica-supported Fe3O4. Gravimetric studies confirm earlier suggestions that the irreversible NO adsorption uptake on unsupported Fe3O4 is dependent upon sample pretreatment. Long (ca. 24 h) vacuum treatment at 650 K leads to increased apparent NO adsorption uptakes due to reduction of the surface. Magnetite particle size estimates were made using irreversible NO adsorption uptakes on silica-supported Fe3O4 samples that had received a  standard 1 h vacuum pretreatment at 650 K. These estimates agreed well with average particle sizes calculated using x-ray line-broadening and magnetization measurements, indicating that NO adsorption can, in fact, be used to measure magnetite surface areas on silica-supported samples.
                NO    Fe3O4  , , Fe3O4    .     , NO Fe3O4  .  ( 24 )  650   NO .  , NO Fe3O4, ,   1- 650 .  , , , NO ,  , .
Camille and Henry Dreyfus Foundation Teacher-Scholar; to whom all correspondence should be addressed. |
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