Synthesis, characterization and reactivity of tungsten oxynitride
<p>High surface area tungsten oxynitride samples have been prepared by the temperature programmed reaction (TPR) of W0<sub>3</sub> with NH<sub>3</sub>. All samples were characterized by X-ray diffraction (XRD), nitrogen physisorption, and CO chemisorption. In addition,...
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| Format: | Others |
| Language: | en |
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Virginia Tech
2014
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| Online Access: | http://hdl.handle.net/10919/45408 http://scholar.lib.vt.edu/theses/available/etd-11012008-063455/ |
| Summary: | <p>High surface area tungsten oxynitride samples have been prepared by the temperature
programmed reaction (TPR) of W0<sub>3</sub> with NH<sub>3</sub>. All samples were characterized by X-ray
diffraction (XRD), nitrogen physisorption, and CO chemisorption. In addition, some
sample compositions were determined by elemental analysis. Samples were prepared at
various heating rates (β), allowing a Redhead analysis to be carried out giving an
activation energy of nitridation of 109 kJ mol<sup>-1</sup>. A heating rate of 0.016 K S<sup>-1</sup> gave
optimum synthesis conditions. Solid state intermediates were studied by interruption of
the temperature program at various stages. No distinct suboxide phases formed along the
synthesis path were found using XRD. An increase in surface area, CO uptake and
nitrogen weight content, were found to occur as the reaction progressed. Reactivity
experiments showed reasonable hydro deoxygenation (HDO) and hydrodenitrogenation
(HDN) activities, but little hydrogenation (HYD) or hydrodesulfurization (HDS)
activities.</p> === Master of Science |
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