Synthesis, characterization, and reactivity of tungsten oxynitride

Abstract

High surface area tungsten oxynitride has been prepared by the temperature programmed reaction (TPR) of WO 3 with NH 3 . All samples were characterized by x-ray diffraction (XRD), nitrogen physisorption, CO chemisorption, and elemental analysis. Samples were prepared at different heating rates (b), and a Redhead analysis yielded an activation energy for nitridation of 109 kJ mol 21 . A heating rate of 0.016 K s 21 gave optimal synthesis conditions. Solid state intermediates were studied by interrupting the temperature program at various stages. No distinct suboxide phases were found using XRD. The nitridation step was determined to be a continuous transformation from oxide to oxynitride. Surface area, CO uptake, and nitrogen weight % were all found to increase as the reaction progressed. Reactivity experiments showed reasonable hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) activity, but little hydrogenation (HYD) or hydrodesulfurization (HDS) activity.

Electrochemical capacitance of mesoporous tungsten oxynitride in aqueous electrolytes

“…Tungsten oxynitride was synthesized by a temperatureprogrammed reduction of tungsten (VI) oxide (Fluka, 95410) in NH 3 atmosphere [35]. Half a gram of WO 3 was loaded in an alumina crucible and placed in a conventional tube furnace (Tetlow Kilns & Furnaces Pty Ltd, Australia).…”

Surface structure and energetics of oxygen and CO adsorption on α-Mo2C(0001)

“…The energetically most favored adsorption site is the threefold C vacancy hollow site (V C /V C ) on the Mo-terminated surface, and the threefold C hollow site (H C /H C ) is the most stable adsorption site on the C-terminated surface. The adsorption energies in Tables 1 and 2 show that the molecular O 2 adsorbs dissociatively on the Mo-terminated surface more easily than on the C-terminated surface, which indicates that Mo-terminated surface is more active [11][12][13][14][15][16].…”

“…In practical applications, the utility of these materials ranges from wear-resistant coatings to superconductors and heterogeneous catalysts [11]. Furthermore, they have potential applications in hydrodenitrogenation (HDN) [12,13] and hydrodesulfurization (HDS) [14,15] processes. Recent studies indicated that molybdenum sulfide under reaction conditions is partially transformed into carbide (MoC x S 2Àx ) where the HDS reactions occur [16].…”

Adsorption and dissociation of H2S on Mo2C(001) surface-A first-principle study

“…Haines et al [24] proposed an eclipsed configuration with a Mo-C-Mo-C stacking where half of the C atoms in the second layer and half of the C atoms in the fourth layer are removed is most likely candidate for ␤-Mo2C structure. Mo-terminated surface is very important for catalytic activity and the catalytic reactions occur mainly on it [25][26][27][28]. Previous results for the H adsorption on this surface indicated that H adsorbs more strongly to the metal-terminated carbide surface than to the C-terminated surface [23].…”