Gasförmige Hydroxide. IV. Über gasförmige Hydroxide des Molybdäns und Wolframs

Abstract

Im Temperaturbereich von 600–690°C wird von MoO3, im Temperaturbereich von 900–1100°C von WO3, die in Gegenwart von Wasserdampf erhöhte Flüchtigkeit der Oxide mit Hilfe der Mitführungsmethode studiert. Die gemessenen Gleichgewichte werden formuliert nach Für beide Reaktionen werden thermochemische Daten mitgeteilt. Die Formulierung der entstandenen gasförmigen Hydroxide wird diskutiert. Bei diesen handelt es sich um neue Verbindungen des Molybdäns(VI) und Wolframs(VI).

Gas Chromatographic Studies of Oxide and Hydroxide Species of Tungsten - Model Experiments with Respect to the Physico-Chemical Characterization of Seaborgium (Element 106)

“…In moist oxygen species such as W02(0H)2 can be formed which should be more volatile than WO3 [9][10][11][12][13].…”

Chemical Vapor Transport Reactions – Arguments for Choosing a Suitable Transport Agent

“…For example, this applies to the compounds BeO, Li 2 O, V 2 O 5 , MoO 3 , WO 3 , ReO 3 , and SiO 2 . Volatile hydroxides or acids are formed during the transport of these compounds: [48,49] (60) 4 (g) (580 Ǟ 480°C) [50] (61) [51] (62)…”

Template Removal via Boudouard Equilibrium Allows for Synthesis of Mesostructured Molybdenum Compounds

“…Unfortunately, the equilibrium partial pressure of MoO 3 is significant and at any temperature orders of magnitude higher than of MoO 2-x (Figure 1a). Consequently, MoO 3 readily sublimes at temperatures usually applied during oxidative template removal by forming polymeric (MoO 3 ) x species [23][24][25] according to:…”

“…. [20,[23][24][25] Relevant MoOx species vary with humidity of the carrier gas. The top grey curve was measured in 100% steam, whereas the bottom one was obtained in dry atmosphere.…”

“…MP and BP denote the melting point and boiling point. [20,24] Removal of the polymeric template was accomplished by two calcination steps: First, the sp 2 -hybridized carbon atoms of the ADM/PB-b-P2VP nanocomposites were converted in argon atmosphere at 973 K into a carbonaceous scaffold which stabilizes and lines the inorganic walls (Scheme 1C). Further details on this carburization reaction can be found in previous reports.…”