7783-77-9Relevant academic research and scientific papers
Kinetics of fluorination of metallic molybdenum with elementary fluorine
Rybakov,Seredenko,Orekhov,Mironov
, p. 1929 - 1934 (2004)
The kinetics of the heterogeneous reaction of metallic molybdenum with elementary fluorine under conditions close to those used in actual technological practice at a concentration of fluorine in the gas mixture equal to 20-50 vol % was studied. The kinetic parameters were evaluated using the Arrhenius equation. A regression equation was obtained using the statistical method of experimental design for practical calculations of the rate of fluorination of metallic molybdenum with elementary fluorine. This equation makes it possible to calculate the fluorination rate at any point of the factor space, at fluorine concentrations of 30-50 vol % and initial temperatures of 250-350°C.
Plasmachemical synthesis of the binary hexafluorides of Mo, Os, Ir, Te, and U
Buchner, M. R.,Chemnitz, T.,Kraus, F.,Petry, W.
, (2021/08/10)
Starting from the respective metal, we have synthesized the binary hexafluorides MF6 of M = Mo, Os, Ir, Te, and U by the use of a remote fluorine plasma source using a mixture of Ar and NF3 as the feed gas. The formation of the binary hexafluorides was confirmed by several different spectroscopic methods including IR, Raman, UV/VIS, and NMR spectroscopy.
Separation of metallic residues from the dissolution of a high-burnup BWR fuel using nitrogen trifluoride
McNamara, Bruce K.,Buck, Edgar C.,Soderquist, Chuck Z.,Smith, Frances N.,Mausolf, Edward J.,Scheele, Randall D.
supporting information, p. 1 - 8 (2014/05/06)
Nitrogen trifluoride (NF3) was used to fluorinate the metallic residue from the dissolution of a high burnup, boiling water reactor fuel (～70 MWd/kgU). The washed residue included the noble-metal phase (containing ruthenium, rhodium, palladium, technetium, and molybdenum), smaller amounts of zirconium, selenium, tellurium, and silver, along with trace quantities of plutonium, uranium, cesium, cobalt, europium, and americium, likely as their oxides. Exposing the noble metal phase to 10% NF3 in argon, between 400 and 550 °C, removed molybdenum and technetium near 400 °C as their volatile fluorides, and ruthenium near 500 °C as its volatile fluoride. The events were thermally and temporally distinct and the conditions specified provide a recipe to separate these transition metals from each other and from the nonvolatile residue. Depletion of the volatile fluorides resulted in substantial exothermicity. Thermal excursion behavior was recorded with the thermal gravimetric instrument operated in a non-adiabatic, isothermal mode; conditions that typically minimize heat release. Physical characterization of the noble-metal phase and its thermal behavior are consistent with high kinetic velocity reactions encouraged by the nanoparticulate phase or perhaps catalytic influences of the mixed platinum metals with nearly pure phase structure. Post-fluorination, only two products were present in the residual nonvolatile fraction. These were identified as a nano-crystalline, metallic palladium cubic phase and a hexagonal rhodium trifluoride (RhF3) phase. The two phases were distinct as the sub-μm crystallites of metallic palladium were in contrast to the RhF3 phase, which grew from the parent, nano-crystalline noble-metal phase during fluorination, to acicular crystals exceeding 20-μm in length.
A thermogravimetric study of the reactions of molybdenum disilicide with anhydrous hydrogen fluoride and fluorine
Gama,Wagener,Crouse
, p. 66 - 69 (2013/02/25)
The results of a thermogravimetric study into the dry fluorination of molybdenum disilicide, MoSi2, using hydrogen fluoride and dilute fluorine gas as fluorinating agents are reported. The reaction between molybdenum disilicide and fluorine follows the thermodynamically preferred route, viz. the formation of the volatile molybdenum hexafluoride along with gaseous silicon tetrafluoride, with the reaction starting just below 200 °C. The reaction with hydrogen fluoride yields solid molybdenum metal and gaseous silicon tetrafluoride, similarly thermodynamically predicted, above 250 °C. No reaction is observed at low temperatures where solid molybdenum trifluoride is expected to form. The results of a kinetic analysis of the data for the reaction with hydrogen fluoride are reported. In the range 250-450 °C the kinetics are chemical reaction controlled. Above this, up to 700 °C, the rate is controlled by diffusion through the stagnant gas films surrounding the solid particles. Evidence for a third, un-quantified, high-temperature mechanism is given.
Development and implementation of industrial technologies for synthesis of fluorine compound with the application of elemental fluorine
Pashkevich,Barabanov,Maksimov
, p. 1142 - 1148 (2009/12/01)
A survey is given on the application of elemental fluorine in chemical plants and research centers of Russian Federation.
Chemical interaction of fluoropolymers with transition metals
Tarasov,Alikhanian,Arkhangel'Skii
, p. 809 - 813 (2009/12/01)
Chemical interaction of transition metals (Mo, W, Ta, Nb, and Ti) with a tetrafluoroethylene-vinylidene fluoride (TFE-VDF) copolymer (21 mol % TFE + 79 mol % VDF) has been studied by differential scanning calorimetry (DSC) and mass spectrometry. The DSC c
Infrared spectra of the products of interaction of tungsten and Molybdenum with fluorine isolated in solid argon
Osin,Davlyatshin,Ogden
, p. 237 - 245 (2007/10/03)
The IR spectra of the products formed when molecular fluorine passed over molybdenum and tungsten (heated to 100-1100°C) and isolated in inert matrices at 12 K were recorded. In the W + F2 system, the major product was tungsten hexafluoride. For the Mo + F2 system, bands of MoF6, MoOF4, (MoF5)3, MoF5, MoF4, and, possibly, MoF3 were identified. The spectra were interpreted with the use of thermodynamic calculations of the equilibrium composition of the gas phase at various temperatures. The structure of metal fluorides of different compositions is discussed.
Enthalpy of Formation of Crystalline Molybdenum Trifluoride
Leonidov,Pervov
, p. 1529 - 1530 (2008/10/08)
The enthalpy of combustion of MoF3 (cryst) in fluorine is measured, for the first time, in a calorimeter with a two-chamber bomb: ΔlH0(298.15 K) = -600.4 ± 2.6 kJ/mol. On the basis of data obtained, a new value of the standard enthalpy of formation of molybdenum trifluoride is calculated: ΔfH0(MoF3, cryst., 298.15 K) = -957.3 ± 2.8 kJ/mol.
Standard molar enthalpy of formation at 298.15 K of the β-modification of molybdenum ditelluride
O'Hare, P. A. G.,Hope, G. A.
, p. 701 - 708 (2007/10/02)
Fluorine-combustion calorimetry of a high-purity sample of molybdenum ditelluride has yielded the standard molar enthalpy of formation: ΔfH0m(MoTe2, cr, β, 298.15 K) = -(84.2 +/- 4.6) kJ * mol-1.At 298.15 K, the enthalpy of the hypothetical β-to-α transition in MoTe2 is approximately -6 kJ * mol-1.The present result for ΔfH0m(MoTe2) has been combined with literature values for the decomposition pressures of MoTe2 to yield ΔfH0m(Mo3Te4, cr, 298.15 K) = -(185 +/- 10) kJ * mol-1.Our previously published ΔfH0m(TeF6) (Trans.Faraday Soc. 1966, 62, 558) has been revised slightly to -(1371.8 +/- 1.8) kJ * mol-1.
A fluorine-combustion calorimetric study of two molybdenum selenides: MoSe2 and Mo6Se6
O'Hare, P. A. G.,Tasker, I. R.,Tarascon, J. M.
, p. 61 - 68 (2007/10/02)
Combustion calorimetric measurements of the energies of fluorination of molybdenum selenides have yielded the following standard molar enthalpies of formation at 298.15 K and p0 = 101.325 kPa: ΔfHm0(MoSe2, cr) = -(234.2+/-3.3) kJ * mol-1 and ΔfHm0(Mo6Se6, cr) = -(477.8+/-10.0) kJ * mol-1.The dissociation enthalpy for the reaction: MoSe2(cr) = Mo(cr) + Se2(g), is (378.3+/-3.4) kJ * mol-1 at 298.15 K.A brief discussion is included of the thermodynamics of dissociation of the molybdenum dichalcogenides.
