Chemical kinetics of the gas-phase reaction between uranium hexafluoride and hydrogen

Journal Article · Thu Dec 10 00:00:00 EST 1981 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150625a040· OSTI ID:5678931

Myerson, A L ^[1]; Chludzinski, Jr, J J

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1. Mote Marine Lab., Sarasota, FL

A study was made of the chemical kinetics of the homogeneous gas-phase reaction between uranium hexafluoride and hydrogen by measuring the rate of disappearance of UF/sub 6/. It has been concluded that the rate-limiting step for which the kinetics have been measured is UF/sub 6/ + HF + H (2). The reaction has been studied in a steady-state flow system over a temperature range of approx.625 to 825 K. Various surface-to-volume ratios were employed to aid in distinguishing gas-phase reactions from surface reactions. The steady-state concentration of the UF/sub 6/ after reaction with H/sub 2/ was monitored in a special multipass infrared spectrophotometer at the 626-cm/sup -1/ absorption band of UF/sub 6/. The principal problems were corrosion, plugging, surface intrusion, and the deleterious effects of minute traces of water; these problems have greatly slowed progress in this field. Several series of measurements involving different initial species concentrations and residence times, with each series at constant temperature, show that the rate is first order in UF/sub 6/. Our measurements yield a dependable Arrhenius curve in terms of a second-order expression for k, the bimolecular specific reaction rate constant for the disappearance of UF/sub 6/. It is believed that this overall rate of the disappearance of UF/sub 6/ is somewhat less than twice that of the critical reaction step 2, indicated above, so that the specific reaction rate constant k/sub 2/ is approx.8.7 c 10/sup 14/ exp(-34550 kcal/RT) cm/sup 3/ mol/sup -1/ s/sup -1/. Conclusions have been reached concerning the relative importance of the various elementary reaction steps involved in the chemical mechanism.

• OSTI ID: 5678931
• Journal Information: J. Phys. Chem.; (United States), Vol. 85:25
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDROGEN
CHEMICAL REACTION KINETICS
URANIUM HEXAFLUORIDE
ARRHENIUS EQUATION
EXPERIMENTAL DATA
HIGH TEMPERATURE
INFRARED SPECTRA
ACTINIDE COMPOUNDS
DATA
ELEMENTS
EQUATIONS
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
INFORMATION
KINETICS
NONMETALS
NUMERICAL DATA
REACTION KINETICS
SPECTRA
URANIUM COMPOUNDS
URANIUM FLUORIDES
400702* - Radiochemistry & Nuclear Chemistry- Properties of Radioactive Materials
400201 - Chemical & Physicochemical Properties