Study on the fluorination reaction of uranium tetrafluoride by nitrogen trifluoride

The fluorination of UF4 by NF3 at different temperatures was investigated using in-line Fourier transform infrared (FTIR) spectroscopy. The results indicated that the fluorination between NF3 and UF4 occurred only when the temperature was above 723 K, and the temperature had a significant effect on the average reaction rate and the utilization rate of NF3. The in-line FTIR spectrum analysis and thermodynamic calculation indicated that UF4 was converted to UF6 with the following reaction mechanism: 2/3NF(3)(g) + UF4(s) = UF6(g) + 1/3N(2)(g). The conversion rate of UF4 to UF6 increased from 1.53 to 2.68 gUh-(1) and the utilization rate of NF3 increased from 10.5%-22.5 % when the reaction temperature increased from 723 K to 873 K. The calculated rate constant increased from 1.6 x 10(-2) to 3.1 x 10(-2) min(-1) in the range of 723 K to 873 K, and the activation energy of the reaction was 22.56 kJ/mol.