Uranium Tetrafluoride via Direct Conversion of Uranium Dioxide Using Silver Bifluoride in an Ionic Liquid Medium

Abstract

Conventional methods to prepare UF₄ involve the fluorination of UO₂ with corrosive chemicals (i.e., HF(g)) at elevated temperatures. Here, a novel method for producing UF₄ in a room temperature ionic liquid (RTIL) medium is presented. This method involves the fluorination of UO₂ in 1-methyl-1-butyl piperidinium bis(trifluoromethylsulfonyl)imide using silver bifluoride (SBF). The effect of RTIL volume, temperature, and water content on reaction yields and products is discussed. The volume of RTIL and reaction temperature are critical parameters in the formation of crystalline UF₄. The reaction of UO₂ with SBF at 200 °C with an RTIL volume of 0.5 mL gives crystalline UF₄ with the highest yield (94 %). The presence of water in the RTIL led to the formation of hydrated UF₄, while the reaction performed at 150 °C resulted in amorphous UF₄.