III International Conference

PP-II-2SYNTHESIS OF MONOPHASE URANIUM OXIDES UO 2 , U 4 O 9 , U 3 O 8 OFSPECIFIED COMPOSITION BY ELECTROLYSIS OF OXIDE SALT MELTS ANDINVESTIGATION OF THEIR PHYSICO-CHEMICAL AND CATALYTICPROPERTIESAfonichkin V.K., Khrustova L.G., Komarov V.E., Ismagilov Z.R. 1 , Kuznetsov V.V. 1 ,Shikina N.V. 1 , Kuntsevich S.V. 1 , Rogov V.A. 1Institute of High Temperature Electrochemistry, Ekaterinburg, Russia1 Boreskov Institute of Catalysis SB RAS, Novosibirsk, RussiaE-mail: afonichkin@ihte.uran.ruBulk monophase uranium oxides UO 2 , U 4 O 9 and U 3 O 8 of specified composition weresynthesized by electrolysis of oxide salt melts. Optimal electrolysis conditions for synthesis ofuranium oxides of given chemical and phase composition were selected. Prepared uraniumoxides were characterized by XRD, S BET , SEM, TPR, TPO and FTIR. Catalytic activity ofuranium oxides in the reactions of thiophene hydrodesulfurization and butane oxidation wastested.This work is devoted to investigation of methods of synthesis of uranium oxides (UO 2 ,U 4 O 9 and U 3 O 8 ) of specified composition by electrolysis of oxide salt melts. The goal of thework is a choice of optimal electrolysis conditions for synthesis of monophase uraniumoxides, which can be used as active components of uranium oxide catalysts.The oxygen coefficient of uranium oxides, their structure, and current efficiency werestudied as influenced by the electrolyte composition, deposition potential, and temperature ofelectrolysis.On the results of the experiments, optimal composition of salt melt electrolytes andelectrolysis conditions were selected to provide synthesis of cathode product of specifiedchemical and phase composition and to obtain maximal uranium oxide yields. It was foundthat the optimal conditions for UO 2 phase synthesis are the electrolyte containing48.33 K 2 WO 4 – 36.24 K 2 W 2 O 7 – 15.43 UO 2 WO 4 (mol. %), electrolysis temperatureТ = 900ºС and deposition potential E = -1.00V relative to Pt(O 2 ) reference electrode.Synthesis of U 4 O 9 was performed in the electrolyte 48.33 Na 2 MoO 4 – 36.24 Na 2 Mo 2 O 7 –15.43 UO 2 MoO 4 (mol. %) at Т= 900ºС and Е = -0.80V. U 3 O 8 phase was synthesized byelectrolysis of eutectic mixture (Li, Na, K) 2 SO 4 with addition of 30 mol. % UO 2 SO 4 atТ=800ºС and Е= -1.00 V.Microphotographs of the cathode deposited crystals are presented in Fig. 1.162