Electrochemical Reduction of Pd-Nd2O3-CeO2 Mixtures in the LiCl-Li2O Melt

Abstract

The electrochemical reduction of pelleted heterophase powder Pd-Nd2O3-CeO2 mixtures was studied in molten LiCl-Li2O (1–1.5 wt%) at 650 °C. The influence of the composition of the mixture, as well as electrochemical factors—i.e., the amount of electricity passed and the cathode potential during electrolysis—were considered. It was found that in the presence of metallic palladium, neodymium and cerium oxides are reduced by lithium released at the cathode and form intermetallic compounds of different compositions. At potentials more positive than the formation of a phase based on liquid lithium at 0.5–0.8 V, CePd3 and NdPd3 intermetallic compounds are present in the reduced product. At potentials close to the formation of liquid lithium, a whole spectrum of intermetallic compounds is synthesized: CePd, NdPd, Ce3Pd4, and Nd3Pd4. The mechanisms of formation of palladium alloys with neodymium and cerium are proposed and considered. The degree of the reduction of lanthanide oxides was calculated from the data on the concentration of residual oxygen in the reduced product.