Compare the Energies of Different Oxofluoro Aluminiumt Structures in Aluminium Electrochemical Cell

Abstract

The fluoroaluminate molten salts are used in the Hall-Heroult industrial process
for the production of aluminum by electrolysis. To better understand the mechanism of the
dissolution of alumina (Al2O3) in cryolitic melts, we have studied the structure stability of
these anions The initial structural models of [Al2OF6]2-, [Al2O2F4]2-, [Al2O2F6]4- and
[Al2OF10]6- were generated using Gauss View Since this study attempts to compare the
energies of different oxofluoroaluminum structures, the geometries should be optimized at
an accurate level of theoryTherefore, geometry optimizations and energy calculations were
carried out by B3LYP density functional while several basis sets including 6-31g, 6-311g**,
6-311g** and 6-311++g** were used. Furthermore, solvent effect on structural energies
was investigated through incorporation of conductor-like polarizable continuum model
(CPCM) at B3LYP/6-311++g** level of theory the structure was optimized at different
levels by applying CPCM solvent model. Similar calculations were performed for the other
complex structures and similar results were obtained for them. Based on the energy values,
the following stability order is achieved: [Al2O2F4]
2-<[Al2OF6]
2-<[Al2O2F6]
4-< [Al2OF10]
6-