Accession Number : ADA183240

Title :   Irreversibility of the Aluminum Electrode in Basic Room-Temperature Chloroaluminate Molten Salts.

Descriptive Note : Technical rept. 1 Jul 86-30 Apr 87,

Corporate Author : FRANK J SEILER RESEARCH LAB UNITED STATES AIR FORCE ACADEMY CO

Personal Author(s) : Dieter,K M ; Dymek,C J , Jr ; Lander,S W ; Oye,H A ; Rovang,J W

PDF Url : ADA183240

Report Date : 18 Jun 1987

Pagination or Media Count : 22

Abstract : The irreversibility of the aluminum electrode in basic room temperature chloroaluminate melts has been attributed to an apparent kinetic barrier to reduction of the stable tetrachloroaluminate ion. six approaches were identified which might lead to promoting reduction of Al form basic melts or at least provide some understanding of whether and how this barrier might be overcome. Our results showed that reduction of Al in basic MEIC1/AlCl3 melts was not promoted by (1) elevated temperatures (up to 181 C), (2) substitution of mixed haloaluminates, AlClXBr4-x for AlCl4-, or (3) introducing LiCl, BF3, and MgCl2 into melts. (4) Cyclic voltammetry of melts dissolved in THF did not provide any evidence of AlCl4 reduction. (5) Melts formed from dimethylethylethoxymethyl ammonium chloride (N211 102Cl) and AlCl3 did have a cathodic limit that was about 0.6 V more negative in basic melt thant that for MEICl/AlCl3. However, no AlCl4- reduction was observed in basic N211 102C;/A;C;3 melts. Finally, (6) some preliminary semi-empirical molecular orbital calculations gave results which indicate that further refinement of a model for the AlCl4 reduction process is worth pursuing. A mechanism for the electrode process at equilibrium is proposed which is consistent with a true thermodynamic equilibrium and the absence of Al deposition at potentials cathodic of the rest potential.

Descriptors :   *ELECTRODES, *ALUMINATES, *CHLORINE COMPOUNDS, *FUSED SALTS, ALUMINUM, AMMONIUM COMPOUNDS, BARRIERS, CHLORIDES, COMPUTATIONS, CYCLES, DEPOSITION, ELECTRODES, EQUILIBRIUM(GENERAL), HIGH TEMPERATURE, IRREVERSIBLE PROCESSES, KINETICS, MELTS, MOLECULAR ORBITALS, REST, THERMODYNAMICS, VOLTAMMETRY, ELECTRIC CHARGE, REVERSIBLE, POTENTIAL ENERGY, VOLTAGE, REDUCTION(CHEMISTRY), OXIDATION, ELECTROCHEMISTRY, CHEMICAL EQUILIBRIUM, CATHODIC PROTECTION

Subject Categories : Electrical and Electronic Equipment
      Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE