EFFECT OF TRACE-ELEMENTS ON THE ELECTROLYTIC PRODUCTION OF NF3

Citation
A. Tasaka et al., EFFECT OF TRACE-ELEMENTS ON THE ELECTROLYTIC PRODUCTION OF NF3, Journal of the Electrochemical Society, 144(1), 1997, pp. 192-197
Citations number
11
Categorie Soggetti
Electrochemistry
ISSN journal
00134651
Volume
144
Issue
1
Year of publication
1997
Pages
192 - 197
Database
ISI
SICI code
0013-4651(1997)144:1<192:EOTOTE>2.0.ZU;2-C
Abstract
The effects of metallic impurities added and dissolved from the struct ure of the cell on the current efficiencies for NF3 formation and the overall generation of anode gas, and on the consumption of the nickel anode were studied in molten NH4F . 2HF at 120 degrees C by galvanosta tic electrolysis. A mixed gas composed of NF3 and N-2 with a small amo unt of N2F2, N2F4, N2O, and O-2 was liberated at the nickel anode duri ng electrolysis at 25 mA/cm(2). The current efficiencies for NF3 forma tion and the overall generation of anode gas under steady-state condit ions depended on the structural material, i.e., the current efficiency of the copper cell was high compared with those of the steel and nick el cells. On the other hand, the current loss caused by the anodic dis solution df nickel in the copper cell was larger than that in the stee l and nickel cells. Water in the melt retarded not only the anode cons umption but also the current efficiency for NF3 formation. Although th e addition of complexes such as NH4NiF3 and (NH4)(3)FeF6 in the melt w as effective for minimizing the anode consumption, the NF3 formation w as affected seriously Therefore, we estimate that the allowable conten ts of Ni2+ and Fe3+ in the melt should be no more than 0.06 and 0.03 m ole percent, respectively.