| 摘要 |
PURPOSE:To suppress the formation of cathode by-products such as NOx and H2 and obtain nitrite at high current efficiency by supplying the aqueous solution of nitrate such as NaNO3 to the cathode chamber of the electrolytic cell segmented by a cation exchange membrane of fluoride polymer base and supplying current while specifying the pH of this aqueous solution. CONSTITUTION:Mixed solution of nitrate solution 21 such as NaNO3 and nitric acid 22 is supplied from a catholyte tank 30 to the cathode chakber 28 of an electrolytic cell 26 which has been segmented by a cation exchange membrane 27 such as of fluoride polymer base having sulfonic acid groups. On the other hand, water 25 is supplied from anolyte tank 31 to the anode chamber 29. Next, the nitrate solution is electrolytically reduced under the following conditions by usikg the anode having covering of one or more kinds of Pt group metals and the cathode composed of Hg, Cd, Zn, Pb or their alloys. Namely, the pH of the nitrate solution is maintained at 4 or over, suitably at 7 or over and yet the solution temperature of the cathode chamber is kept at 95 deg.C or under, preferably room temperature to 70 deg.C. |
