Classifications

• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
  • C01C1/00—Ammonia; Compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B1/00—Electrolytic production of inorganic compounds or non-metals
  • C25B1/01—Products
  • C25B1/24—Halogens or compounds thereof
  • C25B1/26—Chlorine; Compounds thereof

Definitions

• This invention relates to the electrolysis of ammonium chloride for the recovery or production of chlorine or ammonia or both.
• the underlying principle on which the invention is based resides in the electrolysis of aqueous ammonium chloride solutions in the presence of chlorides of alkali metal and alkaline earths which we find inhibit the production of nitrogen trichloride, and such products as nitrogen and chloramines.
• the electrolyte containing ammonium chloride and one or more chlorides of alkali metal or alkaline earths, can be electrolyzed to produce ammonia and chlorine from the ammonium chloride without. substantially reducing the content of the other chlorides. It is, however, important that the other chlorides be present in substantial quantities, for example, one-third chemical equivalent of the ammonium chloride, if the full advantages of the invention are to be obtained.
• the ratio of the other metal chloride to ammonium chloride, on the basis of chemical equivalents, is at least 1-1, that is to say, the other chloride should at least equal and may even exceed the ammonium chloride in terms of chemical equivalents.
• the total concentration of the electrolyte may be, for example, between 25% and 30% solids.
• the temperature in the electrolyte should not be below 35 C., and it should preferably be maintained around to 0., although as high as 90 C. is not at all harmful.
• the anode current density in a 26% aqueous solution of ammonium chloride and sodium chloride may be maintained at fro'm 100 to 150 amperes per square foot, under which conditions, with suitable electrodes and cell construction, the decomposition etficiency of the ammonium chloride may amount to from to of the theoretical, the efllciency approaching the higher figure as the percentage of the sodium chloride approaches or exceeds that of the ammonium chloride.
• anode compartment As small as can conveniently be arranged in an electrolytic cell.
• electrolytic cells such asused for the electrolysis of sodium chloride, may be employed, for example, a diaphragm cell, a cell of the bell-jar type, or a mercury cell. If the diaphragm cell is used, asbestos paper is used as the diaphragm.
• the cathode may be of perforated iron or of any other conducting material which is inert to sodium and ammonium chlorides as well as hydroxides.
• the anode may be of the usual carbon, graphite or magnetite, composition.
• the cathode should be dipped into the mercury and the cathode chamber should be sumciently large to take care of the large volume necessitated by mercury, and ammonium amalgam.
• the current density may be kept between, for example, and amperes per square foot of anode surface in a 26% aqueous solution containing chemical equivalents of sodium chloride and ammonium chloride.
• the flow of electrolyte may be maintained between, say, 15 and 20 liters per hour, and the temperature at about 60 C.
• the rate of flow with respect to the. current density should be so adjusted as to keep the ammonium chloride concentration in the eflluent from the cell as low as possible.
• the two solutions of ammonium chloride and sodium chloride respectively may be separately passed through the anode and cathode compartments, that is to say, the solution of ammonium chloride may be passed through the anode compartment and the solution of sodium chloride through the cathode compartment.
• the operating conditions may in other respects be similar to those employed when the mixed solution is used.
• the electrolysis of the mixed solution of sodium chloride and ammonium chloride is especially advantageous when introduced as a step in the ammonia soda process.
• the ammonium chloride liquor from which the ammonia is to be recovered for use again in the production of sodium bicarbonate, contains substantial quantities of sodium chloride.
• the composition of this liquor commonly runs from 1'? to 18% ammonium chloride, and '7 to 8% sodium chloride.
• the economy of the process of this invention is, therefore, particularly marked when the process is employed in conjunction with the production of. soda by the ammonia soda process.
• the invention may thus be regarded as offering an improvement in the ammonia soda process.
• the electrolyte coming from the decomposition cell has been largely depleted of its ammonium chloride content, and to a much less extent of its sodium chloride.
• the regeneration of the spent electrolyte by the addition of suitable quantities of the liquor from the ammonia soda process ofiers an economical method for the continuous electrolytic production of chlorine from ammonium chloride without the danger of forming nitrogen trichloride and substitution products thereof, while at the same time restoring to the soda process the ammonia which heretofore has usually been recovered at the expense of converting the chlorine into the relatively much cheaper by-product, calcium chloride.
• the method of producing substantially pure chlorine and recovering ammonia in good yield from aqueous ammonium chloride solutions which comprises passing an electrolyzing current through an electrolytic cell having an aqueous electrolyte containing ammonium and sodium chlorides, the concentration of the sodium chloride being at least equal to that of the ammonium chloride, thereby discharging the am monium ions from the catholyte containing chlorides of ammonium and sodium and discharging chlorine ions from the anolyte containing sodium chloride and any residual ammonium chloride.
• the method of producing substantially pure chlorine and recovering ammonia in good yield from aqueous ammonium chloride solutions which comprises passing an electrolyzing current through an electrolytic cell having an aqueous electrolyte containing ammonium chloride and a chloride selected from the group consisting of alkali metal chlorides and alkaline earth metal chlorides at a concentration at least one third of an equivalent of the ammonium chloride, thereby discharging ammonium ions from the catholyte containing chloride of ammonium and the chloride selected from the group consisting of alkali metal chlorides and alkaline earth metal chlorides, and discharging chlorine from the anolyte containing the chloride selected from the group consisting of alkali metal chlorides and while maintaining the temperature in the neighborhood of 60 to 65 0., thereby discharging ammonium ions from the catholyte containing chloride of ammonium and the chloride selected from the group consisting of alkali metal chlorides and alkaline earth metal chlorides, and discharging chlorine from

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)

Priority Applications (2)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22493255

Family Applications (1)

Country Status (2)

Cited By (8)

• 1937
  • 1937-05-05 US US140890A patent/US2209681A/en not_active Expired - Lifetime
• 1938
  • 1938-05-05 DE DEA86732D patent/DE710962C/de not_active Expired

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