EP0305910A1 - Procédé de fabrication de nitrates de métaux alcalins - Google Patents

Procédé de fabrication de nitrates de métaux alcalins Download PDF

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Publication number
EP0305910A1
EP0305910A1 EP88113908A EP88113908A EP0305910A1 EP 0305910 A1 EP0305910 A1 EP 0305910A1 EP 88113908 A EP88113908 A EP 88113908A EP 88113908 A EP88113908 A EP 88113908A EP 0305910 A1 EP0305910 A1 EP 0305910A1
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EP
European Patent Office
Prior art keywords
nitric acid
cathode compartment
alkali metal
solution
alkali
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EP88113908A
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German (de)
English (en)
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EP0305910B1 (fr
Inventor
Wolfgang Dr. Kochanek
Bernd Dr. Leutner
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BASF SE
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BASF SE
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    • 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
    • C25B1/14—Alkali metal compounds

Definitions

  • the present invention relates to a method for producing alkali metal nitrates by electrolysis of alkali metal chloride solutions in a membrane cell with the addition of nitric acid.
  • Alkali nitrates especially sodium and potassium nitrate, are used for numerous technical purposes and as fertilizers. They can be isolated from natural sources, but can also be produced synthetically.
  • Japanese patent publication 1694/1969 discloses a process for the preparation of alkali metal nitrates, in which a solution of alkali metal chlorides and nitric acid in equilibrium is electrolyzed to obtain chlorine and hydrogen. In this process, however, chloride-free nitrates are not obtained, and the chlorine is also contaminated with nitrogen oxides, which are formed by cathodic reduction of the nitric acid.
  • US Pat. No. 4,465,568 describes a process for producing a potassium nitrate-sodium nitrate mixture, in which a sodium chloride / potassium chloride brine is introduced into the anolyte compartment of an electrolysis cell, which is separated from the cathode compartment by a permselective cation exchange membrane. A solution containing potassium sodium hydroxide is withdrawn from the cathode compartment and is reacted outside of the cell with nitric acid to give the corresponding nitrates.
  • This process ultimately consists of two stages, namely the production of an aqueous hydroxide solution by alkali metal chloride electrolysis in a first stage and its neutralization with nitric acid in a second stage.
  • the process has the serious disadvantage that the brine to be electrolyzed has to be subjected to a complex fine cleaning process in order to remove calcium and magnesium salts in order to prevent the corresponding hydroxides from precipitating in the membrane. Otherwise the membrane would clog in no time.
  • the present invention was therefore based on the object of providing a process for producing alkali metal nitrates by electrolysis of an alkali metal chloride solution fed to the anode compartment of an electrolytic cell, which is separated from the cathode compartment by a permselective cation exchange membrane, with the addition of nitric acid to the cathode compartment, in which the proportion of the the cathode reduced nitric acid is as low as possible and in which the reaction products of the nitric acid can be easily worked up.
  • a nitric acid-alkali nitrate solution is supplied to the cathode compartment, the alkali nitrate concentration of which is at least 10% by weight and whose HNO 3 concentration is between 0.1 and 10% by weight and one from the cathode compartment Solution is withdrawn, the pH does not exceed a value of 5.
  • the alkali metal ion contained in the anolyte passes through the cation exchange membrane into the cathode compartment, where with further HNO 3 alkali nitrate is formed, which is removed from the cathode compartment with the catholyte.
  • the nitric acid alkali nitrate solution to be fed to the cathode compartment preferably contains at least 25% by weight of alkali nitrate. There is an upper limit for the alkali nitrate concentration due to the solubility of the alkali nitrate at the respective temperature in the cathode compartment.
  • the concentration of nitric acid can be kept at values of 0.1 to 10% by weight and thus the corrosive effect of the catholyte solution be kept low.
  • care must be taken to ensure that the catholyte has a maximum pH of 5 when leaving the cathode compartment, i.e. in other words, the catholyte in the area of the cathode compartment is always acidic.
  • the process according to the invention can be carried out in a plurality of electrolytic cells connected in series in such a way that the catholyte solution removed from the previous cell is introduced into the following cell, if appropriate after adding nitric acid to adjust an HNO3 concentration of 0.1 to 10% by weight, and withdraws a concentrated alkali nitrate solution from the last cell.
  • the process according to the invention is particularly advantageously carried out in a single cell, part of the catholyte solution corresponding to that in the cell being removed from the catholyte solution removed from the cell alkali nitrate formed and the remaining solution after adjusting the HNO3 content of 0.1 to 10 wt.% By adding fresh nitric acid and optionally adjusting the alkali nitrate content back into the cell. With this procedure, it is expedient to work with alkali nitrate concentrations of at least 25% by weight of the solution introduced into the cathode compartment. If solid alkali nitrate is to be produced by the process according to the invention, the energy expenditure for the evaporation of the solutions is minimized in this way.
  • nitrite ions to the solution to be supplied to the cathode compartment, which react with the ammonium ion to nitrogen. In this way, contamination of the alkali metal nitrate produced by ammonium nitrate is avoided.
  • FIG. 1 A plant for carrying out the method according to the invention is illustrated schematically in FIG. 1 using the example of the production of potassium nitrate.
  • An aqueous potassium chloride solution which contains at least 70% of its saturation concentration of KCl in solution is introduced through line (1) into the anolyte compartment (2) of the electrolytic cell (3) and anolyte is withdrawn through line (4).
  • the anolyte compartment (2) is separated from the cathode compartment (5) by a permselective membrane (6).
  • the anode (7) can consist of titanium coated with RuO2, the cathode (8) made of titanium. Chlorine is drawn off from the anolyte space (2) through line (9).
  • catholyte is drawn off through line (10) which, in addition to potassium nitrate and free nitric acid, also contains NO2 ⁇ , NH4+ and NH3OH+ formed by cathodic reduction and introduced into the reactor (11).
  • this reactor (11) is introduced through line (12) nitric acid with a concentration of 30 to 68 wt.% HNO3.
  • nitric acid with a concentration of 30 to 68 wt.% HNO3.
  • FIG. 2 those parts of the plant which correspond to the parts of the plant in FIG. 1 are shown with the same reference numbers. Different parts of the system are identified by three-digit reference numbers.
  • the nitric acid is not introduced directly into the reactor (11) but through line (105) into a washer (101), and is initially used in the washer (101) to at least partially oxidize the NO (11) leaving the reactor (11) to NO2 , and only then flows into the reactor (11).
  • the NO2 and N2O3 generated in the scrubber (101) passes through line (102) into the absorber (103), in which it is absorbed in the catholyte solution.
  • Nitrite is formed which, as mentioned above, reacts with the catholyte ammonium to form N2.
  • Nitrogen which may still contain residues of NO x , is drawn off through line (104).
  • the gas formed in the place of the nitric acid metering which consists of NO and N2 in an approximate volume ratio of 1: 3, is combined with the cathode gas leaving the cell, so that the system leaves a gas mixture of the following composition. 42 vol.% NO 0.7 vol.% N2O 55 vol.% N2 1.8 vol.% H2 Hourly 152 g of catholyte are removed from behind the cell, which contains 0.3 g NH4+ / kg solution in addition to the KNO3 formed. This discharge contains 48.3 wt.% KNO3, so that a permselectivity of the membrane based on K+ is calculated from 97.3%.
  • the gases leaving the cathode space are washed in countercurrent with the 60% nitric acid used, as illustrated in FIG. 2.
  • the NO contained in the cathode gas is oxidized to NO2, whereby according to NO + 2 HNO3 ⁇ 3 NO2 + H2O by reducing the nitric acid form two more moles of NO2, so that the following gas composition is obtained at the outlet of the scrubber ⁇ 0.2 vol.% NO 60.3 vol.% NO2 38 vol.% N2 0.3 vol.% N2O 1.2 vol.% H2
  • This gas is absorbed in a second scrubber in the catholyte leaving the cathode space, the NH4+ dissolved in the catholyte being converted to N2 with the NO2 ⁇ formed during absorption.
  • This scrubber accordingly leaves a mixture rich in N2 with approximately the following composition: ⁇ 0.2 vol.% NO ⁇ 0.5 vol.% NO2 > 97.0 vol.% N2 ⁇ 0.7 vol.% N2O ⁇ 1.7 vol.% H2
  • the NO x content in the exhaust gas decreases significantly, while the NH4+ content of the catholyte can be reduced at the same time. So the NH4+ content in the KNO3 discharge of the system is only 0.06 g NH4+ / kg solution.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
EP88113908A 1987-09-04 1988-08-26 Procédé de fabrication de nitrates de métaux alcalins Expired - Lifetime EP0305910B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19873729669 DE3729669A1 (de) 1987-09-04 1987-09-04 Verfahren zur herstellung von alkalimetallnitraten
DE3729669 1987-09-04

Publications (2)

Publication Number Publication Date
EP0305910A1 true EP0305910A1 (fr) 1989-03-08
EP0305910B1 EP0305910B1 (fr) 1991-02-27

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EP88113908A Expired - Lifetime EP0305910B1 (fr) 1987-09-04 1988-08-26 Procédé de fabrication de nitrates de métaux alcalins

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US (1) US4995950A (fr)
EP (1) EP0305910B1 (fr)
CA (1) CA1335975C (fr)
DE (2) DE3729669A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0713928A1 (fr) * 1994-11-24 1996-05-29 Basf Aktiengesellschaft Procédé et dispositif pour la préparation de nitrite de sodium

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4410581A1 (de) * 1994-03-26 1995-09-28 Merck Patent Gmbh Elektrochemisches Verfahren zur Herstellung chloridarmer wäßriger Titanylnitratlösungen
ES2160051B1 (es) * 1999-04-20 2002-05-01 Orti Javier Porcar Sistema de electrolisis para la eliminacion del ion cloro del agua del mar mediante la utilizacion de energia solar y obtencion de cloruros insolubles en el agua y obtencion de nitrato sodico.
KR100430333B1 (ko) * 2002-05-03 2004-05-04 윤취주 폐질산을 이용한 질산나트륨 제조방법
CZ2013234A3 (cs) 2013-03-28 2014-06-04 Membrain S.R.O. Způsob výroby dusičnanu draselného metodou elektrodialýzy a zařízení k provádění tohoto způsobu
SE543570C2 (en) * 2020-01-15 2021-03-30 Adam Slabon Method for wastewater treatment and removal of nitrate and/or nitrite ions

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH474449A (de) * 1961-08-11 1969-06-30 Edison Settore Chimico Soc Verfahren zur gleichzeitigen Herstellung von anorganischen Alkalimetallsalzen und Chlorgas
US4465568A (en) * 1981-11-16 1984-08-14 Olin Corporation Electrochemical production of KNO3 /NaNO3 salt mixture
EP0254361A1 (fr) * 1986-07-23 1988-01-27 ENICHEM AGRICOLTURA S.p.A. Procédé pour la préparation de nitrate de potassium

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH474449A (de) * 1961-08-11 1969-06-30 Edison Settore Chimico Soc Verfahren zur gleichzeitigen Herstellung von anorganischen Alkalimetallsalzen und Chlorgas
US4465568A (en) * 1981-11-16 1984-08-14 Olin Corporation Electrochemical production of KNO3 /NaNO3 salt mixture
EP0254361A1 (fr) * 1986-07-23 1988-01-27 ENICHEM AGRICOLTURA S.p.A. Procédé pour la préparation de nitrate de potassium

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0713928A1 (fr) * 1994-11-24 1996-05-29 Basf Aktiengesellschaft Procédé et dispositif pour la préparation de nitrite de sodium

Also Published As

Publication number Publication date
CA1335975C (fr) 1995-06-20
EP0305910B1 (fr) 1991-02-27
DE3861839D1 (de) 1991-04-04
DE3729669A1 (de) 1989-03-16
US4995950A (en) 1991-02-26

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