# US 4,397,719 A · Process for preparing nitrogen by ammonium nitrate decomposition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,397,719 A - Document ID: US4397719A - Status: Granted - Kind: A - Application number: 06/302,129 - Filed: 1981-09-14 - Granted: 1983-08-09 - Earliest claimed: 1978-10-06 - Assignees: Asahi Kasei Kogyo Kabushiki Kaisha; Doryokuro Kakunenryo Kaihatsu Jigyodan - Inventors: Mitsuo Yoshida - Web page: https://patentgrep.com/patent/US4397719A ## CPC - C01B 21/50: Nitrous acid; Salts thereof - C25B 1/00: Electrolytic production of inorganic compounds or non-metals - C25B 1/01: Products - C25B 1/14: Alkali metal compounds - C02F 1/4676: {by electroreduction} - C02F 2001/46133: {characterised by the material} - C02F 2101/163: {Nitrates} - C02F 2201/46115: Electrolytic cell with membranes or diaphragms - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C25B: ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR (anodic or cathodic protection C23F13/00; single-crystal growth C30B) - C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes) ## Abstract Nitrates, such as alkali metal nitrates and ammonium nitrate, are electrolytically reduced to the corresponding nitrites by a process wherein an aqueous solution containing a nitrate is supplied into a cathode chamber of an electrolytic cell including cathode and anode chambers separated by a cation exchange membrane and an electric current is applied to the electrolytic cell, while maintaining the pH of the aqueous solution at a value of at least about 4. This process can be advantageously applied not only to the manufacture of nitrites but, also, to the treatment of waste nitrates. In the treatment of waste ammonium nitrate, the ammonium nitrite so formed is conveniently further treated by subjecting the electrolytically reduced catholyte to thermal decomposition outside the electrolytic cell, and removing the so formed nitrogen and water from the reaction system. ## Claims ### Claim 1 A process for the decomposition of ammonium nitrate, comprising supplying an aqueous solution containing ammonium nitrate as a catholyte into a cathode chamber of an electrolytic cell including cathode and anode chambers separated by a cation exchange membrane, subjecting the solution to electrolytic reduction while maintaining the pH of the solution at a value above about 4, thermally decomposing the electrolytically reduced catholyte outside the electrolytic cell and removing formed nitrogen and water from the reaction system. ### Claim 2 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein the residual solution left after removal of formed nitrogen and water is recycled to the electrolytic cell. ### Claim 3 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein the pH value of the catholyte is adjusted to a value not higher than about 9 prior to the thermal decomposition. ### Claim 4 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein the thermal decomposition is carried out at a temperature higher than the temperature adopted for the electrolytic reduction. ### Claim 5 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein the thermal decomposition is carried out in the presence of at least one catalyst selected from the group consisting of platinum group metals, active carbon, activated alumina and alumina silicate, thereby to promote the thermal decomposition. ### Claim 6 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein prior to supply of the aqueous solution containing ammonium nitrate to the electrolytic cell, the pH value of the aqueous solution is adjusted so that metal compounds and other impurities contained in the aqueous solution are precipitated, and said impurities are removed as much as possible. ### Claim 7 (depends on 6) A process for the decomposition of ammonium nitrate according to claim 6, wherein an ultrafiltration module composed of a synthetic high polymer membrane is used to separate and remove fine colloidal particles. ### Claim 8 (depends on 1) A process for the decomposition of ammonium nitrate according to claim 1, wherein said electrolytic reduction is carried out at a temperature of from about 15.degree. to about 70.degree. C., and said thermal decomposition is carried out at a temperature of about 70.degree. C. or higher. ### Claim 9 A process for the decomposition of ammonium nitrate, comprising supplying an aqueous solution containing ammonium nitrate as a catholyte into a cathode chamber of an electrolytic cell including cathode and anode chambers separated by a cation exchange membrane, subjecting the solution to electrolytic reduction while maintaining the pH of the solution at a value above about 4, thermally decomposing the electrolytically reduced catholyte outside the electrolytic cell, the pH value of said catholyte being adjusted to a value not higher than about 9 prior to the thermal decomposition, removing formed nitrogen and water from the reaction system, and, after removal of formed nitrogen and water, recycling the residual solution to the electrolytic cell. ### Claim 10 (depends on 9) A process for the decomposition of ammonium nitrate according to claim 9, wherein the thermal decomposition is carried out at a temperature higher than the temperature adopted for the electrolytic reduction. ### Claim 11 (depends on 9) A process for the decomposition of ammonium nitrate according to claim 9, wherein the thermal decomposition is carried out in the presence of at least one catalyst selected from the group consisting of platinum group metals, active carbon, activated alumina and alumina silicate, thereby to promote the thermal decomposition. ### Claim 12 (depends on 9) A process for the decomposition of ammonium nitrate according to claim 9, wherein prior to supply of the aqueous solution containing ammonium nitrate to the electrolytic cell, the pH value of the aqueous solution is adjusted so that metal compounds and other impurities contained in the aqueous solution are precipitated, and said impurities are removed as much as possible. ### Claim 13 (depends on 12) A process for the decomposition of ammonium nitrate according to claim 12, wherein an ultrafiltration module composed of a synthetic high polymer membrane is used to separate and remove fine colloidal particles. ### Claim 14 A process for the decomposition of ammonium nitrate comprising: adjusting the pH value of an aqueous solution containing ammonium nitrate so that metal compounds and other impurities contained in the aqueous solution are precipitated, and said impurities are removed as much as possible; separating and removing fine colloidal particles by utilizing an ultrafiltration module composed of a synthetic high polymer membrane; supplying the thereby obtained aqueous solution containing ammonium nitrate as a catholyte into a cathode chamber of an electrolytic cell including cathode and anode chambers separated by a cation exchange membrane; subjecting the solution to electrolytic reduction while maintaining the pH of the solution at a value above about 4; and thermally decomposing the electrolytically reduced catholyte outside the electrolytic cell and removing formed nitrogen and water from the reaction system. ### Claim 15 (depends on 14) A process for the decomposition of ammonium nitrate according to claim 14, wherein the residual solution left after removal of formed nitrogen and water is recycled to the electrolytic cell. ### Claim 16 (depends on 14) A process for the decomposition of ammonium nitrate according to claim 14, wherein the pH value of the catholyte is adjusted to a value not higher than about 9 prior to the thermal decomposition. ### Claim 17 (depends on 14) A process for the decomposition of ammonium nitrate according to claim 14, wherein the thermal decomposition is carried out at a temperature higher than the temperature adopted for the electrolytic reduction. ### Claim 18 (depends on 14) A process for the decomposition of ammonium nitrate according to claim 14, wherein the thermal decomposition is carried out in the presence of at least one catalyst selected from the group consisting of platinum group metals, active carbon, activated alumina and alumina silicate, thereby to promote the thermal decomposition.