Patent EA-002125-B1 (EA)
Title: Process for producing nitric acid and recycling the same
Inventor: DRINCARD WILLIAM F JR
IPC: C01B21/40
Filed: 1996-11-27
Abstract: 1. A process for producing nitric acid or recycling nitric oxide comprising the steps of: reacting nitric oxide (NO) with nitric acid (NO3) in aqueous solution to form diazote trioxide (N2O3) product; and limiting O2 feed in said aqueous solution till the diazote trioxide (N2O3) concentration reaches the value between 0.1 to 40.0 g/l; and  oxidizing N2O3 with oxygen in aqueous solution to form nitric acid (HNO3), maintaining diazote trioxide (N2O3) concentration between 0.1 to 40.0 g/l. 2. The process according to claim 1 wherein the oxygen is gaseous. 3. The process according to claim 1 wherein the nitric acid concentration is maintained from 5 to 65% nitric acid. 4. The process according to claim 1 wherein (N2O3) forms in the presence of nitrite ions. 5. A method of producing nitric acid or recycling nitric oxide comprising the steps of: providing a source of NOx; reacting NO from said source of NOx with HNO3 in the presence of nitrite ions in aqueous solution to produce (N2O3); limiting O2 feed in N2O3 till the (N2O3) concentration reaches the value between 0.1 to 40.0 g/l; and  reacting N2O3 with O2 and with H2O to produce nitric acid, maintaining N2O3 concentration between 0.1 to 40.0 g/l. 6. The method according to claim 5 wherein said source of NOx is comprised mostly of NO. 7. The method according to claim 5 wherein said NOx is in a gaseous state. 8. The method according to claim 5 wherein said HNO3 is in a liquid state. 9. A method according to claim 5 wherein the concentration of said HNO3 ranges from 5% to 65%. 10. The method according to claim 9 wherein said NO2 is in aqueous solution. 11. A process of recovering nitric acid which comprises the steps of: providing a source of NO3(1); reacting a portion of said HNO3(1) with a compound to generate NOx; reacting NO from said NOx with NO3(1) to produce N2O3 (aqueous); limiting O2 feed in N2O3 (aqueous) till the (N2O3) (aqueous) concentration reaches the value between 0.1 to 40.0 g/l; and  reacting N2O3 with O2 and with H2O to form nitric acid HNO3 (1), maintaining diazote trioxide (N2O3) concentration between 0.1 to 40.0 g/l. 12. The process according to claim 11 wherein said source of NOx is comprised mostly of NO. 13. The process according to claim 11 wherein the concentration of said NO3(1) ranges from 5 to 65%. 14. The process according to claim 11 further comprising maintaining trivalent nitrogen in aqueous solution while the reaction is occurring. 15. The process according to claim 11 wherein N2O3 forms in the presence of nitrite ions while reacting NO with HNO3. 16. A method of producing nitric acid comprising the steps of: providing a source of NOx; reacting NO from said source of NOx with HNO3 in the presence of nitrite ions to produce N2O3; limiting O2 feed in N2O3 till the N2O3 concentration reaches the value between 0.1 to 40.0 g/l; and  reacting N2O3 with O2 and with H2O, maintaining diazote trioxide (N2O3) concentration between 0.1 to 40.0 g/l. 17. A process for generating nitric acid comprising the steps of: reacting a +2 valence gaseous nitrogen with a +5 valence nitrogen in solution to obtain a +3 valence nitrogen in solution; and reacting the +3 valence nitrogen, in said solution, with oxygen and water to produce a +5 valence nitrogen while maintaining a level of +3 valence nitrogen in excess of added oxygen. 18. The process according to claim 17 wherein excess oxygen is added to produce a white +3 valence-free nitric acid. 19. The process according to claim 17 wherein the +3 valence nitrogen concentration is maintained from 0.1 to 40.0 g/l as N2O3. 20. The process according to claim 17 wherein the +2 valence nitrogen addition is continually reacted with the +5 valence nitrogen to produce a +3 valence nitrogen which is continuously oxidized with oxygen to continuously increase the concentration of the resulting nitric acid. 21. The process according to claim 20 wherein the operating nitric acid concentration range is 15 to 55% nitric acid. 22. The process according to claim 17 wherein the +2 valence nitrogen addition is repeatedly reacted with the +5 valence nitrogen to produce a +3 valence nitrogen, which is repeatedly oxidized with oxygen to produce a +5 valence nitrogen thereby increasing concentration of the resulting nitric acid. 23. The process according to claim 22 wherein the operating nitric acid concentration range is from 5 to 65% nitric acid.