Method and apparatus for manufacturing nitrogen tetroxide
Dinitrogen tetroxide (N 2 O 4 ) is synthesized in an apparatus by the reaction of concentrated nitric acid with copper. Oxygen is applied as a carrier gas to convert NO to NO 2 , and water vapor is removed with a tube dryer. A molecular sieve is applied to reduce and remove impurities.
1. A method, comprising:
mixing nitric acid with copper pellets in a reaction vessel;
allowing water from the reaction to dilute the nitric acid and produce nitric oxide (NO) and nitrogen dioxide (NO 2 ) in a reaction slurry;
applying oxygen (O 2 ) as a carrier gas to NO 2 , NO, water vapor, and nitric acid that desorbs from the reaction slurry to form a gas mixture, the O 2 configured to convert NO to NO 2 ;
removing water vapor from the gas mixture;
removing nitric acid from the gas mixture using a molecular sieve; and
allowing NO 2 exiting the molecular sieve to dimerize to dinitrogen tetroxide (N 2 O 4 ).
2. The method of claim 1 , further comprising:
filling an ampule with N 2 O 4 after dimerizing;
sealing the ampule; and
analyzing N 2 O 4 in the ampule after sealing.
3. The method of claim 1 , wherein water vapor is removed from the gas mixture using a tube dryer downstream of a condenser column.
4. The method of claim 1 , wherein the NO 2 is allowed to dimerize in a collection vessel, the method further comprising:
passing uncondensed NO 2 leaves through a gas outlet of the collection vessel to a neutralization bed.
5. The method of claim 4 , wherein the neutralization bed is filled with soda lime and water to neutralize the reaction vessel effluent when drained.
6. The method of claim 1 , wherein the nitric acid is removed from the gas mixture via an integrated system of distillation, adsorption, and a final distillation step.
7. The method of claim 1 , further comprising refluxing the N 2 O 4 prior to collecting the N 2 O 4 in a collection vessel.
8. The method of claim 7 , further comprising adding molecular sieves to the N 2 O 4 in the collection vessel for further purification for at least one day after collecting the N 2 O 4 in the collection vessel.
9. The method of claim 1 , further comprising pressurizing the N 2 O 4 to oxidize any dinitrogen trioxide (N 2 O 3 ) or and NO that may have been formed into NO 2 after removing nitric acid using the molecular sieve.
10. The method of claim 1 , further comprising pressurizing the N 2 O 4 is pressurized with 02 for ≥2 hours immediately prior to collecting the N 2 O 4 in a collection vessel.
11. The method of claim 1 , further comprising transferring liquid N 2 O 4 into glass ampules.
12. The method of claim 11 further comprising sealing the glass ampules with a laser or a hot flame without vaporizing at least some of the N 2 O 4 .
13. The method of claim 12 , wherein the glass ampule is placed into an oven that is at a temperature of at least 70° C. after sealing.
14. A method, comprising:
reacting copper and nitric acid in an all glass apparatus to produce nitrogen dioxide (NO 2 );
applying an oxygen sweep gas to oxidize any trace nitric oxide (NO) into NO 2 ;
condensing the NO 2 to a glass condenser with a molecular sieve to reduce the amount of water; and
condensing N 2 O 4 from NO 2 .
15. A method comprising:
providing a mixture that includes dinitrogen tetroxide (N 2 O 4 ), nitrogen dioxide (NO 2 ), water (H 2 O), nitric acid (HNO 3 ), nitric oxide (NO) and dinitrogen trioxide (N 2 O 3 ); and
storing the mixture over a molecular sieve to remove HNO 3 and H 2 O under oxygen gas to oxidize trace NO to NO 2 .
16. The method of claim 15 , wherein storing is for at least 12 hours.
17. The method of claim 15 , wherein storing is for at least 24 hours.
18. The method of claim 15 , wherein storing is for at least 48 hours.