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 . (canceled)
2 . A method, comprising:
reacting copper and nitric acid (HNO 3 ) to produce a reaction mixture comprising nitrogen dioxide (NO 2 );
applying oxygen (O 2 ) to the reaction mixture to convert nitric oxide (NO) in the reaction mixture into NO 2 ;
removing impurities from the reaction mixture using a molecular sieve; and
condensing dinitrogen tetroxide (N 2 O 4 ) from NO 2 .
3 . The method of claim 2 , wherein the reacting step is performed in a glass reaction vessel.
4 . The method of claim 2 , wherein said removing step removes at least a portion of the water and the nitric acid.
5 . The method of claim 2 , wherein water is removed from the reaction mixture using a tube dryer.
6 . The method of claim 2 , wherein NO 2 exits the molecular sieve in the removing step to a neutralization bed.
7 . The method of claim 6 , wherein the neutralization bed is filled with soda lime and water.
8 . The method of claim 2 , wherein the nitric acid is removed from the reaction mixture via an integrated system of distillation, adsorption, and a final distillation step.
9 . The method of claim 2 , further comprising refluxing the N 2 O 4 in the condensing step and then collecting the N 2 O 4 in a collection vessel.
10 . The method of claim 9 , further comprising purifying the N 2 O 4 in the collection vessel using a molecular sieve for at least one day after collecting the N 2 O 4 in the collection vessel.
11 . The method of claim 9 , wherein the collecting step is done at a dry ice temperature.
12 . The method of claim 9 , further comprising pressurizing the N 2 O 4 with O 2 for ≥2 hours immediately prior to collecting the N 2 O 4 in a collection vessel.
13 . The method of claim 2 , further comprising pressurizing the N 2 O 4 to oxidize any dinitrogen trioxide (N 2 O 3 ) and/or NO that may have been formed into NO 2 after the removing step.
14 . The method of claim 2 , further comprising transferring the N 2 O 4 in liquid form into a glass ampule.
15 . The method of claim 14 , further comprising sealing the glass ampule with a laser or a hot flame without vaporizing at least some of the N 2 O 4 .
16 . The method of claim 15 , wherein the glass ampule is placed into an oven that is at a temperature of at least 70° C. after sealing.