Mixed oxides of nitrogen (MON) are solutions of dinitrogen trioxide (N2O3) in dinitrogen tetroxide/nitrogen dioxide (N2O4 and NO2). It may be used as an oxidizing agent in rocket propulsion systems.[1]
Mixed oxides of nitrogen are produced by dissolving nitric oxide (NO) gas in liquid dinitrogen tetroxide. Nitric oxide reacts with nitrogen dioxide, present in dinitrogen tetroxide, to from dinitrogen trioxide. Resulting mixture is greenish blue, while dinitrogen tetroxide is colorless or brownish yellow. Liquid phase of MON contains no nitric oxide.[2]
N2O4 ⇌ 2NO2
NO2 NO ⇌ N2O3
A broad range of compositions is available, and can be denoted as MONi, where i represents the percentage of nitric oxide in the mixture (e.g. MON3 contains 3% nitric oxide, MON25 25% nitric oxide). An upper limit is MON40 (40% by weight). In Europe MON 1.3 is mostly used for rocket propulsion systems, while NASA seems to prefer MON 3. A higher percentage of NO decreases the corrosiveness and oxidation potential of the liquid, but increases costs.
The addition of nitric oxide also reduces the freezing point to a more desirable temperature. The freezing point of pure nitrogen tetroxide is −9 °C (16 °F), while MON3 is −15 °C (5 °F) and MON25 is −55 °C (−67 °F).[3]
References
edit- ^ Wright, Alfred C. (February 1977). USAF Propellant Handbooks. Nitric Acid/Nitrogen Tetroxide Oxidizers. Volume II. USAF (Report). Defense Technical Information Center. AFRPL-TR-76-76 (DTIC Accession Number ADA036741). Archived from the original on March 3, 2016. Retrieved 14 April 2013.
- ^ Schmidt, Eckart W. (2022). "N2O4/N2O3 Mixtures". Dinitrogen Tetroxide. Encyclopedia of Oxidizers. Vol. 1. De Gruyter. pp. 437–453. doi:10.1515/9783110750294-005. ISBN 978-3-11-075029-4.
- ^ Robert A. Braeunig (2008). "Rocket Propellants". Rocket and Space Technology. Archived from the original on 21 May 2013. Retrieved 14 April 2013.
Further reading
edit- Schmidt, Eckart W. (2022). "N2O4/N2O3 Mixtures". Dinitrogen Tetroxide. Encyclopedia of Oxidizers. Vol. 1. De Gruyter. pp. 437–453. doi:10.1515/9783110750294-005. ISBN 978-3-11-075029-4.
- Head, Andrew W. (2021). Nitrogen Tetroxide to Mixed Oxides of Nitrogen: History, Usage, Synthesis, and Composition Determination (MSc thesis). Purdue University. doi:10.25394/PGS.17003098.V1.