Mixed oxides of nitrogen


Mixed oxides of nitrogen (MON) are solutions of nitric oxide (NO) in dinitrogen tetroxide/nitrogen dioxide (N2O4 and NO2). It may be used as an oxidizing agent in rocket propulsion systems.[1] 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 of the liquid, while the costs increase and the oxidation potential is decreased.

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).[2]


  1. ^ 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). Retrieved 14 April 2013.
  2. ^ Robert A. Braeunig (2008). "Rocket Propellants". Rocket and Space Technology. Archived from the original on 21 May 2013. Retrieved 14 April 2013.