Gas-Phase Reactions of NO2 and NO

As is evident from experimental measurements, most kinds of nitrate esters appear to decompose to NOj and C,H,0 species with the breaking of the O-NOj bond as the initial step. A strong heat release occurs in the gas phase near the decomposing surface due to the reduction of NO2 to NO accompanied by the oxidation of C,H,0 species to HjO, CO, and COj. NO reduction, however, is slow and this reaction is not observed in the decomposition of some nitrate ester systems. Even when the reaction occurs, the heat release does not contribute to the heat feedback to the surface because the reaction occurs at a distance far from the surface. 

The decomposition process can be essentially divided into three stages for simple nitrate esters  

Stage 1. RNO2 NO2 -t organic molecules (mainly aldehydes) 

The decomposition process of double-base propellants is autocatalytic, NO2 being evolved first and then reacting to increase the rate of its evolution.I ] phg g gp 

Mixtures of HCHO and NOj react very rapidly at temperatures above 430 K NOj is reduced almost quantitatively to NO, and the aldehyde is oxidized to CO, COj, and H20.[3 1 This process is discussed in detail in Section 5.2.1.4. 

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