Chemistry of tributyl phosphate and nitric acid at constant volume

This paper addresses the reaction of tributyl phosphate (TBP) with nitric acid (HNO3). The reaction pressure of TBP/HNO3 mixtures as a function of time was measured under constant volume. A simplified model, which parametrically includes autocatalysis, was used to plot the total gas production of the reaction as a function of time. Comparison of the functions shows a rough equivalence in the induction time, reaction time, and total gas production. Predictions of the amounts of reaction products as a function of time were made based on assumptions regarding autocatalysis and using rate constants from experimental data. The derived reaction mechanisms and experimental results have several implications. Tests with a large amount of venting and high surface to volume ratio will show very different behavior than tests with increasing confinement and low surface to volume ratios. The amount alkyl nitrate, carbon monoxide, or hydrogen that reacts within the organic phase is limited by their solubilities and volatilities. The overall yield of both heat and gas per mol of nitric acid or TBP will vary significantly depending on the amount of solution, free volume, and vessel vent capacity