L. P. Andrienko

Kinetics of the thermal decomposition of dinitramide 3.* Kinetics of the heat release during the thermal decomposition of dinitramide ammonium salt in the liquid phase

The kinetic regularities of the heat release during the thermal decomposition of liquid NH4N(NO2)2 at 102.4–138.9 °C were studied. Kinetic data for decomposition of different forms of dinitramide and the influence of water on the rate of decomposition of NH4N(NO2)2 show that the contributions of the decomposition of N(NO2)2− and HN(NO2)2 to the initial decomposition rate of the reaction at temperatures about 100 °C are approximately equal. The decomposition has an autocatalytic character. The analysis of the effect of additives of HNO3 solutions and the dependence of the autocatalytic reaction rate constant on the gas volume in the system shows that the self-acceleration is due to an increase in the acidity of the NH4N(NO2)2 melt owing to the accumulation of HNO3 and the corresponding increase in the contribution of the HN(NO2)2 decomposition to the overall rate. The self-acceleration ceases due to the accumulation of NO3− ions decreasing the equilibrium concentration of HN(NO2)2 in the melt.

KINETICS OF THERMAL DECOMPOSITION OF DINITRAMIDE. 1. DECOMPOSITION OF DIFFERENT FORMS OF DINITRAMIDE

Kinetic regularities of thermal decomposition of dinitramide in aqueous and sulfuric acid solutions were studied in a wide temperature range. The rate of the thermal decomposition of dinitramide was established to be determined by the rates of decomposition of different forms of dinitramide as the acidity of the medium increases: first, N(NO2)− anions, then HN(NO2)2 molecules, and finally, protonated H2N(NO2)2+ cations. The temperature dependences of the rate constants of the decomposition of N(NO2)− (kan) and HN(NO2)2 (k′ac) and the equilibrium constant of dissociation of HN(NO2)2 (Ka) were determined:kan=1.7·1017 exp(−20.5·103/T), s−1,k′ac=7.9·1016 exp(−16.1·103/T), s−1, andKa=1.4·10 exp(−2.6·103/T). The temperature dependences of the decomposition rate constant of H2N(NO2)2+ (kd) and the equilibrium constant of the dissociation of H2N(NO2)2+ (Kd) were estimated:kd=1012 exp(−7.9·103/T), s−1 andKd=1.1 exp(6.4·103/T). The kinetic and thermodynamic constants obtained make it possible to calculate the decomposition rate of dinitramide solutions in a wide range of temperatures and acidities of the medium.

Kinetics of heat release during decomposition of cellulose

The kinetic behavior and temperature dependences of the rate constants for thermal decomposition are determined for cellulose of different biological origins and forms. The possibility of thermal decomposition of cellulose in a combustion regime without oxygen is analyzed.

Kinetics and mechanism of thermal decomposition of nitric acid in sulfuric acid solutions

Conclusions1.The initial rates of thermal decomposition of HNO3 in aqueous and nonaqueous H2SO4 media were measured; their temperature dependences were determined for HNO3-H2SO4 systems.2.The thermal decomposition of HNO3 in sulfuric acid solutions proceeds via the decomposition of N2O5.

Study of nitration equilibrium in the glycerin-aqueous nitric acid system. 1. Dependence of the equilibrium constants of nitration reactions on the temperature, acidity of the medium, and structure of the nitrated compound

The equilibrium constants of seven sequential-parallel reactions of conversion of glycerin into glycerin trinitrate in aqueous HNO3 were measured. The effect of the acidity of the medium on the equilibrium nitration constants is correlated with processes of protonation of glycerin and its nitrates. The equilibrium nitration constants are higher for primary hydroxides than for secondary hydroxides, and they decrease in both series in going from glycerin to its dinitrates.

Kinetics and mechanism of oxidation of the ammonium ion by nitric acid solutions

Conclusions1.Within a wide concentration range of HNO3 solutions and mixtures of sulfuric and nitric acids, the velocity of oxidation of NH4+ is proportional to the N2O5 concentration.2.The NH4+ ion is oxidized by equilibrial N2O5 or the products of its dissociation, NO2+ and NO3−, and the decomposition products of HNO3.3.There is a range of temperatures and NH4+ concentrations in which the oxidation velocity is higher than the velocity of decomposition of the corresponding acid.

Kinetics and mechanism of thermal decomposition of hydroxylammonium perchlorate and its complex with hydroxylamine

Conclusions1.In its initial stages, the decomposition of hydroxylammonium perchlorate involves dissociation of the salt followed by decomposition of a complex of hydroxylamine with hydroxylammonium perchlorate. At elevated temperatures the reaction involving hydroxylamine molecules not bound into complexes plays an increasing part.2.As hydroxylammonium perchlorate decomposes, the leading stage changes. The crucial reaction becomes oxidation of NH3OH+ by perchloric acid, leading to autocatalysis of the process.

Heat production kinetics and the scope for thermal self-ignition in wheat drying

Heat production has been examined at various oxygen partial pressures in the oxidation and thermal destruction of grain products by the use of a DAK-1-2 differential microcalorimeter. Estimates have been made on the adiabatic induction periods and critical sizes of the grain product layers on a metal surface (boundary conditions of the first kind) in the absence of heat transfer from the other surface. It is found that thermal self-ignition will occur in degenerate mode when thermal destruction is decisive.

Nitration equilibrium in the meso-erythritol-aqueous nitric acid system

Twelve equilibrium constants have been measured from 16 for sequential-parallel reactions in meso-erythritol nitration to the fully nitrated compound in aqueous HNO3. Free-energy changes during nitration of the aliphatic polyatomic alcohols, glycerol and meso-erythritol, are highest when diprimary dinitrates (NOON) and (NON) are produced.

Study of nitration equilibrium in the glycerin-aqueous nitric acid system. 2. Changes in δH and δS in the nitration reaction

The real enthalpies of seven sequential-parallel reactions of nitration of glycerin into glycerin trinitrate were found by combination of the heats of the reactions obtained by the thermochemical method and with the equation for the isobar of the chemical reaction, and the standard enthalpies of formation of glycerin nitrates were calculated with them. The difference in the enthalpies of nitration with respect to different positions in glycerin and its nitrates basically determines the difference in the corresponding equilibrium constants of the nitration reactions.