Thermal analysis of the reaction of a mixture of ammonium dinitramide and hydroxyethylhydrazinium nitrate

This paper focuses on the thermal behavior of mixtures of ammonium dinitramide (ADN) and amine nitrates. Because some mixtures of ADN and amine nitrate exhibit low melting points and high-energy content, they represent potential liquid propellants for spacecraft. This study focused on the melting behavior and thermal-decomposition mechanisms in the condensed phase of ADN/amine nitrate mixtures during heating. We measured the melting point and exothermal behavior during constant-rate heating using differential scanning calorimetry and performed thermogravimetry–differential thermal analysis–mass spectrometry (TG–DTA–MS) to analyze the thermal behavior and evolved gases of ADN/amine nitrate mixtures during simultaneous heating to investigate their reaction mechanisms. Results showed that the melting point of ADN was significantly lowered upon the addition of amine nitrate with relatively low molecular volume and low melting point. TG–DTA–MS results showed that the onset temperature of the thermal decomposition of ADN/amine nitrates was similar to that of pure ADN. Furthermore, during thermal decomposition in the condensed phase, ADN produced highly acidic products that promoted exothermic reactions, and we observed the nitration and nitrosation of amines from the dissociation of amine nitrates.

This paper reports on the thermal and combustion behaviors of ammonium dinitramide (ADN). The thermal behavior is measured by a pressure thermogravimetric analysis (TGA) at pressures below 8 MPa. The burning rates of pure ADN and ADN/ammonium nitrate (AN) mixtures are measured in the range 0.2–12 MPa, and the burning temperature profiles are obtained using thermocouples with diameters of 5 and 25 μm. This report mainly focuses on the condensed‐phase behavior in the vicinity of a burning surface. The temperature profiles are complicated because the ADN decomposition and AN dissociation compete during the condensed phase, and the bubbles of the decomposition gas and gas‐phase flame also affect the surface temperature. AN addition helps to understand the effects of AN during the condensed phase, and it was shown that the burning temperature rises to the critical temperature of AN. Based on these experimental results, the pressure dependency of the burning rates is also discussed.

A procedure is described to determine the mass balance corresponding to the thermal or catalytic decomposition of several nitrogen-based i onic liquid monopropellants. A dynamic flow reactor with online mass spectroscopy product analysis has been used to establish the gas phase composition after the injection of the pr opellant. The analytical results have been supplemented by Raman scattering spectroscopy and acid-base titration of the aqueous solutions trapped at 0 °C after the reactor. The de composition of ammonium dinitramide (ADN), ammonium nitrate (AN) and hydrazinium nitroformate are investigated. The thermal decomposition results of ADN-water mixture containing 50 wt.-% gave sole major nitrogen N 2 (thermodynamic product) as primary products; secondary kinetic products are medium N 2O, minor nitric oxide NO and traces NO 2. The second expected primary product O2 was not observed. Moreover, the trapped solution contains a mixture of nitric acid and ammonium nitrate. The decomposition in the presence of the platinum-based catalyst gave the same decomposition products except the emergence of NO as primary product and less ammonium nitrate in trapped solution. The thermal behavior of AN(50 wt.-%)-water mixture is much different, as major vaporization ta kes part without catalyst. Only small amounts of primary N 2 and secondary N 2O are detected beside the presence of ammonium nitrate in the cold trap. On the other hand, an imp ortant gas release occurs in the presence of the catalyst, containing major nitrogen N 2 (thermodynamic product) and minor nitric oxide NO (kinetic product) as primary products; secondary product is medium N 2O, whereas NO 2 and O 2 were not observed. The trapped solution analysis r eveals the formation of nitric acid. The thermal decomposition of HNF(50 wt.-%)-water solution reveals the formation of major N 2, medium NO and N 2O, and minor CO 2. However, in the presence of the catalyst, the amounts of CO 2 increases and minor CO is present; the trapped sol ution contains mainly nitrate and nitroformate ions, in a greement with the primary decomposition of the hydrazinium cation.

This study aims to assess the thermal properties of mixtures of sugarcane bagasse and iron(III) nitrate in the following proportions (mass/mass): 1/2, 1/1, and 2/1, using thermogravimetry/differential thermogravimetry and differential thermal analysis. These thermoanalytic techniques were performed to assess the best temperatures for the heat treatment of the mixtures for the subsequent production of the carbonaceous material/iron oxide composites and their behavior at different temperatures. According to thermal analysis, the decomposition profile of the mixture depends on the ratio of sugarcane bagasse to iron nitrate (BC/NF). The synthesized composites were characterized by X-ray diffraction, proving the formation of phases established from thermal analyses performed at 400, 500, and 600 °C. It was concluded that composites of the precursor mixtures may be produced to have different and interesting properties according to their application in sewage treatment processes such as adsorption.

Multi‐walled carbon nanotubes (MWCNTs) were acidified with nitration mixture, and the Fe2O3‐MWCNTs (iron oxide coated multi‐walled carbon nanotubes) hybrid material via sol‐gel method then verified the results through scanning electron microscope, X‐ray diffraction, and thermal gravimetric analysis. We modified the hybrid material with silane coupling agent (KH560), Fe2O3‐MWCNTs/epoxy, MWCNTs/epoxy composites coating, and the pure epoxy coatings were respectively prepared. The properties of the composite coatings were tested through the electrochemical workstation (electrochemical impedance spectroscopy), shock experiments, and thermal gravimetric analysis. Finally, we used scanning electron microscope to observe the surface conditions of the coatings. The results show that Fe2O3‐MWCNTs have good dispersion in the epoxy resin, and the Fe2O3‐MWCNTs/epoxy composite coatings have enhanced mechanical properties and corrosion resistance. Copyright © 2015 John Wiley & Sons, Ltd.

Basic copper nitrate [Cu(NO3)2·3Cu(OH)2, BCN] is a widely used oxidizer for gas-generating compounds. The oxidizers that replace some BCN with ammonium nitrate (NH4NO3, AN) have been investigated to increase the performance of the gas-generating agents. The purpose of this study was to understand the thermal behavior and stability of AN/BCN mixtures. To this end, mixtures prepared by two kinds of methods, with and without heat treatment, were analyzed by X-ray powder diffraction to investigate composition of samples, and differential scanning calorimetry and thermogravimetry–differential thermal analysis with mass spectrometry (TG–DTA–MS) to investigate the thermal behavior and evolved gases. It was found that [Cu(NH3)2](NO3)2 was formed in the sample with thermal treatment. The samples with and without heating exhibited different decomposition processes. It is considered that the residual AN and the amount of [Cu(NH3)2](NO3)2 in the mixture affected the decomposition behavior.

Among the methods of obtaining hematite (α-Fe2O3), the thermal decomposition of goethite (α-FeOOH) or iron (III) nitrate (Fe(NO3)3·9H2O) is of special importance. These solids can be combined with other materials, thus altering the properties of the oxide obtained. The decomposition of goethite or nitrate mixture with biomass in an inert atmosphere yields hematite/carbonaceous material or magnetite/carbonaceous composites with different morphologies and crystallinities, as observed by scanning electron microscopy and X-ray diffraction, respectively. The transformation of hematite to magnetite occurs at 623 K (for biomass/nitrate mixture) and 723 K (for biomass/goethite mixture). The formation of magnetite is a consequence of the pyrolysis of biomass, which produces a reducing mixture, and the difference in the temperature for obtaining Fe3O4 for the two precursors was investigated by thermal analysis by observing the mass and energy variations at each stage.

Preparation of palladium impregnated alumina adsorbents: Thermal and neutron activation analysis

Ammonium dinitramide (ADN) is a promising high energy oxidizer for rocket propellants because it offers a good oxygen balance and has a significant energy content. As a result, ADN-based energetic ionic liquid propellants (EILPs) have been studied, based on ADN combined with urea and monomethyl ammonium nitrate (MMAN). The thermal decomposition of ADN in the condensed phase affects the combustion of both pure ADN and ADN-based EILPs; thus, it is important to understand the reactions of EILPs in the condensed phase. The present study assessed the reactivity of ADN mixtures in the condensed phase, focussing on hydrogen abstraction reactions with NO2· formed from the thermal decomposition of ADN. The potential energy surfaces of these reactions were obtained using ab initio calculations. The effects of functional groups and of carbon chain length on hydrogen abstraction by NO2· were examined. Mixtures of ADN with urea and acetamide (AA) as amide compounds, and with MMAN and monoethanol amine nitrate (MEAN) as nitrate salts, were examined. Thermal analysis was conducted to investigate the properties of these mixtures, using differential scanning calorimetry (DSC). The calculation results shows that AA and MEAN are more reactive with ADN than urea and MMAN, which is supported by the DSC data. Hydrogen abstraction by NO2· is evidently an important condensed phase reaction in ADN mixtures, and substances having alkyl groups and longer carbon chains are more highly reactive.

The mechanism of the thermal denitration of hydrated nitrates is considered. The possibility of applying a unified kinetic equation for describing the kinetics of the overall process of nitrate decomposition is justified. The solutions obtained for this equation make it possible to generalize the experimental data on the kinetics of nitrate decomposition in a contact thermal analyzer and a plasma reactor. Modified Arrhenius equations for the approximation of temperature dependences of the decomposition rate constants for individual hydrated nitrates and nitrate mixtures are proposed.

Effect of shrinkage void on thermal performance of pure and binary phase change materials based thermal energy storage system: A semi-analytical approach

Mixed-ligand terbium terephthalates: Synthesis, photophysical and thermal properties and use for luminescent terbium terephthalate thin film deposition

Stoichiometric and silica-rich mullite gels and powders were prepared using four different sol-gel methods. Thermal analysis, X-ray powder diffraction and dilatometry techniques were used to investigate the thermal decomposition, crystallisation and sintering of these mullite precursor gels. The method of preparation, by controlled hydrolysis of various mixtures of tetraethylorthosilicate, aluminium sec-butoxide and aluminium nitrate, affected the texture of the gels, producing single-phase or diphasic samples. The crystallisation sequence of the gels depended on the composition and method of preparation. Single phase mullite crystallised from homogeneous gels at 980°C, while diphasic gels initially formed of a mixture of γ-Al2O3 spinel and mullite, or simple γ-Al2O3 spinel, which subsequently transformed to mullite at 1260°C. Dilatometry and density measurement were used to investigate the sintering of compacts formed by pressing powders prepared from gels precalcined at 500°C. Varying the heating rates from 2 to 10°C min-1 had little effect on the densification to 1500°C. However, the densification rate was sensitive to the degree of crystallinity and the amount and type of phases present at the sintering temperature. The presence of γ-Al2O3 spinel in the structure initially promoted densification, but the sintering rate was reduced considerably after mullite crystallised. Diphasic materials, especially those with an excess amount of silica in the original gel, sintered to higher densities due to the presence of excess silica promoting densification by viscous phase sintering.

During the 1980s, scientists at the Hanford Site began considering disposal options for wastes in underground storage tanks. As a result of safety concerns, it was determined that special consideration should be given to ferrocyanide-bearing wastes to ensure their continued safe storage. In addition, Westinghouse Hanford Company (WHC) chartered Pacific Northwest Laboratory (PNL) to determine the conditions necessary for vigorous reactions to occur in the Hanford Site ferrocyanide wastes. As part of those studies, PNL has evaluated the effects of selected potential waste constituents to determine how they might affect the reactivity of the wastes. The authors` investigations of the diluent, catalytic, or initiating effects of potential waste constituents included studies (1) to determine the effect of the oxidant-to-ferrocyanide ratio, (2) to establish the effect of sodium aluminate concentration, (3) to identify materials that could affect the explosivity of a mixture of sodium nickel ferricyanide (a potential aging product of ferrocyanide) and sodium nitrate and nitrite, (4) and to determine the effect of nickel sulfide concentration. They also conducted a thermal sensitivity study and analyzed the results to determine the relative behaviors of sodium nickel ferrocyanide and ferricyanide. A statistical evaluation of the time-to-explosion (TTX) test results from the catalyst and initiator screening study found that the ferricyanide reacted at a faster rate than did the ferrocyanide analog. The thermal analyses indicated that the ferricyanide form is more thermally sensitive, exhibiting exothermic behavior at a lower temperature than the ferrocyanide form. The increased thermal sensitivity of the ferricyanide, which is a potential oxidation product of ferrocyanide, relative to the ferrocyanide analog, does not support the hypothesis that aging independent of the reaction pathway will necessarily reduce the reaction hazard of ferrocyanide wastes.

A monoclinic magnesium molybdate, MgMoO 4 , was synthesized via the thermal decomposition at 500 °C of an oxalate precursor that was prepared by grinding and heating at 160 °C a solid state mixture of magnesium nitrate, ammonium molybdate and oxalic acid. The precursor was characterized by thermal gravimetric analysis (TGA), and the final obtained powders were studied by X-ray diffraction (XRD), N 2 adsorption desorption (BET), and Transmission Electron Microscopy (TEM). The results are consistent with the formation of β-MgMoO 4 agglomerated spherical nanoparticles, with an average crystallite size of 40 nm, 36 nm and 76 nm obtained from TEM, XRD and BET, respectively. The β-MgMoO 4 nanoparticles were applied as catalysts in the reduction of 3-Nitrophenol to 3-Aminophenol and the rate constant of the reaction was subsequently determined as 3.1x 10 -2 min -1