Thermal Decomposition Of Ammonium Dinitramide Research Articles

Assessment of the sensitivity to detonation of the gaseous pyrolytic products formed during the thermal decomposition of ammonium dinitramide and its related ionic liquids

Assessment of the sensitivity to detonation of the gaseous pyrolytic products formed during the thermal decomposition of ammonium dinitramide and its related ionic liquids

Research progress on the catalytic and thermal decomposition of ammonium dinitramide (ADN).

Ammonium dinitramide (NH4N(NO3)2, ADN) is regarded as a promising oxidizer due to its low signature and high specific impulse. Generally, ADN undergoes exothermic decomposition above 140 °C accompanied by the byproduct of ammonium nitrate (AN). The inevitable endothermic decomposition of AN decreases the overall heat release, and so there is a need to develop efficient catalysts to guide ADN decomposition along desired pathways with a lower decomposition temperature and higher heat release. A suitable catalyst should be able to withstand the harsh conditions in a thruster to achieve a stable thrust force, which poses a huge obstacle for manufacturing a stable and active catalyst. This review gives a comprehensive summary of the thermal and catalytic decomposition pathways of ADN for the first time, which is expected to deepen the understanding of its reaction mechanism and provide useful guidance for designing prospective catalysts toward efficient ADN decomposition.

Thermal Decomposition of Ammonium Dinitramide (ADN) as Green Energy Source for Space Propulsion

The thermal decomposition of an ammonium dinitramide-based energetic compound was conducted for the first time using a dispersive inductively coupled plasma mass spectrometer, DTA-TG analysis, and pyrolysis at a constant temperature. A liquid droplet was injected over synthesized CuO catalytic particles deposited on lanthanum oxide-doped alumina. The thermal behavior of the ADN liquid monopropellant revealed that decomposition in the presence of catalytic particles occurs in two distinct steps, with the majority of ejected gases being detected in real-time analysis using the DIP-MS technique. At a temperature of 280 °C, pyrolysis confirmed the catalytic decomposition behavior of ADN, which occurred in two distinct steps.

Construction of ammonium dinitramide@monoaminopropyl heptaphenylsilsesquioxane core-shell energetic microspheres with enhanced hygroscopicity inhibition and thermal decomposition properties

To reduce the hygroscopicity of ammonium dinitramide (ADN) and improve its application performance, using ADN as a core material and hydrophobic monoaminopropyl heptaphenylsilsesquioxane (POSS-NH2) as a shell material, the core-shell energetic microspheres ADN@POSS-NH2 were fabricated by a facile solvent evaporation method. This is the first time that ADN was coated with organic-inorganic hybrid material polyhedral oligomeric silsesquioxane (POSS). The results showed that the core-shell energetic microspheres ADN@POSS-NH2 were successfully prepared. The hydrophobicity was improved and hygroscopicity was reduced remarkably. At 75% RH and 20 °C, ADN@POSS-NH2 particles still maintained solid forms after 7 days. In addition, the POSS-NH2 had a catalytic effect on the thermal decomposition of ADN, but had little effect on the friction sensitivity.

RMD simulations of ADN and ADN/GAP-based propellant

Energetic materials have been used over time in civil and military applications. Concomitantly, studies were conducted focusing on the combustion mechanisms of these materials, including their kinetic and thermodynamic behavior during firing. The objective of this work was to systematically study the mechanisms of thermal decomposition of ammonium dinitramide (ADN), and ADN formulated as a solid composite propellant with glycidyl azide polymer (GAP), through reactive molecular dynamics simulations. The main reactions of the mechanisms were elucidated and analyzed, and the Arrhenius parameters were determined for the global processes. Calculated activation energies for the systems were 127.84 and 354.72 kJ/mol for ADN and ADN/GAP, respectively. Comparison to literature data shows up to 14% of deviation, which proves the methodology useful for predictions and kinetic analyzes of combustion/pyrolysis reactions of energetic materials.

Pickering emulsion-templated encapsulation of ammonium dinitramide by graphene sheets for hygroscopic inhibition

Ammonium dinitramide (ADN) has received great attention as a green oxidizer used in propellants, but its high hygroscopic nature makes it very challenging for practical applications. Herein, we report a facile method to encapsulate ADN by using Pickering emulsion as a soft template, and alkylated graphene oxide nanosheets (AmGO) as particle surfactant. We demonstrate that the encapsulation of ADN aqueous droplets by AmGO nanosheets (ADN@AmGO) can be successfully achieved in a water-in-toluene emulsion, and we studied the influence of factors such as AmGO concentration, and toluene/water ratio on the morphologies of Pickering emulsion. The ADN@AmGO composites were obtained through vacuum assisted solvents extraction, and the compositional and morphological characterizations were performed by using optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), Raman spectra, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Furthermore, the thermal behaviors were examined by differential scanning calorimetry (DSC) and thermogravimetry (TG) analysis. We found that ADN encapsulated by 1.0 wt% of AmGO shows more than 60% decrease in water adsorption. Besides, AmGO reveals pronounced catalytic efficiency on the thermal decomposition of ADN. These outstanding properties make ADN@AmGO promising alternative to be used in the fabrication of high energetic, low signature and eco-friendly propellants.

Reactivity analysis of ammonium dinitramide binary mixtures based on ab initio calculations and thermal 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.

Combustion of Composite Propargyl-Terminated Copolyether Propellant Containing Ammonium Dinitramide

ABSTRACT A kind of composite propellant based on a click-chemistry binder, the propargyl-terminated ethylene oxide-tetrahydrofuran copolyether (PTPET), and ammonium perchlorate (AP), aluminum (Al) were studied with ammonium dinitramide (ADN), hexahydro-1,3,5-trinitro-s-triazine (RDX) and hexanitroisowurtzitane (CL20), respectively. Thermogravimetric analysis (TG) and energy calculation of the composite propellants containing ADN and CL20 were carried out. The burning rates of the composite propellants were measured in the pressure range of 3–17 MPa with measurement system of Charge Coupled Device (CCD) line scan camera and high-pressure chamber. Scanning electron microscopy was used to characterize the quenched surfaces of the burning propellants. Microscopic high-speed photography was used to record the flame structure and dynamic burning surface of the propellants in the argon atmosphere. The replacement of RDX with CL20 had less effect on the thermal decomposition of the components in the propellant, but increased the burning rates of the propellant. The replacement of AP with ADN could significantly accelerate the thermal decomposition of the plasticizer A3, AP and PTPET binder, so that the burning rates under high pressure was raised obviously. For the propellants containing ADN and CL20, there were dense and thick molten layer of ADN on the burning surface. The propellants containing ADN and CL20 exhibited characteristic flame different from the propellant containing only AP and RDX. These results were considered to correlate with the early thermal decomposition of ADN and higher burning rate of the propellants.

High-energy coordination polymers (CPs) exhibiting good catalytic effect on the thermal decomposition of ammonium dinitramide

High-energy coordination polymers (CPs) not only exhibit good energetic performances but also have a good catalytic effect on the thermal decomposition of energetic materials. In this contribution, two high-energy CPs Cu2(DNBT)2(CH3OH)(H2O)3·3H2O (1) and [Cu3(DDT)2(H2O)2]n (2) (H2DNBT = 3,3′-dinitro-5,5′-bis(1H−1,2,4-triazole and H3DDT = 4,5-bis(1H-tetrazol-5-yl)-2H-1,2,3-triazole) were synthesized and structurally characterized. Furthermore, 1 was thermos-dehydrated to produce Cu2(DNBT)2(CH3OH)(H2O)3 (1a). The thermal decomposition kinetics of 1, 1a and 2 were studied by Kissinger's method and Ozawa's method. Thermal analyses and sensitivity tests show that all compounds exhibit high thermal stability and low sensitivity for external stimuli. Meanwhile, all compounds have large positive enthalpy of formation, which are calculated as being (1067.67 ± 2.62)kJmol−1 (1), (1464.12 ± 3.12)kJmol−1 (1a) and (3877.82 ± 2.75)kJmol−1 (2), respectively. The catalytic effects of 1a and 2 on the thermal decomposition of ammonium dinitramide (ADN) were also investigated.

On the mechanism of thermal decomposition of ammonium dinitramide (review)

Despite significant progress in studying thermal decomposition of ammonium dinitramide (ADN), the kinetics of the process at the level of elementary stages has not been adequately understood. The aim of this review is to summarize various published data, which are of interest for studying and simulating the processes of thermal decomposition and combustion of ADN. Considerable attention is paid to physical and chemical properties of ADN, dinitramide and its anion N(NO2) 2 - , which play a key role in ADN decomposition. Various paths of decomposition of ADN, dinitramide, and N(NO2) 2 - are discussed. Results illustrating alternative points of view on the decomposition process are presented.

Kinetics analysis of thermal decomposition of ammonium dinitramide (ADN)

Kinetics analyses were performed on the thermal decomposition of ammonium dinitramide (ADN) using thermogravimetry-differential thermal analysis–mass spectrometry–infrared spectroscopy (TG-DTA–MS–IR). The main evolved gases were determined to be NH3, H2O, N2, NO, N2O, and NO2. The apparent activation energies of the exothermic, mass-change and gas-evolving reactions were analyzed on the basis of Friedman methods. The apparent activation energy of evolving N2 has the same value as that of evolving H2O since they occur by the same mechanism. A Friedman plot obtained from the DTA data has a curve similar to those obtained from N2 and H2O. The reaction that generated N2 and H2O plays an important role in the exothermic reaction in the decomposition of ADN. The activation energy for the N2O evolution reaction has a range of approximately 120–152 kJ mol−1 with reaction progress values between 0.1 and 0.9. Quantum chemistry calculations revealed that the total energy barrier of dinitramic acid unimolecular decomposition and ammonium-dinitramic ions collision-induced decomposition is 149.9–156.0 and 160.6 kJ mol−1, respectively. These values are reasonable compared with the experimental value of 152 kJ mol−1.

Thermal decomposition characteristics of mixtures of ammonium dinitramide and copper(II) oxide

Ammonium dinitramide (ADN) is one of the most promising new solid oxidizers for rocket propellants, since its oxygen balance and energy content are relatively high, and it does not contain halogens. To gain a better understanding of the thermal decomposition mechanism of ADN, the thermal decomposition of ADN and copper(II) oxide (CuO) mixtures was investigated. The thermal behavior and activation energy associated with the decomposition of ADN/CuO mixtures were analyzed using sealed cell differential scanning calorimetry (SC-DSC). SC-DSC results showed that CuO affects the thermal characteristics of ADN and promotes its decomposition. Thermogravimetry–differential thermal analysis–evolved gas analysis was also performed, and in addition, the decomposition behavior was observed using hot stage microscopy. From the results, a thermal decomposition mechanism was proposed for ADN/CuO. In this mechanism, copper dinitramide Cu[N(NO2)2]2 is generated at the surface of the CuO almost simultaneously with the melting of the ADN. Next, a significant exothermic reaction occurs, associated with the decomposition of Cu[N(NO2)2]2, followed by decomposition of CuO via [Cu(NH3)2](NO3)2 and Cu(NO3)2.

Thermal decomposition of the high-performance oxidizer ammonium dinitramide under pressure

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because it possesses both high oxygen balance and high energy content, and does not contain halogen atoms. A necessary characteristic of solid propellants is chemical stability under various conditions. This study focused on the thermal decomposition mechanism of ADN under pressurized conditions. The pressure was adjusted from 0.1 to 6 MPa, while ADN was heated at a constant rate. The exothermal behavior and the decomposition products in the condensed phase during heating were measured simultaneously using pressure differential scanning calorimetry (PDSC) and Raman spectrometry. PDSC analyses showed the multiple stages of exotherms after melting. The exothermal behavior at low temperatures varied with pressure. Analysis of the decomposition products indicated that ammonium nitrate (AN) was generated during decomposition of ADN at all pressures. At normal pressure, AN was produced at the same time as start of exotherm. However, the temperature at which the ratio of ADN in chemical species in the condensed phase began to decrease under high pressure was higher than that at atmospheric pressure despite the existence of significant exotherm. At initial stage, thermal decomposition of ADN that does not generate AN was thought to be promoted by increased pressure.

Thermal behavior of new oxidizer ammonium dinitramide

Ammonium dinitramide (ADN) is a promising new oxidizer for solid propellants because of its high oxygen balance and high energy content, and halogen-free combustion products. One of the characteristics needed for solid propellants is stability. Heat, light, and moisture are factors affecting stability during storage, manufacture, and use. For practical use of ADN as a solid propellant, clarification of the mechanism of decomposition by these factors is needed to be able to predict lifetime. This study focused on thermal decomposition of ADN. Exothermal behavior of ADN decomposition was measured by isothermal tests using high-sensitive calorimetry (TAM) and non-isothermal tests using differential scanning calorimetry (DSC). Based on these results, analysis of the decomposition kinetics was conducted. The activation energy determined by TAM tests was lower than that from DSC tests. Thus, the decomposition path in TAM tests was different from that in DSC tests. The amount of ADN decomposition predicted from TAM tests was closer to that found under real storage conditions than the amount of decomposition predicted from DSC tests. Non-isothermal tests may not be able to precisely predict the lifetime of materials with a decomposition mechanism that changes with temperature, such as ADN. The lifetime predicted from DSC results was much longer than that from TAM tests especially at low temperature. It is necessary to use isothermal tests to predict the long-term stability at low temperature.

Combustion and thermal decomposition of ammonium dinitramide catalyzed by carbon nanotubes

The catalysis of carbon nanotubes(CNTs),carbon nanotubes supporting ferric oxide(Fe2O3/CNT) and carbon nanotubes supporting iron and copper(Fe·Cu/CNT) on the combustion and thermal decomposition of ammonium dinitramide(ADN) were investigated through burning rate measurements and TG analysis.Results show that all three catalysts increase the burning rate of ADN.The burning rates are related to combustion pressure by a power function and the pressure exponents decrease with the amount of catalyst for all of the three catalysts.When 3mass% of catalyst is used the burning rate of ADN at 4MPa increases from 30.49 to 50.59,39.72 and 38.79mm·s-1 and the pressure exponents decrease from 0.81 to 0.36,0.67 and 0.75 for the CNTs,Fe2O3/CNTs and Fe·Cu/CNTs respectively,TG tests show that all three catalysts decrease the thermal decomposition temperature of ADN.The primary thermal decomposition temperatures of ADN decrease to 18.3℃,12.1℃,and 11.6℃ for the CNTs,Fe2O3/CNTs and Fe·Cu/CNTs respectively when 1mass% catalyst was added to ADN.

Thermal Decomposition of Ammonium Dinitramide Vapor in a Two-Temperature Flow Reactor

The thermal decomposition of ammonium dinitramide (ADN) was studied using a two-temperature flow reactor. The vapor pressure at temperatures of 80-140°C and the heat of vaporization of ADN were determined. From the results obtained a mechanism for the thermal decomposition of ADN was proposed that includes the ADN vaporization stage, i.e., the transition from the condensed to the gaseous state in the form of the molecular complex NH$3·HN(NO2)2 (ADN vapor) followed by dissociation into NH3 and HN(NO2)2. The composition of the products from the thermal decomposition of ADN vapor at temperatures of 160–900°C was determined by mass spectrometry. The effective rate constant was determined for the dissociation of ADN vapor at temperatures of 160–320°C. The thermal decomposition of ADN vapor in a flow reactor was modeled using the proposed mechanism and the reaction rate constant for ADN vapor dissociation. Key words: ammonium dinitramide, dinitramide, molecular beam mass spectrometry, thermal decomposition, two-temperature flow reactor.

Stabilization of ammonium dinitramide in the liquid phase

The kinetics of accumulation of the main products of thermal decomposition of ammonium dinitramide in the melt was investigated. The isotope composition of nitrogen-containing gases evolved by the decomposition of 15NH4N(NO2)2 and NH4 15N(NO2)2 was found. Easily oxidized salts, amines, amides, iodides, and other compounds soluble in the melt interfere with the liquid-phase decomposition of ammonium dinitramide.

Thermal decomposition of ammonium dinitramide and mechanism of anomalous decay of dinitramide salts

Thermal decomposition of ammonium dinitramide proceedsvia homolytic rupture of the N−NO2 bond and partially by the proton transfer reaction. The monomolecular decay of the anion to N2O and NO3 − in the solid state at 60 °C occurs with higher rates than those in the melt. This is related to a change in the reactivity of the anion due to the violation of its symmetry on going to the solid state. The absence of hydrogen bonds between the anion and cations or water molecules is an additional condition for the fast decay.

Energetics of ammonium dinitramide decomposition steps

The structures, energies at 0 K and enthalpies at 298 K have been computed for 37 molecules, ions and transition states that have been implicated in the thermal decomposition of ammonium dinitramide. A density functional procedure was used: DF/B3P86/6–31 + G ∗∗. These data permit the calculation of ΔH (298 K) for a large number of possible decomposition steps; some of these results are presented and discussed. Computed values are reported for the lattice enthalpy of ammonium dinitramide, ΔH (298 K) = 144 kcal mol −1, its heat of sublimation to NH 3 + HN( NO 2) 2 ΔH, (298 K) = 44 kcal mol −1, and the gas phase heat of formation of HN(NO 2) 2, ΔH 298 ƒ = 19 kcal mol −1 .

Thermal decomposition of gaseous ammonium dinitramide at low pressure: Kinetic modeling of product formation with ab initio MO/cVRRKM calculations

The thermal decomposition of ammonium dinitramide, NH4N(NO2)2) (ADN), in the gas phase has been studied at 373–920 K by pyrolysis/mass spectrometry under low-pressure conditions using a Saalfeld reactor. The reaction of the sublimed mixture of NH3 and HN(NO2)2 (dinitraminic acid, DN) was found to be initiated by the unimolecular decomposition of DN, HN(NO2)2→HNNO2+NO2, followed by the rapid decomposition reaction, HNNO2+M→N2O+OH+M. The measured absolute yields of NH3, H2O, N2, and N2O, calibrated with standard mixtures, could be satisfactorily modeled at 10 Toor He carrier gas pressure by employing the theoretically computed values of k2=6.79×1049 T−11.0 exp(−21780/T) s−1 and k3=7.53×1024 T−29 exp(−12958/T) cm3/(mol s) by high-level ab initio molecular orbital and canonical variational Rice-Ramsperger-Kassel-Marcus (MO/cVRRKM) calculations. The key reactions with recommended rate constants are presented.