Decomposition Of Ammonium Dinitramide Research Articles

Experimental study on microwave ignition of ADN-based liquid propellant droplets doped with alumina nanoparticles

The objective of this study was to investigate the effects of alumina (Al2O3) nanoparticles on the evaporation, ignition, and combustion of ammonium dinitramide (ADN)-based liquid propellants under microwave irradiation. The alumina nanoparticles were uniformly dispersed in the ADN-based propellant at mass ratios of 25, 50, and 100 ppm, resulting in the formation of nano-fuel. Experimental methods were employed to examine the influence of alumina nanoparticles on the micro-explosion intensity, ignition delay time, combustion duration, critical ignition power, and emission spectra of the nano-fuel droplets. The experimental findings revealed a significant increase in the intensity and frequency of micro-explosion events with the inclusion of alumina nanoparticles. Compared to pure propellant, the nano-fuel with a concentration of 25 ppm exhibited a reduction of 33.5% in ignition delay time and a decrease of 9% in critical ignition power. Furthermore, the emission spectra characteristics of the pure propellant and nano-fuel were analyzed, indicating that alumina nanoparticles notably enhanced the thermal decomposition of ADN and the exothermic reaction of methanol combustion. This study provides an effective approach to improve the evaporation and combustion performance of ADN-based liquid propellants, offering potential possibilities for future applications.

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.

Insight into thermal decomposition behavior of ammonium dinitramide‐based liquid propellant through reactive molecular dynamics simulations

AbstractThe thermal decomposition characteristics and fuel oxidation mechanism of ammonium dinitramide (ADN)‐based liquid propellant are of great practical significance, but it is difficult to detect the whole intermediates and products using traditional experimental methods. In this paper, the thermal decomposition of ADN‐based liquid propellant at different temperatures (1500, 2000, 2500, and 3000 K) was simulated using the reactive molecular dynamics method. The effect of temperature on the thermal decomposition of propellant and the distribution of the main products were investigated. The results showed that the temperature played a role in promoting the decomposition of propellant. The main products of ADN‐based liquid propellant were N2, H2O, NH3, HNO3, ⋅NHO, CH2O, CO2, and NO2, while their evolution and generation pathways were also described in detail. The initial decomposition of ADN was the breakage of N−H bonds in ⋅NH4 or N−N/N−O bonds in ⋅N(NO2)2, and methanol generated free radicals by dehydrogenation. There was no direct chemical reaction between ADN and methanol, and the interaction was accomplished through the generation and consumption of free radicals. H2O provided a large amount of ⋅H and ⋅HO leading to a lower activation energy of ADN in propellant than that from reference. The overall reaction mechanism of the liquid propellant was deduced. The results would help to further investigate the reaction mechanism of ADN‐based liquid propellants.

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.

Thermal Behaviors and Interaction Mechanism of Ammonium Dinitramide with Nitrocellulose.

The initial interaction mechanism is very important for the design and safety of nano-scale composite energetic materials composed of ammonium dinitramide (ADN) and nitrocellulose (NC). The thermal behaviors of ADN, NC and an NC/ADN mixture under different conditions were studied by using differential scanning calorimetry (DSC) with sealed crucibles, an accelerating rate calorimeter (ARC), a self-developed gas pressure measurement instrument and a DSC-thermogravimetry (TG)-quadrupole mass spectroscopy (MS)-Fourier transform infrared spectroscopy (FTIR) combined technique. The results show that the exothermic peak temperature of the NC/ADN mixture shifted forward greatly in both open and closed circumstances compared to those of NC or ADN. After 585.5 min under quasi-adiabatic conditions, the NC/ADN mixture stepped into the self-heating stage at 106.4 °C, which was much less than the initial temperatures of NC or ADN. The significant reduction in net pressure increment of NC, ADN and the NC/ADN mixture under vacuum indicates that ADN initiated the interaction of NC with ADN. Compared to gas products of NC or ADN, two new kinds of oxidative gases O2 and HNO2 appeared for the NC/ADN mixture, while NH3 and aldehyde disappeared. The mixing of NC with ADN did not change the initial decomposition pathway of either, but NC made ADN more inclined to decompose into N2O, which resulted in the formation of oxidative gases O2 and HNO2. The thermal decomposition of ADN dominated the initial thermal decomposition stage of the NC/ADN mixture, followed by the oxidation of NC and the cation of ADN.

CARBON NANOTUBE IRIDIUM-CUPRIC OXIDE SUPPORTED CATALYSTS FOR DECOMPOSITION OF AMMONIUM DINITRAMIDE IN THE LIQUID PHASE

Cupric oxide (CuO)/iridium (Ir) (1/5 wt%) catalysts deposited on carbon nanotubes (CNTs) are considered to be adequate active catalysts for ammonium dinitramide (ADN) decomposition. In this study, the decomposition of ADN ionic liquid was performed over CuO crystallites deposited on Ir CNTs, which were highly distributed due to their high surface area. The catalyst activity was evaluated by calculating the turnover frequency (TOF) of CuO crystallites with different content amounts into the catalyst surface. The highest activity for ADN decomposition was demonstrated over CuO at 1 wt% due to its highest calculated TOF. The TOF was influenced by the presence of ammonium nitrate as an impurity in the ADN solution.

Microsized aluminum/ammonium dinitramide core-shell particles to improve the combustion performance of aluminum powders

Microcomposite particles of aluminum (Al) dotted by ammonium dinitramide (ADN) ([email protected]) are successfully prepared by an in-situ crystallization growth method. The morphologies, structures and thermal behavior of [email protected] are characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and simultaneous thermogravimetry and differential scanning calorimetry. The compositions and morphologies of [email protected] after heating are characterized by X-ray photoelectron spectroscopy (XPS) and SEM. A high-speed camera is used to record the combustion performances of [email protected] in a transparent quartz tube. Furthermore, the morphologies and structures of the residues are analyzed by SEM and XRD. The results show that ADN is deposited on the surface of Al to form [email protected] The decomposition of ADN increases the total oxidation degree of the Al particles. Under heating, the acids decomposed by ADN corrode the surficial alumina layer and the internal aluminum react with HNO3 to form Al(NO3)3, which makes the combustion of Al easier. Under an oxygen atmosphere, the pure Al could not be ignited. In contrast, [email protected] could be ignited and [email protected] 5:1 has a shorter ignition and burning time compared with [email protected] 10:1. After burning, the [email protected] composites are completely converted to α- and γ-Al2O3. For [email protected] 10:1, the residues show a cube-like stacking, while a ribbon-like stacking is presented for [email protected] 5:1.

Influence of La and Si promoters on the anaerobic heterogeneous catalytic decomposition of ammonium dinitramide (ADN) via alumina supported iridium active sites

Structural origins of the promotional effects of the La or Si doping of alumina supported Ir catalysts in anaerobic ammonium dinitramide decomposition were investigated. Our findings reveal that Ir/Al2O3 and Ir/La-Al2O3 favorably lower the onset temperature of the ADN decomposition reaction, whereas Si doping boosts the pressure generation during the reaction. Formation of mostly metallic Ir nanoparticles for Ir/Al2O3 and Ir/La-Al2O3 enables the lowering of the activation energy of the reaction. On the other hand, enhancement due to Si promotion is associated to the generation of small oxidic Irnx+ clusters which are strongly interacting with the SiOx-AlOx surface domains of the support material. Fundamental structure-functionality relationships unraveled in the current work may allow design of novel catalytic systems for aerospace monopropellant propulsion systems with higher performance by simultaneous exploitation of Ir active sites with different electronic properties.

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.

Decomposition Pathways of Ammonium Dinitramide (ADN) and its HNO3‐Clusters Elucidated by DFT‐Calculations

AbstractAmmonium dinitramide (ADN) may serve as a ‘green’ oxidizer for rocket propellants since it provides chlorine free and minimum signature exhaust gases. However, stability issues and an erratic decomposition behaviour limit its non‐questionable general usability. Nitric acid (HNO3) is a decomposition product of ADN and is known to accelerate the decomposition autocatalytically. In this study, we investigate the effect of HNO3 on the initial decomposition steps of ADN via quantum chemical calculations based on density functional theory (DFT) in vacuo as well as in an aqueous solution. We establish and compare the reaction profiles of ADN, its anion DN− and its acid HDN as well as their HNO3‐clusters [NO3H_ADN], [NO3H_DN]− and [NO3H_HDN] towards the products NO2, HNO3 and N2O. All species exhibit various isomers with distinct decomposition pathways. We complement our study by investigating the protonated, cationic species [H_ADN]+, which may form in a low pH regime. The HNO3 clusters reveal modulated energy barriers and in part altered decomposition pathways in comparison to the free DN−, HDN, and ADN species. The altered pathways include the formation of reactive intermediates (such as H2NO3+) as well as the formation of two HNO3 molecules starting from one HNO3 molecule, hinting at accelerated decomposition of ADN due to interaction with HNO3.

Study on the State Change of Ir/Al₂O₃ Catalyst by Decomposition of Ammonium Dinitramide (ADN) Based Low-Toxicity Monopropellant.

The change of the Ir/Al₂O₃ catalyst before and after the reaction with ADN based low-toxicity monopropellant was confirmed. The catalyst were recovered after decomposition reaction with propellant in a monopropellant thruster at 350 °C preheating condition. Catalyst analysis was performed using a scanning electron microscope (SEM) and Brunauer-Emmett-Teller (BET) analyzer. The change of the catalyst specific devices.

Catalytic decomposition mechanism of aqueous ammonium dinitramide solution elucidated by thermal and spectroscopic methods

Ammonium dinitramide (ADN) is a green, energetic and oxygen rich molecule, developed to replace the commonly used oxidizer ammonium perchlorate (AP). On combustion ADN produces relatively environmental-friendly species such as H2O, NO2, N2O, NO etc., compared to HCl, Cl2, CO2, CO, H2, H2O, N2 and highly reactive chlorine species produced by AP combustion. The ADN synthesized in our laboratory was dissolved in deionized water to prepare aqueous ADN solutions (aq. ADN). The thermal decomposition of solid ADN and aq. ADN were studied and the products of decomposition are identified using a thermogravimetric analyser hyphenated with a FTIR instrument. Nano CuO catalyst was synthesized and aq. ADN was decomposed over the nanocatalyst and the catalytic decomposition mechanism is also elucidated. The study shows that, the condensed phase decomposition of aq. ADN is influenced by the CuO nanocatalyst leading to the generation of higher concentrations of NO2, which autocatalyzes the remaining ADN decomposition.

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.

Catalytic Decomposition of an Energetic Ionic Liquid Solution over Hexaaluminate Catalysts

The objective of this study was to determine the effect of a synthesis procedure of Sr hexaaluminate on catalytic performance during the decomposition of ionic liquid monopropellants based on ammonium dinitramide (ADN) and hydroxyl ammonium nitrate (HAN). Sr hexaaluminates were prepared via both coprecipitation and a sol–gel process. The surface area of hexaaluminate synthesized via the coprecipitation method was higher than that of hexaaluminate synthesized by the sol–gel process, and calcined at the same temperature of 1200 °C or more. This is because of the sintering of α-Al2O3 on the hexaaluminate synthesized via the sol–gel process, which could not be observed on the catalysts synthesized via the coprecipitation method. The hexaaluminate synthesized via coprecipitation showed a lower decomposition onset temperature during the decomposition of ADN- and HAN-based liquid monopropellants in comparison with the catalysts synthesized via the sol–gel process, and calcined at the same temperature of 1200 °C or more. This is attributed to the differences in the Mn3+ concentration and the surface area between the two hexaaluminates. Consequently, the hexaaluminate synthesized via coprecipitation which calcined above 1200 °C showed high activity during the decomposition of energetic ionic liquid monopropellants compared with the hexaaluminate synthesized via the sol–gel process.

Hydrogen Promoted Decomposition of Ammonium Dinitramide: an ab initio Molecular Dynamics Study

Thermal decomposition of a famous high oxidizer ammonium dinitramide (ADN) under high temperatures (2000 and 3000 K) was studied by using the ab initio molecular dynamics method. Two different temperature-dependent initial decomposition mechanisms were observed in the unimolecular decomposition of ADN, which were the intramolecular hydrogen transfer and N—NO2 cleavage in N(NO2)−. They were competitive at 2000 K, whereas the former one was predominant at 3000 K. As for the multimolecular decomposition of ADN, four different initial decomposition reactions that were also temperature-dependent were observed. Apart from the aforementioned mechanisms, another two new reactions were the intermolecular hydrogen transfer and direct N—H cleavage in NH4+. At the temperature of 2000 K, the N—NO2 cleavage competed with the rest three hydrogen-related decomposition reactions, while the direct N—H cleavage in NH4+ was predominant at 3000 K. After the initial decomposition, it was found that the temperature increase could facilitate the decomposition of ADN, and would not change the key decomposition events. ADN decomposed into small molecules by hydrogen-promoted simple, fast and direct chemical bonds cleavage without forming any large intermediates that may impede the decomposition. The main decomposition products at 2000 and 3000 K were the same, which were NH3, NO2, NO, N2O, N2, H2O, and HNO2.

Flame Structure of Ammonium-Dinitramide-Based Liquid Propellant in a Small Thruster

In this paper, the flame structure of a liquid propellant ammonium dinitramide–methanol aqueous solution in a small model thruster is investigated. The thruster is composed of an injector and a combustion chamber (including a catalyst bed) with optical windows, through which the combustion process in the atmosphere is inspected, and the temperature distribution along the flame is measured by the tunable diode laser absorption spectroscopy method. Obvious fluctuations in temperature and flickering yellowish flame downstream of the combustion chamber are observed, indicating that the combustion is not stable. The mean temperature distribution has a significant peak where a yellowish flame appears. To explain the experimental observations, a detailed gas-phase ammonium dinitramide–methanol reaction model is used to establish the flame structure of an ideal liquid propellant, which can be divided into several different regions, including the liquid phase, aerosol zone, and two flame zones. The decomposition of ammonium dinitramide and the evaporation of methanol take place in the liquid phase and aerosol zone, whereas the gas phase reactions of methanol and the decomposition products of ammonium dinitramide take place in the two flame zones. Based on the proposed theory of flame structure, it is seen that, in our experiment, the physical and chemical processes in the liquid phase and aerosol zone are completed upstream of the catalyst bed, and the unstable yellowish flame appearing in the combustion chamber is caused by competitive influence between the two flame zones.

Experimental and numerical studies of ammonium dinitramide based liquid propellant combustion in space thruster

In this paper, the combustion process of liquid propellant ammonium dinitramide (ADN)-methanol aqueous solution in a small space thruster is investigated experimentally and numerically. The phase Doppler anemometer measurement is used to investigate the injection process and the results are used as the liquid boundary condition in the simulation to minimize uncertainties. Hot fire tests have also been operated to estimate the performance of the thruster. To simulate the complicated processes in the thruster, a modified multi-component droplet model is employed to simulate the evaporation process considering the interaction between the liquid droplet and the porous media. A non-equilibrium model for the porous media is used to describe the heat transfer in the catalyst bed. A reduced chemical mechanism containing 18 species and 40 reactions is used to simulate the reactions of gas-phase ADN and methanol. The results show that the decomposition of ADN and the oxidization of methanol do not happen synchronously in the chamber. The decomposition of ADN takes place near the inlet while methanol is oxidized downstream of the porous media. The establishment of pressure in the thruster depends on the evaporation and reaction processes and the temperature changes relatively slowly because the porous media increases the thermal inertia of the whole system.

Retraction: Catalytic decomposition of ammonium dinitramide (ADN) as high energetic material over CuO-based catalysts

Retraction of ‘Catalytic decomposition of ammonium dinitramide (ADN) as high energetic material over CuO-based catalysts’ by Rachid Amrousse et al., Catalysis Science and Technology, 2013, 3, 2614–2619.

Experimental Investigation on the Evaporation and Combustion Processes of Ammonium-Dinitramide-Based Liquid Propellant

In this work, the evaporation and combustion processes of liquid propellant ammonium dinitramide–methanol aqueous solution were investigated by a thermogravimetric analyzer and a Curie-point pyrolysis unit, respectively, and the gas-phase products were measured by a Fourier transform infrared spectroscopy. The results showed that methanol and water evaporated first, followed by the decomposition of ammonium dinitramide at heating rates of 5–. When a catalyst was added, ammonium dinitramide decomposed much faster and released heat that let methanol evaporate immediately as the propellant solution was in contact with the catalyst particles. To explore how the decomposition of ammonium dinitramide is coupled with the oxidation of methanol, the propellant solution was heated by a Curie-point pyrolysis unit at a rate of to temperatures ranging from 160 to 670°C. Large amounts of nitrous oxide and ammonia were detected at all temperatures, suggesting that most of the decomposition of ammonium dinitramide occurred at the condensed phase. Finally, a detailed gas-phase ammonium dinitramide–methanol reaction model was built to analyze the coupling between the decomposition of ammonium dinitramide and the oxidation of methanol.