Decomposition Of Ammonium Nitrate Research Articles

Catalytic performance of nano-sized cobalt copper ferrite on thermal decomposition of ammonium nitrate

Ammonium nitrate (AN) is being explored as a high energetic oxidizer in propellants. The utilization of pure AN in propellants suffers from a low burning rate. To improve the burning rate, it is important to improve the thermal decomposition characteristics of AN to fasten its thermal decomposition. The effect of CoCuFe2O4 additive was explored to improve the thermos-kinetic parameters of AN's thermal decomposition. Coprecipitation was used to synthesize nanocrystalline CoCuFe2O4. The thermodynamic and kinetic parameters of decomposition of AN: CoCuFe2O4 were investigated using TG-DSC-DTA analysis at 5, 10, and 15 °C min−1. The thermodynamic and kinetic studies suggest that the thermal decomposition of AN+CoCuFe2O4 was more favorable than AN. The decomposition of AN+CoCuFe2O4 occurs at a lower 10 °C lower temperature with ∼44 % decrement in the activation energy and decreased pre-exponential factor. The faster decomposition at a lower temperature was obtained for AN+CoCuFe2O4 composition. Nano-sized particles with efficient optical and polarizable properties made this ferrite material easily separable and eco-friendly for the preparation of a chemical propulsion system based on AN. The AN+CoCuFe2O4 propulsion mixture can be utilized in place of pure AN for better thermal performance in a propellant system.•CoCuFe2O4 was able to influence the thermal decomposition parameters of ammonium nitrate (AN).•AN+CoCuFe2O4 decomposes at lower activation energy with a faster decomposition than pure AN.•Thermodynamics suggest favorable decomposition of AN+CoCuFe2O4 than pure AN.

An Efficient Nanocatalyst Cobalt Copper Zinc Ferrite for the Thermolysis of Ammonium Nitrate.

This work reports synthesis and catalytic effect of cobalt copper zinc ferrite (CoCuZnFe2O4) on the thermal decomposition of ammonium nitrate (AN). AN is a crystalline hygroscopic powder widely applicable as an oxidizer in the propellant formulations for high energetic materials but requires improvement in its thermal decomposition characteristics. Nanocatalyst spinel ferrite CoCuZnFe2O4 was prepared using the coprecipitation method and characterized by various physicochemical instrumental techniques like XRD, FE-SEM, UV-vis, Raman, and TG-DSC. Catalytic study of AN in the presence of nano-CoCuZnFe2O4 was investigated using DSC analysis. The Raman and XRD study confirm the formation of ferrite with a crystalline size 9-22 nm. TG suggests that the catalyst was thermally stable up to 400 °C with ∼10% mass loss. The UV-vis study shows that the optical band gap energy of CoCuZnFe2O4 was 2.6 eV, which may help in fast acceleration of electrons during thermolysis of AN, making the thermal decomposition of AN more favorable in the presence of CoCuZnFe2O4. The thermal decomposition investigation suggests that the activation energy of AN thermolysis in the presence of 2 wt % CoCuZnFe2O4 was decreased by ∼37%. It is concluded that CoCuZnFe2O4 can be used as an efficient catalyst for improving AN's thermal characteristics.

Ammonium nitrate explosion at the main port in Beirut (Lebanon) and air pollution: an analysis of the spatiotemporal distribution of nitrogen dioxide.

An explosion of the ammonium nitrate (AN) stored at Beirut Port devastated the city on Tuesday 4 August 2020. Such an explosion produces pollutants such as nitrogen oxides (NOx). The most common NOx is nitrogen dioxide (NO2), which is present in the atmosphere due to natural and anthropogenic processes. The presence of NO2 is used as indicator of air pollution. However, the specific contribution of NO2 to air quality is uncertain due to the presence of other constituents, especially particulate matter (PM10). Research has shown that extended exposure to NO2 may result in serious health effects. This study investigated the impact of the explosion on NO2 levels in the atmosphere above Beirut and the surrounding area. NO2 data from the Sentinel-5P program were used to map the levels of NO2. Furthermore, ground-monitoring data were used to assess the levels of PM10 and ozone (O3) due to the evident association between these constituents and NO2. Results showed that NO2 levels were higher than before the blast. However, 7 days after the explosion, NO2 levels had returned to normal, while the levels of PM10 and O3 remained normal following the explosion. However, a slight increase in the daily average atmospheric pressure was noticed after the explosion, which was attributed to the decomposition of ammonium nitrate.

Variations in gaseous nitric acid concentrations at Tottori, Japan: Long-range transport from the Asian continent and local production

To evaluate factors affecting variation in gaseous nitric acid (HNO3) concentrations, including long-range transport from the Asian continent, we conducted continuous observations of HNO3 and related species from April 2016 to October 2017 in a coastal region near Tottori, Japan. HNO3 concentrations and concentration ratios of HNO3 to total odd nitrogen species (HNO3/NOy) during sea-breeze periods exhibited similar seasonal variations, with maximum concentrations during spring–summer and minimum concentrations during autumn–winter. The sea-breeze period concentrations were higher than those during land-breeze periods in spring–summer. Similar diurnal variations for HNO3 concentrations and HNO3/NOy with maximum values occurring during the daytime and minimum values during the nighttime were observed regardless of the season. These seasonal and diurnal variations were attributed to the reaction of NO2 with OH radicals and/or the thermal decomposition of ammonium nitrate (NH4NO3) aerosols. In terms of long-range transport from the Asian continent, a thermal equilibrium of HNO3 and gaseous ammonia (NH3) with NH4NO3 can affect variation of the HNO3 concentration. A chemical thermodynamics evaluation was conducted of the equilibrium of HNO3 and gaseous ammonia with NH4NO3. The concentration of extra ammonium ions was determined by taking into consideration that required for full neutralization of non-sea-salt sulfate in formation of ammonium sulfate, and seasonal variation in the results was evaluated. The results suggested that a thermal equilibrium of HNO3 and NH3 with NH4NO3 transported from the Asian continent could contribute to concentration variations of HNO3 in seasons other than summer.

Nano-NiCuZnCo2O4: a promising catalyst for the fast thermal decomposition of ammonium nitrate (AN) in an energetic formulation

Ammonium nitrate (AN) decomposition has been investigated using a metal cobaltite catalyst, NiCuZnCo2O4. Pure AN decomposed (Td) at ∼563 K, while in the presence of nano-NiCuZnCo2O4 the decomposition temperature decreased by ∼40 K.

Al-Doped Maghemite Examined as Catalyst for the Discoloration of Methylene Blue and for the Decomposition of Ammonium Nitrate

Al-Doped Maghemite Examined as Catalyst for the Discoloration of Methylene Blue and for the Decomposition of Ammonium Nitrate

N2O Formation during NH3-SCR over Different Zeolite Frameworks: Effect of Framework Structure, Copper Species, and Water

The formation characteristics of N2O were investigated with respect to copper-functionalized zeolites, i.e., Cu/SSZ-13 (CHA), Cu/ZSM-5 (MFI), and Cu/BEA (BEA) and compared with the corresponding zeolites in the H form as references to elucidate the effect of the framework structure, copper addition, and water. Temperature-programmed reduction with hydrogen showed that the CHA framework has a higher concentration of Cu2+ (Z2Cu) compared to MFI and BEA. The characterizations and catalyst activity results highlight that CHA has a framework structure that favors high formation of ammonium nitrate (AN) in comparison with MFI and BEA. Moreover, AN formation and decomposition were found to be promoted in the presence of Cu species. On the contrary, lower N2O formation was observed from Cu/CHA during standard and fast SCR reactions, which is proposed to be due to highly stabilized AN inside the zeolite cages. On the other hand, significant amounts of N2O were released during heating due to decomposition of AN, implying pros and cons of AN stability for Cu/CHA with possible uncontrolled N2O formation during transient conditions. Additionally, important effects of water were found, where water hinders AN formation and increases the selectivity for decomposition to NO2 instead of N2O. Thus, less available AN forming N2O was observed in the presence of water. This was also observed in fast SCR conditions where all Cu/zeolites exhibited lower continuous N2O formation in the presence of water.

Расчетно-аналитическое обоснование предельных значений массы аммиачной селитры при хранении на складах и терминалах

On the basis of theory of stationary thermal explosion of A.D. Frank-Kamenetsky, depending on the temperature of the critical size of the ammonium nitrate embankment, the calculations were performed, which show that it can be stored in the large volumes at the temperatures up to 30 °C. On the contrary, at the temperatures above 100 °C (for example, at 200 °C), the decomposition of nitrate occurs with acceleration and can lead to an explosion. Based on the studies performed, it is shown that the changes and additions to the fire safety requirements for ammonium nitrate storage in the buildings and structures should be determined by the requirements for fire resistance of buildings (at least II degree of fire resistance), for the purity of the product and its packaging, for the exclusion of contacts with organic substances and materials, storage conditions. Additional fire safety requirements were developed for inclusion in the normative document regarding ammonium nitrate storage. Ammonium nitrate is allowed to be stored in one-story warehouse buildings of at least II degree of fire resistance, structural fire hazard class C0. The floor area within the fire compartment should not exceed 10 500 m2. Between the fire-fighting walls of the 1st type, it is allowed to store no more than 25 000 tons of nitrite in bulk or in the special bags, as well as in the soft specialized containers for bulk products in accordance with GOST 2—2013.The conditions for placing ammonium nitrate in the stacks should be accepted in accordance with the requirements of SP 92.13330.2012. Temperature in the storage room of ammonium nitrate should not exceed 30 °C with a relative humidity of not more than 60 %. Warehouses for storing ammonium nitrate should be equipped with general exchange supply and exhaust and (or) emergency ventilation, in order to exclude the formation of a fire and explosion hazardous environment in the room during the decomposition of ammonium nitrate. Warehouses for storing ammonium nitrate in an amount of not more than 5 thousand tons may be separated from other premises, including from the warehouses for fertilizers and pesticides, by solid (without openings) type 2 fire walls.

Study of the effect of flow rate and decomposition temperature on sensing of ammonium nitrate by carbon nanotubes

Abstract The role of flow rate of carrier gas and decomposition temperature in sensing mechanism of pristine single walled carbon nanotubes (SWCNT) with ammonium nitrate vapor has been studied. For this purpose, sensing studies were carried out at 10 sccm, 25 sccm and 50 sccm flow rates. Three decomposer temperatures (70 °C, 170 °C and 230 °C) were taken while varying the bubbler temperature from 70 °C–120 °C. It was found that both flow rates and decomposition temperature play a vital role in affecting the interaction mechanism between SWCNT and ammonium nitrate vapors. Low decomposition temperature favors the ammonia sensing and higher decomposition temperatures (170 °C and 230 °C) lead to dominance of NOx vapors on account of strong decomposition of ammonium nitrate. These trends were observed irrespective of vapor pressure and concentration of ammonium nitrate vapors. This highlights the significant role of flow rate of carrier gas and decomposition temperature in determining the sensing behavior of ammonium nitrate.

Characterization of Aluminum Powders: IV. Effect of Nanometals on the Combustion of Aluminized Ammonium Nitrate‐Based Solid Propellants

AbstractThis study is devoted to the investigation of the energetic properties of two types of aluminized solid propellants with inert and active binders modified by additives of six different metal nanopowders. The substitution of an inert binder for the active one resulted in significant improvement of energetic properties. However, burning rate regulation become more complicated because the pressure exponent in burning rate law was increased as well. The DSC analysis revealed that the most significant catalytic effects were observed while using Zn, Cu, and Mo powders. Combustion of compositions based on an inert combustible binder and ammonium nitrate was studied in the pressure range 0.1–10.0 MPa. Due to the low combustion rate, no dispersion of burning aluminum particles was observed. During combustion, a single agglomerate of aluminum particles was formed, the mass of which was about 96 % of the initial aluminum mass in the formulation. A comparative analysis of nanosized metal additive effect on the propellant's combustion process was performed. It had been found that the activity of the metal nanopowders depends on the propellant formulation. It had been shown that Al and Zn did not affect the combustion rate of propellant with inert binder but they were effective in compositions with an active binder. Cu and Ni were found to be a good catalyst for the ammonium nitrate and active binder decomposition.

Experimental and theoretical study of the effect of typical halides on thermal decomposition products and energy release of ammonium nitrate based on microcalorimetry and FTIR

Ammonium nitrate (AN) is widely used as a raw material in industry and agriculture. However, the Beirut explosion in Lebanon once again shows that AN has a risk of thermal runaway during storage, especially long-term storage or when some possible substances are mixed therein. This paper focuses on the effect of halides additives, such as sodium fluoride, sodium chloride, sodium bromide and sodium iodide, on the thermal decomposition products and energy release of AN. Especially, the thermal decomposition of AN added with 5% sodium halide and the evolved gases in the thermal decomposition process are investigated by C80 microcalorimetry and FTIR. The results show that all kinds of sodium halides have an effect on the thermal decomposition of AN, although these effects are different. The addition of the halide not only changes the timing of the formation of the AN thermal decomposition characteristic product, but also reduces the heat of the reaction. Combined with optimized kinetic parameters, the engineering prediction of thermal safety was carried out for each type of sample. It is found that sodium iodide is beneficial to the safety of large-scale storage of AN. The research results can provide a reference and guidance for revealing the thermal decomposition mechanism of halide-containing AN and thermal decomposition simulation of AN with additives.

Catalytic effect of lithium titanate oxide doped with praseodymium on thermal decomposition of ammonium nitrate

In this work, lithium titanate oxide (Li4Ti5O12) (LTO) and praseodymium ion doped in lithium titanate oxide (Pr-LTO) were synthesized in a sol–gel simple method, and their catalytic effects on thermal decomposition of ammonium nitrate were reported using thermogravimetric analysis–differential scanning calorimetry (TGA–DSC) techniques. The X-ray powder diffraction, Brunauer–Emmett–Teller surface area measurements, particle size analysis, energy-dispersive X-ray spectroscopy, and scanning electron microscopy techniques were used to identify the structural properties and morphology of LTO and Pr-doped LTO. By doping the praseodymium ion within the LTO spinel structure, the surface area increases (from 204.2 m2 g−1 for LTO semiconductor to 318.9 m2 g−1 for Pr-doped LTO), and the catalytic activity improved. The catalytic effects of LTO and Pr-LTO on the thermal behavior of AN were studied via TG-DSC techniques. The thermal decomposition of pure AN (196–400 °C) shifted to lower temperatures, 154–280 °C, and 131–241 °C, in the presence of LTO and Pr-LTO, respectively. The results showed that the catalytic effects of LTO were improved by praseodymium doping. The Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), Starink, and Tang methods were used to determine activation energies of all AN samples at different conversion values (α). The activation energies of pure AN values were 166 ± 3, 166 ± 2, 166 ± 2, and 162 ± 2 kJ mol−1, while AN/LTO activation energies were 145 ± 2, 144 ± 1, 144 ± 1, and 144 ± 2 kJ mol−1 and finally, those of AN/Pr-LTO were 112 ± 1, 109 ± 2, 110 ± 1, and 110 ± 1 kJ mol−1 using FWO, KAS, Starink, and Tang methods, respectively.

The nature of ammonium nitrate decomposition and explosions

AbstractAmmonium nitrate explosions can cause significant destruction as shown with examples in West, Texas (2013) and Tianjin, China (2015). Yet, ammonium nitrate is available in nearly every garden center, and serves as one of the major fertilizers used throughout the world. Why is it safe to store in a garden center, and yet not safe when stored in wooden framed buildings? This presentation explores the nature of ammonium nitrate decomposition steps using a process simulator where adiabatic, constant pressure, and constant volume scenarios are evaluated. Answers are simple, yet complex. The first decomposition step is endothermic. In other words, there is a natural barrier that needs to be overcome before further decomposition. Further explanations are offered within the paper.

Beirut ammonium nitrate explosion: Are not we really learning anything?

AbstractDisasters caused by large‐scale ammonium nitrate (AN) detonations initiated by fires are well known. The Beirut explosion is again a very sad event with disastrous consequences, but it is not a surprise in the sense of a new phenomenon. It is tragic that calamities with AN occur despite ample guidelines for prevention. Knowledge of the decomposition of AN over the years has greatly progressed, as well how to initiate a detonation with a strong shock wave from a high explosive charge. However, to reproduce the initiation of a detonation by a fire under controlled laboratory conditions never succeeded. The details of the transition of decomposing AN to a detonation remained an open question. Is it a deflagration to detonation mechanism, or is it a shock to detonation one? Knowledge of this may further help process safety measures for the product. The paper will bring research contributions from over a century together, it will develop a scenario how this disaster could happen in Beirut, how much of the AN contributed to the blast, and how further research effort could be beneficial. In addition, the paper estimates the TNT mass equivalent of the AN detonation in Beirut employing three different methods.

Safer emulsion explosives resulting from NOx inhibition

Ammonium nitrate (NH4NO3, AN) is a major commodity chemical. Its principal uses are as a fertilizer and an explosive. Ammonium nitrate is inherently unstable and has been the cause of numerous accidental explosions, sometimes with hundreds of deaths. We have investigated the thermal decomposition and methods of inhibiting the critical reactions of ammonium nitrate. NOx gas was shown to accumulate during an induction period and lead to the generation of nitrous acid (HNO2). Removal of NOx by adsorption or reduction provides alternative approaches to inhibition. In this work we reveal alternative methods to inhibit accidental ammonium nitrate explosions. Layered double hydroxides, such as hydrotalcite, were found to be very effective at inhibiting and delaying detonation by adsorbing NOx. Urea, traditionally used to inhibit explosions, was found to be very ineffective at higher temperatures (above ∼ 80 °C). However, the addition of MnO2 catalysts to urea increased its efficiency at temperatures up to ∼ 130 °C. The urea/MnO2 catalyst system was a highly effective inhibitor for preventing thermal decomposition of ammonium nitrate over a wide temperature range.

Selected magnesium compounds as possible inhibitors of ammonium nitrate decomposition

Abstract Ammonium nitrate (AN) is considered to be a very hazardous and difficult to handle component of mineral fertilizers. Differential thermal analysis coupled with thermogravimetry and mass spectrometry was used to determine the possible inhibiting effect of selected magnesium compounds on thermal decomposition of AN. Each additive was mixed with AN to create samples with AN:magnesium compound mass ratios of 4:1, 9:1 and 49:1. Most of analyzed compounds enhanced thermal stability of ammonium nitrate, increasing the temperature of the beginning of exothermic decomposition and decreasing the amount of generated heat. Magnesium chloride hexahydrate was determined to accelerate the decomposition of AN while magnesium sulphate, sulphate heptahydrate, nitrate hexahydrate together with magnesite and dolomite minerals were defined as inhibiting agents.

Thermal decomposition of ammonium nitrate on rust surface: Risk of low-temperature fire

Ammonium nitrate (AN, NH4NO3) remains classified as an oxidising agent for transport, storage and handling purposes. The safe use of ammonium nitrate requires strict procedures as AN is incompatible with many materials. This study investigates the thermal decomposition of AN on surfaces of rust, potentially present on steel in storage facilities of AN. Infrared spectroscopy and X-ray diffraction served to characterise the mineralogy of the rust, relatively to neat iron (III) oxide. Furthermore, simultaneous thermogravimetric measurements and differential scanning calorimetry afforded the isoconversional analysis that yields the activation energies of the decomposition process. The results, in conjunction with the molecular modelling involving oxygen-deficient Fe2O3 clusters, elucidate the effect of rusts, existing on the surface of corroded steel, in reducing the ignition temperature of AN. This process manifests itself by lowering the activation energies of the initiation channels of the decomposition reactions. On the contrary, pure Fe2O3 does not influence the decomposition of AN. The dehydroxylation of hydrated iron (III) oxide, present on surfaces of rust, exposes the Fe sites that react exothermically with AN, before the material assumes the ordered Fe2O3 phase.

Toward the Mechanistic Understanding of the Additives' Role on Ammonium Nitrate Decomposition: Calcium Carbonate and Calcium Sulfate as Case Studies.

The reaction mechanism involved in the decomposition of ammonium nitrate (AN) in the presence of CaCO3 and CaSO4, commonly used for stabilization and the reduction of explosivity properties of AN, was theoretically investigated using a computational approach based on density functional theory. The presented computational results suggest that both carbonate and sulfate anions can intercept an acid proton from nitric acid issued from the first step of decomposition of AN, thus inhibiting its runaway decomposition and the generation of reactive species (radicals). The reaction then leads to the production of stable products, as experimentally observed. Our modeling outcomes allow for tracing a relationship between the capability of proton acceptance of both carbonate and sulfate anions and the macroscopic behavior of these two additives as inhibitor or inert in the AN mixture.

Multicomponent Nonisothermal Diffusion in Thermal Decomposition of Dispersed Ammonium Nitrate

An analysis of a particular case of the heterogeneous chemical process accompanied by multicomponent nonisothermal diffusion and the thermal decomposition of dispersed ammonium nitrate for the production of nitrous oxide has been carried out. Recommendations on the organization of the process in the reactor are given based on the mathematical model.

Thermal decomposition of ammonium nitrate

SummaryThe thermal decomposition reactions of ammonium nitrate (AN) are reviewed. Both neat AN and AN containing various contaminants are examined, however quantitative kinetics results are not encompassed. Also not included is the performance of AN as the oxidizer in rocket propellants or in explosives such as ANFO. The review is intended to be the most comprehensive review of decomposition reactions of AN since Berthelot's treatise of 1892. Despite hundreds of papers on the topic that have appeared in the intervening years, understanding of decomposition mechanisms remains only modestly more complete than it was in Berthelot's day. However, some additional reaction steps and mechanisms have been identified and these are discussed. Explosions of AN most commonly involve fire as the proximate cause, yet chemical‐mechanism research on the topic is nil. A modest number of studies have explored the potentiation of AN decomposition by organic contaminants. These have, thus far, not produced guidance useful for promoting of safety from fire‐related causes. Contamination from inorganic sources, notably chlorides is better understood and some mechanisms have been studied. The UN classification of AN as an oxidizer, instead of as an explosive, should not be interpreted literally, since AN has been associated with numerous detonation disasters.