Decomposition Of Ammonium Nitrate Research Articles

Nitrogen‐doped reduced graphene oxide/Fe2O3 hybrid as efficient catalyst for ammonium nitrate

AbstractIn this investigation, we successfully synthesized a hybrid material, N‐rGO@Fe2O3, via a one‐step hydrothermal process, comprising nitrogen‐doped reduced graphene oxide and α‐Fe2O3. Thorough characterization using diverse analytical methods validated its structure. Employing this hybrid composite as a catalyst, we studied its efficacy in the catalytic thermal decomposition of ammonium nitrate (AN). The N‐rGO@Fe2O3/AN composite was prepared using a recurrent spray coating method with 3 % mass of the hybrid material. Thermo‐gravimetric (TG) and differential scanning calorimetric (DSC) analyses were employed to investigate the catalytic effect. Computational assessment of Arrhenius parameters was conducted through isoconversional kinetic approaches. Results from the kinetic analysis allowed the determination of the critical ignition temperature. Furthermore, calorific values for pure AN and N‐rGO@Fe2O3/AN were measured using an oxygen calorimetric bombe, revealing a 41 % reduction in activation energy barrier and a lowering of the critical ignition temperature from 292 °C to 283 °C upon incorporation of the hybrid material. Notably, the surface modification of AN with N‐rGO@Fe2O3 resulted in an increase of 1440 J/g in the observed calorific values. These findings highlight the potential of N‐rGO@Fe2O3 as an effective catalyst, offering promising implications for applications in enhancing ammonium nitrate thermal decomposition.

Tuning combustion and energy in hydroxylammonium nitrate (HAN)-based electrically controlled solid propellant

Solid propellants have been widely applied due to its high energy, rapid reaction, easy storage and convenient equipment. However, the further development of solid propellants has been hindered by the challenges associated with controlling their combustion process. In this research, we presented an electrically controlled solid propellant (ECSP), and its burning rate could be continuously adjusted with voltage. We investigated thermal decomposition behavior and gaseous products of ECSP using thermogravimetry–differential scanning calorimetry-mass spectrometry (TG-DSC-MS). The solid products were analyzed through energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Based on the thermal decomposition behavior, gaseous products, and solid products, it was found that the thermal decomposition process could be divided into two stages: decomposition of ammonium nitrate (AN) and interactions between hydroxylamine nitrate (HAN) and other substances. The electrochemical impedance spectroscopy (EIS) experiments revealed that the electrical conductivity of ECSP increased with the pressure. Significantly, the peak combustion pressure of propellant increased by the rise of voltage from 3.17 MPa (150 V) to 5 MPa (250 V) in closed bomb. In addition, electricity reinforced the burning rate and powder force of propellant. Additionally, the electricity simultaneously affects electric and thermal decomposition processes. Electricity is used to control the burning rate and the total energy produced by propellant combustion. The characteristics of controllable energy has the potential to achieve controllable range of weapons, providing a new direction for development of smart weapons.

Oxidation state of copper species rather than ammonium nitrate decomposition determines the N2O generation during NO reduction with NH3 on Cu-AEI catalyst

Cu-based zeolite has excellent performance for nitrogen oxide removal from diesel vehicle exhaust, but a small amount of N2O is still generated in the selective catalytic reduction (SCR) process, and N2O has a strong greenhouse effect, which promotes the policy formulation of strictly regulating N2O emissions. This work systematically investigated the formation mechanism of low temperature N2O on Cu-AEI catalyst during SCR process. Under both steady and transient state test, the bimodal emission distribution and instantaneous generation behavior of N2O were observed. In addition, the contribution of NH4NO3 pathway to N2O formation at low temperature in standard SCR (SSCR) was demonstrated by temperature programmed desorption experiment, Thermogravimetric analysis and in situ diffuse fourier transform infrared spectroscopy experiment. NO + NH3 titration experiment, Raman and density functional theory calculation showed the role of Cu species in low temperature N2O generation. These results indicate that N2O formation during SSCR process on Cu-AEI at 200 ℃ is not generated through the decomposition path of NH4NO3, but due to the oxidation state of copper species, that is, the side reaction on Cu-peroxo.

Thermal Decomposition Mechanism of Ammonium Nitrate on the Main Crystal Surface of Ferric Oxide: Experimental and Theoretical Studies.

Understanding the decomposition process of ammonium nitrate (AN) on catalyst surfaces is crucial for the development of practical and efficient catalysts in AN-based propellants. In this study, two types of nano-Fe2O3 catalysts were synthesized: spherical particles with high-exposure (104) facets and flaky particles with high-exposure (110) facets. Through thermal analysis and particle size analysis, it was found that the nanosheet-Fe2O3 catalyst achieved more complete AN decomposition despite having a larger average particle size compared to nanosphere-Fe2O3. Subsequently, the effects of AN pyrolysis on the (110) and (104) facets were investigated by theoretical simulations. Through studying the interaction between AN and crystal facets, it was determined that the electron transfer efficiency on the (110) facet is stronger compared to that on the (104) facet. Additionally, the free-energy step diagrams for the reaction of the AN molecule on the two facets were calculated with the DFT + U method. Comparative analysis led us to conclude that the (110) facet of α-Fe2O3 is more favorable for AN pyrolysis compared to the (104) facet. Our study seeks to deepen the understanding of the mechanism underlying AN pyrolysis and present new ideas for the development of effective catalysts in AN pyrolysis.

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.

Analysis of the thermal decomposition of munitions wastewater

AbstractThe thermal decomposition of ammonium nitrate (AN) laden munitions wastewater and comparable control samples were studied under air and nitrogen environments at pressures from 0.1 MPa to 10 MPa. The decomposition enthalpies, measured using a Differential Scanning Calorimeter (DSC), and gaseous emissions, measured using a Fourier‐Transform Infrared Spectrometer (FTIR), were used to evaluate the quality of decomposition. Experiments demonstrated that higher pressures improved the energy yield and reduced the quantities of harmful from the decomposition of all samples. At 10 MPa, experimentally measured decomposition enthalpy from the munitions wastewater was 1.8 MJ/kg, approximately 45 % of its standard enthalpy of decomposition, and NO and accounted for only 0.7 % and 0.08 % of the nitrogen in the sample, respectively. The emissions stream from the wastewater was found to primarily consist of , , and . An analysis of the heat releases and the emissions showed that higher pressures improved the extent and enthalpy of decomposition by preventing premature loss of gaseous intermediates and sensible heat through the pin‐hole crucibles used in the experiments. Moreover, high pressures precluded the evaporation of water and promoted the decomposition of AN via a radical mechanism.

Nanostructured Al-doped maghemite: A low-cost and eco-friendly material tested for methylene blue removal from water and as an accelerator in ammonium nitrate decomposition

Maghemite's properties for roles as removable and reusable catalysts or photocatalysts in reactions that promote green chemistry can be enhanced by doping with other metals. We investigated nanostructured aluminum-doped magnetic iron(III) oxides (AlxFe2-xO3, x = 0.33, 0.67, and 1) synthesized via the autocombustion method and characterized using various techniques. These materials were tested as photocatalysts for methylene blue dye degradation without peroxide and as catalysts for the thermal decomposition of ammonium nitrate. The results revealed that the cubic spinel structure predominates in all compositions. Aluminum doping led to decreased cell parameters and grain size and loss of microgranular structure. Saturation magnetization decreased with aluminum doping, reaching a low value (∼2 emu/g) for x = 1. The optical band gaps were red-shifted with respect to pure maghemite, with values near 2 eV. Among compositions, x = 0.33 showed the best photocatalytic efficiency, closely matching incident light energy (1.95 eV). The highest degradation efficiency was around 37 % after 80 min. The catalytic effect on ammonium nitrate decomposition was strongly correlated with aluminum concentration, turning the reaction exothermic with energy release of 200 and 400 J/g for x = 0.33 and 0.67, respectively.

Thermal stability of systems containing ammonium nitrate and sulfate salts: an experimental study

The overall effect of reactants in the form of sulfates of ammonium, calcium, copper(II), iron(III), manganese(II) and zinc on the thermal behavior of ammonium nitrate has been reported. Thermal stability assessment was performed with the use of thermogravimetric analysis and differential thermal analysis coupled with mass spectroscopy. Interestingly, sulfate anions present in the system were often not sufficient to properly inhibit the decomposition of ammonium nitrate. Sulfate ion and cation supplied with the selected compound significantly influence the studied process. Studied mixtures with ammonium sulfate and calcium sulfate were concluded to show the highest stability. Manganese and iron sulfate salts caused a significant acceleration of the initial thermal decomposition. The addition of these compounds led to visible changes in the process mechanism, which allowed them to be classified as catalysts of the decomposition of ammonium nitrate. Furthermore, small amounts of substances in the system, even those that are generally considered to be inhibitors, worsened the thermal stability of AN. Zinc and copper sulfates, under studied conditions, created double salts that were characterized by a higher thermal stability than pure ammonium nitrate. This property indicates the possibility of obtaining systems containing ammonium nitrate with significantly higher thermal stability, what could potentially have multiple useful applications.

Extraction of humic acid from peat and lignite and the thermal behavior of their mixtures with ammonium nitrate

Due to the positive effect on soil structure and the influence on improving the efficiency of plant roots nutrient uptake, humic acids (HA) are widely considered for fertilizer production. Especially, it seems to be particularly promising to use them as additives in technologies of mineral fertilizer production. One of the common mineral fertilizer components, due to its good water solubility and the presence of nitrogen in two forms, is ammonium nitrate (AN). The aim of this study was to determine the influence of the humic acids extracted from peat and lignite on the thermal decomposition of HA and the thermal decomposition of ammonium nitrate and humic acids mixtures. For the quality assessment of HA, spectroscopic methods (FTIR/ATR and CP/MAS 13C NMR) and analysis of elemental composition were used. The analysis of the spectra showed differences in the degree of humification of humic acids extracted from various raw materials. HA isolated from peat were distinguished by the presence of peptides, polysaccharides, and lignin residues. Elemental analysis showed the higher carbon and sulfur content in the extracted HA compared to the reference samples. The results of the TG-DTA-MS analysis confirmed the influence of differences in the molecular structure of humic acids, especially in the aliphatic and aromatic carbon content, on the thermal decomposition process. Total content of carboxylic and/or hydroxylic functional groups had a significant impact on the start of the decomposition temperature. Their increase visibly influenced the acceleration of the exothermic decomposition of AN.

Thermal stability of ammonium nitrate systems containing d-metal nitrate salts under limited mass transfer conditions

The influence of cobalt, copper, iron(III), manganese and zinc nitrate salts on phase transitions and thermal stability of ammonium nitrate (AN) has been studied and discussed. Differential thermal analysis/differential scanning calorimetry coupled with thermogravimetry and mass spectrometry were used to evaluate the stability of analyzed systems. Each nitrate salt was appropriately mixed with ammonium nitrate to create samples with AN:salt mass ratios of 4:1, 9:1 and 49:1. It was concluded that the addition of every studied nitrate influenced phase transitions of AN. Most analyzed salts decreased the stability of AN by accelerating its exothermic decomposition process. Iron and cobalt nitrates were defined as the most hazardous additives, resulting in a creation of a highly destabilized mixture. Copper and manganese nitrates were also defined as catalysts of the AN decomposition process, lowering the initial decomposition temperature and increasing the rate of the observed process. Zinc nitrate hexahydrate was the only salt considered to be relatively neutral in such systems, especially in small amounts. The study allowed to define the influence of selected metal nitrate salts on the thermal stability of AN under conditions that are considered as potentially unsafe for such systems.

Spectroscopic Study of Five-Coordinated Thermal Treated Alumina Formation: FTIR and NMR Applying.

This work represents research into materials designed to improve the environment. The study was carried out on aluminum hydroxide xerogels and alumina catalysts obtained by the Controlled Double Jet Precipitation (CDJP) process at different pH values. It has been shown that the pH of the CDJP process determines the content of aluminum-bound nitrate ions in the aluminum hydroxide. These ions are removed at a higher temperature than the decomposition of ammonium nitrate. The high content of aluminum-bound nitrate ions determines the structural disorder of the alumina and the high content of the penta-coordinated alumina catalyst.

Effects of urea on the thermal decomposition behavior of ammonium nitrate: A reliable thermal safety performance enhancer

To address the actual disaster of thermal decomposition and explosion of ammonium nitrate (AN), a commonly used raw material, urea was selected as an additive to study its effect on the thermal decomposition of AN through experimental and theoretical methods. The thermal decomposition kinetics, energy release, self-reaction properties of adiabatic environments, and escaping gaseous products have all been discussed. It was found that urea has an inhibitory effect on the crystalline transformation of AN stored at room temperature, which is beneficial to its thermal safety. The results showed that urea increased the activation energy of the thermal decomposition of AN, raised the temperature of the initial reaction and reduced heat generation. Furthermore, the action mechanism of urea is suggested to be heat absorption by its thermal decomposition and the escape of ammonia. Finally, the study carried out an engineering assessment of the thermal safety of AN under the action of urea and found that the addition of urea greatly enhanced the thermal safety performance of stored and transported AN. The comprehensive analysis concluded that a small dose of urea could be added to enhance the thermal stability of AN without affecting its normal function.

Comparative study of the thermal decomposition of ammonium nitrate in the presence of nanocrystalline copper ferrite

This study aims to investigate the catalytic effects of nanocrystalline copper ferrite (CF) on the thermal decomposition of ammonium nitrate.

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.