Thermal Decomposition Of Ammonia Research Articles

Heat of Combustion and Thermal Decomposition of Ammonium Perchlorate/Sorbitol Solid Propellant with Metal Additives

Ammonium perchlorate (AP) stands out as the predominant oxidizer in solid rocket propulsion systems, while sorbitol, frequently employed as a fuel in sounding rockets, is expected to generate non-hazardous gases during combustion. This study reports on the effect of sorbitol as potential organic green fuel in addition to additive metals on heat of combustion, thermal properties and specific impulse for ammonium perchlorate based solid propellant. The specific impulse was measured using PROPEP 3.0 (Propellant evaluation program). Solid propellant characterization included measuring energy using a bomb calorimeter and conducting thermal analysis using DSC and TGA. Various compositions were prepared by varying the AP and sorbitol content in the propellant, and additive metals like magnesium and ferrite were introduced. The findings reveal that the formulation of 77% ammonium perchlorate into the 23 % sorbitol releases the optimum combustion energy at 2144.47 KJ/mol and lowers the thermal decomposition temperature of AP to 210.38 °C compared to common AP solid propellant formulation. Meanwhile, the addition of 1 % magnesium metal to the mixture significantly improves the combustion energy, propellant performance, and decreases thermal decomposition temperature of the AP/sorbitol. The addition of 0.05% ferrous oxide shows a catalytic capability to decrease the ignition temperature of the sample to 199.15 °C and merge two exothermic peaks into single peak. The main outcome of this work is, AP can interact synergistically with sorbitol mixed with both additive metals by increase the heat combustion, specific impulse, improve AP sensitivity toward heat and lower the thermal decomposition temperature.

Heat of Combustion and Thermal Decomposition of Ammonium Perchlorate/Sorbitol Solid Propellant with Metal Additives

Ammonium perchlorate (AP) stands out as the predominant oxidizer in solid rocket propulsion systems, while sorbitol, frequently employed as a fuel in sounding rockets, is expected to generate non-hazardous gases during combustion. This study reports on the effect of sorbitol as potential organic green fuel in addition to additive metals on heat of combustion, thermal properties and specific impulse for ammonium perchlorate based solid propellant. The specific impulse was measured using PROPEP 3.0 (Propellant evaluation program). Solid propellant characterization included measuring energy using a bomb calorimeter and conducting thermal analysis using DSC and TGA. Various compositions were prepared by varying the AP and sorbitol content in the propellant, and additive metals like magnesium and ferrite were introduced. The findings reveal that the formulation of 77% ammonium perchlorate into the 23 % sorbitol releases the optimum combustion energy at 2144.47 KJ/mol and lowers the thermal decomposition temperature of AP to 210.38 °C compared to common AP solid propellant formulation. Meanwhile, the addition of 1 % magnesium metal to the mixture significantly improves the combustion energy, propellant performance, and decreases thermal decomposition temperature of the AP/sorbitol. The addition of 0.05% ferrous oxide shows a catalytic capability to decrease the ignition temperature of the sample to 199.15 °C and merge two exothermic peaks into single peak. The main outcome of this work is, AP can interact synergistically with sorbitol mixed with both additive metals by increase the heat combustion, specific impulse, improve AP sensitivity toward heat and lower the thermal decomposition temperature.

Influence of the Gas Medium Composition on the Thermal Decomposition of Ammonium, Sodium, Potassium, and Calcium Hypophosphites

Influence of the Gas Medium Composition on the Thermal Decomposition of Ammonium, Sodium, Potassium, and Calcium Hypophosphites

Ammonia thermal decomposition on quartz and stainless steel walls

Ammonia thermal decomposition on quartz and stainless steel walls

Применение продуктов процесса риформинга аммиака для питания двигателя внутреннего сгорания, работающего по циклу Дизеля

This article discusses the use of ammonia reforming to generate hydrogen to be used as an additive to the main type of fuel in the internal combustion engine operating on the Diesel cycle. The feed of the hydrogen additive with the reforming products is implemented through the intake manifold to the engine cylinders. There was carried out a comparative analysis of ammonia with other types of fuel in terms of gross calorific value and hydrogen content. Autothermal reforming of ammonia (NH3 - ATR), combining selective oxidation of ammonia (to nitrogen (N) and water (H2O)) and thermal decomposition of ammonia on a ruthenium catalyst with using air as a source of oxygen is considered. The article provides an assessment of the application of reforming and the effect of the product on the combustion of fuel and exhaust gases. The addition of a fairly small amount of non-carbon reformate, approximately 5 % of the diesel fuel, is quite effective in reducing engine carbon emissions, including CO2, CO and total hydrocarbons (CHx).

Apparent autocatalysis due to liquefaction: thermal decomposition of ammonium 3,4,5-trinitropyrazolate.

Thermal decomposition of solids is often accompanied by autocatalysis, one of the possible causes of which is the formation of a liquid phase. The kinetic model considering the liquefaction of solid reactants under isothermal conditions was proposed by Bawn in the 1950s. The present study reports the application of the Bawn model to the thermolysis of 3,4,5-trinitropyrazole ammonium salt (ATNP) under nonisothermal conditions. The thermal decomposition of ATNP is comprised of low-temperature and high-temperature stages. The low-temperature stage exhibits two distinct exothermic peaks in differential scanning calorimetry (DSC), fitted by two consecutive autocatalytic reactions with a model-fitting kinetic analysis. The liquefaction of the solid reactant during the first reaction is directly observed, giving mechanistic evidence for the Bawn model. We have expressed the Bawn model by a combination of two extended Prout-Tompkins (ePT) equations with the activation energy for the leading liquid-state reaction of Ea = 140.6 ± 0.3 kJ mol-1. The release of ammonia is detected from the beginning, suggesting that the thermal dissociation of ATNP to 3,4,5-trinitropyrazole is an initiation reaction of the thermal decomposition. We proposed ATNP liquefication, leading to the apparent autocatalytic behavior of the first global decomposition reaction, is caused by the eutectic formation between ATNP and 3,4,5-trinitropyrazole, as it was confirmed by DSC analysis of the artificial mixture. The presented approach of the combination of ePT formalism with a Bawn model is generally applicable to a broader range of thermal processes accompanied by liquid phase formation and apparent acceleration.

Solid Acid Electrochemical Cell for the Production of Hydrogen from Ammonia

Solid Acid Electrochemical Cell for the Production of Hydrogen from Ammonia

Plasma-activated catalytic formation of ammonia from N2–H2: influence of temperature and noble gas addition

In the ITER tokamak, injection of nitrogen is foreseen to decrease the heat loads on the divertor surfaces. However, once dissociated, nitrogen atoms react with hydrogen isotopes to form ammonia isotopologues. The formation of tritiated ammonia may pose some issues with regards to tritium inventory and operation duty cycle. In this paper, we report a study of the effect of three parameters of relevance for the fusion environment on the ammonia production, including the presence of a catalytic surface, sample temperature and noble gas addition. Results of ammonia formation from N2/H2 RF plasma (both with and without tungsten or stainless steel surface) show the importance of the presence of a catalyst in the ammonia formation process. By increasing the temperature of the W samples up to 1270 K, ammonia formation demonstrated a continuous decrease due to two major factors. For high temperatures above 650 K and 830 K, for stainless steel and W, respectively, the reduction results from the thermal decomposition of ammonia. For the lower temperature range, the temperature rise leads to the formation of more stable nitrides that do not tend to react further with hydrogen to form NH2 and NH3. Interestingly, the addition of helium or argon to the N2/H2 plasma show opposite effects on the ammonia production. He effectively decreases the percentage of NH3 by acting as a barrier for the surface processes. On the other hand, argon impacts the plasma processes more, probably by increasing the active nitrogen species in the plasma and as a consequence the percentage of formed ammonia.

Thermal decomposition of ammonium perchlorate/exfoliated-graphene and the relationship between activation energy and band gap

ABSTRACTThe thermal decomposition of ammonium perchlorate AP with electrochemically exfoliated graphene flakes (EGF) was studied at different heating rates in nitrogen and the combustion behavior of AP/EGF propellant was evaluated. The exothermic reaction kinetics were studied by simultaneous thermal analysis (STA) in non-isothermal conditions and compare with the thermal decomposition of pure AP applying the same experimental conditions. Using the Kissinger method, the calculated activation energies Ea for the low- and high-temperature exothermic reactions were 87 and 198 kJ/mol for pure AP, contrasting with 91 and 55 kJ/mol obtained from AP with 5 wt% EGF. From our experimental activation energy values together with reported and calculated band gaps Eg, it was found the empirical relationship:where Ea0 corresponds to the activation energy associated with the high-temperature thermal decomposition of pure AP, Eac is the activation energy associated to the high-temperature thermal decomposition of AP-EGF, E0 = 2.7 eV is the catalyst band gap threshold required to activate the electron transfer mechanism and n = 6 is the exponential factor associated to pure AP.

Morphologically controlled synthesis of ferric oxide nano/micro particles and their catalytic application in dry and wet media: a new approach

Morphologically controlled synthesis of ferric oxide nano/micro particles has been carried out by using solvothermal route. Structural characterization displays that the predominant morphologies are porous hollow spheres, microspheres, micro rectangular platelets, octahedral and irregular shaped particles. It is also observed that solvent has significant effect on morphology such as shape and size of the particles. All the morphologies obtained by using different solvents are nearly uniform with narrow size distribution range. The values of full width at half maxima (FWHM) of all the products were calculated to compare their size distribution. The FWHM value varies with size of the particles for example small size particles show polydispersity whereas large size particles have shown monodispersity. The size of particles increases with decrease in polarity of the solvent whereas their shape changes from spherical to rectangular/irregular with decrease in polarity of the solvent. The catalytic activities of all the products were investigated for both dry and wet processes such as thermal decomposition of ammonium per chlorate (AP) and reduction of 4-nitrophenol in aqueous media. The results indicate that each product has a tendency to act as a catalyst. The porous hollow spheres decrease the thermal decomposition temperature of AP by 140 °C and octahedral Fe3O4 particles decrease the decomposition temperature by 30 °C. The value of apparent rate constant (kapp) of reduction of 4-NP has also been calculated.

Effect of ammonia gas addition to the synthesis environment of single-walled carbon nanotubes on their surface chemistry

Effect of ammonia gas addition to the synthesis environment of single-walled carbon nanotubes on their surface chemistry

Ironmaking with Ammonia at Low Temperature

This paper describes the reduction of hematite with ammonia for ironmaking, in which the effect of temperature on the products was examined. The results showed that the reduction process began at 430 °C during heating, and with an increase in temperature, the reduction mechanism changed apparently from a direct reduction of ammonia (Fe(2)O(3) + 2NH(3) → 2Fe + N(2) + 3H(2)O) to an indirect reduction via the thermal decomposition of ammonia (2NH(3) → N(2) + 3H(2), Fe(2)O(3) + 3H(2) → 2Fe + 3H(2)O) at temperatures over 530 °C. The final product obtained at 600 and 700 °C was pure metallic iron, in contrast with that formed at 450 °C, that is, a mixture of metallic iron and iron nitride. The results suggest the possibility of using ammonia as a reducing agent for carbonless ironmaking, which is operated at a much lower temperature than 900 °C in conventional coal-based ironmaking.

Kinetic nitrogen isotope fractionation associated with thermal decomposition of NH 3: Experimental results and potential applications to trace the origin of N 2 in natural gas and hydrothermal systems

Kinetic nitrogen isotope fractionation associated with thermal decomposition of NH 3: Experimental results and potential applications to trace the origin of N 2 in natural gas and hydrothermal systems

Role of surface strain in the subsurface migration of adsorbates on silicon

Modification of silicon surfaces through the insertion of atoms or even small molecular fragments of an adsorbate into a silicon-silicon bond can be affected tremendously by the effects of surface strain. This process takes place as either surface insertion or subsurface insertion, depending on whether the inserted species remains within the topmost layer or undergoes migration into subsurface layers, respectively. Using density-functional-theory cluster calculations, we show that insertion can be both thermodynamically and kinetically favorable if it takes place in such a way that surface strain is mitigated by neighboring surface sites. By considering the thermal decomposition of ammonia $({\text{NH}}_{3})$ adsorbed on a $\text{Si}(100)\text{\ensuremath{-}}2\ifmmode\times\else\texttimes\fi{}1$ surface, we find that insertion mainly depends on the initial distribution of adsorbates and the orientation taken by inserted species with respect to neighboring structures along the surface. These factors seem to greatly affect the subsurface insertion, which can therefore be considered a long-range process. On the other hand, for surface-insertion processes the factors mentioned above are less influential, and insertion has more of a local character. Understanding the factors governing insertion mechanisms may lead to development of more approaches to surface functionalization, where the adsorbates decorating the surface can decompose in a controllable fashion.

Thermal decomposition of ammonia over nickel/gadolinium-doped ceria cermet

A biogas, which contains 60% of methane, 40% of carbon dioxide and a small amount of hydrogen sulfide and ammonia, is a possible fuel of solid oxide fuel cell. Thermal decomposition of 1000 ppm NH 3 in Ar gas was measured over Ni (30 vol%) / Ce 0.8 Gd 0.2 O 1.9 (GDC) electrode attached to dense GDC electrolyte at 673-1073 K. Pyrolysis of NH 3 started above 773 K and reached 94% at 1073 K. Although N 2 gas was detected in the exhaust gas, H 2 gas was not measured. Furthermore, the oxygen partial pressure of the outlet gas was high. These results are discussed with the properties of GDC mixed conductor (oxide ions and electrons).

Enceladus' plume: Compositional evidence for a hot interior

Enceladus' plume: Compositional evidence for a hot interior

High‐energy vibrational modes in nitrogen‐doped ZnO

AbstractWe present results of Raman‐scattering experiments on a series of nitrogen‐doped ZnO epilayers grown by chemical vapor deposition. Nitrogen, a potential acceptor in ZnO, was introduced by the thermal decomposition of ammonia (NH3). We found a structure consisting of at least four lines with frequencies of 2253, 2277, 2291, and 2304 cm–1. They increase in intensity simultaneously with additional modes in the energy range of the host phonons: both scale with the nitrogen concentration in the samples. The origin of the high‐energy structure is tentatively assigned to vibrations of lattice‐bound nitrogen or complexes, composed of the constituents of the dopant NH3. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Thermal behaviour of ammonium molybdate-basic magnesium carbonate system doped with lithium nitrate

The thermal decomposition of ammonium molybdate-basic magnesium carbonate and the solid- solid interactions of the resulting solids were studied for pure and lithium nitrate doped samples. The techniques employed were TG, DTG, DTA and XRD. The composition of pure calcined solids was 0.5 MoO3-MgO and the dopant concentrations were 1, 2 and 4 mol% Li2O. Pure mixed solids were prepared by wet impregnation method using a known mass of finely powdered basic magnesium carbonate with a calculated amount of ammonium molybdate dissolved in the least amount of distilled water. The three doped samples were prepared by treating basic magnesium carbonate with different proportions of lithium nitrate dissolved in the least amount of distilled water prior to impregnation with ammonium molybdate. The results revealed that lithium doping of the reacting solids enhanced their decomposition and stimulated their solid-solid interaction taking place at ≤;500°C yielding MgMoO4 to an extent proportional to its amount added. Opposite effect was observed when the doped solids were heated at >600°C. These results were discussed in terms of an effective increase in the mobility of reacting molybdenum and magnesium species.

Adsorption and thermal decomposition of NH 3 on NiAl(001) and NiAl(111)

Adsorption and thermal decomposition of NH 3 on NiAl(001) and NiAl(111)

Elemental steps in the growth of AlN thin films on NiAl upon thermal decomposition of ammonia

Ammonia adsorption at T=80 K on NiAl(111) and NiAl(001) and subsequent thermal decomposition at elevated temperatures leads to the formation of aluminum nitride (AlN). After annealing to T=600 K, NH3 is dissociated completely and atomic nitrogen is adsorbed on the surface. At temperatures between 800 and 1200 K, an intermediate AlN state is found. The formation process of AlN has finished after annealing to 1200 K. Well-ordered AlN thin films on NiAl(001) and NiAl(111) can be prepared by several cycles of ammonia adsorption at T=80 K and annealing to 1250 K. The films render a distinct low-energy electron diffraction pattern with hexagonal (AlN/NiAl(111)) or pseudo-twelvefold (AlN/NiAl(001)) symmetry. High resolution electron energy loss spectra of ordered AlN films show a Fuchs–Kliewer phonon mode at 865 cm−1 in good agreement with theoretical spectra on the base of the dielectric theory. The electronic gap of the thin AlN films is determined to be Eg≂6.1 eV. Gap states at 1.1 and 5.1 eV were found for AlN/NiAl(111) as well as for AlN/NiAl(001).