Showing papers on "Ammonium perchlorate published in 2022"

Promotion of the Co3O4/TiO2 Interface on Catalytic Decomposition of Ammonium Perchlorate.

Abstract: Supports can widely affect or even dominate the catalytic activity and selectivity of nanoparticles because atomic geometry and electronic structures of active sites can be regulated, especially at the interface of nanoparticles and supports. However, the underlying mechanisms of most systems are still not fully understood yet. Herein, we construct the interface of Co3O4/TiO2 to boost ammonium perchlorate (AP) catalytic decomposition. This catalyst shows enhanced catalytic performance. With the addition of 2 wt % Co3O4/TiO2 catalysts, AP decomposition peak temperature decreases from 435.7 to 295.0 °C and activation energy decreases from 211.5 to 137.7 kJ mol-1. By combining experimental and theoretical studies, we find that Co3O4 nanoparticles can be strongly anchored onto TiO2 supports accompanied by charge transfer. Moreover, at the interfaces in the Co3O4/TiO2 nanostructure, NH3 adsorption can be enhanced through hydrogen bonds. Our research studies provide new insights into the promotion effects of the nanoparticle/support system on the AP decomposition process and inspire the design of efficient catalysts.

First-Principles Investigation of Graphene and Fe2O3 Catalytic Activity for Decomposition of Ammonium Perchlorate.

Abstract: The employment of catalysts is an effective way to improve ammonium perchlorate (AP) decomposition performance during the combustion of composite solid propellants. Understanding the micromechanism of catalysts at the atomic level, which is hard to be observed by experiments, can help attain more excellent decomposition properties of AP. In this study, first-principles simulations based on density functional theory were used to explore the effect of the graphene catalyst and iron oxide (Fe2O3) catalyst on AP decomposition. Considering the transfer of a H atom during AP decomposition, the most stable adsorption sites for aforementioned catalysts were found: the top of the C atom of the graphene surface with the adsorption energy of -0.378 eV and the top of the Fe atom of the Fe2O3 surface with the adsorption energy of -1.596 eV. On the basis of adsorption results, our transition state calculations indicate that, in comparison to control groups, graphene and Fe2O3 can reduce the activation energy barrier by ∼19 and ∼37%, respectively, to promote AP decomposition with a transfer process of a H atom on the catalyst surface. Our calculations provide a way for explaining the micromechanism of the catalytic activity of graphene and Fe2O3 nanocomposites in AP decomposition and guide experimental applications of graphene and Fe2O3 for catalytic reactions.

Mechanistic Insights into the Thermal Decomposition of Ammonium Perchlorate: The Role of Amino-Functionalized Magnetic Nanoparticles.

Abstract: This work reports the characterization and application of two promising nanocatalysts for the thermal decomposition of ammonium perchlorate (AP). To obtain these composite materials, magnetite nanoparticles (Fe3O4 NPs) were functionalized with two different amine derivative groups, tertiary amine (Fe3O4 NPs-A1) and quaternary amine. X-ray photoelectron spectroscopy and differential scanning calorimetry provided mechanistic insights into the thermal decomposition of AP. Furthermore, tertiary and quaternary amine groups play a critical role, where the presence of an extra proton could favor an electron-proton transfer as the rate-determining step. Moreover, Fe3O4 NPs-A1 causes a diminution of the high-temperature decomposition of AP positively to 335 °C, increasing the energy release by 278 J g-1 and consequently affording the lowest activation energy (102 kJ mol-1), indicating a low degree of thermal stability, and accelerating the thermal decomposition of AP.

Potential energetic salts of 5,5′-methylenedi(4H-1,2,4-triazole-3,4-diamine) cation: Synthesis, characterization and detonation performance

Abstract: 1,2,3-Triazole and 1,2,4-triazole have been vigorously used in energetic materials research. Among these two, 1,2,4-triazole has been a widely used backbone in designing new energetic materials with improved performance. This study showed the synthesis of nitrogen-enriched dianionic energetic salts (3–6) based on methylene bridged 3,4-diamino-1,2,4-triazole combined with nitrate, perchlorate, picrate, and azide anions. Structures of 5,5′-methylenedi(4H-1,2,4-triazole-3,4-diamine) and its salts 4 and 5 were confirmed by single-crystal X-ray diffraction studies, showing a strong hydrogen-bonding network owing to the presence of –NH2 groups, numerous oxygen and nitrogen atoms in the structure. The DSC results indicate acceptable thermal stabilities with the observed decomposition temperatures over 180 °C. All the compounds are dense (1.70–1.86 g cm−3) and exhibit reasonable detonation velocities (7.49–8.99 km s−1) and pressures (21.9–28.2 GPa). Interestingly, salt 6 possess detonation velocity comparable to that of RDX. These properties illustrate that incorporating a methylene bridge in a 3,4-diamino-1,2,4-triazole ring can effectively support the progress of mechanically insensitive and thermally stable energetic compounds in future research.

Graphene Oxide–(Ferrocenylmethyl) Dimethylammonium Nitrate Composites as Catalysts for Ammonium Perchlorate Thermolysis

Abstract: Graphene oxide has attracted attention due to its excellent catalytic properties, and it is expected to be used in the field of burning rate catalysis. To investigate the synergistic effect of graphene oxide and ferrocene derivatives, graphene oxide–(ferrocenylmethyl) dimethylammonium nitrate composites (GO–FcMANO3) were prepared and characterized by X-ray photoelectron spectroscopy (XPS), Raman analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM), and their thermal stability and catalytic effect on ammonium perchlorate (AP) were studied by thermogravimetry–differential scanning calorimetry (TG–DSC) techniques. Based on interaction region indicator (IRI) analysis, electrostatic potential (ESP) and energy decomposition analysis on the basis of forcefield (EDA-FF), the dispersion effect is the dominant component of interaction energy, and the contribution of electrostatic attraction is small. The frontier molecular orbitals illustrate that a higher highest occupied molecular orbital (HOMO) energy makes GO–FcMANO3 more susceptible to oxidization and is more conducive to catalyzing AP decomposition. The TG data illustrated that the presence of GO in the composites increased the thermal stability of FcMANO3 during AP decomposition. The catalytic effect of GO–FcMANO3 for AP decomposition manifested in two ways: it advanced the peak temperature in the second stage of AP decomposition and reduced the exothermic temperature width between two stages; it also increased the heat released during AP decomposition. Combined kinetic analysis and the Friedman method provided more detailed information about the catalytic behavior of composites for AP thermolysis, and GO–FcMANO3 composites decreased the Ea of the second stage of AP decomposition. The introduction of GO influenced the decomposition physical model of FcMANO3 for AP catalysis. The first stage of AP decomposition transformed from random nucleation and two-dimensional growth of nuclei model (A2) to random nucleation and three-dimensional growth of nuclei model (A3), and the second stage changed from the phase boundary-controlled reaction (R2) to random nucleation and two-dimensional growth of nuclei model (A2).

Advances in the molecular simulation and numerical calculations of the green high-energy oxidant ADN

Abstract: As a new green energetic oxidant, ammonium dinitramide (ADN) has excellent energy density and produces a low amount of combustion pollution, making it suitable for use in low-pollution solid propellants, space shuttle boosters, space transportation power systems and future strategic and tactical missiles. However, due to its strong hygroscopic properties, the development and applications of ADN have been hindered. To better understand, develop and use ADN, in practical applications, simulations and calculation methods have been proposed, which are efficient, economical and valid methods for studying the properties and potential applications of ADN. In this review, the literature on the simulation of ADN based on density functional theory (DFT), molecular dynamics (MD) calculations, the Monte Carlo (MC) method and numerical calculations is summarized. The research progress on the simulation and numerical calculation of ADN is systematically introduced from five directions: the simulation of the molecular properties of ADN molecules, the simulation of the thermal decomposition of ADN, the simulation of the ADN crystals and their modified ones, the simulation of the interaction between other molecules and ADN molecules, and the numerical simulation of ADN-based propellants used in engines/thrusters, with the aim of deepening the understanding of its basic characteristics, pyrolysis mechanism, MD characteristics and potential application potential of ADN, and providing theoretical support for basic research on this material and its practical applications.