Showing papers on "Ammonium perchlorate published in 2015"

Graphitic carbon nitride (g-C3N4) as a metal-free catalyst for thermal decomposition of ammonium perchlorate

Abstract: Development of metal-free and environmentally friendly catalysts is of great significance for thermal decomposition of ammonium perchlorate (AP). In the present study, graphitic carbon nitride (g-C3N4) has been demonstrated to possess intrinsic catalytic activity for thermal decomposition of AP. Adding 10 wt% g-C3N4 to AP decreases the decomposition temperature by 70 °C and the activation energy (Ea) by 119.8 kJ mol−1. Moreover, the apparent decomposition heat of AP in the presence of 10 wt% g-C3N4 reaches up to 1362.6 J g−1, which is much higher than that of the pure AP (574.2 J g−1). Furthermore, a possible catalytic mechanism for the thermal decomposition of AP with g-C3N4 has been proposed. The unique surface structure of g-C3N4 consisting of triazine units connected by planar amino groups can be favourable for the adsorption and diffusion of perchloric acid via Lewis acid–base interactions, which decreases the reaction activation energy of AP and facilitates the formation of superoxide radical anions (˙O2−) and holes (h+), leading to the oxidation reaction of ammonia more completely in the catalytic decomposition of AP.

Green synthesis of Co3O4 nanoparticles and their applications in thermal decomposition of ammonium perchlorate and dye-sensitized solar cells

Abstract: In this paper, we report on the green synthesis of cobalt oxide nanoparticles (Co 3 O 4 NPs) using leaves extract of plant Calotropis gigantea and characterize by X-ray diffraction (XRD), UV–vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The green synthesized Co 3 O 4 NPs showed excellent catalytic effect on the thermal decomposition of ammonium perchlorate (AP) and burning rate of composite solid propellants (CSPs). Kinetics of slow and rapid thermal decomposition has been investigated by isoconversional and ignition delay methods, respectively. Moreover, the electrocatalytic performance of green synthesized Co 3 O 4 NPs in dye-sensitized solar cells (DSSC) has also been evaluated. The cyclic voltametry measurement shows good electrocatalytic activity of Co 3 O 4 NPs toward the reduction of I 3 − to I − ions.

Boron nitride encapsulated copper nanoparticles: a facile one-step synthesis and their effect on thermal decomposition of ammonium perchlorate

Abstract: Reactivity is of great importance for metal nanoparticles used as catalysts, biomaterials and advanced sensors, but seeking for high reactivity seems to be conflict with high chemical stability required for metal nanoparticles. There is a subtle balance between reactivity and stability. This could be reached for colloidal metal nanoparticles using organic capping reagents, whereas it is challenging for powder metal nanoparticles. Here, we developed an alternative approach to encapsulate copper nanoparticles with a chemical inertness material—hexagonal boron nitride. The wrapped copper nanoparticles not only exhibit high oxidation resistance under air atmosphere, but also keep excellent promoting effect on thermal decomposition of ammonium perchlorate. This approach opens the way to design metal nanoparticles with both high stability and reactivity for nanocatalysts and their technological application.

Sol–gel method to prepare graphene/Fe 2 O 3 aerogel and its catalytic application for the thermal decomposition of ammonium perchlorate

Abstract: Graphene/Fe2O3 (Gr/Fe2O3) aerogel was synthesized by a simple sol–gel method and supercritical carbon dioxide drying technique. In this study, the morphology and structure were characterized by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and nitrogen sorption tests. The catalytic performance of the as-synthesized Gr/Fe2O3 aerogel on the thermal decomposition of ammonium perchlorate (AP) was investigated by thermogravimetric and differential scanning calorimeter. The experimental results showed that Fe2O3 with particle sizes in the nanometer range was anchored on the Gr sheets and Gr/Fe2O3 aerogel exhibits promising catalytic effects for the thermal decomposition of AP. The decomposition temperature of AP was obviously decreased and the total heat release increased as well.

Preparation and characterization of graphene aerogel/Fe2O3/ammonium perchlorate nanostructured energetic composite

Abstract: A novel graphene aerogel (GA)/ferric oxide (Fe2O3)/ammonium perchlorate (AP) nanostructured energetic composite was prepared by a facile sol–gel method and supercritical carbon dioxide drying technique. In this study, the morphology and structure of the obtained GA/Fe2O3/AP nanostructured energetic composite were characterized by scanning electron microscopy, nitrogen sorption tests and X-ray diffraction. The thermal decomposition characteristic was investigated by thermogravimetry and differential scanning calorimetry. The results demonstrated that Fe2O3 and AP dispersed in the as-prepared energetic composite at nanometer, showing promising catalytic effects for the thermal decomposition of AP. For the nanostructured energetic composite, GA and Fe2O3 played a catalytic role in the thermal decomposition of AP. Only one decomposition step was observed, instead of two, which was common in previous report. The decomposition temperature of the nanocomposite was obviously decreased as well. Moreover, the total heat release increased significantly. The experimental results showed that the as-prepared GA/Fe2O3/AP nanostructured energetic composite could be a promising candidate material for the solid propellants. A novel GA/Fe2O3/AP nanostructured energetic composite was prepared by a facile sol–gel method and supercritical carbon dioxide drying technique. Fe2O3 and AP nanoparticles are added and trapped in the porous three-dimensional networks of GA. The decomposition temperature of the nanocomposite was obviously decreased, and the total heat release increased significantly. Moreover, the thermal decomposition mechanism of the nanocomposite was analyzed.

Low-migratory ionic ferrocene-based burning rate catalysts with high combustion catalytic efficiency

Abstract: Alkyl substituted ferrocenes can catalyze the burning of composited solid propellants efficiently. These non-polar and volatile ferrocenes, however, migrate to the surface of the propellants during prolonged storage, which would alter the designed burning parameters, and more seriously cause unexpected explosions. To tackle this problem, twelve ionic ferrocene derivatives bearing methylimidazolium and methyltriazolium substituents with nitrate and picrate anions as new ionic ferrocene-based burning rate catalysts were synthesized. The compounds were fully characterized by 1H NMR, 13C NMR and elemental analysis. Ten of them were characterized by single-crystal X-ray diffraction. Compounds 2 and 3 crystallize in the monoclinic space group P2(1)/n and P2(1)/c, respectively. Compounds 4·H2O, 6·1/2H2O, 8–10 and 12 crystallize in the triclinic space group P. Compounds 7 and 11 crystallize in the orthorhombic space group Pna21 and Pna2(1), respectively. Cyclic voltammetry investigations revealed that all the compounds exhibit quasi-reversible redox systems. Migration studies confirmed that the migration of these ionic ferrocenes is much slower than that of 2,2-bis(ethylferrocenyl)propane. The migration trend of the compounds is dependent on molecular structures of the ionic ferrocenes and that shorter alkyl chain lengths in the heterocyclic rings lead to slower migration rates. Their high thermal stability was determined by TG and DSC analyses (peak temperatures >172 °C). The thermal degradation of ammonium perchlorate (AP) catalyzed by the new burning-rate catalysts was evaluated by DSC methods. In the presence of nitrate (1–6) in 4 wt% or picrate (7–12) in 5 wt%, the peak decomposition temperature of AP shifts left significantly while the released heat increases dramatically. The catalytic activity of an ionic compound with a triazole ring in its cation is higher than its corresponding analog with an imidazole ring and the catalytic activity of a nitrate is generally higher than its picrate counterpart.

Catalytic activity of Co 3 O 4 nanomaterials with different morphologies for the thermal decomposition of ammonium perchlorate

Abstract: Nano-Co3O4 with different morphologies was successfully synthesized by annealing CoC2O4ċ2H2O precursors. The as-obtained samples were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and low-temperature nitrogen adsorption-desorption. It was found that the volume ratio of N,N-dimethylformamide (DMF) and water played an important role in the formation of cobalt oxalate precursors with different morphologies. After calcination in air, cobalt oxalate precursors converted to Co3O4 nanomaterials while their original morphologies were maintained. The catalytic effect was investigated for nano-Co3O4 with different morphologies on the thermal decomposition of ammonium perchlorate (AP) by differential scanning calorimeter (DSC). The results indicated that all products showed excellent catalytic activity for thermal decomposition of AP and the Co3O4 nanorods with larger BET surface area and pore volume had the highest catalytic activity.

One-step synthesis of SnO2 nanoparticles-loaded graphitic carbon nitride and their application in thermal decomposition of ammonium perchlorate

Abstract: SnO2 nanoparticle-loaded graphitic carbon nitride (SnO2NPs/g-C3N4) hybrids were successfully synthesized by one-pot calcination. Various characterization means and detection techniques were used to analyse their structure and properties. It was found that SnO2 NPs possess the synergistic effect on g-C3N4. The addition of SnO2 NPs not only increases the surface of g-C3N4 but provides extra electrons. Having added 10 wt% SnO2NPs/g-C3N4 hybrids, the onset decomposition temperature of ammonium perchlorate (AP) was decreased to 352.2 °C. Furthermore, considering the band gap of g-C3N4 (Eg = 2.7 eV) and SnO2 (Eg = 3.6 eV), the conduction band electrons (ecb− and valence band holes (h+)) were generated on their surface upon heat excitation. In addition, on the basis of the synergistic effect (the ecb− would transfer from g-C3N4 to SnO2) of SnO2, a possible synergistic mechanism was proposed to understand the thermal decomposition of AP.

Shape-controlled synthesis of cobalt particles by a surfactant-free solvothermal method and their catalytic application to the thermal decomposition of ammonium perchlorate

Abstract: Submicro-Co particles with different morphologies were successfully synthesized by a simple solvothermal and surfactant-free approach. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed that the average size was approximately 2 μm and the microstructure of the as-synthesized particles could be regulated by the contents and ratio of Co2+/NaOH. The phase structure and composition of the as-synthesized samples were characterized by X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS) and Raman spectroscopy. The results indicated that the as-synthesized Co particles were covered with a thin layer of CoO. Based on time-dependent experiments, the growth mechanisms of three kinds of typical structures and morphologies were proposed. The magnetic hysteresis loops showed ferromagnetic characteristics and the best saturation magnetization (Ms) and coercivity (Hc) were found to be 162.5 emu g−1 and 104.3 Oe, respectively. Moreover, the exothermic peak of ammonium perchlorate thermal decomposition shifted towards the lower temperatures by 108 °C through addition of 4% Co particles, indicating that the Co particles exhibited a good catalytic effect for potential applications.

Study on the Synthesis and Interfacial Interaction Performance of Novel Dodecylamine‐Based Bonding Agents Used for Composite Solid Propellants

Abstract: An effective pathway was explored to design and select proper bonding agents that could effectively improve the interfacial interactions between bonding agents and solid particles, with three novel synthesized alkyl bonding agents, dodecylamine-N,N-di-2-hydroxypropyl-acetate (DIHPA), dodecylamine-N,N-di-2-hydroxypropyl-hydroxy-acetate (DIHPHA) and dodecylamine-N,N-di-2-hydroxypropyl-cyano-acetate (DIHPCA), as examples. Molecular dynamics simulation was applied to compare unit bond energies of these bonding agents with the [110] crystal face of ammonium perchlorate (AP) and the [120] crystal face of hexogen (RDX). The infrared test was used to characterize the interfacial interactions of these bonding agents with AP or RDX. XPS test was applied to calculate the adhesion percentage of the bonding agents on the surface of precoated AP or RDX particles. All of the above results indicated that these three bonding agents have strong interfacial interactions with AP or RDX in the order of DIHPCA>DIHPHA>DIHPA. The prepared three bonding agents were used in HTPB/AP/RDX/Al propellants, and their effects on tensile strength (σ), elongation under maximum tensile strength (em), elongation at breaking point of the propellant (eb) and adhesion index (Φ) of the propellant were studied. The results show that the bonding agents improve the mechanical properties of the propellant in the order of DIHPCA>DIHPHA>DIHPA. The methods found from theoretical design, materials synthesis, and mechanistics studies up to practical application show effective guiding significance for choosing the proper bonding agent and improving the interfacial interactions between the solid particles and binder matrix.

Hierarchical ZnO hollow microspheres with exposed (001) facets as promising catalysts for the thermal decomposition of ammonium perchlorate

Abstract: Hierarchical porous ZnO hollow microspheres assembled from nanorods with exposed (001) facets on their external surface were prepared in one pot by a simple low-temperature wet chemical method without templates. The formation mechanism based on their chemical self-transformation was proposed. Importantly, these ZnO hollow microspheres exhibited better catalytic activity for the thermal decomposition of ammonium perchlorate (AP) than the dispersed ZnO nanorods by lowering its decomposition temperature from 409 °C to 308 °C and decreasing its activation energy from 150 ± 14 kJ mol−1 to 63 ± 7 kJ mol−1. This is attributed to their hierarchical porous structure with larger surface area and exposed (001) facets dominant on their external surface, which can facilitate the adsorption of HClO4 and NH3 gases from AP and the formation of active oxygen. The active oxygen will promote the oxidation reaction of NH3 more completely in AP decomposition, thus leading to a significant decrease in decomposition temperature and activation energy. Therefore, this work could provide a new insight into the thermal decomposition mechanism of AP catalyzed by hierarchical micro/nanostructures of metal oxides.

Thermal decomposition of HTPB/AP and HTPB/HMX mixtures with low content of oxidizer

Abstract: In this paper, hydroxyl-terminated polybutadiene (HTPB)/ammonium perchlorate (AP) and HTPB/cyclotetramethylene tetranitramine (HMX) mixtures with low content of oxidizer were prepared, and the thermal decomposition process of these mixtures was investigated with TG-FTIR and Raman spectrum. The experimental results indicated that during the thermal decomposition process under an inert atmosphere, HTPB and the two oxidizers could both decompose into gaseous products completely, while the mixture of HTPB and the two oxidizers produced some solid residue with carbon as the main ingredient; unlike the thermal decomposition of HTPB under argon atmosphere, HTPB cannot decompose completely under air or oxygen atmosphere, and the more the concentration of oxygen, the more the solid residue produced. Decreasing the content of oxidizer reacting with HTPB may improve the combustion performance of fuel-rich propellants by increasing the combustion temperature and the percentage of gaseous products. The results of this paper can provide the useful information for improving the combustion performance of fuel-rich propellants.

Synthesis, characterization and catalytic activity of Al/Fe2O3 nanothermite

Abstract: Nanothermites have attracted much attention owing to their excellent sensitivity and catalytic activity. In this paper, Fe2O3 is used to achieve Al/Fe2O3 nanothermite by mixing nano-Al with Fe2O3 nanopowder. X-ray diffraction, field emission gun scanning electron microscopy, energy dispersive X-ray spectra, and transmission electron microscopy were employed to study the structural features of the nanothermite. Its catalytic activity was investigated on the thermal decomposition of ammonium perchlorate (AP) and composite solid propellants (CSPs) using thermogravimetric analysis (TG), TG coupled with differential scanning calorimetry, and ignition delay measurements. Kinetics of thermal decomposition of AP with and without Al/Fe2O3 has also been investigated using model fitting and isoconversional methods which have been applied to data for isothermal TG decomposition. Activation energy values have been found to be lowered in case of AP + Al/Fe2O3. The results revealed enhancement in the rate of decomposition of AP and CSPs.

Thermal decomposition of AP/HTPB propellants in presence of Zn nanoalloys

Abstract: Composite solid propellants were prepared with and without nanoalloys (Zn–Cu, Zn–Ni, Zn–Fe), where nanoalloys are used as catalyst. Catalytic properties of these nanomaterials measured on ammonium perchlorate/hydroxyl-terminated polybutadiene propellant by thermogravimetric analysis and differential thermal analysis. Both experimental results show enhancement in the thermal decomposition of propellants in presence of nanoalloys. In differential thermal analysis method, experiments had done at three heating rates, β1 = 5°, β2 = 10°, β3 = 15° per minute. Calculation of activation energy of high temperature decomposition step was done by using following Kissinger equation. Zn–Cu was found to be the best.

Iron Nanoparticle Additives as Burning Rate Enhancers in AP/HTPB Composite Propellants

Abstract: Burning rate measurements were carried out for ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) composite propellants with iron (Fe) nanoparticles as additives. Experiments were performed in a strand burner at pressures from 0.2 to 10 MPa for propellants containing approximately 80 % AP and Fe nanoparticles (60–80 nm) at concentration from 0 to 3 % by weight. It was found that the addition of 1 % Fe nanoparticles increased burning rate by factors of 1.2–1.6. Because Fe nanoparticles are oxidized on the surface and have high surface-to-volume ratio, they provide a large surface area of Fe2O3 for AP thermal decomposition catalysis at the burning propellant surface, while also providing added energy release due to the oxidation of nanoparticle sub-shell Fe. The increase in burning rate due to Fe nanoparticle content is similar to the increase in burning rate caused by the addition of iron oxide (Fe2O3) particles observed in prior literature.

Zinc(II) and Cadmium(II) Complexes of 5-Ferrocenyl-1H-tetrazole: Synthesis, Structures, and Catalytic Effects on Thermal Decomposition of Energetic Compounds†

Abstract: Alkyl-substituted ferrocenes as ferrocene-based burning rate (BR) catalysts in composite solid propellants have high migration tendency and strong volatility during processing and long-time storage of the propellants. For developing low-migratory alternatives, zinc(II) and cadmium(II) complexes, [Zn(phen)3](FcTz)2·9H2O (1), [Cd(phen)2(H2O)2](FcTz)2 (3), and [Cd(bpy)2(FcTz)2]·H2O (4) (bpy = 2, 2′-bipyridine; phen = 1, 10-phenanthroline; FcTz = 5-ferrocenyl-1H-tetrazolate), derived from 5-ferrocenyl-1H-tetrazole (HFcTz) were synthesized and structurally characterized. Compound 4 was also studied by density functional theory calculations (DFT). Additionally, a few single-crystals of [Zn(phen)2(H2O)2](FcTz)2 (2) suitable for single-crystal X-ray diffraction formed and therefore only its crystal structure was analyzed. The cyclic voltammetry results suggested that 1, 3, and 4 are quasi-reversible redox systems. The TG analysis showed they are of highly thermal stability when their lattice water molecules are not taken into account. Their catalytic performances for thermal decomposition of ammonium perchlorate (AP), 1, 3,5-trinitro-1, 3,5-triazacyclohexane (RDX), and 1, 2,5, 7-tetranitro-1, 3,5, 7-tetraazacyclooctane (HMX) were accessed by DSC/TG techniques. Their optimum contents in AP, RDX, and HMX are 5 wt- %, 5 wt- %, and 2 wt- %, respectively. They exhibit highly catalytic activities in thermal degradation of AP and RDX.

Fuel–oxidizer mixtures: their stabilities and burn characteristics

Abstract: A survey of the stability and performance of eleven solid oxidizers and thirteen fuels was performed by differential scanning calorimetry, simultaneous differential thermolysis, and hot-wire ignition. Sugars, alcohols, hydrocarbons, benzoic acid, sulfur, charcoal, and aluminum were used as fuels; all fuels except charcoal and aluminum melted at or below 200 °C. It was found that the reaction between the oxidizer and the fuel was usually triggered by a thermal event, i.e., melt, phase change, or decomposition. Although the fuel usually underwent such a transition at a lower temperature than the oxidizer, the phase change of the fuel was not always the triggering event. When sugars or sulfur were the fuels, their phase change usually triggered their oxidation. However, three oxidizers, KNO3, KClO4, and NH4ClO4, tended to react only after they underwent a phase change or began to decompose, which meant that their oxidization reaction, regardless of the fuel, was usually above 400 °C. KClO4–fuel mixtures decomposed at the highest temperatures, often over 500 °C, with the ammonium salt decomposing almost 100 °C lower. Mixtures with ammonium nitrate (AN) also decomposed at much lower temperatures than those with the corresponding potassium salt. With the exception of the oxidizers triggered to react by the phase changes of the polyols and sulfur, the oxidizer–fuel mixtures generally decomposed between 230 and 300 °C, with AN formulations generally decomposing at the lowest temperature. In terms of heat release, potassium dichromate–fuel mixtures were the least energetic, generally releasing less than 200 J g−1. Most of the mixtures released 1000–1500 J g−1, with potassium chlorate, ammonium perchlorate, and AN releasing significantly more heat, around 2000 J g−1. When the fuel was aluminum, most of the oxidizers decomposed below 500 °C leaving the aluminum to oxidize at over 800 °C. Only two oxidizers reduced the temperature of the aluminum exotherm—chlorate and potassium nitrite. To go to temperatures above 500 °C, unsealed crucibles were necessary, and with these containers, the endothermic volatilization of reactants and products effectively competed against the exothermic decomposition so that heat release values were artificially low.

Preparation of Nano‐Sized Copper β‐Resorcylate (β‐Cu) and its Excellent Catalytic Activity for the Thermal Decomposition of Ammonium Perchlorate

Abstract: Copper β-resorcylate (cupric 2,4-dihydroxy-benzoate, β-Cu) nanoparticles were prepared at a large-scale via a facile wet mechanical grinding method and vacuum freeze-drying process. The as-prepared β-Cu nanoparticles were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). The results revealed that the nano-sized β-Cu is of semi-spherical shape and of homogeneous distribution, with a fairly uniform size of 100 nm. The formation mechanism of β-Cu nanoparticles in the whole process was discussed in detail. Furthermore, the catalytic properties of as-obtained β-Cu were investigated. The TG/DSC study showed that nano-sized β-Cu could be a promising additive for accelerating the thermal decomposition of ammonium perchlorate (AP).

TeO2 Nanoparticle Loaded Graphitic Carbon Nitride Hybrids: Their Preparation and Catalytic Activities in the Thermal Decomposition of Ammonium Perchlorate

Abstract: TeO2 nanoparticle-loaded graphitic carbon nitride hybrids (TeO2NPs/g-C3N4) were successfully prepared by a calcination strategy Various characterization and detection techniques were used to analyze its structure and properties It was found that upon the addition of 10 wt-% of the as-prepared hybrids, the onset decomposition temperature of ammonium perchlorate (AP) decreased by 1044 °C In addition, the addition of TeO2 NPs resulted in an increase in the surface area up to 88 m2 g–1 for g-C3N4, which is three times larger than that of the bulk g-C3N4 (28 m2 g–1) Furthermore, g-C3N4 reacted with HClO4 by Lewis acid–base interaction, which resulted in separation of HClO4 from AP lattice Notably, the separation of the HClO4 gas molecule led to continued decomposition of AP, as this decomposition reaction is reversible With this in mind, a catalytic mechanism based on Lewis acid–base interaction was proposed to illustrate the catalytic process in the thermal decomposition of AP