Aluminium/tin (IV) oxide thermite composite: sensitivities and reaction propagation

ABSTRACT

Thermites are energetic composites made of metal and oxidizer particles that react according to an exothermic reaction and release large amounts of energy. Many possible metal and oxidizer couples exist in the literature. Here, the performance of the aluminum reducing metal and tin (IV) oxide (SnO₂) combination was reported as a function of the fuel/oxidizer mass ratio. The Al/SnO₂ energetic composite, in stoichiometric conditions, was insensitive to impact, sensitive to friction and extremely sensitive to electrostatic discharge. The combustion velocity was determined to be close to 600 m/s. Changing the stoichiometry affected both the sensitivity thresholds to the friction test (160 N to > 360 N) and flame propagation velocity (480–588 m/s) of the Al/SnO₂ composite. These results are reported for the first time.     

Copper (II) complexes of 1-methyl-5-aminotetrazole with different energetic anions: syntheses,crystal structures and properties

ABSTRRACT

Three energetic copper (II) complexes, [Cu(1-MAT)₂(HDNBA)₂](DNBA)₂ (1), [Cu(1-MAT)₂](PA)₂ (2) and [Cu(1-MAT)₄(H₂O)₂](ClO₄)₂ (3) [1-MAT: 1-methyl-5-aminotetrazole; HDNBA: 3,5-dinitrobenzoic acid; PA: picric acid] were synthesized and characterized. The X-ray single-crystal diffraction results illustrate that the structure of the coordination compounds 1, 2 and 3 belong to the P21/c, P2₁2₁2 and C2/m space group, respectively. The central copper ion forms a hexacoordinated octahedral structure with N and O atoms. All of them possess good thermal stability, with the thermal decomposition temperatures of 254°C (1), 272°C (2) and 322°C (3), respectively, due to their plenty of coordination bonds, intramolecular and intermolecular H-bonds. According to the results of impact sensitivity and friction sensitivity, these compounds are insensitive to impact (>40 J) and friction (>360 N), except the impact sensitivity of 3 is 2.7 J. The measured constant volume combustion energies of 1, 2 and 3 are 13480, 3537 and 7442 kJ mol^?1, respectively.     

Ammonium perchlorate-based molecular perovskite energetic materials: preparation,characterization, and thermal catalysis performance with MoS2

ABSTRACT

In this study, ammonium perchlorate (AP)-based molecular perovskite structural high-energetic materials (H₂dabco)[NH₄(ClO₄)₃] (DAP) were fabricated and their catalytic performance upon the addition of MoS₂ nanosheets was investigated. The DAP samples were succesfully prepared via a self-assembly reaction and their morphology and structure were characterized via scanning electron microscopy, X-ray diffractometry, and Fourier transform infrared spectroscopy. The thermal decomposition performance of a pure DAP sample and of a mixture of DAP with MoS₂ nanosheets were analyzed via differential scanning calorimetry. The results show that DAP has a high thermal stability at its initial decomposition temperature of 319.8°C, and that its apparent decomposition heat measures 4199 J/g. This value is higher than for AP (829.7 J/g). Furthermore, the thermal decomposition peak temperature of DAP upon the addition of 1 wt% and 3 wt% MoS₂ nanosheets decreases from 394.4°C to 343.3°C and 328.8°C, respectively. The investigation of the catalysis thermal performance of DAP may foster its practical application in composite propellant.     

Electrospray Preparation and Properties of RDX/F2604 Composites

This article was an attempt to prepare energetic materials based on 1, 3, 5-trinitro-1, 3, 5-triazinane (RDX) using the electrospray method to expand its scope of application. After preparation, the morphologies and crystal structures of the samples were characterized, and thermal decomposition properties as well as mechanical sensitivities were also investigated. The sizes of the composite particles were found to be in the range of 2–4 μm. Compared with raw RDX, the crystal structures of the RDX/F2604 composites were unchanged. The activation energy of the composites was decreased with the increase of the F2604 mass ratio, and 10 wt% F2604 composites had the lowest activation energy. In the mechanical sensitivity aspect, the impact sensitivity and friction sensitivity of the RDX/F2604 composites were lower than those of raw RDX. 10 wt% F2604 composites had the highest H₅₀ (65.9 cm) and the lowest friction sensitivity (76%).     

Study on flame propagation of premixed N2O–NH3/N2O–NH3–C3H8 in cylindrical vessels

The flame propagation behavior of premixed N₂O–NH₃/N₂O–NH₃–C₃H₈ was experimentally investigated in elongated vented cylindrical vessels with central ignition. The effect of vessel diameter and propane concentration ([C₃H₈] = 1.96–7.41 wt.%) on the process of flame acceleration was studied and discussed. The results revealed that the maximum value of flame acceleration rate was found in the cylindrical vessel with an inner diameter of 7 mm, followed by 5 mm, 10 mm, and 15 mm. At a constant vessel diameter, the rate of flame acceleration was noticeably improved by adding propane ([C₃H₈] = 1.96–3.85 wt.%) to the premixed N₂O–NH₃. However, a further increase in the propane fraction up to 5.66%, caused a decline in the flame acceleration rate, probably as a consequence of a combined effect between the reduction of oxygen and greater dilution of the ammonia in the total concentration.     

Hydrothermal synthesis of unsupported MoS2 as catalyst for hydrodesulfurization of gas oil

Hydrothermal synthesis with ammonium heptamolybdate and thiourea as precursors was used to obtain an unsupported MoS₂ catalyst. The catalyst was obtained in sulfide state directly at mild reaction conditions (i.e., 180°C during 5 h). After catalyst was obtained, it was characterized through nitrogen physisorption, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Catalytic evaluation was carried out in a batch reactor at 350°C, 55 bar of hydrogen pressure, 750 rpm, and 3 h of reaction time using straight-run gas oil (SRGO) as feedstock. A commercial CoMo/Al₂O₃ catalyst was used for comparison of activity. The synthesized catalyst was slightly more active toward SRGO hydrodesulfurization than commercial one keeping constant the sulfur removal after two runs.     

A New Synthetic Route for 3,3′-Bis(fluorodinitromethyl)difurazanyl Ether (FOF-13) and Its Energetic Properties

A new protocol for preparation of 3,3-bis(fluorodinitromethyl)difurazanyl ether (FOF-13) was developed. It involves (i) nitration of 3,3’-bis(chlorohydroxyminomethyl)difurazanyl ether with N₂O₅/MeCN to give 3,3-bis(chlorodinitromethyl)difurazanyl ether (4), (ii) reduction of 4 with KI/MeOH to obtain potassium salt of 3,3’-bis(dinitromethyl)difurazanyl ether (6) and (iii) fluorination of 6 with XeF₂ in anhydrous acetonitrile to form the desired FOF-13. FOF-13 was fully characterized by IR, ¹³C NMR, ¹⁹F NMR, and elemental analysis. FOF-13 exhibits excellent physicochemical and detonation properties, such as high density (1.91 g cm^?3), good thermal stability, reasonable impact sensitivity (14 J) and friction sensitivity (64%), high measured detonation velocity (8497 m s^?1 at 1.69 g cm^?3). Furthermore, the precursors 4 and 6 were developed for the first time.     

Studies on Triple Base Gun Propellant Based on Two Energetic Azido Esters

Triple base propellant is the workhorse propellant because it possesses several advantages like reduced flash, flame temperature, and erosion of the barrel as compared to double and single base propellant. Hence, efforts are going on worldwide to increase its performance by increasing its energy using energetic plasticizers and binders. In the present article, nonenergetic plasticizer dibutyl phthalate (DBP) is replaced by two energetic azido ester plasticizers, tris(azido acetoxy methyl) propane (TAAMP) and bis(azido acetoxy) bis(azido methyl) propane (BABAMP), in triple base composition and their different properties are studied.

Experimental closed vessel (CV) results (loading density 0.2 g/cm³) clearly indicate that the triple base composition with 2% DBP has force constant 1018 J/g, which is increased to 1026 and 1030 J/g on replacement of DBP by 1 and 2% TAAMP, respectively. Mechanical properties of propellant compositions containing 1 and 2% TAAMP (compression strength 279 and 291 kg_f/cm², percentage compression 11.2 and 10.5, respectively) are also better than those of composition containing DBP (compression strength 275 kg_f/cm² and 10.3% compression). Similarly, 1 and 2% replacement of DBP by BABAMP shows further rise in energy (1032 J/g, 1038 J/g respectively) than that of compositions containing 1 and 2% TAAMP. These two compositions also exhibit better mechanical properties (compression strength 311.2 and 312.3 kg_f/cm², % compression 11.0 and 10.5, respectively) than compositions containing 1 and 2% TAAMP. The differential thermal analysis (DTA) results brought out the fact that the compositions containing energetic plasticizers revealed maximum decomposition temperature in the range of 172–174°C which is close to DBP plasticized triple base gun propellants (174°C). The energetic plasticized propellant compositions of both (TAAMP and BABAMP) showed sensitivity data in the range of (H₅₀ 19 to 22 cm, F of I 25 to 29 and friction insensitivity 19.2 kg) acceptable limit for gun propellant.     

Novel high-energy ionic molecules deriving from new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties

ABSTRACT

In recent years, the exploration of a practical strategy for novel energetic molecules with high energy and low sensitivity is very desirable but highly challenging. Novel ionic energetic molecules have attracted much attention in this area due to their prominent advantages including low sensitivities, high thermal stability, and excellent energy performances. Herein, five different ionic energetic molecules based on new monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties with enhanced oxygen balance have been synthesized, characterized and evaluated as potential high-energy materials. Thermal stability, sensitivities and energy output test were measured and studied in detail. The heats of formation and energetic parameters were calculated by using Gaussian 09 suite of programs and EXPLO 5 code. The results suggest that all as-prepared new molecules exhibit good thermal stability with high decomposition temperature (3, 231°C; 5, 160°C; 6, 185°C; 7, 180°C; 8, 213°C), and relative low sensitivity (IS > 20 J, FS = 324 N). Inheriting the significant oxygen content of monovalent and divalent 4-oxyl-3,5-dinitropyrazolate moieties, they also possess good energy properties (v _D = 8238 ~ 9208 m s^?1, P = 26.8 ~ 36.7 GPa, V _o = 481.8 ~ 959.4 L kg^?1), which make them competitive high-energy materials.     

Dibenzothiophene Hydrodesulfurization Activity of MoS2 Supported in Sol–Gel ZrO2–TiO2 Mixed Oxides

Abstract

In this work, we report the effect of support composition on the properties of MoS₂ impregnated in sol–gel ZrO₂–TiO₂ mixed oxides as dibenzothiophene hydrodesulfurization catalyst. The supports calcined at 500°C were characterized by N₂ physisorption and X-ray diffraction (electronic radial distribution function). The oxidic impregnated materials (2.8 Mo atoms/nm²) were sulfided at 400°C under a H₂S/H₂ stream. The sample impregnated on the equimolar support showed the highest activity per mass of catalysts whereas the one with TiO₂ carrier was superior in a per mass of Mo basis. Marked differences in products selectivity were observed by TiO₂ addition in the supports. The hydrodesulfurization route to partially hydrogenated compounds was favored over the mixed oxides-supported catalysts meanwhile the direct desulfurization (to biphenyl) was promoted on the ZrO₂-supported solid. It is suggested that among other properties the dispersion and morphology of the MoS₂ phase could influence that behavior.     

CHARACTERIZATION OF HEAVY RESIDUA BY AAPPLICATION OF A MODIFIED D 2007 SEPARATION AND ELECTRON PARAMAGNETIC RESONANCE

ABSTRACT

Seven atmospheric residua (343^°C + [ 65O^°F + ]) were separated into saturate, aromatic, resin, and asphaltene fractions for detailled assessment of feed structure. The weight percent distribution of the fractions revealed two groupings of the residua. One grouping exhibited 20 wt % saturate composition, while the other only 10 wt %. The residua also exhibited high polar content (resin and asphaltene fractions) consisting of over 40% of the total residua. These results are related to the sulfur composition of the residua, and Indicate a fundamental relationship between the aromatic content and sulfur content. Discussion of the accuracy of the separation technique Is also Included.

The vanadium binding sites In the separated fractions were investigated by EPR spectroscopy. The resin and asphaltene fractions all appear to be dominated by 4N and N 0 2S coordination spheres. Discussion of this technique is also included.     

The properties of ammonium dinitramide (ADN): Part 1, basic properties and spectroscopic data

Abstract

Basic properties and spectroscopic data for the energetic oxidizer ADN (Ammonium dinitramide (NH₄N(NO₂)₂)) are presented. The ADN used for this work was synthesized by a new efficient and environmentally friendly method. The method is based on a direct nitration of salts of sulfamic acid by ordinary mixed acid, followed by neutralization and separation of the ADN by the use of an adsorption column. The heat of formation was measured by burning in hydrogen atmosphere in an adiabatic bomb calorimeter and was found to be 148 kJ/mole ±10 kJ/mole. The melting point was determined using DSC technique and is 93.5°C. This paper reports drop weight, friction and bullet impact sensitivity data. The friction sensitivity of ADN is much lower than that of RDX. The impact sensitivity of ADN is of the same magnitude as that of RDX but varies a great deal with the morphology of the particles, e. g. prilled ADN is nearly twice as insensitive as RDX. The bulk density measured by powder X-ray diffraction and was found to be 1.82 gcm^?3. ADN does not show any sign of phase transitions in the -150°C to +80°C temperature interval (measured by single crystal X-ray diffraction). FTIR and FT-Raman spectra are also presented. In the UV-VIS region, ADN is characterized by two absorption peaks at 214 and 284 nm. UV-VIS spectroscopy was also found to be the most useful method for quantitative routine analysis of ADN.     

EFFECTS OF HYDROTREATING COKER LIGHT GAS OIL ON FUEL QUALITY

ABSTRACT

Coker light gas oil (LGO) derived from Athabasca bitumen was hydrotreated in a fixed bed reactor using two commercial NiO-MoO₃/Al₂0₃ catalysts. The effect of temperature on product quality was investigated in a pilot plant between 330 and 390 °C at 12.4 MPa, space velocity of 0.5 Ir1 and 700 liter of hydrogen per liter of coker LGO (L/L). The product quality was monitored by ^I3C NMR spectroscopy, elemental analysis, density and distillation techniques.

The data showed that coker LGO can be hydrotreated using nickel-molybdenum catalysts at 350 °C, 0.5 h¹, 12.4 MPa and 700 L/L to meet the diesel product specifications, namely, 0.5 wt % sulfur, 20% aromatics and cetane index of 40. The cetane index improvement and aromatic saturation, which are affected by thermodynamic equilibrium at temperature higher than 370?°C, could reach 29 and 86% respectively. The cetane improvement was attributed to aromatic saturation and hydrocracking with hydrogen consumption ranging from 215-340 L/L. The Ketjenfine KF-840 catalyst was found slightly better performance than Procatalyse HR-348 catalyst.     

Polarography in the Study of Chemical Micro-Mechanism of Initiation of Polynitro Arenes

The half-wave potentials E_1/2 of 24 polynitro arenes have been determined in an aqueous medium buffered at pH 7; the final concentrations of their solutions are 0.5 × 10^?4 and 0.5 × 10^?5 M. The logical relationships found between the E_1/2 values and squares of the detonation velocity are of the type of the modified Evans–Polanyi–Semenov equation for energetic materials. It has been stated that the strong dependence of E^1/2 values on the conditions and method of realization of the polarographic measurements considerably restricts the application of this method to studies of the micromechanism of the initiation of organic energetic materials.     

RECOVERY OF ASPHALTENES FROM TAR SAND BY SUPERCRITICAL FLUID EXTRACTION

ABSTRACT

Many non-oil producing countries are enriched with other sources of energy, for example tar sand, oil shale, coal, biomass, and uranium, that are not fully utilized. Supercritical fluid extraction (SFE) of tar sand was carried out in a batch autoclave at different temperatures. Extracts recovered from SFE were fractionated into oils, asphaltenes, preasphaltenes and gases by solvent extraction. The highest yield) of SFE (24.3 wt % dry basis) from tar sand was obtained with n-pentane/benzene (1/1, v/v’) mixture at 655 K. Comparison of the amount of n-alkanes (C1–C4) evolved at 585 K and 685 K shows that the amount of methane is significantly increased at 685 K whereas the amount of C4 alkane is reduced. At 685 K, hydrogen and methane represent 45·1 vol % of the gases evolved from the SFE. The yields of C1–C3 alkane hydrocarbons were higher for supercritical fluid extracts at 685 K as compared to those obtained at 585 K. The quantity of olefines (C₂H₄ + C₃H₆) was found between 5·1 and 10·1 vol %.     

Effect of methanol, ethanol, and formaldehyde addition on the steam conversion of methane in the presence of nickel catalysts of various porous structure

The effect of CH₂O, CH₃OH, and C₂H₅OH on the methane conversion and the CO, CO₂, and coke yield in the methane steam conversion on commercial nickel catalysts for steam reforming C 11-9-09 (12.8 wt % Ni/α-Al₂O₃) and hydrogenation (54.0 wt % Ni/kieselguhr) was studied at a temperature of 750°C and an H₂O:CH₄ ratio of 1.5–2.0. The action of these compounds was studied both individually and for their joint presence in the methane-steam mixture. Their effect on the reaction depends on the pore structure of the catalyst. Using the catalyst C 11-9-09 as an example, it was found that the introduction of formaldehyde into steam suppressed the methane conversion into C_s and high-boiling-point carbon compounds and gave the desired products with a yield close to the equilibrium value. When all three additives were present in the steam, ethanol was responsible for the formation of C_s.     

Hydroisomerization of n-dodecane on bifunctional catalysts containing mesoporous aluminosilicates

The hydroisomerization of n-dodecane on bifunctional catalysts with mesostructured aluminosilicates as an active component has been studied. Aluminosilicates with an Si/Al atomic ratio of 5 to 48 have been prepared using hexadecylamine as a template. Catalyst supports contained 35 wt % mesoporous material and 65 wt % ??-Al₂O₃. The platinum loading of the catalysts was 0.5% of the support mass. It has been found that the catalysts based on mesoporous aluminosilicates with an Si/Al ratio of 10 and 22 exhibit the highest selectivity. In their presence, the conversion reaches 43?C46 wt % with the selectivity for iso-C₁₂H₂₆ of more than 90%.     

Formulation of fumed silica grease from waste transformer oil as base oil

This study aimed to formulate fumed silica (FS) grease using waste transformer oil (WTO) and to investigate the grease properties. Various unexplored application of the reused WTO due to its reusable characteristic. WTO and fresh transformer oil (ITO) were used as grease base fluid and the properties of oil and grease were evaluated using ASTM International standards and SKF’s Grease Test Kit. The oil and grease chemical compound were determined using Fourier Transform-Infrared Spectroscopy at wavenumber of 500–4000?cm^?1. It was found that WTO have high viscosity index of 96 and low moisture content of 0.05% after pre-treatment than ITO. FS greases with and without MoS₂ were classified as NLGI 2 greases when FS content was 8%. Grease formulated with MoS₂ shows better performances in term of corrosiveness, oil bleed within ?15% to +15%, oil separation less than 4%, and dropping point of >300?°C. FTIR results shows no significant different between ITO and WTO, and between all formulated greases. Based on the findings, it was concluded that WTO can be utilized as an alternative base oil in grease formulation due to the good properties exhibited by the formulated WTO-based FS grease blended with MoS₂.     

钻头及涡轮钻具轴承组件MoS2滑化处理研究

结合三牙轮钻头及涡轮钻具轴承组件的工况和失效分析,讨论了MoS     

Desulfurization of Fuel by Leaching Using H2O2 and H2SO4

Abstract

In this research, different concentrations of H₂O₂ and H₂SO₄ solutions were used in order to remove the sulfur from high sulfur contented No. 6 fuel oil. In desulphurization experiments, reaction temperature, reaction time, and the concentration of H₂O₂ and H₂SO₄ were varied in a range of 20–50^○C, 30–150 min, 5–35%, and 0.05–2.00 N, respectively. The ratio of reagent/fuel oil was taken as 10/1 and the stirring speed as 1,000 rpm. According to the results obtained, considering the desulphurization and the organic structure of the fuel, the most appropriate method was found as the H₂O₂ leaching method. It was barely determined that the highest desulphurization was achieved by H₂O₂/0.1N H₂SO₄ leaching method. The optimum process parameters for H₂O₂ leaching method were found as a concentration of 15%, reaction temperature of 30^○C, and reaction time of 60 min; and for H₂SO₄ leaching method were found as concentration of 0.1 N, reaction temperature of 30^○C, and reaction time of 150 min.

It was observed that by increasing the reaction temperature, reaction time, and reagent concentration, the carbon and hydrogen contents of the fuel decreased considerably and on the contrary the oxygen content increased very rapidly. A partial decrease of nitrogen content was also observed.