The Interaction between Otto Fuel II and Aqueous Hydroxylammonium Perchlorate (HAP), Part II: Gas Evolution and Changes in HAP Solution Acidity

Headspace gas analysis has shown that nitrous oxide (N₂O) is the principal gas evolved during contact between small volumes of Otto Fuel II (OF) and 82% aqueous hydroxylammonium perchlorate (HAP) at temperatures close to ambient. The gas is produced mainly from the 82% HAP layer and is generated in significant amounts only after the OF has become blackened as a result of extreme degradation. The pH of the HAP solution falls during contact with OF and the OF blackening point is the same for each of three storage temperatures investigated, suggesting that the production of N₂O may depend upon the attainment of a specific HAP solution acidity. It is suggested that the propyleneglycol dinitrate (PGDN) component in OF undergoes acid hydrolysis at the liquid/liquid interface and that the nitric acid produced leads to the decrease in HAP solution pH and to stabilizer depletion in OF. Experiments involving contact between 82% HAP and the other components of OF confirm the key role of PGDN: in its absence there is no change in HAP solution acidity, no gas evolution and no violent reaction between the two liquids.     

Adiabatic Calorimetric Decomposition Studies of 35 Mass% Hydroxylamine Hydrochloride/water

The HH (35 mass% hydroxylamine hydrochloride/water solution) and HH‐ind (stabilized 35 mass% hydroxylamine hydrochloride/water solution for industrial use) decomposition reaction has an onset temperature of ～145°C. The measured gas phase decomposition products are 0.25 mol N₂ and 0.06 mol O₂ per mol of hydroxylamine hydrochloride with small quantities of N₂O and H₂, and a trace amount of NO for a total noncondensable gas production of ～0.39 mol/mol of hydroxylamine hydrochloride. The reaction system is tempered by the evaporation of the solvent (water) and the reaction is drastically catalyzed by stainless and carbon steel.     

NO – oxygen scavenger or reaction intermediate in the decomposition of N2O?

Nitric oxide and nitrogen dioxide were found during the thermal desorption of surface species left on Fe-ferrierites after the decomposition of nitrous oxide. This demonstrates the formation of surface NOx species during N₂O decomposition. Repeated decomposition and subsequent desorption of surface species confirm the active role of surface NOx species. Addition of NO up to a fraction of 0.1 times the amount of N₂O increased the decomposition of nitrous oxide as well as the amount of surface NOx species. The use of nitrous oxide labeled with ¹⁸O demonstrated that the zeolite oxygens participate in the reaction and that the presence of NO enhances this participation.     

The Interaction between Otto Fuel II and Aqueous Hydroxylammonium Perchlorate (HAP), Part I: Initial Observations and Time‐to‐Event Measurements

Investigations have shown that a violent event (normally auto‐ignition) occurs after a relatively short period of time when the two immiscible liquids Otto Fuel II and 82% aqueous hydroxylammonium perchlorate (HAP) come into contact at temperatures between 30 °C and 50 °C. Under quiescent conditions the time from initial contact to an event (time‐to‐event) depends on the relative volumes of the liquids as well as the temperature but there is no significant difference between the time‐to‐event recorded in an open container and that recorded in a sealed container at the same temperature. It is concluded that key reactions in the build up to an event are taking place in both the Otto Fuel II and in the HAP solution.     

羟胺稳定化研究进展

综述了近年来羟胺稳定化研究进展,讨论了羟胺及其盐溶液分解的机理、影响因素以及抑制手段,重点对相关稳定剂的特点进行了论述和分析,以期为高能氧化剂如硝酸羟胺的稳定化研究提供参考。     

Behavior of Active Oxygen During the Decomposition of Nitrous Oxide Over Fe-FER

Isotope exchange (I.E) of ¹⁸O₂ for oxygen captured in Fe-FER after decomposition of nitrous oxide proceeds readily even at room temperature, provided that the amount of surface NO _x species, formed as a secondary product of the N₂O decomposition, is relatively low. If ¹⁸O₂ is present during the decomposition of nitrous oxide above 250 °C, or if nitrous oxide labeled with ¹⁸O is employed, ¹⁸O appears also in NO _x species, and I.E easily occurs with zeolite framework oxygens.     

Reduction of oxygen by hydroxylammonium salt or hydroxylamine over supported Au nanoparticles for in situ generation of hydrogen peroxide in aqueous or non-aqueous medium

Reaction of O₂ with hydroxylamine or its salts over a number of supported gold catalysts containing Au nanoparticles (at 10–70 °C) has been studied at atmospheric pressure for the in situ generation of H₂O₂ (required for organic oxidation reactions in the synthesis of fine/specialty chemicals) in aqueous (water) or non-aqueous medium. Hydrogen peroxide in high yields with harmless by-products (viz. water and nitrogen) can be generated in situ by the reduction of O₂ by hydroxylammonium sulfate (or chloride) or hydroxylamine using the supported gold catalysts particularly Au/Gd₂O₃, Au/La₂O₃ and Au/MgO, in aqueous (water) or non-aqueous (viz. methanol) medium at close to ambient conditions. The reduction of O₂ by hydroxylammonium salt to H₂O₂, however, requires preneutralization of the salt by alkali; in the absence of the neutralization, only water is formed in the reaction.     

The effect of particle size on nitric oxide decomposition and reaction with carbon monoxide on palladium catalysts

The effect of palladium particle size on its catalytic activity was investigated by the decomposition of chemisorbed nitric oxide and the reaction of nitric oxide with carbon monoxide in flow conditions. Palladium particles (30–500 Å) were prepared on silica thin films (100 Å) which were supported on a Mo(110) surface. The reactivity of the supported palladium varied with the metal particle size. On large palladium particles, nitric oxide (NO) reacts to form nitrous oxide (N₂O), dinitrogen (N₂) and atomic oxygen during temperature-programmed reaction, whereas on small particles (< 50 Å), nitrous oxide is not formed. Similarly, reactions of NO with CO on large particles, in flow conditions produce N₂O, N₂ and CO₂, whereas N₂O is not produced on small particles. In addition, more extensive NO decomposition is observed on the smaller particles.     

The Influence of Water Vapor and Sulfur Dioxide on the Catalytic Decomposition of Nitrous Oxide

In a catalysts screening for the nitrous oxide decomposition, three groups of catalysts (metals on supports, hydrotalcites, and perovskites) were studied relating to their activity in the presence of vapor or sulfur dioxide, in the temperature range from 200 to 500 °C. It was found that the water vapor strongly inhibates the nitrous oxide decomposition at T = 200–400 °C. The sulfur dioxide poisons the catalysts, in particular the perovskites. The catalysts Rh‐ZrO₂ and Ex‐Co, Rh‐Al‐HTlc are potentially suitable for the nitrous oxide decomposition in exhaust gas at around T = 500 °C.     

Direct Decomposition of N2O over Cesium-doped CuO Catalysts

A series of Cs promoted copper oxide catalysts were prepared by co-precipitation method and tested for the direct decomposition of nitrous oxide (N₂O). The Cs promoted catalysts were more active particularly with a molar ratio of Cs/Cu at 0.1 compared to bulk CuO. Methods of XRD, BET, XPS, H₂-TPR, and N₂O-TPD were used to characterize these catalysts to evaluate structure activity relationship. The characterization results indicated that the addition of Cs could improve the reduction of Cu²⁺–Cu⁰ by facilitating the desorption of adsorbed oxygen species, during the N₂O decomposition. The influences of oxygen and steam on N₂O decomposition over these catalysts were also studied.     

Effect of noble metals in the decomposition of nitrous oxide over Fe-ferrierites

The decomposition of nitrous oxide was studied over Fe-ferrierite, Me-ferrierites and Fe/Me-ferrierites (Me: Pt, Rh and Ru). Flow as well as batch experiments were carried out and showed a synergy between Fe and Me ions. Ions of noble metals in Fe-ferrierite increased the catalytic activity in the sequence Pt < Rh ≅ Ru. Addition of NO substantially decreased the decomposition of N₂O over Rh/ferrierite and Ru/ferrierite, but not over bimetallic ferrierites. NO _x species created during the decomposition of nitrous oxide alone as well as with addition of NO, and employment of nitrous oxide labeled with ¹⁸O allowed us to assume a changing decomposition mechanism in the presence of Me ions in Fe-ferrierites.     

高氯酸羟胺热分解动力学

引言 高氯酸羟胺(HAP)是一种用于推进技术领域的新型高能氧化剂,在高性能推进系统中具有极为重要的价值[1～3].     

Nitrous Oxide Reduction with Ammonia and Methane Over Mesoporous Silica Materials Modified with Transition Metal Oxides

Transition metal oxides (Cu, Cr and Fe) were deposited on various mesoporous silicas (MCM-48, SBA-15, MCF and x-MSU) by an impregnation method. Electron microprobe analysis, BET, UV-VIS-DRS and temperature programmed desorption of NH₃ were used for the characterization of the samples. The modified mesoporous silicas were tested as catalysts of the N₂O decomposition and the N₂O reduction using ammonia and methane. The Cu-containing samples presented the highest catalytic activity in the N₂O decomposition, while the Cr- and Fe-modified materials were more active in the reduction of nitrous oxide with NH₃ and CH₄. The type of the silica support strongly influenced the catalytic performance of the studied materials.     

Nitrous Oxide Decomposition Over MCO3–Co3O4 (M = Ca, Sr, Ba) Catalysts

In this paper, nitrous oxide decomposition over a series of MCO₃–Co₃O₄ (M = Ca, Sr, Ba) catalysts having M/Co ratios of 0.1–0.4 has been studied. The various catalysts were characterized using thermal (TGA, DTA), XRD, IR and N₂ sorption techniques. N₂O decomposition activity was found to be dependent on the type of the alkaline earth cation, the M/Co ratio, cobalt oxide crystallites sizes, and the calcination temperature.     

Characterization of ADN and ADN‐Based Propellants

Ammonium dinitramide (ADN), NH₄N(NO₂)₂ is being considered as one of the potential new energetic oxidizers for composite propellants. In this study, ADN crystals, prills and two ADN‐based propellants having different relative amounts of ingredients were characterized. The concentration of the crystals and the prills samples was determined using ion chromatography. The thermal behavior of the crystals, prills and propellants was studied using DSC, simultaneous TG‐DTA‐FTIR‐MS, ARC (accelerating rate calorimeter), HFC (heat flux calorimeter) and INC (isothermal nanocalorimeter). Decomposition of ADN was observed from all of the samples at temperatures above the melting point of ADN (~ 92 °C). Formation of N₂O, NO₂, H₂O, CO₂, CO, N₂ and NO was detected during the ADN decomposition. The thermal stability of the ADN samples at temperatures below the melting point of ADN was studied. Early solid decomposition of ADN, which generates N₂O and H₂O, was observed at 60 °C. Electrostatic discharge (ESD) and impact sensitivity of the ADN samples were determined. The crystals and prills are sensitive to impact, while the two propellants are relatively less ESD and impact sensitive.     

Emissions of ammonia and nitrous oxide following incorporation into the soil of farmyard manures stored at different densities

Before spreading to land, farmyard manures (FYM) from pigs (Sus scrofa) and beef cattle (Bos taurus) were stored, for c. 120–150 days, either uncompacted or compacted. Compaction was carried out as the manures were put into store and the compacted manures were covered with plastic sheeting. Both compacted and uncompacted FYM were either incorporated by ploughing immediately after spreading, within 4 h, within 24 h or left on the surface until the soil was cultivated prior to planting. Despite greater amounts of total ammoniacal nitrogen (TAN) remaining in the compacted pig FYM, ammonia (NH₃) emissions following spreading were not significantly greater than from the uncompacted FYM, even when left on the soil surface. Incorporation of pig FYM reduced NH₃ emissions by c. 90, 60 and 30% for immediate, within 4 h and within 24 h incorporation, respectively. There were no effects of compaction during storage on nitrous oxide (N₂O) emissions following spreading for the measurement period of 60 days. Incorporation had no effect on N₂O emissions from pig FYM following spreading in the first experiment, but reduced emissions following spreading in the second year and reduced N₂O emissions following the spreading of cattle FYM in both experiments. These results indicate that rapid incorporation of FYM after spreading to land is an effective means of reducing NH₃ emissions and need not lead to increases in N₂O emissions.     

A mechanistic study of nitrous oxide adsorption and decomposition on zirconia

FT-IR spectroscopy and mass spectrometry have been used to study the adsorption and decomposition of nitrous oxide on zirconia. It was determined that zirconia cations in the 4+ oxidation state are the site for molecular adsorption of N₂O, whereas Zr³⁺ sites are active toward dissociative adsorption of N₂O at temperatures as low as 25°C. Catalytic decomposition of N₂O on ZrO₂ occurs at temperatures above 350°C and follows first-order reaction kinetics. Experiments utilizing isotopic labeling in conjunction with mass spectrometry were done to elucidate the details of the reaction mechanism. Based on the results presented here, a mechanism for N₂O decomposition on ZrO₂ is proposed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Curing and pyrolysis of cresol novolac epoxy resins containing BABODOPN

This work investigates the curing kinetics, thermal stability, flammability, and decomposition kinetics of cresol novolac epoxy (CNE) cured with two curing agents, [1,4‐bis(3‐aminobenzoyloxy)‐2‐(6‐oxido‐6h‐dibenz(c,e)(1,2) oxaphosphorin‐6‐yl)‐naphthalene] (BABODOPN) and diamino diphenyl methane (DDM). The DSC curing study shows that the activation energy (E_a) can be estimated by Kissinger's method and the E_a of CNE/DDM, 54.3 KJ/mole, is one‐half that of CNE/BABODOPN, 112.6 KJ/mole; also, the glass transition temperature (T_g) of the latter, 479.5 K, is substantially higher than that, 383 K, of the former. Both increases are attributed to the incorporation of phosphorus‐containing a bulky pendant aromatic group into the BABODOPN molecule, which inhibits its mobility. In comparison with the conventional DDM system, the phosphorus‐nitrogen synergistic effect of BABODOPN improves the limiting oxygen index (LOI) from 26 to 47, and increases the char yield from 30.4% to 38.3%. Moreover, the CNE/BABODOPN system even exhibits better flame retardancy than the excellent CNE/ODOPN system, developed by the authors previously, because of the synergistic effect. Finally, the investigation of thermal gravimetric analysis (TGA) decomposition in N₂ by Ozawa's method demonstrates that the mean E_a declines as the phosphorus content increases, because the ease of decomposition of the phosphorus in the initiation stage facilitates the formation of an insulating layer. POLYM. ENG. SCI., 45:478–486, 2005. © 2005 Society of Plastics Engineers     

Selective N2O Removal from the Process Gas of Nitric Acid Plants Over Ceramic 12CaO · 7Al2O3 Catalyst

Catalytic high temperature decomposition (secondary abatement) of nitrous oxide over calcium aluminate 12CaO · 7Al₂O₃ (mayenite) was studied in the model laboratory tests (TPSR) and pilot units (steady-state) using the real feed. X-ray diffraction (XRD), scanning electron microscopy (SEM), N₂-sorption (BET), electron paramagnetic resonance (EPR) and Raman spectroscopies were used to characterize the synthesized material. The catalyst exhibited high efficiency and selectivity in N₂O removal, reaching practically 100% conversion at 1150 K without appreciable total losses of NO _x . Owing to its high thermal stability and resistivity to sintering and low cost of production raw materials, mayenite was found to be a promising catalyst for economically appealing secondary abatement of nitrous oxide in nitric acid plants.     

Cage Compounds as Potential Energetic Oxidizers: A Theoretical Study of a Cage Isomer of N2O3

Ab initio electronic structure calculations are employed to investigate the cage isomer of N₂O₃ (c‐N₂O₃) as a viable energetic oxidizer. c‐N₂O₃ is vibrationally stable with a large heat of formation of 7.95 kJ g⁻¹ and can produce larger enthalpies of combustion than other commonly used oxidizers such as ammonium perchlorate, O₂(l) and N₂O₄. c‐N₂O₃ is shown to have a unimolecular decomposition barrier of 24.4 kJ mol⁻¹ at the CCSD(T)/CBS(Q‐5) level of theory, and a dimer‐induced decomposition barrier of 100.8 kJ mol⁻¹. Although c‐N₂O₃ is predicted to perform well as an oxidizer, the low barrier to unimolecular decomposition is likely to render it impractical as an energetic oxidizer.