Influence of catalysts on the combustion of ammonium bichromate

The influence of inorganic and organic catalysts on the combustion of ammonium bichromate has been investigated at pressures ranging from 1 to 1000 atm. The maximum catalytic action of additives has been found to occur at atmospheric pressure, with the combustion rate for the most effective additives decreasing by a factor of four to five. The influence of the same additives on the combustion of other ammonium salts studied earlier is compared. Institute of Chemical Physics, Russian Academy of Sciences, 117977 Moscow. Translated from Fizika Goreniya i Vzyrva, Vol. 31, No. 6, pp. 28–36, November–December, 1995.     

Mechanism and features of nitriding of ferrosilicon in the combustion regime

The nitriding of ferrosilicon in the combustion regime is studied. It is found that by diluting the starting alloy by the end product and by introducing halide salts of ammonium and magnesium, it is possible to increase the degree of conversion and to obtain a two-phase combustion product consisting of silicon nitride and iron. It is shown that the nitriding of ferrosilicon occurs in the temperature range from 900°C to the combustion temperature and includes several steps. The temperature at the beginning of interaction of ferrosilicon with nitrogen coincides with the temperature of the α-leboite → β-leboite phase transition. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 3, pp. 71–78, May–June, 2006.     

Effect of catalysts on the combustion of layered systems

An experimental study is made of a “chemical arc”, a model layered system of solid components, between the end surfaces of which stationary combustion takes place. The rates of combustion of the components in ammonium perchlorate-polyether, ammonium perchlorate-polyethylene, and ammonium perchlorate-butyl rubber systems with catalytic additives (diethyl ferrocene, epoxyethyl ferrocene, and iron oxide) are measured as functions of the distance between the components. A maximum mass combustion velocity is found to exist as a result of the transition from a low velocity (kinetic) to a high velocity reaction regime. The data are in qualitative agreement with theory. The mechanism by which the catalysts affect the combustion characteristics is analyzed. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 3, pp. 57–62, May–June 1999.     

Alkylation of Ammonium Salts Catalyzed by Imidazolium‐Based Ionic Liquid Catalysts

Quaternary ammonium salts were synthesized from ammonium salts and dialkyl carbonates over imidazolium ionic liquid catalysts. The reaction gave almost stoichiometric amounts of the quaternary ammonium salts for halides and nitrates. It was found that the electron‐donating property of the alkyl moieties of ammonium cations, the electrophilic nature of the alkyl group of the carbonate, the acidity of the acid that the anion of the ammonium salt corresponds to, and the steric hindrance of the ammonium salts and the dialkyl carbonates are the key factors that influence the yields of quaternary ammonium salts. Strong electron‐donating alkyl groups on the nitrogen atom of the ammonium salt, electron‐withdrawing groups on the methylene carbon of dialkyl carbonate, and weaker steric hindrance of the starting ammonium salts and dialkyl carbonates favor the alkylation reaction of ammonium salts.     

Mathematical Combustion Model of a Two–Component Gas Suspension Including a Powder Combustible and a Powder Oxidizer

A mathematical model of the ignition and combustion of aluminum and ammonium perchlorate powders in a propulsion system that takes into account their polydisperse distribution and the difference between the gas and disperse–phase velocities and temperatures is developed. The effect of the pressure, the ratios between the components, and the dispersivity of aluminum particles on the structure of a gas–disperse flame, the basic characteristics of the combustion of a gas suspension, and the completeness of propellant combustion is studied.     

Micellar-improved synthesis of bis-quaternary ammonium salts by the epichlorohydrin route

A convenient procedure for the synthesis of bis-quaternary ammonium salts from long-chain alkyldimethylamines and epichlorohydrin is studied. An improved preparation of bis-quaternary ammonium salts from N,N-dimethyloctylamine, N,N-dimethyldodecylamine or N,N-dimethyloleylamine, their amine hydrochlorides, and epichlorohydrin can be achieved by carrying out the reaction in an aqueous micellar medium. The amine hydrochlorides are used as functional surfactants to produce the self-micellization and solubilization of reactants. The formation of micelles is a necessary condition for a successful quaternization. Comparison of the quaternization performance in ethanol, ethanol/water mixtures, and aqueous micellar medium leads to the conclusion that this micellar-improved synthesis enables easier and cheaper access to bis-quaternary ammonium salts by avoiding the formation of the mono-quaternary ammonium salts as intermediates, and by using water as solvent under mild reaction conditions. Mechanistic aspects of the quaternization reaction in micellized medium are also suggested.     

Effect of ammonium salts on poly(ethylene terephthalate) materials

The study of the effect of solutions of ammonium salts of low concentrations on polyester fibre material showed that modification of the material with ammonia formed by thermal hydrolysis of ammonium salts differs from modification with ammonia obtained by the reaction of equimolar quantities of ammonium nitrate and sodium hydroxide and is similar to the process that takes place when ammonia is added to the working solution. Of the salts examined, ammonium fluoride in the concentration of 0.02–0.35 M at 130°C and 30-min process time is the most active modifying agent. In these conditions, ammonium fluoride and the products of its high-temperature hydrolysis — hydrogen fluoride and ammonia — have the strongest catalytic effect on hydrolysis of cyclic oligomers with formation of their linear form. On the whole, ammonium fluoride has a stronger modifying effect on polyester material than aqueous ammonia. __________ Translated from Khimicheskie Volokna, No. 1, pp. 17–21, January–February, 2007.     

New Takes on Nitrate Ester Chemistry: Salts with Oxygen‐Rich Ammonium Cations

Nitrate (anion) salts with nitroxy‐functionalized ammonium cations were synthesized. Several revealed surprising thermal and hydrolytic stability. Various physical properties were measured, and Gibbs free energy (ΔG_r(298)) differences between the salts and postulated products of their thermal decomposition were computed. The computed differences indicate that salts with cations that have more than one nitroxy group are endothermic at 298 K. Nevertheless, the stability observed for some salts with this property indicates that kinetic barriers are sufficient to prevent facile decomposition at this temperature. This is in contrast to the case observed for nitrate salts of nitroxy‐functionalized ammonium cations with acidic protons.     

Synthesis,Characterization and Surface-Activity of Hydroxyethyl Group-Containing Quaternary Ammonium Surfactants

A novel series of hydroxyethyl group-containing quaternary ammonium salts were synthesized from mono-, di-, tri-alkyl tertiary amines, hydrochloric acid and ethylene oxide by a two-step process with mild reaction conditions. The structures of the quaternary ammonium salts were characterized by infrared spectroscopy and ¹H-nuclear magnetic resonance spectroscopy. The surface tensions at the critical micelle concentrations were measured to investigate the surface activities of the prepared compounds. The results showed that the hydroxyethyl group quaternary ammonium salts exhibit high surface activities.     

Preparation of bulk and supported heteropolyacid salts

We describe the preparation of bulk and supported cesium and ammonium heteropolyacid and acid salts of 12-tungstophosphoric acid. Novel synthetic schemes to prepare supported forms of insoluble cesium- and ammonium-acid salts are discussed, and their behavior in model compound isomerization and alkylation reactions is described. In particular, we discuss the egg-white morphology associated with Cs-acid salts supported on silica extrudates prepared by a novel in situ-reaction/precipitation route. We also describe hydrothermal techniques developed for directly preparing the ammonium-acid salts of 12-tungstophosphoric acid and the extension of that technique to other heteropolyacid salts.     

季铵盐链长及用量对CnTA+/蒙脱石纳米复合物吸附PAEs的影响

用具有相同结构但不同烷基碳链长度的系列季铵盐制得C_nTA⁺/蒙脱石纳米复合物,并对水溶液中邻苯二甲酸酯进行吸附实验。探讨了季铵盐烷基碳链链长和用量对制得的C_nTA⁺/蒙脱石纳米复合物吸附水溶液中PAEs效果的影响。结果表明:C_nTA⁺/蒙脱石纳米复合物能有效地吸附溶液中的PAEs,季铵盐烷基碳链链长及用量均对C_nTA⁺/蒙脱石纳米复合物的吸附效果产生影响。当季铵盐用量较低时,随着季铵盐烷基链长的增加,PAEs的吸附去除率增加;增大季铵盐用量,随着季铵盐烷基链长的增加,PAEs的吸附去除率先增大后减小。     

Combustion of model compositions based on furazanotetrazine dioxide and dinitrodiazapentane. I. Binary systems

The combustion behavior of high-energy systems based on furazano[3,4-e]tetrazine-4,6-dioxide and 2,4-dinitro-2,4-diazapentane with metal and energetic additives (Al, AlH₃ ammonium perchlorate, ammonium dinitramide, and HMX) has been studied. The burning rate, combustion stability, and characteristic combustion temperatures with pressure variation are estimated. It is found that there is a critical burning rate above which a deflagration-to-explosion transition occurs. The critical conditions depend on the formulation of the compositions.     

Comparative performance of impregnated molybdenum-sulphur catalysts in hydrogenation of Spanish lignite

Hydrogenation of a Spanish lignite of 12% sulphur content was conducted using three molybdenum-containing catalysts impregnated into the lignite: ammonium tetrathiomolybdate, a sulphided ammonium heptamolybdate, and molybdenum disulphide. The conversions to liquids and hydrodesulphurization were investigated for a series of residence times and temperatures. At 275 °C, the ammonium salts provide no greater conversion or sulphur removal than obtained in the absence of catalyst, because these salts have not decomposed to an active catalyst at this temperature. However, lignite impregnated with molybdenum disulphide does experience greater conversion and desulphurization than lignite reacted without catalyst. At 325 °C, the lignite impregnated with the ammonium salts gives conversions and desulphurization substantially superior to that achieved with molybdenum disulphide or without catalyst. This is attributed to the superior dispersion that can be achieved by impregnation using a solution of a soluble salt rather than a slurry of the insoluble disulphide. The best conversions, liquid yield, and desulphurization are achieved using impregnated sulphided ammonium heptamolybdate.     

Mechanisms of combustion catalysis by ferrocene derivatives. 1. Combustion of ammonium perchlorate and ferrocene

Combustion of ammonium perchlorate (20–90%) mixtures with ferrocene is studied. It is demonstrated that, depending on the ratio of the components in the examined compositions, in addition to the usual gas-phase combustion model, another possible combustion mechanism exists. A somewhat unusual condensed-phase (c-phase) model may be realized, in which the heat-generating reaction occurs in a foam/aerosol layer at the temperature of evaporation of the less volatile component, which the surface temperature is defined by evaporation of the more volatile component. The efficiency of ferrocene depends on the propellant combustion mechanism: in systems that obey the gas-phase combustion mechanism, the influence of ferrocene addition is higher than the influence of addition of a hydrocarbon fuel; in systems with the c-phase mechanism of combustion, ferrocene addition produces a significant effect. Depending on the ratio of the components, ferrocene first acts in these compositions simply as a highly reactive fuel; it is only in fuel-enriched compositions with a high equivalence ratio that the burning rate increases owing to catalysis of the combustion process by the ferric oxide on the soot skeleton.     

Empirical Correlation of Minimum Burning Pressures of Ammonium Nitrate Emulsions

Experimental minimum burning pressures (MBP) of emulsions with solution phase containing ammonium nitrate/water, ammonium nitrate/sodium nitrate/water, and ammonium nitrate/sodium nitrate/sodium perchlorate/water are investigated. A correlation is proposed to relate the MBP’s with the combustion temperatures. The formulations containing sodium nitrate or sodium perchlorate have much lower MBP’s and can be accounted for by an activation energy of 150.7 kJ mol⁻¹ obtained from literature for ingredients having catalyzing effects on the reaction of ammonium nitrate, e.g. sodium nitrate. The ammonium nitrate/water formulations have a higher activation energy of 173.4 kJ mol⁻¹ deduced from an analysis of the data. The MBP vs. combustion temperature plot is linearized by a multiplication factor to the MBP that includes the activation energy of the corresponding system. This allows the MBP to be predicted from combustion temperatures determined from the formulations and the corresponding activation energy.     

Hydroformylation of C8 olefins catalyzed by rhodium–inorganic ammonium salt systems

The effect of inorganic ammonium salts which contain group VIB metals of the periodic table (ammonium chromate, ammonium dichromate, ammonium molybdate and ammonium tungstate) as additives on the catalytic performance of Rh catalysts for the hydroformylation of C₈-olefins and 1-dodecylene has been investigated. Modification of rhodium with ammonium salts could increase the yield of aldehydes in the hydroformylation of the olefins without phosphine oxide or phosphine ligands and also decrease Rh loss in the distillation process for the separation of the products from the catalyst.     

燃烧催化剂对EMCDB推进剂交联固化反应的催化作用

设计了一种研究燃烧催化剂对EMCDB推进剂交联固化反应催化作用的实验方法，比较了十多种铅盐、铜盐对交联固化反应催化活性的强弱，筛选出了可用作粒铸EMCDB推进剂燃烧催化剂的铅盐、铜盐。实验结果表明，某些铅盐对交联固化反应有较强的催化加速作用，铜盐和炭黑对交 联固化反应没有明显的催化加速作用，只有对交联固化反应催化加速作用很小的铅盐才能用作EMCDB推进的燃料催化剂。     

Effect of small cation addition on the conductivity of quaternary ammonium ionic liquids

Several quaternary ammonium or lithium bis(trifluoromethane sulfone) imide (TFSI) salts were dissolved into N,N,N,N-hexyltrimethyl ammonium TFSI ionic liquid, and the conductivities of the resulting solutions were measured. Some asymmetric quaternary ammonium salts contributed to increase the conductivity of the solution, while cyano-containing quaternary ammonium and lithium salts decreased the conductivity. Based on the results of differential scanning calorimetry (DSC) measurements, such conductivity behaviors appeared to be related to the intrinsic miscibility of the ionic liquid solutions.     

菱苦土处理铵氮废水的研究

在以氨或碳铵法工艺制备镁盐过程中有大量的铵氮废水产生,对环境造成了污染。为了寻找铵氮废水的合适的综合利用途径,以菱苦土为分解剂与废水中的铵盐反应,研究了菱苦土加入量、反应时间和温度条件对废水中铵盐分解率的影响。结果表明,在优化工艺条件下铵盐分解率达到90%以上。优化工艺条件的确定,为以氨法制备氢氧化镁或以碳铵法制备碱式碳酸镁生产过程中工艺废水的处理奠定了理论基础,也为氨的回收及循环利用提供了条件。