Formation Of Nitrogen Compounds Research Articles

Study on Hydrogen-Based Reactive Ion Etching of Ovonic Threshold Switch (OTS) Materials for Phase Change Memory Devices

Ovonic threshold switch (OTS) materials are used in selector devices for phase change random access memory (PcRAM) circuits and are generally composed of chalcogenide compounds. In this study, etch characteristics of OTS material composed of Ge-As-Te have been investigated using reactive ion etching (RIE) by hydrogen-based gases such as H2, CH4, NH3, etc. Among the investigated hydrogen-based plasmas, NH3 showed the highest etch rate due to the high vapor pressures of the hydrides, but the formation of nitride compounds and the increased roughness were observed on the OTS surface. In the case of CH4+NH3 (1:1 ratio) plasma, the OTS material could be etched at high OTS etch rates without the formation of nitrogen compounds and without increasing the chemical and physical damage on the OTS surface through the formation of volatile CN-related compounds.

Blooming-forming cyanobacteria pyrolysis over Ni-Al layered double oxides/MCM-41 for nitriles under nitrogen and methanol atmosphere

Blooming-forming cyanobacteria were catalytically pyrolyzed over Ni-Al layered double oxides/MCM-41 (NiAl-LDO/MCM-41) composites with nitrogen or methanol as sweep gas for the production of nitrogenous compounds. The effect of catalysts and gas atmosphere on the product distribution and the formation of nitrogenous compounds was investigated. The results showed that the amount of nitrogenous compounds increased with the increase of catalyst/cyanobacteria ratio; liquid yields of about 50% were obtained over NiAl-LDO/MCM-41 under both nitrogen and methanol atmosphere. However, composites of the hydrocarbons and aromatic compounds in bio-oil under methanol atmosphere were lower than those under nitrogen atmosphere. Nitrogenous compound content of 78.6%, especially a 68.5% content of nitriles with low oxygen content and acidity, demonstrated that the bio-oil obtained was promising in producing value-added platform chemicals.

A revised model of silicon oxidation during the dissolution of silicon in HF/HNO3 mixtures.

The stoichiometry of wet chemical etching of silicon in concentrated HF/HNO3 mixtures was investigated. The formation of nitrogen species enriched in the etching mixture and their reactivity during the etching process was studied. The main focus of the investigations was the comprehensive quantification of the gaseous reaction products using mass spectrometry. Whereas previously it could only be speculated that nitrogen was a product, its formation was detected for the first time. The formation of hydrogen, N2, N2O and NH4+ showed a dependence on the etching bath volume used, which indicates the formation of nitrogen compounds by side reactions. Simultaneously, the ratio of the nitrogen oxides, NO and NO2, formed decreases with increasing etching bath volume, while nitric acid consumption increases, so that the formation of NO2 could also be identified as a side reaction. Based on the stoichiometries obtained, a new reaction scheme for the reduction of nitric acid during etching in HF/HNO3 mixtures and an electron balance for the oxidation of silicon is presented.

Chemical–Mineralogical Systems That Are Able To Generate Nitrogen Compounds on Earth and Even Mars

The formation of nitrogen compounds by chemical fixing of atmospheric nitrogen in ambient conditions in only one technological step is of particular interest for the chemical industry and science. The effect is achieved by air bubbling through the reactor containing a cross-linked ionic polymer with strongly basic functional groups and sulfate solution of a trivalent metal. The lower the temperature of the reactor, the higher the yield production of nitrogen compounds. In the polymer phase, jarosite-type compound formation occurs that participates in the redox processes, followed by the partial destruction and synthesis of nitrogen compounds. The results from this work demonstrate that, under certain conditions, systems containing a strongly basic cross-linked polymer and solution of three valence metal sulfates (Fe3+, Ga3+, and others) are able to generate nitrogen-containing compounds, using atmospheric nitrogen. The spontaneous and uncontrolled processes of nitrogen compound generation could occur in n...

Reactions of N+(3P) ions with H2and HD molecules at low temperatures

Context. This work is motivated by the necessity to take account of both the nuclear spin symmetries of H 2 and the spin-orbit interaction of N + ions in order to investigate gas phase reactions in interstellar chemistry, leading to the formation of nitrogenous and deuterated compounds. Aims. The main objective in this work is to determine the rate coefficients for each possible initial quantum state of the reactants N + (3 P j) + H 2 (J) (and their isotopic variants). Only in this way does it become possible both to analyse experimental data and to develop realistic applications to interstellar chemical models to constrain the gas phase chemistry of ammonia and its isotopologues. Methods. A statistical treatment is presented of state selective reactive collisions involving N + ions in fine structure state j with H 2 or HD molecules in a rotation level J of the ground vibration state, leading either to the production of NH + ions and H in the case of the H 2 reactant, and to the production of either NH + ions or ND + in the case of the HD reactant. The energies of fine structure states (j = 0, 1, 2) of the N + ions are treated on an equal footing with the other energies of internal motions. All fine structure states are considered to be reactive. Results. Cross sections for state-to-state collisions are calculated for collision energies ranging from 0.1–30 meV. These cross sections are then averaged over the kinetic energies of the reactants for each (J, j) to obtain the rate coefficients for a range of kinetic temperatures 10–200 K. The exo/endothermicity of the reactions involving N + (3 P j) + H 2 (J) (and isotopic variants) is derived from the difference ∆E e between the dissociation energies of the electronic molecular potentials of NH + and H 2. The value ∆E e = 101 meV is found to satisfactorily reproduce the experiments performed with ortho-H 2 and to a lesser extent with para-H 2. This value is used to determine the rate coefficient of the N + + HD reaction leading to the formation of ND +. The calculated value is consistent with the available experimental data. Conclusions. The present results allow for the determination of reaction rate coefficients for any given distribution of specific fine structure and rotational state populations of the reactants. In interstellar conditions, where N + is in its 3 P 0 state and para-and ortho-H 2 respectively in J = 0 and J = 1. Our results enable a study of the influence of the ortho/para evolution of molecular hydrogen on the formation of nitrogen compounds.

Formation of Nitrogenous Compounds in the Photooxidation of n-Butane under Atmospheric Conditions

The photooxidation of n-butane under atmospheric conditions in the presence of NOx resulted in the formation of the following nitrogenous products: peroxy acetyl nitrate 23, sec-butyl nitrate 16, n-butyl nitrate 1.3, ethyl nitrate 1.3, peroxy n-butyryl nitrate 1.3, and peroxy propionyl nitrate 0.5% of the initially added odd nitrogen. In addition, an electron capturing compound eluting at the retention time of sec-propyl nitrate was also observed accounting for 5% of initial NOx. Butan-2-one was the major product of conversion of n-butane with a yield of 37%. From product ratios it is evident that the formation of sec-butyl nitrate is favored over that of n-butyl nitrate by a factor of 2.1. The rate of reaction of sec-butoxy radicals with oxygen is equal to their decomposition rate.

NO reduction and the formation of nitrogen compounds over a metal-supported three-way catalyst

The fundamental characteristics of NO reduction and the formation of nitrogen compounds such as N 2O, NH 3 and HCN were investigated on a metal-honeycomb-supported three-way catalyst. Experiments were carried out in a quartz glass tube reactor by flowing simulated gas mixtures in the NO/H 2/Ar, NO/CH 4/Ar and NO/CO/Ar systems. In the NO/H 2/Ar system, NO reduction began at the lowest temperature of all the systems examined. In any system, the conversion ratio of NO reduction was over 90% at gas temperature higher than 900 K. However, depending on temperature, NO reduction resulted in nitrogen-compound formation as NH 3 in the NO/H 2/Ar system, HCN in the NO/CH 4/Ar system, and N 2O in all systems. In particular, N 2O formation was dominant at relatively low temperature. The effect of the coexistence of the oxygen on NO reduction was also examined and a sufficient conversion was observed if the O 2 concentration was less than 1 vol%.

95/03406 Formation of nitrogen compounds from nitrogen-containing rings during oxidative regeneration of spent hydroprocessing catalysts

95/03406 Formation of nitrogen compounds from nitrogen-containing rings during oxidative regeneration of spent hydroprocessing catalysts

Formation of Nitrogen Compounds from Nitrogen-Containing Rings during Oxidative Regeneration of Spent Hydroprocessing Catalysts

Commercial CoMo and NiMo catalysts in an oxidic and sulfided form and a γ-alumina were deposited with pyrrole, pyridine, and quinoline. The deposited catalysts and two spent hydroprocessing catalysts were pyrolyzed and oxidized under conditions typical of regeneration of hydroprocessing catalysts. The formation of NH 2 and HCN, as well as selected cases of N 2 O and NO, was monitored during the experiments. NH 2 and HCN were formed during pyrolysis of pyrrole-deposited catalysts whereas only NH 2 was formed during that of pyridine- and quinolinedeposited catalysts. For all deposited catalysts, both NH 2 and HCN were formed during temperature programmed oxidation in 2% O 2 . For spent catalysts, a small amount of N 2 O was formed in 2 and 4% O 2 . For pyrrole-deposited catalysts, large yields of N 2 O were formed in 4% O 2 . Under the same conditions, N 2 O yields for pyridine- and quinoline-deposited catalysts were very small

Fourier transform infrared measurement of the formation of nitrogen compounds on sodium chloride particles exposed to the ambient air in the Arctic

The role of heterogeneous reactions on sea salts in the formation of particle nitrogen compounds in the Arctic during polar sunrise was studied. A diffuse reflection type Fourier transform infrared spectrometer was used to measure surface products on sodium chloride (NaCl) particles exposed to the ambient air at Alert, Northwest Territories, Canada (82.5°N, 62.3°W). The accumulation of nitrogen compounds on NaCl was observed in both winter and spring, while the rate in winter was greater. The important role of ambient N2O5 as well as HNO3 in the formation of nitrogen compounds on NaCl is deduced. The nitrogen compounds observed might be mainly composed of nitrate ion whose electronic states were different from those of nitrate ion in water solution and/or crystal. Its reactivity, including its possible photolysis to NO2−, is noted as to a potential formation pathway of particle nitrite in spring.

Influence of the gas phase during treatment of kraft pulp with nitrogen oxides

While nitric oxide (NO) is virtually inert against water-impregnated kraft pulp it participates in important reactions when reactive nitrogen compounds, e.g. NO 2 and HNO 2 , have initiated lignin reactions. Experiments with kraft lignin (Indulin AT) showed that nitric oxide was both produced and consumed during treatment with NO 2 . One reaction path in which NO was consumed was its reaction with NO 2 to nitrogen(III)compounds, e.g. HNO 2 and N 2 O 3 . These compounds were consumed in reactions with the lignin. The introduction of oxygen into the reactor suppressed the formation of nitrogen(III)compounds and favored the formation of nitrogen compounds of oxidation states IV and V. The influence of the gas phase on the pulp properties depended on the conditions during the pretreatment. During pretreatments at 65-70 oC the kappa number was higher when oxygen was added compared to pretreatments in which the oxygen addition was omitted. The influence of the oxygen addition on the kappa number was reversed when the temperature was increased to 80-90 oC. The drop in viscosity during the pretreatment was smaller in treatments without the addition of oxygen than in those with added oxygen. This contributed significantly, especially at high temperatures, to the superior selectivities (viscosity at a given kappa number) obtained after the subsequent oxygen bleaching of pulps pretreated without the addition of oxygen. This can be mainly ascribed to a pH-buffering effect of HNO 2 , promoted by high partial pressure of NO, resulting in a suppressed acid hydrolysis of the polysaccharides. The detrimental effect of oxygen on the viscosity after pretreatment and on the selectivity after the subsequent oxygen bleaching decreased when the oxygen was introduced during a late stage of the pretreatment. The importance of efficient generation reactions of NO 2 (including other reactive nitrogen compounds) was confirmed in experiments with consecutive treatments with NO 2 and washing with water after each treatment. Superior selectivity was obtained when the pulp was pretreated once (2 % NO 2 ) under favorable conditions compared to nine consecutive treatments with a total of 18 % NO 2 under conditions unfavorable for the generation reactions.

Penetration and chemical reactions in carbon cathodes during aluminum electrolysis: part i. laboratory experiments

Penetration of metallic sodium and salt melt into cathodic carbon materials was studied in a laboratory aluminum electrolysis cell. Variables were cryolite ratio, current density, N2 or Ar atmosphere, degree of graphitization, and strain on the carbon samples. The carbon sample was analyzed by optical and electron microscopy, ash analysis, sodium detection by phenolphtalein, density, and X-ray diffraction (XRD). The developed XRD technique proved especially useful and allowed quantitative determination of concentration profiles for the crystallized compounds. Sodium was found to be the primary penetration agent and its velocity and saturation concentration increased with increased cryolite ratio of the melt and decreased graphitization of the carbon material. Sodium was found to be important as a wetting agent facilitating melt penetration. Al4C3 was not present within the pores of the carbon material. Melt penetration was enhanced by polarization and formation of nitrogen compounds. NaCN was formed directly from the elements and was destabilized by the advancing melt. In nitrogen atmosphere, A1N was the major nitrogen component and was formed within the melt phase.

Air gasification of peat, wood and brown coal in a pressurized fluidized-bed reactor. II. Formation of nitrogen compounds

The formation of nitrogen compounds in the air gasification of peat, wood and brown coal was studied in a small fluidized bed reactor, which was operated under pressure (0.4 MPa to 1.0 MPa) and at temperatures ranging from 800°C to 995°C. The fuel nitrogen of all fuels studied was converted mainly into ammonia. Smaller amounts of HCN and nitrogen-containing tar compounds were formed too. The ammonia concentration of the product gas was in the range of 0.56–1.13 vol% in peat gasification, representing 55–95 wt% of the peat nitrogen. Raising the freeboard temperature from 800 to 950°C resulted only in a small reduction in the conversion of peat nitrogen into ammonia. Similar conversions were also observed in brown coal and wood gasification, but since the nitrogen content of these fuels is lower, the ammonia concentrations were correspondingly lower and ranged between 0.05 and 0.09 vol% for wood and between 0.21 and 0.28 vol% for brown coal. The HCN concentration of the product gas in peat gasification increased with the rising temperature and ranged between 50 ppmv at 820°C and 200 ppmv at 920°C. In brown coal gasification the HCN concentration was in the range of 60–100 ppm at gasification temperatures of 850–910°C.

Behaviour of nitrogen compounds and tars in fluidized bed air gasification of peat

Formation of nitrogen compounds and tars, and the effect of process parameters on these were studied in a laboratory scale fluidized bed air gasifier under atmospheric pressure, using peat as fuel. Benzene was the main component of the tars, representing 50–75 wt% of the total tar. Addition of both secondary air and dolomite reduced the tar content of the gas. NH 3 concentration ranged from 3170 to 4600 ppm and HCN concentration from 520 to 930 ppm in the measurements. With no secondary air, 30% of fuel nitrogen formed NH 3 and 10% formed HCN. A rise in the freeboard temperature, caused by the addition of secondary air, had no significant effect on the concentration of nitrogen compounds. On the other hand, the presence of dolomite increased the NH 3 concentration and reduced the HCN concentration of the gas.

Behavior of Nitrogen Compounds in Radiation Field and Nuclear Reactor Systems

Formation of nitrogen compounds in N2-H2O systems under radiation was studied. A reaction scheme with 24 species and 73 reactions was proposed. Two trigger reactions for nitrogen atom generation: N2 → 2N (g-value of 1.6 μmol per 1 kJ absorbed energy in N2 molecules), and N2+H2O*→NH2+NO (κ=3.0×109 S−1·M−1 at 298 K with activation energy of 34.4kJ/mol) were included. Calculated results with the reaction scheme agreed within an error factor of two with ammonium formation rates from an aqueous solution with dissolved nitrogen and hydrogen gasses under γ-irradiation at temperatures of 288~473 K. The reaction scheme was also verified with BWR plant observations on nitric acid formation from in-leaked air under hydrogen water chemistry and ammonium injection tests.

Oxidation of Chemically‐Vapor‐Deposited Silicon Nitride and Slnglem‐Crystal Silicon

Oxidation of {111} single‐crystal silicon and dense, chemically‐vapor‐deposited silicon nitride was done in clean silica tubes at temperatures of 1000° to woo°C. The oxidation rates of silicon nitride under various atmospheres (dry O2, wet O2, wet inert gas, and steam) were several orders of magnitude slower than those of silicon under the identical conditions. The activation energy for the oxidation of silicon nitride decreased from 330 to 259 kJ/mol in going from dry O2 to steam while that for Si decreased from 120 to 94 kJ/mol. The parabolic rate constant for Si increased linearly as the water vapor pressure increased. However, the parabolic rate constant for silicon nitride showed nonlinear dependency on the water vapor pressure in the presence of oxygen. The oxidation kinetics of silicon nitride is explained by the formation of nitrogen compounds (NO and NH3) at the reaction interface and the counterpermeation of these reaction products.

Behavior of nitrogen compounds in radiation field and nuclear reactor systems.

Formation of nitrogen compounds in N2-H2O systems under radiation was studied. A reaction scheme with 24 species and 73 reactions was proposed. Two trigger reactions for nitrogen atom generation: N2 → 2N (g-value of 1.6 μmol per 1 kJ absorbed energy in N2 molecules), and N2+H2O*→NH2+NO (κ=3.0×109 S−1·M−1 at 298 K with activation energy of 34.4kJ/mol) were included. Calculated results with the reaction scheme agreed within an error factor of two with ammonium formation rates from an aqueous solution with dissolved nitrogen and hydrogen gasses under γ-irradiation at temperatures of 288~473 K. The reaction scheme was also verified with BWR plant observations on nitric acid formation from in-leaked air under hydrogen water chemistry and ammonium injection tests.

F2 fuel performance in XeF lasers at ambient and elevated temperatures

Extraction measurements of an electron beam pumped XeF laser using either F2 or NF3 as the halogen fuel (neon diluent) are presented. The laser efficiency is measured as a function of output coupling reflectivity and initial gas temperature. Despite the known absorption of F2 at the lasing wavelength (351, 353 nm), the laser efficiency is essentially identical when using either halogen fuel. Gas lifetime when using NF3 is shortened by the formation of nitrogen compounds which degrade the laser performance; this is not the case when using F2. Hence, the ability to use F2 without sacrificing laser efficiency has important implications with regard to the selection of a halogen fuel for extended gas lifetime operation.

Volatile components of cured and uncured pork: the role of nitrite and the formation of nitrogen compounds.

AbstractA slice‐curing method was used to prepare bacon and nitrite‐free salt pork. Headspace volatiles from the cooked products, and from cooked untreated pork, were entrained on Tenax GC and analysed by combined gas chromatography‐mass spectrometry. Aliphatic alcohols and aldehydes dominated the volatiles of all samples; small amounts of ketones, alkybenzenes, pyrazines, pyridines, thiazoles and furans were also present. Untreated pork and salt pork contained essentially the same volatiles, while the bacon showed a number of qualitative differences: several unsaturated and aromatic aldehydes were only present in nitrite free samples and benzonitrile, phenylacetonitrile and four alkyl nitrates were found only in bacon volatiles. The possible origins of these nitrogen‐compounds from the reaction of nitrite with flavour precursors are discussed.

Effect of iron and copper ions on the formation of nitrogen compounds in biacetyl/?-amino-acid model systems

Deep fat frying of foods with different moisture levels in different metallic containers imparts various aromas. The effect of metals, viz. iron and copper, in trace amounts (10 ppm) in biacetyl/α-amino acid model systems heated at 180 °C and 0–80% moisture levels on the formation of heterocyclic nitrogen compounds was studied. Biacetyl-glycine systems gave 2-methylpyridine and three pyrazines,dl-alanine formed three pyrazines and isoleucine formed two pyrazines. The catalytic effect of copper was greater compared with that of iron. The effect of metallic ions was very much enhanced in low-moisture systems, particularly in the formation of tetramethylpyrazine.