利用温度跃升傅立叶变换红外原位分析技术对斯蒂酚酸碳酰肼和斯蒂酚酸氨基脲快速热解反应的研究

Flash pyrolysis of （CHZ）2TNR and （SCZ）2TNR was conducted by T-jump/FTIR spectroscopy under 0.1 MPa Ar atmosphere. The results show that eleven IR-active gas products obtained during flash pyrolysis process of the two title compounds are NO, CO, HCN, NH3, NO2, N2O, HNCO, HNO2, CO2, H2O and HCHO, of which NO and CO are the main gas products. The molar fraction of the individual product in the pyrolysis gas mixture was described as a function of time. At least some of the NO2, N2O and H2O can result from the oxidization reaction of NH3 during flash pyrolysis of （CHZ）2TNR. It can be concluded that the two compounds are not worthy of further in-depth consideration of the adoption in detonators as eco-friendly primary explosive, and should not be used as gas generation composition of automobile crash airbag system taking into account the toxicity.     

Thermal degradation and evolved gas analysis of thiourea-formaldehyde resin (TFR) during pyrolysis and combustion

Thiourea formaldehyde resin (TFR) has been synthesized by condensation of thiourea and formaldehyde in acidic medium and its thermal degradation has been investigated using TG-FTIR-MS technique during pyrolysis and combustion. The results revealed that the thermal decomposition of TFR occurs in three steps assigned to drying of the sample, fast thermal decomposition of polymers, and further cracking. The similar TG and DTG characteristics were found for the first two stages during pyrolysis and combustion. The combustion process was almost finished at 680?°C, while during pyrolysis a total mass loss of 93 wt% is found at 950?°C. The release of volatile products during pyrolysis are NH₃, CS₂, CO, HCN, HNCS, and NH₂CN. The main products in the second stage are NH₃ CO₂, CS₂, SO₂, and H₂O during combustion. In the next stage, the combustion products mentioned above keep on increasing, but some new volatiles such as HCN, COS etc., are identified. Among the above volatiles, CO₂ is the dominant gaseous product in the whole combustion process. It is found that the thermal degradation during pyrolysis of TFR produced more hazardous gases like HCN, NH₃, and CO when compared with combustion in similar conditions.     

Electric discharge-induced oxidation of hydrogen cyanide

The AC high-voltage discharge-induced decomposition chemistry of trace levels of hydrogen cyanide in helium has been studied. In the absence of oxygen only low levels of molecular nitrogen were evolved. With oxygen added, the principal products were CO, CO₂, and N₂. No significant concentrations of NO or N₂O were observed. The response of a commercial NO_x analyzer to HCN and C₂N₂, in the NO_x mode, was determined to be linear through three decades in concentration. The oxidation chemistry of HCN and C₂N₂ in the stainless steel converter of the analyzer was studied as a function of the amount of added oxygen.NRL/NRC Postdoctoral Fellow (1983–1985).     

用T-jump/FTIR研究MnCP、NiCP和PbCP的快速热分解(英)

0IntroductionCarbohydrazideisahydrazinederivativewithwhitecrystalofstrongreducingbehaviors.Becauseithasmanycoordinationatoms(fournitrogenatomsandoneoxygenatom),carbohydrazidecan,therefore,beusedasmultidentateligand.Itscoordinationcom鄄poundiswidelyusedint…     

Synthesis of HCN Polymer from Thermal Decomposition of Formamide

Prolonged heating of formamide (HCONH₂) at 185°C or 220°C produces a black insoluble product. The FT-IR spectroscopy and the X-ray photoelectron spectroscopy (XPS) suggest that the product has the chemical structure of a polymer of hydrocyanic acid: (HCN)_x. The pyrolysis of (HCN)_x prepared from formamide produces a large amount of gaseous HCN in a wide range of temperatures together with ammonia (NH₃) and isocyanic acid (H─N─C═O).

During the thermal decomposition of formamide to produce (HCN)_x, the volatile products evolved were monitored with gas phase infrared spectroscopy. At 185°C, the gaseous product released were CO₂, CO and NH₃ while at 220°C, also HCN was detected. In both cases, a white sublimate was collected in the upper part of the reaction vessel. It consists of ammonium carbamate and its hydrolysis products ammonium carbonate and hydrogen carbonate. It is therefore possible to synthesize the polymer of hydrocyanic acid (HCN)_x starting from formamide avoiding to handle the dangerous hydrocyanic acid.     

Basis set and correlation effects on computed proton affinities of some oxygen and nitrogen bases

Basis set expansion and correlation effects on the computed proton affinities of the oxygen and nitrogen bases CH₃OH, H₂CO, CO, CH₃NH₂, CH₂NH, and HCN have been evaluated. Basis set enhancements lead to systematic changes in computed proton affinities. These effects appear to be additive, and are greater for correlated proton affinities than for Hartree-Fock energies. Inclusion of correlation decreases proton affinities, with fourth-order Møller-Plesset energies bracketed by second and third order energies.     

Basis set and correlation effects on computed lithium ion affinities of some oxygen and nitrogen bases

Basis set expansion and correlation effects on computed lithium cation affinities have been evaluated for the oxygen and nitrogen bases CH₃OH, H₂CO, CO, CH₃NH₂, CH₂NH, and HCN. The presence of diffuse functions on nonhydrogen atoms is found to be the most important single enhancement of double- and triple-split valence plus polarization basis sets. With the triple-split basis, enhancement effects are nearly additive. Correlation usually decreases computed lithium ion affinities, with the second order Møller-Plesset correlation term being the dominant term.     

Experimental characterization of gaseous species emitted by the fast pyrolysis of biomass and polyethylene

This study aims to experimentally characterize the carbonaceous and nitrogenous species, from the flash pyrolysis of millet stalks and polyethylene plastic bags, using the device of the tubular kiln, coupled to two gas analyzers: Analyzer Fourier Transform Infrared (FTIR) and an analyzer Infrared Non-Dispersive (IRND). Gaseous products analyzed are: CH₄, C₂H₂, C₂H₄, C₃H₈, C₆H₆, CO, CO₂, NO₂, NO, N₂O, HCN and NH₃. Whatever the temperature of thermal degradation, the pyrolysis shows us that in terms of mass:

• •For the millet stalks, the gaseous compounds are formed mainly CO and CO₂ to the carbonaceous species, HCN and NH₃, for the nitrogenous species analyzed;
• •As regards the polyethylene bags, hydrocarbons for carbonaceous species and HCN, NH₃ and NO₂ for the nitrogenous species, are most abundant.

In addition, the results suppose that in our experimental conditions, the hydrocarbon which is involved primarily in the formation of CO is ethylene C₂H₄. At the end of this characterization, we determined the rate of carbon and nitrogen found in the volatile gas. With millet stalks we have about 45% of volatile carbon and 15% of the nitrogen of fuel that are found in gaseous products. The results obtained with the plastic bags give 68% carbon and 15% nitrogen found in the nitrogenous species analyzed.     

Isothermal decomposition of urea nitrate

The kinetics of isothermal decomposition of urea nitrate, an organic secondary explosive with monoclinic structure and chemical formula CO(NH₂)₂ · HNO₃, which melts with decomposition at 152°C, was studied in open air in the temperature range 106-150°C, using a gravimetric method. Gas chromatographic analysis of product gases indicate CO₂, N₂O and traces of water vapor as product gases. A pasty amorphous product on the basis of wet chemical and infrared analysis was found to be cyanourea. The weight loss-time curve exhibited an acceleratory region extending almost to the end of the main reaction (35% decomposition) and followed a three-dimensional nucleation model obeying the relation x^1/3 = K(t—t₀ where α = fraction of sample reacted at time t, K = reaction rate constant, and t₀ = induction time. On the basis of this model, an enthalpy of activation of 27.6 ± 1.2 kcal/mole was calculated at 95% confidence range. The rate of decomposition was slightly accelerated in He atmosphere and slightly retarded in N₂O and CO₂ atmospheres, while water vapor drastically reduced the rate. The reaction 3CO(NH₂)₂ · HNO₃ → CNNHCONH₂ (cyanourea) + 6H₂O+3N₂O+CO₂ is presented as the most likely one for decomposition of urea nitrate in open air.     

Identification of Thermal Decomposition Products and Reactions for Liquid Ammonium Nitrate on the Basis of Ab Initio Calculation

This work analyzed the thermal decomposition of ammonium nitrate (AN) in the liquid phase, using computations based on quantum mechanics to confirm the identity of the products observed in past experimental studies. During these ab initio calculations, the CBS‐QB3//ωB97XD/6–311++G(d,p) method was employed. It was found that one of the most reasonable reaction pathways is HNO₃ + NH₄⁺ → NH₃NO₂⁺ + H₂O followed by NH₃NO₂⁺ + NO₃^– → NH₂NO₂ + HNO₃. In the case in which HNO₃ accumulates in the molten AN, alternate reactions producing NH₂NO₂ are HNO₃ + HNO₃ → N₂O₅ + H₂O and subsequently N₂O₅ + NH₄⁺ → NH₂NO₂ + H₂O. In both scenarios, HNO₃ plays the role of a catalyst and the overall reaction can be written as NH₄⁺ + NO₃^– (AN) → NH₂NO₂ + H₂O. Although the unimolecular decomposition of NH₂NO₂ is thermodynamically unfavorable, water and bases both promote the decomposition of this molecule to N₂O and H₂O. Thus AN thermal decomposition in the liquid phase can be summarized as NH₄⁺ + NO₃^– (AN) → N₂O + 2H₂O.     

煤热解过程中含氮气相产物转化规律的实验研究

为了研究煤在热解过程中含氮气相产物的生成规律,在滴管炉反应系统中对四种原煤以及两种脱除矿物质煤样分别在500℃、700℃、900℃和1100℃进行了实验研究。结果表明,随着温度的升高,作为NO前驱物的HCN和NH3的收率随之增加,N2的收率也增加。煤种对含氮气相产物的生成规律也有着较大的影响,煤化程度比较低的煤在热解过程中,燃料氮向气相含氮产物的转化率较高;煤化程度比较高的煤转化率则偏低,大部分的氮缩聚在多环芳香结构中,成为焦炭氮。煤中的矿物质对燃料氮向N2的转化起到了促进作用,而对燃料氮向HCN和NH3的转化起到了抑制作用。     

Airborne gaseous 13N species and noxious gases produced at the 12 GeV proton synchrotron

The irradiation of atmospheric air with high-energy protons has been performed at the 12 GeV proton synchrotron. The specific activity of ¹³N, one of the principal airborne radioactivities, was measured as a function of the irradiation time at a dose rate of about 6·10¹⁶ eV/g/s, and compared with the calculated values. The predominant chemical species of ¹³N produced were found to be ¹³N₂and ¹³NO₂. Their proportions were approximately 55% for ¹³N₂ and 45% for¹³NO₂, being almost independent of the irradiation time. Smaller quantities of ¹³NO and H¹³NO₂ were also observed. Measurements of radiolytic products showed that ozone is a main product and that NO₂predominates among the products of nitrogen compounds, including HNO₂ and HNO₃. The G-value for ozone formation in air was estimated from the experimental data as 6.4 molecules/100 eV.     

Tunable Diode Laser Diagnostic Studies of H2-Ar-O2 Microwave Plasmas Containing Methane or Methanol

Tunable infrared diode laser absorption spectroscopy has been used to detect the methyl radical and ten stable molecules in H₂-Ar-O₂ microwave plasmas containing up to 7.2% of methane or methanol, under both flowing and static conditions. The degree of dissociation of the hydrocarbons varied between 30 and 90% and the methyl radical concentration was found to be in the range 10 ¹⁰ –10 ¹² molecules cm ^–3 . The methyl radical concentration and the concentrations of the stable C-2 hydrocarbons C ₂ H ₂ , C ₂ H ₄ , and C ₂ H ₆ , produced in the plasma decayed exponentially when increasing amounts of O ₂ were added at fixed methane or methanol partial pressures. In addition to detecting the hydrocarbon species, the major products CO, CO ₂ , and H ₂ O were also monitored. For the first time, formaldehyde, formic acid, and methane were detected in methanol microwave plasmas, formaldehyde was detected in methane microwave plasmas. Chemical modeling with 57 reactions was used to successfully predict the concentrations in methane plasmas in the absence of oxygen and the trends for the major chemical product species as oxygen was added.     

The reactions of atomic hydrogen and active nitrogen with hydrogen azide

Detection of atoms by mass spectrometry has been used to study the reactions of hydrogen azide, HN₃, with H atoms and active nitrogen, in a fast flow reactor at pressures of about 1 torr. Stoichiometry and products of the H + HN₃ reaction have been determined and the rate constant of the initial step, assumed to be H + HN₃ → NH₂ + N₂, was found to be 2.54 × 10^?11 exp (?4600/RT) cm³ molecule^?1 s^?1, in the temperature range of 300–460K. The formation of NH₃ and H₂ products has been discussed from the different secondary steps which may occur in the mechanism. For the reaction of active nitrogen with HN₃, evidence has been found for the participation of excited nitrogen molecules produced by a microwave discharge through molecular nitrogen. The influence of excited nitrogen molecules has been reduced by lowering the gas flow velocity. It was then possible to study the N + HN₃ reaction for which the rate constant of the initial step was found to be 4.9 × 10^?15 cm³ molecule^?1 s^?1 at room temperature. Finally, the occurrence of these elementary reactions has been discussed in the mechanism of the decomposition flame of HN₃.     

The thermal decomposition of the new energetic material ammoniumdinitramide (NH4N(NO2)2) in relation to Nitramide (NH2NO2) and NH4NO3

This qualitative study examines the response of the novel energetic material ammonium dinitramide (ADN), NH₄N(NO₂)₂, to thermal stress under low heating rate conditions in a new experimental apparatus. It involved a combination of residual gas mass spectrometry and FTIR absorption spectroscopy of a thin cryogenic condensate film resulting from deposition of ADN pyrolysis products on a KCl window. The results of ADN pyrolysis were compared under similar conditions with the behavior of NH₄NO₃ and NH₂NO₂ (nitramide), which served as reference materials. NH₄NO₃ decomposes into HNO₃ and NH₃ at 182°C and is regenerated on the cold cryostat surface. HNO₃ undergoes presumably heterogeneous loss to a minor extent such that the condensed film of NH₄NO₃ contains occluded NH₃. Nitramide undergoes efficient heterogeneous decomposition to N₂O and H₂O even at ambient temperature so that pyrolysis experiments at higher temperatures were not possible. However, the presence of nitramide can be monitored by mass spectrometry at its molecular ion (m/? 62). ADN pyrolysis is dominated by decomposition into NH₃ and HN(NO₂)₂ (HDN) in analogy to NH₄NO₃, with a maximum rate of decomposition under our conditions at approximately 155°C. The two vapor phase components regenerate ADN on the cold cryostat surface in addition to deposition of the pure acid HDN and H₂O. Condensed phase HDN is found to be stable for indefinite periods of time at ambient temperature and vacuum conditions, whereas fast heterogeneous decomposition of HDN at higher temperature leads to N₂O and HNO₃. The HNO₃ then undergoes fast (heterogeneous) decomposition in some experiments. Gas phase HDN also undergoes fast heterogeneous decomposition to NO and other products, probably on the internal surface (ca. 60°C) of the vacuum chamber before mass spectrometric detection. © 1993 John Wiley & Sons, Inc.     

On the reduction of Cr3+ during the thermal decomposition of fluorochromates(III) with nitrogen containing cations

The thermal decomposition of [CO(NH₂)₂H]CrF₆·H₂O, (C₃N₆H₈)CrF₅·H₂O and the solid state reaction of CrF₃ and melamine are investigated under non-reciprocal quasi-static conditions and compared with the thermal behaviour of other fluorochromates(III) ([Cr(NH₃)₆]CrF₆, (NH₄)₃CrF and [C(NH₂)₃]₃CrF₆). The comparison of the results shows that the amount of chromium(II) in the final product is determined by the thermal stability and consequently by the decomposition temperature of the intermediates. Neither bonding properties in the starting materials nor the absolute amount of generated NH₃ influence the composition of the final product.     

The Formation and Reactions of Hydrogen Cyanide During Isobutane-SCR over Fe-MFI Catalysts

The extent to which HCN is produced as a significant product during isobutane-SCR over Fe-MFI catalysts has been investigated together with its origin and further conversion. Catalysts made by both vapor-phase sublimation and solid-state ion exchange can produce well over 100-ppm HCN, which is a major intermediate for N₂ production, but the peak concentration is less with the former material due to a higher oxidation activity. HCN production is confined to temperatures giving partial conversion of isobutane, when deposited material suppresses the very high intrinsic activity of Fe-MFI for the further conversion of HCN to N₂, largely via hydrolysis to ammonia and NH₃-SCR. Activity for the oxidation of NO to NO₂ is similarly suppressed. This oxidation step is likely to be the rate determining one in isobutane-SCR rather than the activation of the alkane since there is no deuterium kinetic isotope effect. Decomposition of isobutyronitrile, formed by dehydration of a primary nitroso species via its oxime tautomer, is a possible source of HCN. This decomposition gives propene as a coproduct, which reacts completely during isobutane-SCR and may also be a source of deposits through oligomerization. Secondary and tertiary nitroso intermediates cannot react in this way and, based on the reactions of nitroanalogues, are more likely to undergo elimination to form alkenes. The overall effect is to convert alkane-SCR to SCR with alkenes containing the same number or one less carbon atom.     

Optical detection of NO3 and NO2 in “pure” HNO3 vapor,the liquid-phase decomposition of HNO3

Flowing and static gas-phase samples of HNO₃ in O₂ and N₂ were analyzed by long-path ultraviolet/visible (UV/VIS) spectroscopy to reveal the presence of both NO₂ and NO₃, the concentrations of which were calculated using differential absorption cross sections. NO₂ is produced predominantly by the heterogeneous decomposition of HNO₃, whereas NO₃ is generated in the gas phase by the thermal decomposition of N₂O₅, a product of the self-disproportionation of liquid HNO₃. © 1993 John Wiley & Sons, Inc.     

Surface characterization of plasma‐modified poly(ethylene terephthalate) film surfaces

Poly(ethylene terephthalate) (PET) film surfaces were modified by argon (Ar), oxygen (O₂), hydrogen (H₂), nitrogen (N₂), and ammonia (NH₃) plasmas, and the plasma‐modified PET surfaces were investigated with scanning probe microscopy, contact‐angle measurements, and X‐ray photoelectron spectroscopy to characterize the surfaces. The exposure of the PET film surfaces to the plasmas led to the etching process on the surfaces and to changes in the topography of the surfaces. The etching rate and surface roughness were closely related to what kind of plasma was used and how high the radio frequency (RF) power was that was input into the plasmas. The etching rate was in the order of O₂ plasma > H₂ plasma > N₂ plasma > Ar plasma > NH₃ plasma, and the surface roughness was in the order of NH₃ plasma > N₂ plasma > H₂ plasma > Ar plasma > O₂ plasma. Heavy etching reactions did not always lead to large increases in the surface roughness. The plasmas also led to changes in the surface properties of the PET surfaces from hydrophobic to hydrophilic; and the contact angle of water on the surfaces decreased. Modification reactions occurring on the PET surfaces depended on what plasma had been used for the modification. The O₂, Ar, H₂, and N₂ plasmas modified mainly CH₂ or phenyl rings rather than ester groups in the PET polymer chains to form C? O groups. On the other hand, the NH₃ plasma modified ester groups to form C? O groups. Aging effects of the plasma‐modified PET film surfaces continued as long as 15 days after the modification was finished. The aging effects were related to the movement of C?O groups in ester residues toward the topmost layer and to the movement of C? O groups away from the topmost layer. Such movement of the C?O groups could occur within at least 3 nm from the surface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3727–3740, 2004     

A density functional investigation of the reaction mechanism of H2O + HCNO

A theoretical investigation of the H₂O + HCNO reaction, which is carried out by means of CCSD(T)/6‐311G(d,p)//B3LYP/6‐311G(d,p)+ZPVE computational method to determine a set of reasonable pathways, there are seven product pathways, P _i with i = 1 , 2 , …, 7 are involved. It is shown that P ₁ (H₂O + NCOH), P ₂ (CO + NH₂ + OH), P ₄ (HCN + HO₂ + H), and P ₆ (CO + NH₂OH) are the major product channels; and P ₇ (HOC + H₂ + NO) is the minor product channels, whereas the other channels for P ₃ (HNO + HCOH) and P ₅ (HNO + H₂CO) are very minor, the minor product channels. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011