Pyrolysis of propane in the presence of acetylene

Pyrolysis of propane in the presence of acetylene and acetylene labeled with C-14 has been studied in the temperature range of 833–1019 K. The inhibition effect of acetylene on the thermal decomposition of propane is turning into an accelerating effect at higher temperature.

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C¹⁴ 833–1019 . .

     

Pyrolysis of propane in the presence of propylene

Pyrolysis of propane in the presence of propylene and propylene labeled with C-14 has been studied in the temperature range of 833–1019 K. The strong inhibition effect of propylene on the thermal decomposition of propane has been confirmed.     

Pyrolysis of propane in the presence of ethylene

Pyrolysis of propane in the presence of ethylene and ethylene labeled with¹⁴C has been studied in the temperature range 773–1019 K. The disappearance of the inhibiting effect of ethylene on the thermal decomposition of propane with increasing temperature was observed.

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¹⁴C 773–1019 . .

     

Pyrolysis of propane in the presence of14C2H4 studied by the kinetic isotope method

The kinetic isotope method was used to explain the role of ethylene in the pyrolysis of propane. The mechanism of the radioactivity appearance in methane and propylene is proposed.     

Pyrolysis of trichlorosilane in the presence of chloroform

The pyrolysis of trichlorosilane in the presence of different amounts of chloroform and the copyrolysis of HSiCl₃ with buta-1,3-diene in the presence of 1 mol.% chloroform were studied. The enthalpies of formation of products resulting from the pyrolysis of HSiCl₃ in the presence of chloroform were calculated by the quantum chemical method. Based on the thermochemical data as well as data from GLC and mass spectrometry, it was concluded from the condensate composition that introduction of chloroform into the zone of pyrolysis of HSiCl₃ favors generation of silylenes.     

Effect of hydrogen on the aromatization of propane on H-pentasil

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1931–1932, August, 1990.     

Dehydrogenation of propane in the presence of carbon dioxide over oxide-based catalysts

In the present study, we show the advantages of CO₂ use for the dehydrogenation of propane to propene on the basis of thermodynamic considerations and some experimental results. Several metal oxides Ga₂O₃, Cr₂O₃, Fe₂O₃ unsupported and supported on g- Al₂O₃ and SiO₂ were tested. Ga₂O₃ catalyst was found to be an effective agent for dehydrogenation of propane to propene. The yield of propene at 873 K was 30.1 %. This revised version was published online in June 2006 with corrections to the Cover Date.     

Gas hydrate phase equilibria for propane in the presence of additive components

A proper discussion on the possibility and feasibility of technological applications for gas hydrates requires knowledge of the phase behaviour and its relation to the gas hydrate structure and its occupation. This paper presents experimental data on gas hydrate phase equilibria for the system water+propane and for various systems of the kind water+propane+additive. The additives considered are tetrahydropyran, cyclobutanone and cyclohexane, which are assumed to occupy the large cavity of structure II (sII) hydrate, and methylcyclohexane that is a typical structure H (sH) hydrate former. All additives have in common that they are very poorly soluble in water and, therefore, an additional liquid phase is present in these systems. The pressure for the equilibrium hydrate–liquid water–vapour (H–L_w–V) in the system water+propane is reduced upon addition of each of these components. Simultaneously, the hydrate equilibrium hydrate–liquid water–liquid propane (H–L_w–L_C3H8) is shifted to lower temperatures. These observations can be explained in terms of mutual miscibility of propane and the additive component. However, it cannot be excluded that propane molecules are exchanged by additive molecules in occupying the large cavity of sII.     

Reactions of high translational energy hydrogen atoms with propane

The reactions of translationally excited deuterium atoms with propane have been investigated by use of photochemically produced atoms of 157kJmol(-1) initial energy. The reaction mechanism was tested by comparing the results for the DBr scavenged system to those where Br(2) was used as radical scavenger. Values were obtained for the fraction of atoms undergoing "hot" reaction on collision with propane, and the relative cross sections for the interaction of deuterium atoms with propane and DBr. The effect of the initial energy of the "hot" atoms is discussed.     

The hetero‐homogeneous pyrolysis of propane,in the presence or in the absence of dihydrogen,and the measurement of uptake coefficients of hydrogen atoms

Propane pyrolysis is studied in the presence and the absence of dihydrogen between 743 and 803 K, in the propane pressure range 10–100 Torr, and at 20–254 Torr dihydrogen pressure. In unpacked Pyrex reactors, dihydrogen accelerates propane dehydrogenation and demethanation. The reaction is modeled by a conventional homogeneous free‐radical chain mechanism. Propane pyrolysis is strongly inhibited by the walls of reactors packed with stainless steel, zirconium, or palladium foils. Adding dihydrogen to propane still increases the rates of product formation. The reaction in these packed reactors is modeled by the kinetic scheme proposed for the homogeneous reaction and by the heterogeneous process H. ⇄ ½H₂ (w₂)(−w₂) of chain termination and initiation. In the absence of dihydrogen, step (−w₂) is negligible and precise values of uptake coefficients of hydrogen atoms are obtained at 773 K: 0.31 for stainless steel 0.10 for zirconium 0.05 for palladium In the presence of dihydrogen, steps (w₂) and (−:w₂) are instantaneously at equilibrium. The latter system should be useful to study any reaction of hydrogen atoms in the temperature range. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 340–364, 2000     

Reaction space organization effect on propane pyrolysis in the presence of a nickel-copper catalyst

Propane pyrolysis at atmospheric pressures and temperatures of 500–700°C in the presence of a bimetallic catalyst containing 50 wt % Ni, 40 wt % Cu, and a silicon dioxide textural promoter has been investigated. It has been established experimentally that the reactor geometry and the way the reactants are let in and out exert an effect on the catalytic pyrolysis. The overall process rate is mainly determined by the heterogeneous reaction occurring on the catalyst surface. The homogeneous constituent of the process has an effect on the propane conversion at the early stages of the reaction.     

Oxygen and hydrogen atom concentration profiles in the premixed propane/oxygen flame

The oxygen and hydrogen free radical (atom) concentration profiles in the premixed propane/oxygen flame at 92.5% oxygen were determined using electron spin resonance (ESR) spectroscopy techniques. The ESR instrument was specially modified so that the flame can be probed for determining the oxygen and hydrogen atom population densities during the actual combustion process of propane burning in oxygen. The technique used for propane is similar to that suggested by Fristrom and Westenberg to measure the free radical concentration profiles in CC hydro- carbon/oxygen combustion.     

污染物甲胺为电子给体可见光下Pt/ZnIn2S4光催化制氢

用水热法制备了ZnIn2S4固溶体,并通过XRD和UV-vis漫反射光谱进行了表征.研究了一甲胺、二甲胺和三甲胺为给电子体,在Pt/ZnIn2S4上的可见光光催化制氢及自身的降解反应.3种甲胺都能显著提高光催化分解水制氢活性,同时自身得到很好的降解.电子给体的放氢活性顺序为:TMADMAMMA.通过红外衰减全反射(ATR-IR)法检测电子给体在ZnIn2S4表面的吸附行为,吸附强度大小依次为MMADMATMA.光催化活性与分子结构和在催化剂表面的吸附行为有关.3种污染物浓度对放氢活性的影响都符合Langmuir-Hinshelwood动力学模型.讨论了可能的化学反应机理.     

Photolysis of azomethane–propane mixtures. Arrhenius parameters for the hydrogen abstraction reactions of methyl with azomethane and with propane

Mixtures of up to 14% azomethane in propane have been photolyzed using mainly 366 nm radiation in the ranges of 323–453 K and 25–200 torr. Detailed measurements were made of the yields of nitrogen, methane, and ethane. Other products observed were isobutane, n-butane, ethene, and propene. A detailed mechanism is proposed and shown to account for the observed variation of product yields with experimental conditions. The quantum yield of the molecular process is found to be given by the temperature-independent equation The values of rate constants obtained are where the reactions are and it is assumed that the rate constant for the reaction is given by      

Ozonation of deciduous wood in the presence of hydrogen peroxide

The kinetic curves of the dependence of ozone specific absorption (Q _{r, sp} ) upon aspen wood ozonation in the presence and absence of hydrogen peroxide are obtained. It is established that the rate of ozone and Q _{r, sp} absorption increase in the O₃/H₂O₂ system. It is demonstrated by ESR, IR, and UV spectroscopy of diffuse reflection that wood ozonation in the O₃/H₂O₂ system results in the destruction of lignin aromatic and quinoid structures. The ozonation process in the presence of H₂O₂ is accompanied by destruction of the carbohydrate component of the lignocarbohydrate complex. We conclude that O₃/H₂O₂ can be used in the deep delignification of wood. It is shown that the presence of hydrogen peroxide upon ozonation increases the efficiency of the process, allowing its duration and total ozone consumption to be reduced.     

Role of silica-alumina catalyst texture in the reaction of propane oxidative dehydrogenation in the presence of sulfur dioxide

The effects of preparation conditions, component ratio, and pretreatment temperature (1000–1550‡C) of silica-alumina samples on their phase composition, texture characteristics, and catalytic properties are studied in the reaction of the oxidative dehydrogenation of propane by sulfur dioxide. It is shown that the samples contain individual silicon and aluminum oxides. The product of their interaction (mullite) is formed only at 1550°C. Mesoporous and macroporous catalysts with monoand polydispersed pore distributions over sizes are obtained. It is found that the porous structure of the catalyst plays a key role in the process of the oxidative dehydrogenation of propane in the presence of sulfur dioxide at 600–700°C. The apparent rate of propylene formation increases with an increase in the pore volume with radii between 10 and 100 nm. Propane is transformed into propylene more selectively on the catalyst where the pores with radii of 10–100 nm dominate; narrower pores (< 10 nm) are favorable for the formation of coke and complete oxidation products.