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1.
Summary The oxidative coupling of methane to C2 hydrocarbons was studied over a Bi2O3–P2O5–K2O catalyst. Catalysts containing Bi and P are known to be active and selective catalysts for the oxidative dimerization of propylene to 1,5-hexadiene. This catalyst system was found to also be active and selective for the oxidative coupling of methane. The experimental results are interpreted in terms of a dual-site, redox model. Methane activation to form CH3. is proposed to occur on Bi sites. The Bi site is subsequently reoxidized by bulk oxide ions and P becomes the oxygen inlet site. Adsorbed surface oxygen species reduce the selectivity to C2 hydrocarbons. 相似文献
2.
S. A. Gromilov S. V. Korenev I. V. Korolkov K. V. Yusenko I. A. Baidina 《Journal of Structural Chemistry》2004,45(3):482-489
Synthesis of five binary complex salts with an [Ir(NH3)5Cl]2+ complex cation is described. The counterions are [ReCl6]2–, [IrCl6]2–, [ReBr6]2–, and Cl–. A polycrystal X-ray diffraction study has been performed for [Ir(NH3)5Cl]2[ReCl6]Cl2, and its crystal structure has been determined. A series of Ir
x
Re1–x
phases (0.5 x > 1) were obtained by reductive thermolysis. For the Ir-Re system, the history of the V/Z(x) dependence has been refined.Original Russian Text Copyright © 2004 by S. A. Gromilov, S. V. Korenev, I. V. Korolkov, K. V. Yusenko, and I. A. BaidinaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 508–515, May–June 2004. 相似文献
3.
P. Yu. Savechenkov A. V. Vasil’ev A. P. Rudenko 《Russian Journal of Organic Chemistry》2004,40(9):1279-1283
Regio- and stereoselective oxidative dimerization of alkyl 3-arylpropynoates in the system CF3CO2H-CH2Cl2-PbO2 (1–30 h, 0–20°C) leads to dialkyl (E)-2,3-bis(arylcarbonyl)-2-butene-1,4-dioates with trans arrangement of the substituents at the double bond.Translated from Zhurnal Organicheskoi Khimii, Vol. 40, No. 9, 2004, pp. 1329–1333.Original Russian Text Copyright © 2004 by Savechenkov, Vasilev, Rudenko.For communication XI, see [1]. 相似文献
4.
A. G. Aglulin 《Kinetics and Catalysis》2009,50(3):427-434
The kinetics of the oxidative dechlorination of CCl4 on two supported salt catalysts for methane oxychlorination (CuCl2-KCl and CuCl2-KCl-LaCl3) in the presence of methane at 350–450°C was studied using a gradientless method. It was found that, at \(P_{Cl_2 } \) > 0.15 kPa, the presence of methane in the reaction mixture had no effect on the kinetics of CCl4 oxidation but decreased the activation energy E to ~22 kcal/mol. At \(P_{Cl_2 } \) < 0.15 kPa, the kinetic orders with respect to oxygen and chlorine changed and E decreased to ~17 kcal/mol. The rate of formation of CO2 as a by-product of the reaction of methane oxychlorination was described by an exponential equation in combination with rate equations for the oxidation of other chloromethanes and methane. An equation consistent with the observed rate laws of this reaction in the presence of methane was derived from the previously proposed reaction scheme for the mechanism of the oxidative dechlorination of CCl4. 相似文献
5.
A. V. Shlyakhtina A. E. Ukshe L. G. Shcherbakova 《Russian Journal of Electrochemistry》2005,41(3):265-269
A nanoceramic product of the composition Lu2Ti2O7 is synthesized by a coprecipitation method with a subsequent sublimation drying and an annealing at 650–1650°C. The conduction of Lu2Ti2O7 synthesized at 1650°C is ionic (10–3 S cm–1 at 800°C). Thus, a new material with a high ionic conduction has been discovered. The ordering in Lu2Ti2O7 is studied by methods of RFA, RSA, IK spectroscopy, electron microscopy, and impedance spectroscopy. The existence of a low-temperature phase transition fluorite-pyrochlore at 800°C and a high-temperature conversion order-disorder at 1650°C are established.Translated from Elektrokhimiya, Vol. 41, No. 3, 2005, pp. 298–303.Original Russian Text Copyright © 2005 by Shlyakhtina, Ukshe, Shcherbakova. 相似文献
6.
T. A. Bazhenova N. V. Bardina G. N. Petrova M. A. Borovinskaya 《Russian Chemical Bulletin》2004,53(8):1646-1654
The effect of potential value and chemical properties of an external electron donor on C2H2 reduction catalyzed by nitrogenase active center (cluster [(6-N)Fe7MoS9·homocitrate] FeMoco isolated from the enzyme) has been investigated in the presence of proton donors of different acidity. The temperature—reaction rate dependences of these reactions have been studied. It has been shown that the rate-limiting steps of the reactions differ depending on the proton donor used. When thiophenol or water are used as proton donors, and electrochemical step — the electron transfer from cathode to adsorbed catalytic cluster — has been found to be a rate-limiting one. The effective activation energy of ethane formation as a product of four-electron C2H2 reduction is found to be 1.5 times lower than that of ethylene, namely, 13 kcal mol–1. When stronger acid, pentafluorothiophenol, is used as a proton donor, the chemical step of intramolecular rearrangement of the catalyst—substrate complex taking place in solution becomes a rate-limiting one. The effective activation energies of both ethylene and ethane become equal to 32 kcal mol–1.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1583–1591, August, 2004. 相似文献
7.
The electronic structure of the Ca2 molecule has been investigated by use of a two-valence-electron semiempirical pseudopotential and applying the internally contracted multireference configuration interaction method with complete-active-space self-consistent-field reference wave functions. Core–valence correlation effects have been accounted for by adding a core-polarization potential to the Hamiltonian. The ground-state properties of the Ca2 and Ca2+ dimers have also been studied at the single-reference coupled-cluster level with single and double excitations including a perturbative treatment of triple excitations. Good agreement with experiment has been obtained for the ground-state potential curve and the only experimentally known A1u+ excited state of Ca2. The spectroscopic parameters De and Re deduced from the calculated potential curves for other states are also reported. In addition, spin–orbit coupling between the singlet and triplet molecular states correlating, respectively, with the (4p)1P and (4p)3P Ca terms has been investigated using a semi-empirical two-electron spin–orbit pseudopotential.
Acknowledgement.This work was supported by grant 5 P03B 082 21 from the Polish State Committee for Scientific Research (KBN). 相似文献
8.
Yu. I. Pyatnitskii A. I. Bostan L. N. Raevskaya S. A. Nedil’ko A. G. Dzyaz’ko E. G. Zen’kovich 《Theoretical and Experimental Chemistry》2005,41(2):117-121
The catalytic properties of complex oxide catalysts with ABO3 perovskite structure (A = Sr, Ba, La; B = Mn, Co, Ni) in the oxidative coupling of methane were studied with separate introduction of methane and oxygen onto the catalyst. The greatest catalytic activity was found for the nickel-containing oxides but these catalysts have much lower operational stability than Mn- and Co-containing catalysts. Modification of the oxide systems studied by partial replacement of the strontium or transition metal ions by alkali metal ions considerably improves their activity and selectivity.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 110–114, March– April, 2005. 相似文献
9.
The kinetics of methane steam reforming and pyrolysis on Ru/Al2O3(T= 650–750°C,
= 0.001–0.030 MPa) is studied. The values of the rates and activation energies are compared with the kinetic parameters for nickel catalysts. It was shown that steam reforming can occur on the ruthenium catalyst both heterogeneously and heterogeneously–homogeneously depending on the reaction conditions. Comparative activities of the Ru/Al2O3and Ni–Al2O3catalysts are discussed under the conditions of purely heterogeneous and heterogeneous–homogeneous steam reforming. 相似文献
10.
V. N. Snytnikov V. O. Stoyanovskii V. A. Ushakov V. N. Parmon 《Kinetics and Catalysis》2005,46(2):260-268
Luminescence spectra induced by a high-power UV laser pulse in the excitation range of extraneous ions in alumina can provide valuable information on this compound. The laser-induced luminescence (LIL) technique markedly extends the capabilities and the area of application of photoluminescence spectroscopy. Luminescence measurements in the red spectral region enable one to detect octahedrally coordinated Cr3+ ions at concentrations down to 10–7 wt % in metastable alumina modifications. The fact that the Cr3+ luminescence line occurs in different positions in the - and -alumina allows LIL spectroscopy to be used in phase and elemental analysis of thin surface layers and in surface temperature measurements when studying the microstructure of heterogeneous catalysts under real pressures and in a real gas medium, including in situ measurements.__________Translated from Kinetika i Kataliz, Vol. 46, No. 2, 2005, pp. 278–287.Original Russian Text Copyright © 2005 by Snytnikov, Stoyanovskii, Ushakov, Parmon. 相似文献
11.
N. V. Pervukhina S. V. Borisov S. A. Magarill D. Yu. Naumov V. I. Vasiliev B. G. Nenashev 《Journal of Structural Chemistry》2004,45(4):720-723
The results of structural studies of the synthetic analog of the radtkeite mineral Hg3S2Cl1.00I1.00 are analyzed. The crystal structure of the compound has been refined; the unit cell parameters are a
m = 16.827(4) , b
m = 9.117(1) , c
m = 13.165(5) , = 130.17(2)°, V = 1543.3(8) 3, space group C2/m, Z = 8, R = 0.0527. A possible transition a
0
= a
m; b
0
= a
m + 2c
m; c
0
= –b
m to the pseudo-orthorhombic F cell previously determined for radtkeite, where one of the angles (
0
) is slightly different from 90° (89.55°), has been found. Each sulfur atom in the structure is bonded to three mercury atoms, forming SHg3 umbrellas with distances 2.240(6) –2.474(8) and angles HgSHg 94.7(2)°–102.9(2)°. The SHg3 fragments are linked through Hg vertices to form corrugated [Hg12S8] layers. The halogen atoms lie inside and between the [Hg12S8] layers; the distances are Hg-Cl and Hg-I 2.783(7) , 2.961(7) , and 3.083(4) –3.311(3) , respectively.Original Russian Text Copyright © 2004 by N. V. Pervukhina, S. V. Borisov, S. A. Magarill, D. Yu. Naumov, V. I. Vasiliev, and B. G. NenashevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 755–758, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date. 相似文献
12.
T. V. Mironyuk V. L. Struzhko S. N. Orlik G. M. Tel’biz 《Theoretical and Experimental Chemistry》2005,41(2):129-134
We have shown that the activity of cobalt-containing catalysts based on sulfated zirconium dioxide in selective catalytic reduction (SCR) of NO by methane depends on the amount of sulfur and the preparation method. Modification of Fe and Mn improves the catalytic behavior of SO
4
2−
/ZrO2 as a result of the increase in the concentration of active sites.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 121–125, March– April, 2005. 相似文献
13.
The dependences of the maximum selectivity and the limiting yield of C2 hydrocarbons on the degree of methane conversion during its gas-phase oxidative coupling were calculated by means of kinetic simulation. The correlation between the results of the calculations and the rersults obtained in the experimental studies dealing with catalytic oxidative coupling of methane is discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 568–570, March, 1995. 相似文献
14.
Antal Sárkány 《Reaction Kinetics and Catalysis Letters》2001,74(2):299-307
Selectivity of product formation has been tested in hydrogenation of acetylene over 0.3 wt.% Pd/-alumina and 0.5 wt.% Pd/TiO2catalysts. Non-steady-state regime of catalyst operation was tested in pulse-flow experiments. Significant carbon poisoning appears to be a necessaryrequisite for selective formation of ethylene. The effect of hydrogen and acetylene partial pressure has been tested on the selectivity of C4products. At 273–298 K the catalysts showed 26–35% selectivity for C4 hydrocarbons and <2.5% for ethane production at conversionsof 30–40%. Deuterium distribution in ethylene and 1,3-butadiene and the deuterium content of the surface hydrogen pool have been compared and mechanismof diene formation has been discussed. 相似文献
15.
The phase diagram of the system CdI2-Bi2O3 is studied by means of X-ray diffraction, differential thermal analysis and measurements of the density of the material. As a result of the synthetic and peritectic interactions, two incongruently melting intermediate phases i.e. phase A — CdI2·2Bi2O3 and phase B — CdI2·4Bi2O3 (stable in the temperature interval 370–850°C) are formed.The phase A exists in two polymorphic forms with a temperature of the phase transition T
=320–370°C. The unit cell parameters at low temperature modification of -CdI2°2Bi2O3 were determined. (a=1.032 nm, b=1.046 nm, c=1.046 nm, =115.02°, =109.11° and =82.04°). The phases A and B have fields of homogeneity.The authors acknowledge thankfully the financial support for this work from the Ministry of Education and Science (Fond Scientific investigations — contract TN-1102). 相似文献
16.
N. I. Il'chenko N. V. Pavlenko L. N. Raevskaya A. I. Bostan 《Theoretical and Experimental Chemistry》2000,36(1):48-53
The oxidative coupling of methane in a periodic regime was studied using Co-containing perovskites as solid oxidants. Partial
substitution of strontium with alkali metals in the perovskite SrCoO3 increased the activity and selectivity of the catalyst with respect to higher hydrocarbons. The substituted catalysts continued
to work after many oxidation-reduction cycles.
L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of Ukraine, 31 Prospekt Nauki, Kiev 252039,
Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 1, pp. 47–52, January–February, 2000. 相似文献
17.
B. V. Suvorov A. D. Kagarlitskii T. A. Afanas'eva O. B. Lebedeva A. I. Loiko V. A. Serazetdinova 《Chemistry of Heterocyclic Compounds》1972,5(6):768-773
The oxidative ammonolysis of 3-picoline has been studied on the following catalysts: V2O5 on corundum, V2O5 with the addition of 1% of H2WO4 on corundum, V2O5 + MoO3 + P2O5 (10.350.35) on silica gel, V2O5 + Al2O3, and a melt of V2O5 + TiO2 (10.22). Mixed catalysts of vanadium and titanium oxides exhibited the highest activity and selectivity. With the passage of 25–45 moles of oxygen (in the form of air), 5–10 moles of ammonia, and 50–70 moles of water per mole of 3-picoline at a temperature of 390–410° C, the amount of nicotinonitrile formed on these catalysts amounted to 85–90% of the theoretically possible amount.Part LXIII of the series Oxidation of organic compounds; for part LXII, see [1]. 相似文献
18.
N. I. Il'chenko 《Theoretical and Experimental Chemistry》1994,30(3):129-132
A mechanism for the heterogeneous-homogeneous reaction of oxidative coupling of methane on metal-like catalysts has been proposed to explain the dependence of the specific reaction rate on the magnitude of the total surface area of catalysts, including catalysts of the same chemical composition but different specific surface area.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 30, No. 3, pp. 158–162, May–June, 1994.The author is grateful to Yu. T. Pytnitskii for a very useful discussion of this work. 相似文献
19.
W. K. Jóźwiak T. P. Maniecki A. Basińska J. Góralski R. Fiedorow 《Kinetics and Catalysis》2004,45(6):879-889
This paper is focused upon the influence of potassium on the reduction behavior and catalytic properties of Fe2O3, Ru/Fe2O3 and Ru/(K)Fe2O3 catalysts for the water gas shift (WGS) reaction. The effect of promotion by potassium is attributed to stabilization of a highly dispersed ruthenium phase on the iron oxide surface. The hydrogen reduction behavior of Fe2O3 catalysts is strongly influenced by time-pressure dependent processes and comprises two or three heavily overlapped TPR peaks which can be ascribed to the following stages of the iron(III) oxide reduction 3Fe2O3 2Fe3O4 6FeO 6Fe. The appearance of FeO as an intermediate phase was confirmed by XRD. The presence of ruthenium(IV) oxide substantially changes the kinetics of the reduction process. In the case of potassium-doped catalysts, the reduction of Fe2O3 is substantially different and is assigned to the reduction phase of KFeO2. Both ruthenium and potassium have a promoting effect on the catalytic activity for the WGS reaction.From Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 930–941.Original English Text Copyright © 2004 by Jówiak, Maniecki, Basiska, Góralski, Fiedorow.This article was submitted by the authors in English. 相似文献
20.
T. V. Mironyuk V. L. Struzhko S. N. Orlik 《Theoretical and Experimental Chemistry》2007,43(4):255-260
A series of cobalt-containing granulated and structured catalysts based on zirconium and aluminum oxides has been studied.
The optimum composition of binary oxide samples (80% ZrO2 − 20% Al2O3) for the selective reduction of nitrogen monoxide with methane (84% conversion of NO achieved at 320 °C) has been determined.
The activity of the structured catalysts depends on both the composition of the secondary carrier (ZrO2, Al2O3, and their mixture) and on the nature of the skeleton of the cellular structure (cordierite, kaolin-aerosil).
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 43, No. 4, pp. 237–241, July–August, 2007. 相似文献