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981.
D. I. Kiryanov M. D. Smolikov V. V. Pashkov A. G. Proskura E. V. Zatolokina I. E. Udras A. S. Belyi 《Russian Journal of General Chemistry》2007,77(12):2255-2264
Analysis of the modern state of catalytic reforming is performed. Comparative assessment of the efficiency of various technologies
of the process is given and their distribution in Russia and abroad is shown. Experience of the modernization of reforming
installations with periodic catalyst regeneration is summarized. The state of manufacture of reforming catalysts in our country
and accumulated experience of the development of catalysts of the PR series are presented. Results of industrial exploitation
of new domestic reforming catalysts are shown. On this basis comparative assessment of Russian and imported catalysts is given.
Original Russian Text D.I. Kiryanov, M.D. Smolikov, V.V. Pashkov, A.G. Proskura, E.V. Zatolokina, I.E. Udras, A.S. Belyi,
2007, published in Russkii Khimicheskii Zhurnal, 2007, Vol. 51, No. 4, pp. 60–68. 相似文献
982.
V. G. Berezkin E. Yu. Sorokina A. I. Sokolov B. A. Rudenko 《Journal of Analytical Chemistry》2003,58(1):61-67
The effects of the presence of water vapor in the carrier gas and the temperature on the retention of achiral and chiral compounds, enantioselectivity, and performance of an open-tubular column with a cyclodextrin-containing phase were studied. The use of a carrier gas containing water vapor in the determination of optically active isomers, such as camphor, slightly increases the retention factor. A substantial improvement of performance characteristics of the column was found: for hydroxy compounds, the column performance increased by two to three times and the peak symmetry improved by more than twice. 相似文献
983.
Tsventarnyi E. G. Kravtsov V. I. Kurtova O. Yu. 《Russian Journal of Electrochemistry》2003,39(3):215-222
The electroreduction kinetics of Pd(en)2+
2 complexes (0.01 M) is studied on a rotating disk electrode of Pd by recording CVA at 25, 50, and 70°C in solutions of pH 12–13 at ethylenediamine concentrations of 0.03–1.0 M. Established is a diffusion nature of limiting currents, from which diffusion coefficients for Pd(en)2+
2 complexes are calculated. The Pd electrode capacitance, determined by a pulsed galvanostatic method, is used for taking into account the true surface areas of electrolytic Pd deposits. Parameters of the slow electrochemical stage, which involves Pd(en)2+
2 complexes, are determined. The temperature dependence of the rate constant of cathodic reduction of Pd(en)2+
2 complexes is used for calculating an apparent activation energy. An electroreduction mechanism of Pd(en)2+
2 complexes on a Pd electrode is discussed. 相似文献
984.
Ju-Chun Huang Chien Hong Cheng Shyang Roeng Sheen Zhi Ling Lee Chien Ming Lei Maw Kuen Wu 《中国化学会会志》1996,43(2):139-143
The synthesis of bulk Y2Ba4Cu7O15-δ superconductor at atmospheric oxygen pressure via solid state sintering is reported. Temperature ranging from 860 to 890 °C as well as time interval over 2 to 15 days were used to investigate the formation of the Y2Ba4Cu7O15-δ phase. A time-temperature profile characterizing the conditions for the preparation of Y2Ba4Cu7O15-δ phase suggests the optimal condition to be sintering at 890 °C for over 10 days. Detailed results of X-ray diffraction, electrical resistivity, iodometric titration and magnetization measurements are described. 相似文献
985.
L. N. Raevskaya N. I. Il’chenko Yu. I. Pyatnitskii N. V. Pavlenko 《Theoretical and Experimental Chemistry》1997,33(2):78-81
The catalytic transformation of methane into higher hydrocarbons was studied under unsteady conditions on oxides of various
metals (Pb, Fe, Nb, Ti, Cd, Mo, Mg, Zn, Zr, Bi, Mn), and also on Sr-, La-, Y-, and Mn-containing oxides of perovskite structure.
It is shown that the effectiveness of the catalysts not only depends on their chemical composition, but also is determined
to a considerable degree by the specific surface of the oxides.
L. V. Pisarzhevskii Institute of Physical Chemistry, Academy of Sciences of Ukraine, 252039 Kiev, Prosp. Nauki, 31, Ukraine.
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 2, pp. 91–95, March–April, 1997. 相似文献
986.
The concentration dependence of the apparent molar volumes of lithium halides (and electrolytes in general) in alcohols (and
solvents permitting association in general) is, in the first instance, due to changes in the degree of association and to
the inherent difference between the apparent molar volumes of the ions and of the ion pairs. Previous publications on the
molar volumes of electrolytes in organic solvents, disregarding altogether ion pairing, appear to be incorrect. Data from
the literature for lithium chloride and lithium bromide in normal primary alcohols and several branched alcohols from C1 to C8 and data from our laboratory for lithium halides in 1-hexanol and 2-ethyl-1-hexanol served for the determination of φ
V
and φ
E
. Electrical and structural contributions to the values of these functions for the ions and for the ion pairs are discussed. 相似文献
987.
Y. Ohsumi T. Higashimura S. Okamura 《Journal of polymer science. Part A, Polymer chemistry》1967,5(4):849-862
Methyl vinyl ether (MVE) was polymerized under various conditions by BF3·O(C2H5)2 and SnCl4·CCl3CO2H catalysts. The effect of polymerization conditions on the steric structure of poly(methyl vinyl ether) (PMVE) was studied by NMR spectra. It was found that the triad isotacticity of PMVE decreased and the syndiotacticity and heterotacticity increased with increasing polarity of the solvent and increasing polymerization temperature. This result coincided with the qualitative conclusion estimated from softening point and infrared spectra. However, the variation of tacticity by the change of the polarity of a solvent was not so large as expected. There was no large difference between the behavior of BF3·O(C2H5)2 and SnCl4·CCl3CO2H as catalysts. From the relation between the difference of free energy of monomer addition due to the steric structure of the polymer and the polymerization temperature, it was concluded that the penultimate effect really existed and was due to only the difference in enthalpy in the MVE–BF3. O(C2H5)2 or MVE–SnCl4·CCl3CO2H systems. The penultimate effect was not greatly changed by the polymerization conditions in these systems. 相似文献
988.
Electroreduction of benzo-1,2,3-dithiazolium salts and their selenium analogs in nonaqueous solution
V. Sh. Tsveniashvili M. V. Malashkhiya V. N. Gaprindashvili B. Kh. Strelets M. M. Gel'mont Yu. I. Akulin 《Chemistry of Heterocyclic Compounds》1985,21(2):181-184
The electroreduction of benzo-1,2,3-dithiazolium cations and their selenium analogs in aprotic solvents takes place in two steps. The first step is a reversible, one-electron transfer leading to the formation of stable radicals detected by EPR. As a result of further electroreduction, the radicals obtained combine with six electrons to form the corresponding o-aminothio(seleno)phenols. Analysis of the reduction potentials of the compounds studied shows that the substitution of a selenium atom for a sulfur in these cations, especially in the 2 position of the heterocycle, facilitates their electrochemical reduction. The electrochemical activity and the kinetics of nulceophilic substitution in the cations studied are compared.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 219–222, February, 1985. 相似文献
989.
S. I. Dikhtyarev M. M. Yanina R. G. Kuznetsova B. I. Kurganov V. T. Chernobai 《Chemistry of Natural Compounds》1984,19(5):587-591
The enzyme urease has been isolated from the seeds of the watermelon of the Ogonek variety and has been characterized. The molecular weight of a rechromatographed sample of the enzyme has been determined as 480,000. The pH dependence of the activity of the urease and the kinetic parameters of the enzyme have been studied.All-Union Scientific-Research Institute of the Chemistry and Technology of Drugs, Khar'kov. Vitaminy Scientific-Production Amalgamation, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 624–628, September–October, 1983. 相似文献
990.
The effects of acidity, fluoride concentration, temperature and concentration of manganese in the reaction between KMnO(4) and Mn(II) were studied potentiometrically. The rate of reaction is increased by increasing the fluoride concentration and/or decreasing the acidity of the solution. The formal redox potentials of the MnO(-)(4)/Mn(III) and the Mn(III)/Mn(II) systems were determined at different pH values. The E degrees values obtained by extrapolation to pH = 0 were 1.58 and 1.52 V respectively. The amount of Mn(II) determined was varied from 5 to 56 mg. The net reaction can be represented as MnO(-)(4) + 10HF(-)(2) + 4Mn(2+) right harpoon over left harpoon 5MnF(-)(4) + 2H(+) + 4H(2)O. 相似文献