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X-Ray Spectrometry     Hybrid Journal   (Followers: 9)
Zeitschrift für Naturforschung B : A Journal of Chemical Sciences     Open Access   (Followers: 1)

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Journal Cover Kinetics and Catalysis
  [SJR: 0.317]   [H-I: 23]   [3 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1608-3210 - ISSN (Online) 0023-1584
   Published by Springer-Verlag Homepage  [2335 journals]
  • Biotechnology is storming the heights of petrochemistry
    • Authors: I. I. Moiseev
      Pages: 405 - 421
      Abstract: Abstract This brief review deals with the most important recent achievements of industrial biotechnology in its competition with petrochemistry: creation of the bioethanol industry; discovery of the fermentation of CO-containing gases, a new way of converting biomass into chemicals; carrying out the fermentation of С5 and С6 carbohydrates at similar rates; development of new methods of producing divinyl, isoprene, nylon, butanol, higher straight-chain alcohols, isopropanol, isobutanol, 1,4-butanediol, 2,3-butanediol, and succinic acid; progress in the culturing and processing of microalgae, an important source of glycerol and higher carboxylic acids.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040078
      Issue No: Vol. 57, No. 4 (2016)
  • Kinetics of urethane formation from isophorone diisocyanate: The catalyst
           and solvent effects
    • Authors: S. V. Karpov; V. P. Lodygina; V. V. Komratova; A. S. Dzhalmukhanova; G. V. Malkov; E. R. Badamshina
      Pages: 422 - 428
      Abstract: Abstract The dependence of the kinetic parameters of urethane formation in the reaction between isophorone diisocyanate and alcohols of different structure (n-propanol, isopropanol, propargyl alcohol, 1,3-diazidopropan-2-ol, and phenol) in diluted solutions on the natures of solvent (toluene, carbon tetrachloride) and catalyst (dibutyltin dilaurate, diazobicyclooctane) was found using an original IR spectroscopic procedure. The ratio of the apparent rate constants for the reactions involving the aliphatic and cycloaliphatic NCO groups of isophorone diisocyanate was determined, and the efficiency of catalysis in these reactions was estimated. The reaction conditions under which the difference between the reactivities of isocyanate groups can reach 40 were determined.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040066
      Issue No: Vol. 57, No. 4 (2016)
  • Photocatalytic degradation of Br-trihalomethanes by nanosized TiO 2
           /diatomite hybrid photocatalyst
    • Authors: J. Zhang; A. Wei; Q. Wu; D. Zhang
      Pages: 429 - 433
      Abstract: Abstract Nanosized TiO2/diatomite catalyst was prepared by sol–gel method at ambient temperature. Diatomite was used as a carrier, tetrabutyl titanate served as a source of titanium. The photocatalytic degradation of Br-THMs was successfully achieved in the presence of TiO2/diatomite under Xe-light irradiation. It was suggested that Br-THMs were debromized in a stepwise manner. The rate of degradation increases markedly with increasing extent of substitution of Br-THMs by bromine because the C–Br bond is less stable than the C–Cl bond. Furthermore, the degradation of Br-THMs was caused by the action of hydroxyl free radicals, the signals of which were registered by means of electron spin resonance (ESR) spectroscopy.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040030
      Issue No: Vol. 57, No. 4 (2016)
  • Nontransition metal–crown ether complexes as hydroperoxide
           decomposition catalysts
    • Authors: N. M. Nurullina; N. N. Batyrshin; Kh. E. Kharlampidi; V. I. Anisimova; I. A. Suvorova
      Pages: 434 - 438
      Abstract: Abstract The decomposition of tert-butyl hydroperoxide in a chlorobenzene medium in the presence of complexes of dibenzo-18-crown-6 with calcium, strontium, and barium chlorides has been studied. It has been found and kinetically proven that the decomposition of tert-butyl hydroperoxide is preceded by the formation of an intermediate hydroperoxide–catalyst complex. Kinetic and thermodynamic parameters of the complex formation have been determined.
      PubDate: 2016-07-01
      DOI: 10.1134/s002315841604008x
      Issue No: Vol. 57, No. 4 (2016)
  • High efficient Aldol condensation reaction utilizing modified calcium
           oxide as stable solid base catalyst
    • Authors: Jin Wang; Tianlan Yan; Ying Tang; Yanqing Miao
      Pages: 439 - 445
      Abstract: Abstract Aldol condensation of acetophenone and benzaldehyde, as well as various benzaldehydes was carried out efficiently to produce chalcone with a good selectivity and high yields by using modified CaO as a solid base catalyst. Stability and catalytic activity of commercial CaO were significantly improved after modifying calcium oxide with bromobenzene in a simple way. An Aldol yield higher than 98.9% was obtained after the reaction was conducted for 3 h. This time interval is considerably shorter when compared to a period of 12 h needed for the commercial CaO to reach 92.1% yield under optimum activation. The high catalytic activity of modified CaO suggests that heterogeneous aldolisation was greatly improved by changing its hydrophilic properties. The influence of several reaction parameters, such as temperature and catalyst loading, was investigated. The humidity test over modified CaO reveals that the basic sites of modified CaO are resistant to CO2 and moisture. The type of aldehyde has great influence on the yield of Aldol condensation. Based on the results of characterization by Fourier transform-infrared spectrometry (FT-IR) and thermogravimetric measurements (TG), it was concluded that the modifier was chemically bonded to the surface of CaO and nearly no Ca(OH)2 was formed during the modification process.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040145
      Issue No: Vol. 57, No. 4 (2016)
  • Effect of various admixtures on the properties of Mn-substituted
    • Authors: E. F. Sutormina; L. A. Isupova; N. A. Kulikovskaya; N. A. Rudina; V. A. Rogov
      Pages: 446 - 454
      Abstract: Abstract The effect of various admixtures (graphite, sawdust, mullite–silica fiber, vermiculite, boric acid, different size fractions of cordierite, corundum microspheres) in the cordierite stock (mixture of talc, clay, manganese oxide, and aluminum hydroxide) on the formation of Mn-substituted cordierite has been investigated. The admixtures exert an effect on the degree of cordierite formation, on the impurity phase content of the product (including its Mn2O3 content), on the surface concentration of manganese cations, on their oxidation state, on the texture of the catalysts, and on their ammonia oxidation activity. The highest NO x yield is observed with the catalysts containing a coarse fraction of cordierite and corundum microspheres, which are characterized by a high surface concentration of oxidized manganese cations and have large transport pores.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040133
      Issue No: Vol. 57, No. 4 (2016)
  • Mechanisms of the action of alkali metal admixtures on the properties of
           copper–zinc–aluminum water–gas shift catalysts
    • Authors: O. L. Ovsienko
      Pages: 455 - 465
      Abstract: Abstract The effect of alkali metal (Cs, Na) admixtures on the catalytic and physicochemical properties of coprecipitated Cu–Zn–Al catalysts for the low-temperature water–gas shift reaction has been investigated. The inhibition of the formation of methanol, an undesired by-product, by alkali metals is accompanied by a decrease in the activity of the catalyst in the main, water–gas shift reaction ion. The alkali metals exert an adverse effect on the thermal stability of the catalyst. Experimental data are explained in a consistent way on the basis of the following conceptions of the mechanism of the action of alkali metals: (1) the alkali metals stimulate sintering of the crystal structure of the main components of the catalyst, diminishing the activity of the catalyst in the water–gas shift reaction and in methanol formation; (2) the alkali metals directly or indirectly accelerate methanol conversion into other chemical products.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040108
      Issue No: Vol. 57, No. 4 (2016)
  • Kinetics of propylene epoxidation with hydrogen peroxide catalyzed by
           extruded titanium silicalite in methanol
    • Authors: A. V. Sulimov; S. M. Danov; A. V. Ovcharova; A. A. Ovcharov; V. R. Flid
      Pages: 466 - 473
      Abstract: Abstract The kinetics of propylene oxidation into propylene oxide in the presence of extruded titanium silicalite was studied. Based on the experimental data, a kinetic model of the process was designed and the activation energies of the target and side reactions, the rate constants, and the adsorption equilibrium constants were determined. The adequacy of the proposed kinetic model was verified on a continuously-operated test bench laboratory unit.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040121
      Issue No: Vol. 57, No. 4 (2016)
  • Homopolymerization and copolymerization of vinyl chloride over supported
           metalorganic catalysts
    • Authors: N. Yu. Kovaleva; L. A. Novokshonova
      Pages: 474 - 481
      Abstract: Abstract The homopolymerization of vinyl chloride and its copolymerization with ethylene over dibutyl ether–modified SiO2-supported Ziegler–Natta catalysts based on titanium and vanadium chlorides have been studied. The supported metal complexes are sufficiently active in the polymerization of vinyl chloride. Their activity depends on the catalyst composition and conditions of formation of the catalyst on the surface of the support. The chain structure of the resulting polyvinyl chloride (PVC) has been studied by NMR spectroscopy. The thermal properties of the synthesized PVC have been investigated by differential scanning calorimetry. The PVC obtained possesses enhanced thermal stability owing to the specific features of its chain structure. Vinyl chloride polymerization over the supported metalorganic catalyst proceeds mainly via a free-radical mechanism. Process conditions have been found for conducting the copolymerization of vinyl chloride with ethylene over supported metal complexes resulting in the formation of true statistical copolymers, which is confirmed by IR and NMR spectroscopy.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416030071
      Issue No: Vol. 57, No. 4 (2016)
  • Catalytic activation of layered silicates for the synthesis of
    • Authors: P. N. Brevnov; A. S. Zabolotnov; V. G. Krasheninnikov; B. V. Pokid’ko; A. V. Bakirov; O. N. Babkina; L. A. Novokshonova
      Pages: 482 - 489
      Abstract: Abstract The effects of the structure of organomodified montmorillonite and the conditions of its catalytic activation by titanium and vanadium chlorides on the synthesis of nanocomposite materials based on ultra-high molecular weight polyethylene with an exfoliated structure by an in situ polymerization method were studied. It was shown that, with the use of organomodified montmorillonite with the interplanar spacing d 001 = 1.6–1.8 nm, in which the alkyl radicals of a modifier are arranged in parallel to the basal silicate surfaces, the catalyst is adsorbed only on the external surface of particle, and it does not penetrate into the interlayer space (in this case, the exfoliation of a filler does not occur). With the use of montmorillonite samples with d 001 > 2 nm with the packing of a modifier as paraffin-like mono- or bilayers, the catalyst is predominantly intercalated into the interlayer space of the layer silicate. As a result, in the course of polymerization, polyethylene is formed in the interlayer space of particles to facilitate the exfoliation of the filler in separate nanolayers. Conditions for the supporting of a catalyst onto organomodified montmorillonite, which prevent the transfer of the catalyst into solvent and the formation of a free polymer on the synthesis of nanocomposites under the conditions of suspension polymerization in n-heptane, were determined. The intercalation of a catalyst into the interlayer space of the particles of layered silicates and the exfoliation of filler particles in the course of the synthesis of composites were confirmed by X-ray diffraction analysis.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416030010
      Issue No: Vol. 57, No. 4 (2016)
  • Pd/Ga 2 O 3 –Al 2 O 3 catalysts for the selective liquid-phase
           hydrogenation of acetylene to ethylene
    • Authors: T. N. Afonasenko; N. S. Smirnova; V. L. Temerev; N. N. Leont’eva; T. I. Gulyaeva; P. G. Tsyrul’nikov
      Pages: 490 - 496
      Abstract: Abstract The structure of Ga2O3–Al2O3 supports and Pd/Ga2O3–Al2O3 catalysts and the performance of these catalysts in liquid-phase acetylene hydrogenation have been investigated. The deposition of Ga(NO3)3 onto Al2O3 by impregnation followed by calcination of the impregnated support at 600°C yields γ-Ga2O3–Al2O3 solid solutions containing up to 50 wt % Ga2O3. X-ray diffraction characterization of model palladium catalysts and their temperature-programmed reduction with hydrogen have demonstrated that, while palladium in Pd/Ga2O3 is in the form of a Pd2Ga alloy, in the Pd/γ-Ga2O3–Al2O3 catalyst there is no direct interaction between PdО and Ga2O3 particles and palladium is in the monometallic state. The introduction of 10–20 wt % gallium oxide into Al2O3 lowers the activity of the supported palladium catalyst relative to that of the initial Pd/Al2O3 but increases the ethylene yield by enhancing the ethylene formation selectivity.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040017
      Issue No: Vol. 57, No. 4 (2016)
  • Capillary microreactor with a catalytic coating based on mesoporous
    • Authors: L. B. Okhlopkova; M. A. Kerzhentsev; Z. R. Ismagilov
      Pages: 497 - 503
      Abstract: Abstract A continuously working capillary microreactor with a catalytic coating based on mesoporous titanium dioxide with embedded Pd nanoparticles was tested in a reaction of the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBI). The catalytic coatings were obtained by the supporting of a carrier sol, which contained colloidal Pd nanoparticles, onto the internal wall of a quartz capillary with a diameter of 250 μm in the dynamic mode. The effects of the concentration of MBI in methanol (0.05–0.2 mol/L), the partial pressure of hydrogen (0.28–1.0 atm), and the reaction temperature (308–333 K) on the catalyst activity and the selectivity of reaction were studied. High selectivity for the formation of the semi-hydrogenated product 2-methyl-3-buten-2-ol was reached at 313 K in an atmosphere of pure hydrogen. At a conversion of 99.9%, the selectivity was 92.3%, which is 15.5% higher than that in a batch reactor. The rate of hydrogenation on the Pd/TiO2 coating was higher by one order of magnitude than that on a commercial Lindlar catalyst. The coating remained stable upon the continuous passage of the flow of a reaction mixture for 500 h.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040091
      Issue No: Vol. 57, No. 4 (2016)
  • Nonoxidative conversion of methane and n -pentane over a platinum/alumina
    • Authors: D. V. Golinskii; N. V. Vinichenko; V. V. Pashkov; I. E. Udras; O. V. Krol’; V. P. Talzi; A. S. Belyi
      Pages: 504 - 510
      Abstract: Abstract Methane adsorption on the Pt–H/Al2O3 and Pt/Al2O3 catalysts begins at Т = 475°C and is accompanied by the appearance of hydrogen in the reaction medium. At a higher temperature is raised to 550°C, the amount of adsorbed hydrogen increases to 1.1 and 0.8 mol/(mol Pt), respectively. According to the calculated degree of methane dehydrogenation on platinum sites at Т = 550°C, the Н/C ratio is 1.3 (at/at) for the Pt–H/Al2O3 catalyst and 1.5 (at/at) for the Pt/Al2O3 catalyst. The introduction of n-pentane into the reaction medium increases the yield of aromatic hydrocarbons (benzene and toluene) by a factor of 8.8 over the arene yield observed in individual n-pentane conversion. A mass spectrometric analysis of the arenes obtained with the Pt/Al2O3 catalyst has demonstrated that 37.5% of the adsorbed methane is involved in the methane–n-pentane coaromatization yielding benzene and toluene.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040042
      Issue No: Vol. 57, No. 4 (2016)
  • Low-temperature catalytic decomposition of hydrogen sulfide into hydrogen
           and diatomic gaseous sulfur
    • Authors: A. N. Startsev
      Pages: 511 - 522
      Abstract: Abstract The thermodynamics of three pathways of the hydrogen sulfide decomposition reaction is considered. In the thermal process, the gas-phase dissociation of hydrogen sulfide yields hydrogen and diatomic singlet sulfur. Over sulfide catalysts, the reaction proceeds via the formation of disulfane (H2S2) as the key surface intermediate. This intermediate then decomposes to release hydrogen into the gas phase, and adsorbed singlet sulfur recombines into cyclooctasulfur. Over metal catalysts, H2S decomposes via dissociation into surface atoms followed by the formation of gaseous hydrogen and gaseous triplet disulfur. The last two pathways are thermodynamically forbidden in the gas phase and can take place at room temperature only on the surface of a catalyst. An alternative mechanism is suggested for hydrogen sulfide assimilation in the chemosynthesis process involving sulfur bacteria. To shift the hydrogen sulfide decomposition equilibrium toward the target product (hydrogen), it is suggested that the reaction should be conducted at room temperature as a three-phase process over a solid catalyst under a layer of a solvent that can dissolve hydrogen sulfide and sulfur. In this case, it is possible to attain an H2S conversion close to 100%. Therefore, hydrogen sulfide can be considered as an inexhaustible source of hydrogen, a valuable chemical and an environmentally friendly energetic product.
      PubDate: 2016-07-01
      DOI: 10.1134/s002315841604011x
      Issue No: Vol. 57, No. 4 (2016)
  • Study of the nature and mechanism of the formation of paramagnetic species
           in nickel-based Brookhart-type catalytic systems
    • Authors: N. S. Gurinovich; S. K. Petrovskii; V. V. Saraev; I. V. Salii
      Pages: 523 - 527
      Abstract: Abstract The catalytic systems NiBr2(DPP-DAB) + 20 MAO and NiBr2(DPP-BIAN) + 20 MAO (DPP-BIAN = bis(2,6-diisopropylphenyl)-bis(imino)-acenaphtene, MAO = methylaluminoxane), as well as a number of model systems, are studied under conditions of their activation and functioning. There are paramagnetic nickel complexes and radical-anion aluminum complexes in the systems under real conditions of activation and functioning. The highest activity is observed when the Ni(I) signal intensity in the ESR spectrum is maximal. A mechanism of paramagnetic species formation is proposed.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040054
      Issue No: Vol. 57, No. 4 (2016)
  • Structure and properties of Pd–Mn hexaaluminate catalysts modified with
           platinum for the high-temperature oxidation of methane
    • Authors: S. A. Yashnik; T. A. Surovtsova; A. V. Ishchenko; V. V. Kaichev; Z. R. Ismagilov
      Pages: 528 - 539
      Abstract: Abstract The effect of Pt additives on the catalytic characteristics of a Pd-containing catalyst based on manganese hexaaluminate was studied. It was found that the bimetallic PtPd-containing catalysts based on MnLaAl11O19 with the Pt/Pd atomic ratio smaller than 0.25 exhibited a comparable or somewhat smaller activity in the methane oxidation, but their stability at elevated temperatures and gas flow rates was higher than that of the Pd-based catalyst. The state of the active constituent of the resulting catalysts was investigated. Main correlations between the state of the active component and the catalytic activity were revealed.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040157
      Issue No: Vol. 57, No. 4 (2016)
  • Evaluation of the acidic properties of the B 2 O 3 –Al 2 O 3 and Pt/B 2
           O 3 –Al 2 O 3 systems by spin probe EPR spectroscopy and their
           correlation with the occurrence of the joint hydroisomerization of heptane
           and benzene
    • Authors: V. L. Yurpalov; E. D. Fedorova; V. A. Drozdov; A. V. Lavrenov
      Pages: 540 - 545
      Abstract: Abstract The acidity of a series of borate-containing aluminum oxide samples with the concentrations of B2O3 from 0.9 to 27.5 wt % and Pt-containing catalysts obtained on their basis was studied by spin probe EPR spectroscopy. With the use of anthracene and the TEMPO nitroxide radical as probe molecules, it was established that an increase in the B2O3 content of the B2O3–Al2O3 and Pt/B2O3–Al2O3 systems leads to a symbatic increase in the number of medium-strength Brønsted acid sites (BASs). In this case, the yields of target hydroisomerization products (isoheptanes and methylcyclopentane) correlate with the number of BASs.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040169
      Issue No: Vol. 57, No. 4 (2016)
  • Synthesis of Mg 2+ -, Al 3+ -, and Ga 3+ -containing layered hydroxides
           and supported platinum catalysts based thereon
    • Authors: O. B. Belskaya; L. N. Stepanova; T. I. Gulyaeva; N. N. Leont’eva; V. I. Zaikovskii; A. N. Salanov; V. A. Likholobov
      Pages: 546 - 556
      Abstract: Abstract The effect of the cationic composition of MgAl(Ga) layered double hydroxides on the structure, texture, and acid–base properties of related oxide supports for platinum catalysts has been investigated. As gallium is progressively substituted for aluminum in the mixed oxide, the properties of the support change only slightly, while the activity of the Ga–Pt catalysts in propane conversion increases, the propylene selectivity remains high (99%), and C–C bond hydrogenolysis is hampered.
      PubDate: 2016-07-01
      DOI: 10.1134/s0023158416040029
      Issue No: Vol. 57, No. 4 (2016)
  • Measuring the rate constant of the reaction between chlorine atoms and CHF
           2 Br by Cl atom resonance fluorescence
    • Authors: I. K. Larin; A. I. Spasskii; E. M. Trofimova; N. G. Proncheva
      Pages: 308 - 312
      Abstract: Abstract The rate constant of the reaction between Cl atoms and CHF2Br has been measured by chlorine atom resonance fluorescence in a flow reactor at temperatures of 295–368 K and a pressure of ~1.5 Torr. Lining the inner surface of the reactor with F-32L fluoroplastic makes the rate of the heterogeneous loss of chlorine atoms very low (k het ≤ 5 s–1). The rate constant of the reaction is given by the formula k = (4.23 ± 0.13) × 10–12 e (–15.56 ± 1.58)/RT cm3 molecule–1 s–1 (with the activation energy in kJ/mol units). The possible role of this reaction in the extinguishing of fires producing high concentrations of chlorine atoms is discussed.
      PubDate: 2016-05-01
      DOI: 10.1134/s0023158416030101
      Issue No: Vol. 57, No. 3 (2016)
  • Dynamics of topochemical reactions in supported iron Fischer–Tropsch
           synthesis catalysts during their reduction in flowing CO and CO + H 2
    • Authors: P. A. Chernavskii; V. O. Kazak; G. V. Pankina; V. V. Lunin
      Pages: 333 - 338
      Abstract: Abstract The reduction of Fe2O3/SiO2 catalysts in flowing CO and CO + H2 in the temperature-programmed and isothermal modes has been investigated by in situ magnetization measurements. The process takes place in two steps, successively yielding magnetite and Hägg carbide. The carbide concentration in the case of reduction with CO is higher than in the case of reduction with the CO + H2. This is assumed to be due to the formation of Fe2SiO4 in the reduction of the catalysts with CO + H2.
      PubDate: 2016-05-01
      DOI: 10.1134/s0023158416030034
      Issue No: Vol. 57, No. 3 (2016)
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