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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  [2352 journals]
  • Carboxymethyl cellulose- and fluorapatite-coated
           silver[orthophosphate-bromide] nanostructures for photodegradation of an
           azo dye from the textile industry
    • Authors: Mohsen Padervand
      Pages: 493 - 498
      Abstract: Visible light photoactive silver[orthophosphate-bromide] loaded on fluorapatite (FA) and carboxymethyl cellulose (CMC) supports were prepared by an ionic liquid-assisted precipitation method and used as effective light driven heterogeneous systems for removal of Acid Blue 92 (AB92) azo dye and E. coli gram-negative bacteria from the wastewaters. The prepared samples were characterized by X-ray diffraction (XRD) powder, diffuse reflectance spectroscopy (DRS), Furrier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and nitrogen adsorption-desorption isotherms (BET). The XRD patterns well proved the formation of Ag3PO4 and AgBr photocatalytic crystalline phases of the nanostructures. Besides, the SEM images demonstrated that the photoactive particles were homogenously dispersed on the surface and the average size of the particles is below 90 nm. The antibacterial experiments showed that the products particularly the FA-based photocatalyst can also be utilized as efficient antimicrobial agents. According to the results, the CMC-based photocatalyst was more active during the first time of using while the other one was determined to be promising enough during the recycling tests.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050172
      Issue No: Vol. 58, No. 5 (2017)
       
  • Promotion of iridium complex catalysts for HCOOH dehydrogenation by trace
           oxygen
    • Authors: Yulu Zhan; Yangbin Shen; Ying Du; Baohua Yue; Xiaochun Zhou
      Pages: 499 - 505
      Abstract: Ir complexes are important homogeneous catalysts for formic acid (FA) dehydrogenation. This paper reports that the activity of Ir complexes can be greatly improved through the activation by trace amounts of oxygen. After activation the activity of the heterodinuclear Ir–Ru catalyst increased 18-fold whereas for the mononuclear catalyst a 23-fold increase was observed. Oxygen is the key factor for the activation. But an excessive concentration of oxygen has a negative effect on the activity. There is an optimal concentration of H2O2 for the activation of Ir complex catalysts in HCOOH dehydrogenation. A very low concentration of oxygen (2.4 × 10–6 M) is needed for the activation of the heterodinuclear Ir–Ru catalyst while the mononuclear catalyst requires the presence of oxygen in a much higher concentration (290 × 10–6 M). From the results of the study it can be inferred that the activation of complex catalysts is due to the interplay of chemical and structural changes. These findings may be helpful in the attempts to improve the catalytic activity of homogeneous catalysts, which are widely used in formic acid dehydrogenation, CO2 reduction and in other processes. In addition, this paper indicates that iridium complexes are excellent catalysts for the direct synthesis of H2O2 from the H2 and O2.
      PubDate: 2017-09-01
      DOI: 10.1134/s002315841705024x
      Issue No: Vol. 58, No. 5 (2017)
       
  • Y-type zeolites for the catalytic oxidative degradation of organic azo
           dyes in wastewater
    • Authors: M. B. Alekhina; K. A. Khabirova; T. V. Kon’kova; I. P. Prosvirin
      Pages: 506 - 512
      Abstract: Cobalt- and iron-containing catalysts active in the oxidation of organic dyes with hydrogen peroxide have been prepared from granular synthetic NaY and HY zeolites without a binder by ion exchange followed by heat treatment at 350–500°C. It has been demonstrated by X-ray photoelectron spectroscopy that cobalt and iron in these catalysts are in the form of Co2+ and Fe3+ ions on the support surface. The FeHY and CoNaY catalysts are most effective and stable in the oxidation of the anionic dye carmoisine in weakly acidic and alkaline media.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050019
      Issue No: Vol. 58, No. 5 (2017)
       
  • Catalytic effects of cationic nanoparticle (CTABr/NaX/H 2 O, X = Cl, Br)
           for the piperidinolysis of phenyl salicylate ions
    • Authors: Khalisanni Khalid; Sharifuddin Md. Zain; M. Niyaz Khan
      Pages: 513 - 521
      Abstract: The expression of pseudo-second-order rate constants (k X) for cationic nanoparticle (CN) [CTABr/NaX/H2O, X = Br, Cl, CTABr = cetyltrimethylammonium bromide] catalyzed piperidinolysis-ionized phenyl salicylate (PSa–), at constant [CTABr]T, 0.1 M piperidine (Pip), and 35°C, were calculated from the relationship: k obs = (k 0 + k X[NaX])/(1 + K X/S[NaX]), in which k 0, k X, and K X/S are constant kinetic parameters and k obs represents the pseudo-first-order rate constant for Pip reaction with phenyl salicylate ion in the presence of CN. The source of the large catalytic effect of CN catalyst was shown to be due to the transfer of PSa– from pseudo-phase of the CNs to the bulk aqueous phase through X–/PSa– ion exchange at the surface of the CNs.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050111
      Issue No: Vol. 58, No. 5 (2017)
       
  • Cyclohexane oxidation with an O 2 –H 2 mixture in the presence of a
           two-component Pt/C–heteropoly acid catalyst and ionic liquids
    • Authors: L. I. Kuznetsova; N. I. Kuznetsova
      Pages: 522 - 532
      Abstract: Approaches to increase the efficiency of Pt/C–heteropoly acid catalyst in a liquid-phase oxidation of cyclohexane using an O2–H2 mixture were studied. It was shown that small additives of ionic liquid (BMImBr, Bu4NBr, or Bu4NHSO4) significantly improve the catalytic effect of the Pt/C–H3PMo12O40–CH3CN system at 35°C, by slowing the rate of side reactions resulting in water formation, increasing the rate of oxygenate formation, and inhibiting their secondary oxidation reactions. The efficiency of H2 consumption increases from 2 to 18–25%, while the selectivity of cyclohexane conversion is 92–98%. The substitution of one or two Mo(VI) ions by V(V) in the structure of the heteropoly acid decreases these parameters. In the presence of Bu4NHSO4, a Pt/C catalyst can be used many times. During the reaction, the heteropoly acid present in the solution is in a reduced state under the action of the reaction medium and undergoes reversible redox transformations. The nature of the catalytic action of the studied system is explained from the viewpoint of the effect of ionic liquids on the properties of a Pt/C catalyst in activating O2, heteropoly molybdate chemistry, and the known mechanisms of the peroxide oxidation of hydrocarbons.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050147
      Issue No: Vol. 58, No. 5 (2017)
       
  • Catalytic hydrochlorination of acetylene on PdCl 2 /C supported catalysts:
           Kinetic isotopic effect of HCl/DCl, stereoselectivity, and mechanism
    • Authors: T. V. Krasnyakova; D. V. Nikitenko; E. V. Khomutova; S. A. Mitchenko
      Pages: 533 - 540
      Abstract: Two routes of catalytic hydrochlorination of acetylene were found by the isotopic label method for systems with supported palladium K2PdCl4/C and Н2PdCl4/C catalysts: with formation of the products of syn- and anti-addition of the H(D)Cl molecule to the triple bond of acetylene. Two isotopic effects that differ in magnitude were determined for these systems from the reaction kinetics and the ratio of the yields of the nondeuterated and monodeuterated isotopomers of the product, which are due to the participation of the H(D)Cl molecule in the two reaction stages: limiting chloropalladation and rapid protodemetallation. The effective activation energies and kinetic isotope effects coincided within the experimental errors, which suggests that the reaction mechanisms are similar and the active centers of the catalysts in systems with K2PdCl4/C and Н2PdCl4/C are of the same nature.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050135
      Issue No: Vol. 58, No. 5 (2017)
       
  • Synthesis of nano/micro scale ZSM-5 from kaolin and its catalytic
           performance
    • Authors: Feng Pan; Xuchen Lu; Yan Yan; Tizhuang Wang
      Pages: 541 - 548
      Abstract: Nano/micro scale ZSM-5 zeolites were synthesized by using natural kaolin as raw material. The effect of particle size on the catalytic performance of ZSM-5 zeolite for the methanol to olefins conversion was evaluated in a fixed-bed reactor. The results indicated the crystal size had a significant effect on the catalytic stability and the products distribution. ZSM-5 with nanosize showed better tolerance to coke formation, longer catalytic lifetime, and higher selectivity to propylene. The selectivity to propylene on nanosized ZSM-5 was on average 4.5% higher than on the submicron sample and 10% higher than on microsized ZSM-5. After the reaction was conducted for 20 h the ZSM-5 catalyst synthesized from kaolin showed longer lifetime and higher propylene selectivity than the sample synthesized with chemical materials The reason can be explained by the occurence of such elements as Fe, P, and especially Ti.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050184
      Issue No: Vol. 58, No. 5 (2017)
       
  • Mechanism of catalytic cycloboration of α-olefins with boron trichloride:
           the synthesis of hardly obtainable boriranes and the mechanistic DFT study
           of transmetalation of titanacyclopropane intermediates
    • Authors: T. V. Tyumkina; L. O. Khafizova; S. M. Idrisova; L. I. Khusainova; L. M. Khalilov; U. M. Dzhemilev
      Pages: 549 - 555
      Abstract: A theoretically justified mechanism of transmetalation of 2-alkyl substituted titanacyclopropanes with BCl3 is proposed based on the DFT calculations of the thermodynamic and activation parameters of possible reaction pathways. Based on the data obtained, phenyl- and alkyldichloroboranes were proposed to be used as transmetalating agents along with BCl3 in the catalytic cycloboration in the presence of Cp2TiCl2 and Mg metal. It was shown that the barely accessible 1-phenyl-2-hexylborirane can be synthesized using PhBCl2.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050226
      Issue No: Vol. 58, No. 5 (2017)
       
  • Catalysis of radical reactions in mixed micelles of surfactants with
           hydroperoxides
    • Authors: O. T. Kasaikina; N. V. Potapova; D. A. Krugovov; L. M. Pisarenko
      Pages: 556 - 562
      Abstract: The peculiarities of the catalytic action of cationic surfactants (CSurf) in combination with hydroperoxides on the generation of radicals and the influence of various factors on this process (transition metal compounds, oxygen, and external magnetic field) were considered. In the oxidized hydrocarbons (RH), hydroperoxides (ROOH), which are the primary amphiphilic products of oxidation, form mixed micelles {mROOH…nCSurf} with CSurf, in which fast decomposition of ROOH into radicals occurs and other polar components (metal compounds, inhibitors, etc.) can concentrate, which significantly affects the rate and mechanism of oxidation. The cationic surfactants immobilized on a solid support retain the ability to catalyze the decomposition of hydroperoxides, forming radicals, and to initiate radical oxidation and polymerization. It was found that acetylcholine, which is the most important neurotransmitter that plays an important role in the neuromuscular and cognitive activity of living beings, like cationic surfactants, catalyzes the radical decomposition of hydroperoxides in organic media, and the yield of radicals in this process decreases in a magnetic field and in the presence of oxygen.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050093
      Issue No: Vol. 58, No. 5 (2017)
       
  • Steam reforming of dimethoxymethane, methanol and dimethyl ether on
           CuO–ZnO/γ-Al 2 O 3 catalyst
    • Authors: A. A. Pechenkin; S. D. Badmaev; V. D. Belyaev; E. A. Paukshtis; O. A. Stonkus; V. A. Sobyanin
      Pages: 577 - 584
      Abstract: The performance of a СuO–ZnO/γ-Al2O3 catalyst for the reactions of methanol, dimethyl ether (DME) and dimethoxymethane (DMM) steam reforming (SR) to hydrogen-rich gas was studied. The catalyst was found to be active and selective for methanol and DMM SR producing hydrogen-rich gas with low content of CO (<1 vol %). It provided complete conversion of methanol and DMM at 300°C, and hydrogen productivity of, respectively, 15 and 16.5 LH2g cat -1 h-1. With the use of physicochemical methods and catalytic experiments, it was shown that the catalyst surface contained the acid sites typical for γ-Al2O3, and CuO–ZnO agglomerates, responsible, respectively, for DMM hydration to methanol and formaldehyde, and SR of these compounds to hydrogen-rich gas.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050196
      Issue No: Vol. 58, No. 5 (2017)
       
  • Promoting effect of potassium and calcium additives to cerium–zirconium
           oxide catalysts for the complete oxidation of carbon monoxide
    • Authors: I. Yu. Kaplin; E. S. Lokteva; E. V. Golubina; K. I. Maslakov; S. A. Chernyak; V. V. Lunin
      Pages: 585 - 592
      Abstract: The effect of potassium and calcium additives on the catalytic activity of the Ce0.8Zr0.2O2 system in the reaction of CO oxidation was studied. With the use of X-ray diffraction analysis, it was found that the Ce0.8Zr0.2O2 and Ce0.8Zr0.2O2–Ca,K samples contained a mixed oxide of cerium and zirconium; the presence of the independent phases of potassium and calcium compounds in the modified system was not detected. With the use of the low-temperature adsorption–desorption of nitrogen, X-ray photoelectron spectroscopy, and temperature-programmed reduction, it was established that the Ce0.8Zr0.2O2–Ca,K system (in spite of the fact that its specific surface area was lower than that of Ce0.8Zr0.2O2) contained more active oxygen on the surface; peroxide and superoxide complexes formed upon the chemisorption of O2 can act as active oxygen species. This can be the reason for a higher efficiency of the Ce0.8Zr0.2O2–Ca,K system in comparison with that of the unmodified oxide. The results obtained indicate that the ash impurities of Ca and K can increase the catalytic activity of the biomorphic mixed oxides Ce0.8Zr0.2O2 prepared with the use of sawdust as a template.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050081
      Issue No: Vol. 58, No. 5 (2017)
       
  • Synthesis and photocatalytic properties of materials based on bismuth
           silicates
    • Authors: A. A. Vodyankin; I. P. Ushakov; Yu. A. Belik; O. V. Vodyankina
      Pages: 593 - 600
      Abstract: The influence of the preparation technique of bismuth silicate-based catalysts on their formation, phase composition, absorption characteristics, and photocatalytic properties is investigated. Samples the with initial ratio of Bi: Si = 2: 1 are prepared via the hydrothermal method with varied temperature conditions in the hydrothermal aging and calcination stages. The synthesized catalysts demonstrate photocatalytic activity in the decomposition of the methanol equilibrium vapor and visible light-induced decolorization of a methylene blue (MB) aqueous solution.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050238
      Issue No: Vol. 58, No. 5 (2017)
       
  • Development of a Ni–Pd/CeZrO 2 /Al 2 O 3 catalyst for the effective
           conversion of methane into hydrogen-containing gas
    • Authors: M. A. Kerzhentsev; E. V. Matus; I. A. Rundau; V. V. Kuznetsov; I. Z. Ismagilov; V. A. Ushakov; S. A. Yashnik; Z. R. Ismagilov
      Pages: 601 - 609
      Abstract: The effects of the Pd content (0–1 wt %) and the synthesis method (joint impregnation with Ni + Pd and Pd/Ni or Ni/Pd sequential impregnation) on the physicochemical and catalytic properties of Ni–Pd/CeZrO2/Al2O3 were studied in order to develop an efficient catalyst for the conversion of methane into hydrogen-containing gas. It was shown that variation in the palladium content and a change in the method used for the introduction of an active constituent into the support matrix make it possible to regulate the redox properties of nickel cations but do not affect the size of NiO particles (14.0 ± 0.5 nm) and the phase composition of the catalyst ((γ + δ)-Al2O3, CeZrO2 solid solution, and NiO). It was established that the activity of Ni–Pd catalysts in the reaction of autothermal methane reforming depends on the method of synthesis and increases in the following order: Ni + Pd < Ni/Pd < Pd/Ni. It was found that, as the Pd content of the Ni–Pd/CeZrO2/Al2O3 catalyst was decreased from 1 to 0.05 wt %, the ability for self-activation, high activity, and operational stability of the catalyst under the conditions of autothermal methane reforming remained unaffected: at 850°C, the yield of hydrogen was ~70% at a methane conversion of ~100% during a 24-h reaction.
      PubDate: 2017-09-01
      DOI: 10.1134/s002315841705010x
      Issue No: Vol. 58, No. 5 (2017)
       
  • Effect of the support composition on the physicochemical properties of
           Ni/Ce 1–x La x O y catalysts and their activity in an autothermal
           methane reforming reaction
    • Authors: E. V. Matus; D. V. Nefedova; V. V. Kuznetsov; V. A. Ushakov; O. A. Stonkus; I. Z. Ismagilov; M. A. Kerzhentsev; Z. R. Ismagilov
      Pages: 610 - 621
      Abstract: The effect of the Ce1–x La x O y (x = 0–1, 1.5 ≤ y ≤ 2.0) support composition on the physicochemical properties of supported Ni catalysts and their activity in autothermal methane reforming was studied. The textural and structural characteristics of Ce1–x La x O y and Ni/Ce1–x La x O y samples and the process of their reduction in an atmosphere of hydrogen were examined using a set of techniques (low-temperature nitrogen adsorption, X-ray diffraction analysis, transmission electron microscopy, and thermal analysis). It was established that the Ce1–x La x O y supports (x = 0–0.9) are mesoporous materials containing a fluorite-like solid solution based on cerium dioxide, in which the unit cell parameter increases and the average crystallite size decreases with the mole fraction of La. It was shown that the average size and composition of Ni-containing particles in the Ni/Ce1–x La x O y catalysts depends on the composition of the support: at x = 0–0.8, a phase of NiO was formed, whereas a phase of LaNiO3 was formed at x = 0.9–1. The dispersity of the active constituent and its stability to agglomeration increased as the mole fraction of La in the Ce1–x La x O y support was increased from 0 to 0.8, whereas the reduction of Ni-containing oxide particles shifted to the higher temperature region. The Ni/Ce1–x La x O y catalysts provided high methane conversion (96–100%) and the yield of H2 (35–55%). The yield of hydrogen increased with decreasing the mole fraction of La in the Ce1–x La x O y support composition; this can be caused by a decrease in the fraction of difficult-to-reduce Ni n+ cations due to the weakening of metal–support interactions.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050160
      Issue No: Vol. 58, No. 5 (2017)
       
  • Ethylene production by the oxidative condensation of methane in the
           presence of MnMW/SiO 2 catalysts (M = Na, K, and Rb)
    • Authors: I. Z. Ismagilov; E. V. Matus; V. S. Popkova; V. V. Kuznetsov; V. A. Ushakov; S. A. Yashnik; I. P. Prosvirin; M. A. Kerzhentsev; Z. R. Ismagilov
      Pages: 622 - 629
      Abstract: The samples of MnMW/SiO2 (M = Na, K, and Rb) were synthesized using various synthesis methods under varied heat treatment conditions and their physicochemical properties and activity in the reaction of the oxidative condensation of methane (OCM) were studied for the development of an effective catalyst for the resource-saving process of natural gas conversion into ethylene. It was found that the preparation method exerts an effect on the textural characteristics of the samples and the reducing properties of the cations of manganese and tungsten. It was determined that the composition of a W-containing phase depends on the alkali metal, and a ratio between the polymorphous modifications of SiO2 is controlled by the method of synthesis and the conditions of catalyst heat treatment. It was established that the yield of C2 hydrocarbons in the OCM reaction increased with the use of incipient wetness impregnation instead of the method of mixing with a suspension for catalyst preparation and with an increase in the catalyst heat treatment temperature from 700 to 1000°C. The optimum composition of the catalyst and the condition of its synthesis were found: 2Mn0.8Na3W/SiO2 obtained by the impregnation method and calcined at 1000°C ensured the yield of target products of ~20% with a CH4 conversion of ~35% at a reaction temperature of 850°C.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050068
      Issue No: Vol. 58, No. 5 (2017)
       
  • Supported MgO–V 2 O 5 /Al 2 O 3 catalysts for oxidative propane
           dehydration: Effect of the molar Mg : V ratio on the phase composition and
           catalytic properties of samples
    • Authors: E. D. Sushchenko; T. S. Kharlamova; T. I. Izaak; O. V. Vodyankina
      Pages: 630 - 641
      Abstract: The physicochemical properties of V2O5/Al2O3 and MgO–V2O5/Al2O3 supported catalysts (Mg : V = 1 : 1, 2 : 1, and 3 : 2) obtained by consecutive impregnation of the support with solutions of vanadium and magnesium precursors are studied using a complex of mutually complementary methods (XRD, Raman spectroscopy, UV–Vis spectrometry, and TPR-H2). The effect of the formation of surface magnesium vanadates of various composition and structure on the catalytic properties of the supported vanadium oxide catalysts in the oxidative dehydrogenation of propane is studied. The introduction of magnesium in the samples and an increase in its content, accompanied by a change in the structure of the surface vanadium oxide phases from polymeric VO6/VO5 species to surface metavanadate species, magnesium metavanadate, and further to magnesium divanadate, significantly affects their catalytic properties in the reaction of the oxidative dehydrogenation of propane to propylene.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050202
      Issue No: Vol. 58, No. 5 (2017)
       
  • Effect of the metal−support interaction in Ag/CeO 2 catalysts on their
           activity in ethanol oxidation
    • Authors: M. V. Grabchenko; G. V. Mamontov; V. I. Zaikovskii; O. V. Vodyankina
      Pages: 642 - 648
      Abstract: The interaction of silver with the surface of CeO2 in the Ag/CeO2 catalysts prepared by coprecipitation and impregnation techniques was studied by temperature-programmed reduction, X-ray diffraction, and high-resolution transmission electron microscopy. It was shown that coprecipitation technique led to formation of strong silver–support interaction and the epitaxy of silver particles (d 111 = 2.35 Å) on the surface of CeO2 (d 111 = 3.1 Å). This provided incresed catalytic activity in the oxidative dehydrogenation of ethanol at relatively low temperatures (a 15% conversion of ethanol with 100% selectivity for the formation of acetaldehyde was reached at 85°C). Above 130°C, the deep oxidation of ethanol to CO2 becomes the predominant direction of a catalytic reaction, and the Ag/CеО2 catalyst obtained by impregnation technique was most active in this region as a consequence of the weaker metal–support interaction.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050056
      Issue No: Vol. 58, No. 5 (2017)
       
  • Properties of Pd–Ag/C catalysts in the reaction of selective
           hydrogenation of acetylene
    • Authors: V. V. Chesnokov; A. S. Chichkan; Z. R. Ismagilov
      Pages: 649 - 654
      Abstract: Samples of Pd/C and Pd–Ag/C, where C represents carbon nanofibers (CNFs), are synthesized by methane decomposition on a Ni–Cu–Fe/Al2O3 catalyst. The properties of Pd/CNF are studied in the reaction of selective hydrogenation of acetylene into ethylene. It is found that the activity of the catalyst in hydrogenation reaction increases, while selectivity decreases considerably when the palladium content rises. The obtained dependences are caused by the features of palladium’s interaction with the carbon support. At a low Pd content (up to 0.04 wt %) in the catalyst, the metal is inserted into the interlayer space of graphite and the catalytic activity is zero. It is established by EXAFS that the main share of palladium in catalysts of 0.05–0.1 wt % Pd/CNF constitutes the metal in the atomically dispersed state. The coordination environment of palladium atoms consists of carbon atoms. An increase in the palladium content in a Pd/CNF catalyst up to 0.3 wt % leads to the formation of highly dispersed (0.8–1 nm) Pd particles. The Pd/CNF samples where palladium is mainly in the atomically dispersed state exhibit the highest selectivity in the acetylene hydrogenation reaction. The addition of silver to a 0.1 wt % Pd/CNF catalyst initially probably leads to the formation of Pd–Ag clusters and then to alloyed Pd–Ag particles. An increase in the silver content in the catalyst above 0.3% causes the enlargement of the alloyed particles and the palladium atoms are blocked by a silver layer, which considerably decreases the catalytic activity in the selective hydrogenation of acetylene.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050020
      Issue No: Vol. 58, No. 5 (2017)
       
  • The synthesis and study of the physicochemical and catalytic properties of
           composites with the sulfated perfluoropolymer/carbon nanofiber composition
           
    • Authors: A. P. Koskin; Yu. V. Larichev; A. I. Lysikov; O. N. Primachenko; S. S. Ivanchev
      Pages: 655 - 662
      Abstract: Composites with the sulfated perfluoropolymer (SFP) (Nafion, etc.)—mesoporous support composition (SFP/support)—are promising solid acid catalysts with strong acid sites and very stable sulfo groups towards leaching processes. The effect of the SFP on the carbon nanofiber (CNF) (SFP/CNF) composite synthesis method, as well as the precursors of the acid phase, on the key acid catalyst characteristics (specific surface area and concentration and accessibility of the acid sites) is studied. The possibility of the direct composite synthesis from SO2F-polymer latexes obtained as a result of the water emulsion SFP synthesis (without the intermediate stages of isolating the SO3H form) is shown. The acid phase precursor types which are acceptable for the SFP/CNF composite synthesis (the equivalent polymer weight > 580 g/mol) are selected. The effect of the amount of the supported polymer on the total specific surface area and concentration and accessibility of the composite acid site is investigated. The structure of the synthesized composites is studied (by TEM, SAXS, and isopropanol TPD), and their catalytic activity in the test acetic acid esterification reaction is compared to the catalytic activity of pure polymer samples and acetic acid. It is found that the synthesized SFP/CNF samples outperform commercial SFP/SiO2 samples (SAC, DuPont), as well as the SFP/CNF samples prepared using polymer solutions in the SO3H form, in terms of the catalytic characteristics.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050123
      Issue No: Vol. 58, No. 5 (2017)
       
  • Effect of vanadium compounds on the sulfonation of carbon materials
    • Authors: Yu. V. Larichev; A. P. Koskin
      Pages: 663 - 667
      Abstract: The synthesis of sulfonated carbon materials (SCMs) via the direct sulfonation of carbon nanofibers with sulfuric acid in the presence of vanadium compounds is studied. An efficient sulfiding system (98% H2SO4–NaVO3) providing a high sulfur content in a carbon material without oleum is proposed. It is established that the introduced sulfur exists in samples in the form of sulfo groups located predominantly on the surface. No intrusion of sulfuric acid residues between graphene layers with the formation of clathrates is revealed. It is shown that the surface of a carbon material is partially oxidized with the formation of carbonyl and carboxyl groups. The kinetic activity of the synthesized SCMs in the liquid-phase reaction of acetic acid esterification with ethanol is studied.
      PubDate: 2017-09-01
      DOI: 10.1134/s0023158417050159
      Issue No: Vol. 58, No. 5 (2017)
       
 
 
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