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  Subjects -> CHEMISTRY (Total: 836 journals)
    - ANALYTICAL CHEMISTRY (47 journals)
    - CHEMISTRY (586 journals)
    - CRYSTALLOGRAPHY (22 journals)
    - ELECTROCHEMISTRY (26 journals)
    - INORGANIC CHEMISTRY (41 journals)
    - ORGANIC CHEMISTRY (46 journals)
    - PHYSICAL CHEMISTRY (68 journals)

CHEMISTRY (586 journals)            First | 1 2 3 4 5 6 | Last

Journal of Catalysts     Open Access  
Journal of Chemical & Engineering Data     Full-text available via subscription   (Followers: 11)
Journal of Chemical and Biological Interfaces     Full-text available via subscription  
Journal of Chemical Education     Full-text available via subscription   (Followers: 17)
Journal of Chemical Health Risks     Open Access   (Followers: 2)
Journal of Chemical Information and Modeling     Full-text available via subscription   (Followers: 6)
Journal of Chemical Research     Full-text available via subscription   (Followers: 5)
Journal of Chemical Science and Technology     Open Access   (Followers: 3)
Journal of Chemical Sciences     Partially Free   (Followers: 17)
Journal of Chemical Theory and Computation     Full-text available via subscription   (Followers: 13)
Journal of Cheminformatics     Open Access   (Followers: 1)
Journal of Chemistry     Open Access   (Followers: 3)
Journal of Chemometrics     Hybrid Journal   (Followers: 10)
Journal of Chromatography A     Hybrid Journal   (Followers: 54)
Journal of Clinical Toxicology     Open Access   (Followers: 1)
Journal of Colloid and Interface Science     Hybrid Journal   (Followers: 14)
Journal of Computational Chemistry     Hybrid Journal   (Followers: 15)
Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Journal of Dispersion Science and Technology     Hybrid Journal  
Journal of Encapsulation and Adsorption Sciences     Open Access   (Followers: 4)
Journal of Environmental Chemistry and Ecotoxicology     Open Access   (Followers: 2)
Journal of Flow Chemistry     Full-text available via subscription   (Followers: 1)
Journal of Fluorescence     Hybrid Journal   (Followers: 4)
Journal of Fluorine Chemistry     Hybrid Journal   (Followers: 6)
Journal of Fuel Chemistry and Technology     Full-text available via subscription   (Followers: 5)
Journal of Great Lakes Research     Hybrid Journal   (Followers: 7)
Journal of Heterocyclic Chemistry     Hybrid Journal   (Followers: 5)
Journal of Immunoassay and Immunochemistry     Hybrid Journal   (Followers: 3)
Journal of Inclusion Phenomena and Macrocyclic Chemistry     Hybrid Journal   (Followers: 1)
Journal of Inorganic Biochemistry     Hybrid Journal   (Followers: 2)
Journal of Labelled Compounds and Radiopharmaceuticals     Hybrid Journal   (Followers: 1)
Journal of Macromolecular Science, Part A: Pure and Applied Chemistry     Hybrid Journal   (Followers: 3)
Journal of Mass Spectrometry     Hybrid Journal   (Followers: 24)
Journal of Materials Chemistry A : Materials for Energy and Sustainability     Full-text available via subscription   (Followers: 22)
Journal of Materials Chemistry B : Materials for Biology and Medicine     Full-text available via subscription   (Followers: 5)
Journal of Materials Chemistry C : Materials for Optical, Magnetic and Electronic Devices     Full-text available via subscription   (Followers: 5)
Journal of Materials Physics and Chemistry     Open Access  
Journal of Materials Research     Full-text available via subscription   (Followers: 10)
Journal of Mathematical Chemistry     Hybrid Journal   (Followers: 6)
Journal of Medicinal Chemistry     Full-text available via subscription   (Followers: 92)
Journal of Membrane and Separation Technology     Hybrid Journal  
Journal of Membrane Science     Hybrid Journal   (Followers: 11)
Journal of Modern Chemistry & Chemical Technology     Full-text available via subscription   (Followers: 2)
Journal of Molecular Catalysis A: Chemical     Hybrid Journal   (Followers: 3)
Journal of Molecular Graphics and Modelling     Hybrid Journal   (Followers: 4)
Journal of Molecular Liquids     Hybrid Journal   (Followers: 1)
Journal of Molecular Modeling     Hybrid Journal   (Followers: 3)
Journal of Molecular Recognition     Hybrid Journal   (Followers: 2)
Journal of Molecular Spectroscopy     Hybrid Journal   (Followers: 7)
Journal of Molecular Structure     Hybrid Journal   (Followers: 3)
Journal of Nanoparticles     Open Access  
Journal of Nanostructure in Chemistry     Open Access   (Followers: 3)
Journal of Natural Gas Chemistry     Full-text available via subscription   (Followers: 2)
Journal of Nepal Chemical Society     Open Access  
Journal of Nucleic Acids Investigation     Open Access   (Followers: 2)
Journal of Ocean University of China (English Edition)     Hybrid Journal   (Followers: 1)
Journal of Organometallic Chemistry     Hybrid Journal   (Followers: 13)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 4)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (Followers: 3)
Journal of Polymer & Composites     Full-text available via subscription   (Followers: 3)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 2)
Journal of Polymer Science Part A: Polymer Chemistry     Hybrid Journal   (Followers: 131)
Journal of Polymers     Open Access   (Followers: 1)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 2)
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 1)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 11)
Journal of Research Updates in Polymer Science     Hybrid Journal  
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 14)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 4)
Journal of Structural Chemistry     Hybrid Journal  
Journal of Sulfur Chemistry     Hybrid Journal   (Followers: 2)
Journal of Superhard Materials     Hybrid Journal   (Followers: 1)
Journal of Surfactants and Detergents     Hybrid Journal   (Followers: 5)
Journal of Systems Chemistry     Open Access  
Journal of Taibah University for Science     Open Access  
Journal of the American Chemical Society     Full-text available via subscription   (Followers: 217)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 21)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 1)
Journal of the Bangladesh Chemical Society     Open Access  
Journal of the Chilean Chemical Society     Open Access   (Followers: 1)
Journal of the Iranian Chemical Society     Hybrid Journal  
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal   (Followers: 1)
Journal of the Mexican Chemical Society     Open Access   (Followers: 1)
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (Followers: 8)
Journal of Theoretical Chemistry     Open Access  
Journal of Wood Chemistry and Technology     Hybrid Journal   (Followers: 7)
JPC - Journal of Planar Chromatography - Modern TLC     Full-text available via subscription   (Followers: 5)
Jurnal Penelitian Sains (JPS)     Open Access  
Jurnal Teknologi Informasi     Open Access   (Followers: 3)
Karbala International Journal of Modern Science     Open Access  
Kinetics and Catalysis     Hybrid Journal   (Followers: 3)
Korea-Australia Rheology Journal     Hybrid Journal  
Langmuir     Full-text available via subscription   (Followers: 42)
Latvian Journal of Chemistry     Open Access   (Followers: 1)
Lebensmittelchemie     Hybrid Journal   (Followers: 1)
Lipid Insights     Open Access  
Luminescence     Hybrid Journal   (Followers: 1)
Macromolecular Materials & Engineering     Hybrid Journal   (Followers: 5)
Macromolecular Rapid Communications     Hybrid Journal   (Followers: 5)

  First | 1 2 3 4 5 6 | Last

Journal Cover   Kinetics and Catalysis
  [SJR: 0.367]   [H-I: 21]   [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  [2291 journals]
  • Adsorption and catalysis for sustainable energy applications
    • Abstract: Abstract This review addresses adsorption and catalytic thermochemical energy conversion (TEC) methods used to recover waste heat resulting from the combustion of primary organic fuels (oil, gas, and coal). We will consider the thermodynamic foundations of these methods, promising reactions and sorbents, the history and current state of the art in the R&D and practical implementation of TEC technologies, modern trends in TEC, and the ways of enhancing the TEC efficiency and specific power. Further progress in adsorption and catalytic TEC methods could provide a reliable base for the sustainable world energy sector.
      PubDate: 2015-07-01
       
  • Development of carbon supports with increased corrosion resistance for
           Pt/C catalysts for oxygen electroreduction
    • Abstract: Abstract The influence of different surface modifications of carbon supports on the corrosion resistance of 50 wt % Pt/C catalysts on their basis was studied. The corrosion resistance was measured from changes in the electroactive surface area of platinum in the course of potential cycling from 1.0 to 1.5 V versus the reversible hydrogen electrode (potential sweep rate, 0.5 V/s) during 60000 cycles. A 40% Pt/Vulcan XC-72 commercial catalyst was used as the reference sample. The supports were modified by the carbonization of the high surface area carbon black Ketjenblack DJ-600 and by the additional activation of the carbon-carbon composite Sibunit-1562. It was found that the preliminary carbonization of the Ketjenblack DJ-600 support with a propane-butane mixture at 770°C and the activation of Sibunit-1562 with subsequent thermal treatment at 500°C increased and decreased, respectively, the corrosion resistance of the 50 wt % Pt/C catalysts on their basis.
      PubDate: 2015-07-01
       
  • Kinetic study of the gas-phase hydrofluorination of tetrachloroethylene
           into pentafluoroethane over a Cr-Mg catalyst
    • Abstract: Abstract The influence of the tetrachloroethylene (TCE) hydrofluorination reaction conditions (temperature and residence time) on the activity of the Cr-Mg catalyst and pentafluoroethane selectivity has been experimentally studied. It has been established that the process proceeds via a complex parallel-consecutive mechanism that includes, along with hydrogen fluoride (HF) molecule addition at the double bond and consecutive substitution of fluorine for chlorine, the disproportionation reaction resulting in the formation of by-products. A kinetic model of the process has been proposed and its parameters, such as rate constants and activation energies, have been determined. The model allows predicting the composition of the target and intermediate products and by-products in wide ranges of residence times and reaction temperatures (300–400°C).
      PubDate: 2015-07-01
       
  • The activity of titanium silicalite-1 (TS-1): Some considerations on its
           origin
    • Abstract: Abstract The high activity of titanium silicate (TS-1) in oxidations with hydrogen peroxide is the result of different factors, directly referable to the MFI structure. The configuration of Ti site (tetrahedral), the nature of active species (Ti-OOH) and the nature of the surface (hydrophobic) are the three factors that are immediately apparent. Hydrophobicity alone, however, cannot fully explain certain catalytic performances and trends in the oxidation of the olefins, without envisaging a major involvement of porosity. Actually, the molecular dimensions of pores (ca. 0.55 nm), normally perceived as just a drawback for the limits set to the range of potential substrates, play a relevant and positive role in TS-1 catalysis. The purpose of the paper is to illustrate and discuss these issues, with supporting evidences mostly taken from the oxidation of olefins and alkanes.
      PubDate: 2015-07-01
       
  • Nature of the active sites of ferrospheres in the oxidative condensation
           of methane
    • Abstract: Abstract The catalytic properties of ferrospheres containing 76–97 wt % Fe2O3 in the oxidative condensation of methane were compared with their phase composition and the distribution of iron cations over the crystallographic positions of iron-containing phases in a steady state. It was established that the reaction route of methane oxidation changed at a Fe2O3 content of 89 wt %. Deep oxidation was the main reaction route on ferrospheres with a Fe2O3 content of <88.8 wt %. At a Fe2O3 content of ≥89 wt %, the yield of C2 hydrocarbons sharply increased and the contribution of deep oxidation decreased. The yield of C2 hydrocarbons correlated with the amount of defects in the structure of iron spinel, which are iron ions with the tetrahedral cation of Ca2+ and the octahedral cation vacancy among the nearest neighbors.
      PubDate: 2015-07-01
       
  • NMR and EPR spectroscopy applied to homogeneous catalysis
    • Abstract: Abstract The article deals with applying NMR and EPR spectroscopy to the study of the active sites of catalysts in two important classes of reactions: enantioselective olefin epoxidation with hydrogen peroxide catalyzed by iron aminopyridine complexes and olefin polymerization in the presence of titanium and vanadium post-metallocene catalysts.
      PubDate: 2015-07-01
       
  • Photocyclization of a mixed phosphonium-iodonium ylide with
           phenylacetylene: A formal kinetic approach to the mechanistic study
    • Abstract: Abstract The recently discovered photoheterocyclization of a mixture of mixed phosphonium-iodonium ylides and acetylene compounds to give λ5-phosphinoline, a new phosphorus-containing heterocycle, occurs with self-acceleration and an induction period at relatively high concentrations of the reactants. The reaction was found to be catalyzed by the acid formed during photolysis. We developed a spectrophotometric method to study the kinetics of photocyclization between phenylacetylene and a phosphonium-iodonium ylide in the presence of trifluoroacetic acid and studied how the yield of target λ5-phosphinoline and kinetic parameters of the reaction, such as the induction period and maximum rate of product formation, depend on the initial concentrations of the starting compounds and catalyst. It was shown that the addition of the acid has no effect on the critical character of the dependence of the reaction on the concentration of the starting compound: the reaction proceeds only at an ylide concentration of >0.02 mol/L in a microheterogeneous suspension and the self-accelerating character of λ5-phosphinoline formation is preserved. The optimum reagent ratios maximizing the yield of the target product were determined. The acid was found to play a dual role: it catalyzes the reaction only at concentrations not higher than the initial ylide concentration. At higher acid concentrations, no formation of λ5-phosphinoline was observed.
      PubDate: 2015-07-01
       
  • Reactions of isobutanol over a NASICON-type Ni-containing catalyst
           activated by plasma treatments
    • Abstract: Abstract The effect of hydrogen and argon high-frequency (HF) plasma treatment on the catalytic activity of the nickel zirconium phosphate Ni0.5Zr2(PO4)3 in isobutanol dehydration and dehydrogenation has been investigated. The catalyst treated with H2-HF and Ar-HF plasmas shows a ∼2 times higher activity in both reactions. This effect is due to surface restructuring changing the number and accessibility of catalytic sites on the phosphate surface.
      PubDate: 2015-07-01
       
  • Photoactivity of TiO 2 /CdS and SiO 2 /CdS hybrid nanostructured systems
           in the partial oxidation of ethanol under irradiation with visible light
    • Abstract: Abstract The activity of hybrid nanostructured core-shell photocatalysts based on cadmium sulfide, titanium dioxide, and silicon dioxide has been investigated in the partial oxidation of ethanol under irradiation with visible light. The SiO2/CdS and TiO2/CdS photocatalysts have been synthesized by the sol-gel method and have been characterized by a variety of physicochemical methods, including X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and diffuse reflectance infrared Fourier-transform spectroscopy. The synthesized TiO2/CdS samples exhibit a high activity in the partial photocatalytic oxidation of ethanol to acetaldehyde under irradiation with visible light (λ > 420 nm) in a batch reactor. Their high activity can be due to heterojunctions occurring between cadmium sulfide and titanium dioxide nanoparticles and causing the separation of photogenerated charges.
      PubDate: 2015-07-01
       
  • Kinetic study of esterification of acetic acid with methanol over Indion
           190 acidic solid catalyst
    • Abstract: Abstract Esterification of acetic acid with methanol to synthesize methyl acetate in an isothermal well-mixed batch reactor was studied in the temperature range of 323.15–353.15 K. Indion 190 ion-exchange resin was used as a solid catalyst. Feed molar ratios were varied from 1: 1 to 1: 4. The influence of temperature, catalyst loading, stirring rate, catalyst particle size and initial molar ratio on the reaction rate was investigated. Experimental results showed that the reaction is kinetically controlled. The sorption experiments were carried out independently to find the adsorption constants. For the constituent components the values of adsorption constants decrease in the order of water > methanol > acetic acid > methyl acetate. The kinetic data were correlated with the pseudo-homogeneous (ideal and non-ideal), Eley-Rideal and Langmuir-Hinshelwood-Hougen-Watson (LHHW) models to determine the kinetic parameters. All the models were suitable to predict the experimental data, but with the LHHW model a more accurate match of the experimental data was achieved.
      PubDate: 2015-07-01
       
  • Effect of the Cr/Fe ratio on the structure of Fe-Cr-Cu-containing oxide
           catalysts
    • Abstract: Abstract The morphology and structural and electronic states of nanodispersed copper ferrite-chromites of with different Cr/Fe ratios calcined at 900°C in an atmosphere of air were studied using a set of physical methods. The morphology, the homogeneity of chemical composition, and the degree of perfection of spinels formed from mixed Fe-Cr-Cu hydroxo compounds upon heat treatment were studied by HRTEM. From an analysis of atomic radial distribution curves, it follows that copper ferrite-chromite with a partially inverted spinel structure was formed at the ratio Cr/Fe = 1. With the use of DRS, it was found that all of the Fe-Cr-Cu-containing oxide samples contained Cu2+ cations in tetrahedral and tetragonally distorted octahedral oxygen coordination. In this case, the DRS spectra exhibited a decrease in the absorption energy of Cu2+ cations as the Cr/Fe ratio was decreased from 2 to 1, which indicated a decrease in the tetragonal distortion of the octahedral oxygen environment of the Cu2+ cations. In general, the data on the distribution of cations in Fe-Cr-Cu oxides with different Cr/Fe ratios obtained by EXAFS and DRS are consistent with the results of crystallochemical analysis. It was confirmed that the distribution of Cu2+ cations significantly affected the activation energy of water gas shift reaction.
      PubDate: 2015-07-01
       
  • Propane chlorination over ruthenium oxychloride catalysts
    • Abstract: Abstract The gas-phase chlorination of propane over different catalysts, including those containing ruthenium oxychlorides as the active component, has been investigated. The propylene and chlorine-containing product formation selectivities in propane chlorination at 150–450°C in a fixed-bed flow reactor have been determined.
      PubDate: 2015-07-01
       
  • Cu-Zn-Al-O catalysts for the oxidative desulfurization of
           dibenzothiophene, a typical sulfur-containing compound of the diesel
           fraction
    • Abstract: Abstract The possibility of oxidative desulfurization of dibenzothiophene dissolved in toluene as a model organosulfur compound of diesel fuel in the presence of catalytic CuZnAl compositions was studied. It was shown that the CuZnAl catalysts at 350–450°C ensure sulfur removal from the model fuel to the extent of up to 40–45%. Part of the sulfur is removed as SO2, and some sulfur is absorbed on the catalyst surface.
      PubDate: 2015-07-01
       
  • Template-free sol-gel synthesis of catalytically active mesoporous
           aluminosilicates
    • Abstract: Abstract A template-free sol-gel synthesis method has been developed for obtaining mesoporous alumino-silicates with a narrow pore size distribution. The effect of the synthesis conditions on the formation of the porous structure and on the phase composition and surface acidity of the aluminosilicates has been elucidated. The catalytic properties of the synthesized aluminosilicates with SiO2/Al2O3 = 20 in the oligomerization of α-methylstyrene and 1-octene have been investigated. The highest oligomerization activity is shown by the aluminosilicate synthesized in two steps. The mesoporous aluminosilicates far exceed zeolite H-Beta (SiO2/Al2O3 = 18) in activity and in selectivity toward products with a higher degree of oligomerization.
      PubDate: 2015-07-01
       
  • Model sulfur-resistant NSR catalysts: An XPS study of the interaction of
           BaO/TiO 2 -ZrO 2 and Pt-BaO/TiO 2 -ZrO 2 with NO 2
    • Abstract: Abstract The interaction of NO2 with BaO/TiO2-ZrO2 and Pt-BaO/TiO2-ZrO2 model NO x storage-reduction (NSR) catalysts prepared on the surface of FeCrAl alloy substrates has been investigated by X-ray photoelectron spectroscopy. The action of nitrogen dioxide on these catalysts at room temperature causes the consecutive formation of surface barium nitrite and nitrate. Supposedly, NO2 reduction yielding barium nitrite at the early stages of the interaction is due to the oxidation of amorphous carbon impurities. The introduction of platinum into the catalyst accelerates nitrogen dioxide sorption. On being exposed to NO2 for a long time, platinum oxidizes to PtO2. This process is more pronounced in the sample containing freshly deposited platinum. Heat treatment of this sample in a vacuum, which coarsens the platinum particles, makes them more resistant to oxidation.
      PubDate: 2015-07-01
       
  • Oxidative condensation of methane in the presence of modified MnNaW/SiO 2
           catalysts
    • Abstract: Abstract The effects of cationic (Ce, Zr, and La) and anionic (S, P, and Cl) admixtures on the activity and physicochemical properties of MnNaW/SiO2 were studied in order to optimize the composition of a catalyst for the oxidative condensation of methane (OCM). It was found that OCM process characteristics can be regulated by varying the type (Ce, Zr, La, S, P, and Cl) and concentration (0.5–5 wt %) of a modifying admixture. For the modified MnNaW/SiO2 catalysts, the yield of the target reaction products increased in the following order of modifying admixtures: S < Zr < P < Ce < La < Cl. The addition of lanthanum, cerium, or phosphorus admixtures insignificantly affected the activity of the MnNaW/SiO2 catalyst, whereas the introduction of sulfur or zirconium led to a decrease in the yield of C2 hydrocarbons. Modification with chlorine improved process characteristics and shifted a maximum yield of C2 hydrocarbons to the low-temperature region. It was established that the introduction of lanthanum considerably improved the stability of catalyst operation. The catalyst composition 2Mn-1.6Na-3.1W-2La/SiO2 was developed to afford a 22% yield of target C2 hydrocarbons at a 54% conversion of methane after a 24-h reaction performed under optimum conditions (reaction temperature, 800°C; reaction mixture flow rate, 117 mL min−1g Cat −1 and O2/CH4 molar ratio, 0.5).
      PubDate: 2015-07-01
       
  • Design of micro/mesoporous zeolite-based catalysts for petrochemical and
           organic syntheses
    • Abstract: Abstract This review systematizes and analyzes the physicochemical and catalytic properties of micro/mesoporous materials prepared by two-step recrystallization. The materials are divided into three groups according to the degree of recrystallization: (1) mesostructured zeolites (RZEO-1), (2) micro/mesoporous nanocomposites (RZEO-2), and (3) mesoporous materials with zeolite fragments (RZEO-3). Particular attention is focused on the catalytic properties of the recrystallized materials in petrochemical and organic syntheses. Main advantages of the micro/mesoporous molecular sieves over zeolites and mesoporous materials are demonstrated, and ways of obtaining new catalytic systems based on these molecular sieves are suggested.
      PubDate: 2015-07-01
       
  • Photocatalytic degradation of parabens in aquatic environment: Kinetics
           and degradation pathway
    • Abstract: Abstract Parabens are p-hydroxybenzoic acid ester compounds widely used as preservatives in foods, cosmetics, toiletries and pharmaceuticals. These compounds exert a weak estrogenic activity as determined by in vitro estrogen receptor assay and in vivo uterotrophic assay. The photocatalytic degradation of parabens (butylparaben and ethylparaben), as a function of pH and initial concentration of parabens, was investigated in the presence of TiO2 photocatalyst (P-25, “Degussa”). Experiments conducted at pH 4 with O2-sparged concentration of 15 mg/L showed that in terms of the photocatalytic efficiency the catalysts were slightly superior to those tested at pH 6-11. The intrinsic reaction rates of 2.08 × 102 and 1.81 × 102 μmol L−1min−1 were estimated, and Langmuir-Hinshelwood model adsorption constants K were calculated as 0.05 and 0.06 L/μmol for butylparaben and ethylparaben, respectively. Ten organic intermediates appeared during the photocatalytic degradation of parabens, and were identified by LC/MS/MS. In addition, a tentative reaction pathway was proposed.
      PubDate: 2015-07-01
       
  • Adsorption and interaction of hydrogen and oxygen on the surface of
           separate crystalline gold nanoparticles
    • Abstract: Abstract Crystalline 4- to 5-nm gold nanoparticles supported on graphite and oxidized silicon have been obtained by the impregnation method. Specific features of the adsorption and interaction of H2 and O2 on the Au surface have been investigated by scanning tunneling microscopy, Auger electron spectroscopy, and mass spectrometry. Hydrogen adsorbs dissociatively on separate Au nanoparticles. The Au-H bond energy is ∼1.7 eV. Oxygen adsorbs on the separate Au nanoparticles after hydrogen adsorption. The support nature has a significant effect on the reactivity of the H2 and O2 molecules adsorbed on the surface of the Au nanoparticles. A sufficient condition for water formation from oxygen and hydrogen on Au/SiO2/Si is that Au/SiO2/Si is exposed to H2 and then to O2. As distinct from what is observed for Au/SiO2/Si, water on the Au/graphite surface forms solely due to the successive adsorption of H2, O2, and H2.
      PubDate: 2015-07-01
       
  • Lignin conversion in supercritical ethanol in the presence of solid acid
           catalysts
    • Abstract: Abstract The effects of sulfated ZrO2 and ZrO2-Al2O3 catalysts and acidic zeolite catalysts with various Si/Al ratios on the thermal conversion of alkali lignin in supercritical ethanol at 300–400°C and on the composition of the resulting products have been investigated. All of the catalysts enhance lignin conversion into liquid products. The strongest effect with the catalysts based on sulfated ZrO2 is attained at 400°C; with the zeolites, at 350°C. The catalysts diminish the concentration of phenol and its derivatives and increase the concentration of ethers (mainly the 1,1-diethoxyethane concentration) in the liquid products. The zeolite catalysts are preferable, since the reaction over the ZrO2-containing catalysts produces gaseous compounds in higher yields. The maximum lignin conversion and a high yield of low-boiling liquid products are achieved at 350°C with the zeolite catalyst with Si/Al = 30, which contains a high concentration of acid sites that are stable at elevated temperatures. The most abundant phenolic liquid products of lignin conversion over the zeolite catalysts at 350°C are methoxyphenols and their methylated and ethylated derivatives.
      PubDate: 2015-07-01
       
 
 
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