Subjects -> CHEMISTRY (Total: 928 journals)
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CHEMISTRY (661 journals)            First | 1 2 3 4 | Last

Showing 401 - 600 of 735 Journals sorted alphabetically
Journal of Molecular Liquids     Hybrid Journal   (Followers: 3)
Journal of Molecular Modeling     Hybrid Journal   (Followers: 5)
Journal of Molecular Recognition     Hybrid Journal   (Followers: 2)
Journal of Molecular Spectroscopy     Hybrid Journal   (Followers: 6)
Journal of Molecular Structure     Hybrid Journal   (Followers: 6)
Journal of Nanoparticles     Open Access   (Followers: 4)
Journal of Nanostructure in Chemistry     Open Access   (Followers: 8)
Journal of Organometallic Chemistry     Hybrid Journal   (Followers: 25)
Journal of Photochemistry and Photobiology     Open Access  
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 3)
Journal of Photochemistry and Photobiology B: Biology     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: 17)
Journal of Polymer and Biopolymer Physics Chemistry     Open Access   (Followers: 7)
Journal of Polymer Science Part A: Polymer Chemistry     Hybrid Journal   (Followers: 92)
Journal of Polymers     Open Access   (Followers: 7)
Journal of Porphyrins and Phthalocyanines     Hybrid Journal   (Followers: 1)
Journal of Progressive Research in Chemistry     Open Access  
Journal of Pure and Applied Chemistry Research     Open Access   (Followers: 3)
Journal of Raman Spectroscopy     Hybrid Journal   (Followers: 14)
Journal of Research and Education Chemistry     Open Access   (Followers: 1)
Journal of Research Updates in Polymer Science     Hybrid Journal   (Followers: 2)
Journal of Rubber Research     Hybrid Journal   (Followers: 1)
Journal of Saudi Chemical Society     Open Access  
Journal of Solid State Chemistry     Hybrid Journal   (Followers: 13)
Journal of Solution Chemistry     Hybrid Journal   (Followers: 1)
Journal of Structural Chemistry     Hybrid Journal   (Followers: 1)
Journal of Sulfur Chemistry     Hybrid Journal   (Followers: 1)
Journal of Supercritical Fluids     Hybrid Journal   (Followers: 3)
Journal of Superhard Materials     Hybrid Journal  
Journal of Surface Science and Technology     Hybrid Journal  
Journal of Surfactants and Detergents     Hybrid Journal   (Followers: 3)
Journal of Taibah University for Science     Open Access  
Journal of the American Chemical Society     Hybrid Journal   (Followers: 323)
Journal of the American Society for Mass Spectrometry     Hybrid Journal   (Followers: 32)
Journal of the American Society of Brewing Chemists     Full-text available via subscription   (Followers: 2)
Journal of the Chilean Chemical Society     Open Access   (Followers: 2)
Journal of the Chinese Chemical Society     Hybrid Journal  
Journal of the Indian Chemical Society     Hybrid Journal  
Journal of The Indonesian Society of Integrated Chemistry     Open Access  
Journal of the Iranian Chemical Society     Hybrid Journal   (Followers: 1)
Journal of the Korean Society for Applied Biological Chemistry     Hybrid Journal  
Journal of the Mexican Chemical Society     Open Access   (Followers: 1)
Journal of the Serbian Chemical Society     Open Access  
Journal of the Turkish Chemical Society, Section A : Chemistry     Open Access  
Journal of Theoretical and Computational Chemistry     Hybrid Journal   (Followers: 9)
Jurnal Inovasi Pendidikan Kimia     Open Access  
Jurnal Kimia (Journal of Chemistry)     Open Access  
Jurnal Kimia Riset     Open Access  
Jurnal Pendidikan Kimia     Open Access  
Jurnal Penelitian Sains (JPS)     Open Access  
Karbala International Journal of Modern Science     Open Access  
Kinetics and Catalysis     Hybrid Journal   (Followers: 4)
Konfigurasi : Jurnal Pendidikan Kimia dan Terapan     Open Access  
Korea-Australia Rheology Journal     Hybrid Journal   (Followers: 1)
Langmuir     Hybrid Journal   (Followers: 58)
Lebensmittelchemie     Hybrid Journal   (Followers: 1)
Lipid Insights     Open Access  
Luminescence     Hybrid Journal   (Followers: 2)
Macromolecular Materials & Engineering     Hybrid Journal   (Followers: 5)
Macromolecular Rapid Communications     Hybrid Journal   (Followers: 10)
Macromolecular Research     Hybrid Journal   (Followers: 2)
Macromolecular Symposia     Hybrid Journal   (Followers: 3)
Macromolecular Theory and Simulations     Hybrid Journal   (Followers: 2)
Macromolecules     Hybrid Journal   (Followers: 48)
Magnetic Resonance in Chemistry     Hybrid Journal   (Followers: 8)
Magnetochemistry     Open Access  
Marine Chemistry     Hybrid Journal   (Followers: 6)
Marine Drugs     Open Access   (Followers: 1)
MATEC Web of Conferences     Open Access  
Materials Advances     Open Access   (Followers: 2)
Materials and Devices     Open Access  
Materials Characterization     Hybrid Journal   (Followers: 32)
Materials Chemistry Frontiers     Hybrid Journal   (Followers: 4)
Materials Horizons     Hybrid Journal   (Followers: 6)
Materials Research Bulletin     Hybrid Journal   (Followers: 25)
Materials Science-Poland     Open Access   (Followers: 1)
Materials Sciences and Applications     Open Access   (Followers: 2)
Medicinal Chemistry Research     Hybrid Journal   (Followers: 9)
Mediterranean Journal of Chemistry     Open Access  
Metallography, Microstructure, and Analysis     Hybrid Journal   (Followers: 1)
Micro and Nano Systems Letters     Open Access   (Followers: 6)
Microchimica Acta     Hybrid Journal   (Followers: 2)
Microporous and Mesoporous Materials     Hybrid Journal   (Followers: 9)
Modern Chemistry & Applications     Open Access   (Followers: 1)
Modern Research in Catalysis     Open Access  
Molbank     Open Access  
Molecular Catalysis     Hybrid Journal   (Followers: 6)
Molecules     Open Access   (Followers: 4)
Molecules and Cells     Hybrid Journal   (Followers: 1)
Monatshefte für Chemie - Chemical Monthly     Hybrid Journal   (Followers: 4)
Mongolian Journal of Chemistry     Open Access  
Moscow University Chemistry Bulletin     Hybrid Journal   (Followers: 1)
MRS Bulletin     Full-text available via subscription   (Followers: 4)
Nachrichten aus der Chemie     Hybrid Journal   (Followers: 18)
Nano Convergence     Open Access   (Followers: 1)
Nano Materials Science     Open Access   (Followers: 1)
Nano Reviews & Experiments     Open Access   (Followers: 14)
Nano Select     Open Access  
Nanochemistry Research     Open Access   (Followers: 1)
Nanoscale     Hybrid Journal   (Followers: 18)
Nanoscale Advances     Open Access  
Nanoscale Horizons     Hybrid Journal  
Nanoscale Research Letters     Open Access   (Followers: 8)
Nanoscience and Nanotechnology Letters     Full-text available via subscription   (Followers: 24)
Natural Product Communications     Open Access  
Natural Product Reports     Hybrid Journal   (Followers: 10)
Natural Science     Open Access   (Followers: 8)
Natural Volatiles & Essential Oils     Open Access  
Nature Chemistry     Full-text available via subscription   (Followers: 97)
Nature Protocols     Full-text available via subscription   (Followers: 72)
Nature Reviews Chemistry     Hybrid Journal   (Followers: 17)
New Journal of Chemistry     Hybrid Journal   (Followers: 17)
Nitric Oxide     Hybrid Journal  
Nitrogen     Open Access  
Nukleonika     Open Access  
Open Chemistry Journal     Open Access  
Open Conference Proceedings Journal     Open Access  
Open Journal of Chemistry     Open Access  
Open Journal of Composite Materials     Open Access   (Followers: 22)
Open Journal of Inorganic Non-metallic Materials     Open Access   (Followers: 2)
Open Journal of Medicinal Chemistry     Open Access   (Followers: 4)
Open Journal of Polymer Chemistry     Open Access   (Followers: 12)
Open Journal of Synthesis Theory and Applications     Open Access  
Open Medicinal Chemistry Journal     Open Access  
Orbital - The Electronic Journal of Chemistry     Open Access   (Followers: 1)
Organic & Biomolecular Chemistry     Hybrid Journal   (Followers: 57)
Organometallics     Hybrid Journal   (Followers: 19)
Oxidation of Metals     Hybrid Journal   (Followers: 16)
Passer Journal of Basic and Applied Sciences     Open Access  
Peptide Science     Full-text available via subscription  
Pharmaceuticals     Open Access   (Followers: 4)
Pharmaceutics     Open Access   (Followers: 5)
Phosphorus, Sulfur, and Silicon and the Related Elements     Hybrid Journal   (Followers: 2)
Photochemistry and Photobiology     Hybrid Journal   (Followers: 3)
Physical Science International Journal     Open Access  
Physics and Materials Chemistry     Open Access   (Followers: 1)
Phytochemistry     Hybrid Journal   (Followers: 4)
Phytochemistry Letters     Full-text available via subscription   (Followers: 1)
Plasma     Open Access   (Followers: 3)
Plasma Chemistry and Plasma Processing     Hybrid Journal   (Followers: 3)
Polycyclic Aromatic Compounds     Hybrid Journal  
Polyhedron     Hybrid Journal   (Followers: 4)
Polymer Chemistry     Hybrid Journal   (Followers: 24)
Polymer crystallization     Hybrid Journal  
Polymer Degradation and Stability     Hybrid Journal   (Followers: 23)
Polymer Engineering & Science     Hybrid Journal   (Followers: 14)
Polymer Reviews     Hybrid Journal   (Followers: 32)
Polymer Science Series D     Hybrid Journal   (Followers: 3)
Polymer Testing     Hybrid Journal   (Followers: 193)
Polymer-Plastics Technology and Materials     Hybrid Journal   (Followers: 5)
Polymers     Open Access   (Followers: 21)
Polymers from Renewable Resources     Hybrid Journal  
Proceedings of the Combustion Institute     Full-text available via subscription   (Followers: 8)
Processes     Open Access  
Progress in Lipid Research     Hybrid Journal   (Followers: 3)
Progress in Organic Coatings     Hybrid Journal   (Followers: 7)
Progress in Polymer Science     Full-text available via subscription   (Followers: 36)
Progress in Reaction Kinetics and Mechanism     Open Access  
Progress in Solid State Chemistry     Full-text available via subscription   (Followers: 3)
Progress in Surface Science     Full-text available via subscription   (Followers: 3)
Protein Science     Hybrid Journal   (Followers: 45)
Radiochemistry     Hybrid Journal   (Followers: 1)
Rapid Communications in Mass Spectrometry     Hybrid Journal   (Followers: 33)
Reaction Chemistry & Engineering     Hybrid Journal  
Reaction Kinetics, Mechanisms and Catalysis     Hybrid Journal   (Followers: 3)
Reactions     Open Access  
Reportes Científicos de la FaCEN     Open Access  
Research Journal of Phytochemistry     Open Access   (Followers: 1)
Resources Chemicals and Materials     Full-text available via subscription   (Followers: 2)
Results in Chemistry     Open Access  
Results in Geochemistry     Open Access  
Results in Surfaces and Interfaces     Open Access  
Review Journal of Chemistry     Hybrid Journal   (Followers: 1)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 4)
Revista Boliviana de Química     Open Access  
Revista CENIC. Ciencias Quimicas     Open Access  
Revista Colombiana de Ciencias Químico-Farmacéuticas     Open Access  
Revista Colombiana de Química     Open Access  
Revista Cubana de Química     Open Access  
Revista de Ciencia y Tecnología     Open Access  
Revista de Ciencias     Open Access  
Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales     Open Access  
Revista de la Sociedad Química del Perú     Open Access  
Revista de la Societat Catalana de Química     Open Access  
Revista de Química     Open Access   (Followers: 3)
Revista Debates em Ensino de Química     Open Access  
Revista ION     Open Access  
RSC Advances     Open Access   (Followers: 27)
RSC Chemical Biology     Open Access  
RSC Medicinal Chemistry     Hybrid Journal   (Followers: 6)
Russian Journal of Bioorganic Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Coordination Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of General Chemistry     Hybrid Journal   (Followers: 1)
Russian Journal of Inorganic Chemistry     Hybrid Journal  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Science China Chemistry     Hybrid Journal   (Followers: 2)
Science Talks     Full-text available via subscription   (Followers: 2)
Sciences & Technologie A : sciences exactes     Open Access  
Scientific Journal of Frontier Chemical Development     Open Access   (Followers: 2)

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Journal Cover
Kinetics and Catalysis
Journal Prestige (SJR): 0.262
Citation Impact (citeScore): 1
Number of Followers: 4  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1608-3210 - ISSN (Online) 0023-1584
Published by Springer-Verlag Homepage  [2469 journals]
  • Specific Features of the Liquid-Phase Hydrogenation of 2-Butyne-1,4-Diol
           under the Action of Palladium–Phosphorus Particles

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      Abstract: Efficient catalyst systems based on Pd–P particles for the chemoselective hydrogenation of 2‑butyne-1,4-diol, which are superior to Ziegler-type systems in turnover frequency under mild conditions, have been proposed. The introduction of phosphorus into the composition of palladium nanoparticles makes it possible to maintain a nearly 100% 2-butene-1,4-diol selectivity up to a 90% alkynediol conversion and affects the ratio between the hydrogenation rates of the triple and double bonds of alkynediol. Poly(N-vinylpyrrolidone) increases the aggregative stability of Pd–P particles during their functioning; however, it has hardly any effect on the activity and selectivity in 2-butyne-1,4-diol hydrogenation.
      PubDate: 2022-04-01
       
  • Effect of Salt and Phosphine Additives on the Composition of Active
           Palladium Complexes in the Mizoroki–Heck Reaction with Aromatic
           Carboxylic Anhydrides

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      Abstract: This paper presents the results of studies on changes in the composition of palladium complexes responsible for the activation of substrates in the Mizoroki–Heck reaction between aromatic acid anhydrides and alkenes. The differential selectivity of the reaction under conditions of competition between a pair of anhydrides or alkenes indicates the catalytic activity of palladium complexes, the composition of which varies depending on the concentration ratio of a tertiary phosphine, an alkali metal halide used as a promoting additive, and a palladium catalyst precursor loaded into the system. It was found that, when the threshold values of the concentrations ratio between halide ions and the tertiary phosphine were achieved, only phosphine-free palladium complexes containing halide anions in their coordination sphere made a decisive contribution to the formation of reaction products in spite of the presence of phosphine in the system. At the same time, when a halide salt was present in low concentrations or absent at all, active Pd complexes could include tertiary phosphine (in phosphine-containing catalytic systems) and solvent molecules and aromatic carboxylate anions formed as a result of the conversion of the initial anhydride. Under the “noncompetitive” conditions of the Mizoroki–Heck reaction, it was found that the nature of the cation and anion of a halide salt added to the catalytic system had a key effect on the differential selectivity of the formation of a classical “Heck” product of alkene arylation and a carbonyl product (chalcone) formed through the parallel reaction pathway. It was demonstrated that the differential selectivity and the yield of the carbonyl-containing reaction product increased when bromide salt additives were used. Therefore, in principle, it is possible to control the composition of active palladium complexes responsible for the selective formation of various products in the Mizoroki–Heck reaction with aromatic acid anhydrides.
      PubDate: 2022-04-01
       
  • Kinetic Model and Mechanism of Hydrogenation of Unsaturated Carbocyclic
           Compounds Based on Norbornadiene

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      Abstract: Liquid-phase hydrogenation of bicyclo[2.2.1]hepta-2,5-diene (norbornadiene, ND) proceeds in the presence of an industrial palladium catalyst Pd/γ-Al2O3 (PK-25) in an n-heptane solution at 76°C via consecutive formation of bicyclo[2.2.1]hept-2-ene (norbornene, NE) and bicyclo[2.2.1]heptane (norbornane, NA), as well as tricyclo[2.2.1.02,6]heptane (nortricyclane, NT) as a minor product. The reaction products were identified, the main routes were determined, and the material balance was studied. Preferable adsorption of ND at the active palladium site over adsorption of other components of the system was confirmed. A parallel-serial scheme of the process mechanism was proposed based on the sum of experimental and theoretical data. Zero order kinetics was observed in a wide range of initial substrate concentrations. The apparent rate constants of each stage were measured. A detailed kinetic model was developed based on the Langmuir–Hinshelwood approach, assuming multiple adsorption of substrates at a single active site of the heterogeneous catalyst. The model adequately describes the available experimental data using the proposed mechanism of ND hydrogenation. The possibility of a “cocktail” mechanism for the given reaction was discussed.
      PubDate: 2022-04-01
       
  • Catalytic Ozonation of Oxalic Acid in Aqueous Solution in the Presence of
           Manganese Ions

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      Abstract: The kinetics of mineralization of oxalic acid Н2С2О4 under the action of ozone in acidic aqueous solution (С(НClО4) = 0.1 M, pH ~ 1) with the addition of \({\text{MnO}}_{4}^{ - }\) or Mn2+ ions was studied. It was found that manganese ions are effective catalysts for the reaction of O3 with oxalic acid. Regardless of the manganese species ( \({\text{MnO}}_{4}^{ - }\) or Mn2+) added to the solution, it was converted into an oxalate complex of tetravalent manganese in the course of the reaction, and this complex was the stable form of the catalyst in the system under consideration. The kinetics of release of carbon dioxide—a product of the reaction of Н2С2О4 with О3—was determined depending on the concentrations of ozone in the gas stream and oxalic acid and manganese in the solution. A basic scheme of the catalysis of the test reaction by manganese ions was proposed, and a kinetic model was constructed to adequately describe the experimental results. The reaction scheme is based on the fact that oxalate is oxidized to CO2 in the course of a complex decomposition reaction of the oxalate complex of tetravalent manganese; in this case, Mn(IV) is reduced to Mn2+. The complex is regenerated by the oxidation of Mn2+ to Mn(IV) with ozone.
      PubDate: 2022-04-01
       
  • Production of Alcohols and Olefins from CO and H2 on a Cobalt Catalyst at
           High Pressures and in the Gas Circulation Mode

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      Abstract: The results of a study of the synthesis of products from CO and H2 on a supported industrial Co–Al2O3/SiO2 catalyst under medium and high pressures in the gas circulation mode are presented. It was found that an increase in pressure from 2.0 to 8.0 MPa led to an increase in the amount of formed alcohols and synthesis olefins by factors of 10.5 and 2.0, respectively. It was determined that alcohols obtained in the synthesis were not the products of olefin hydration. The effect of an increase in selectivity for C5+ products with temperature at a high pressure in the gas recirculation mode, which is atypical for the Fischer–Tropsch synthesis, was confirmed.
      PubDate: 2022-04-01
       
  • On the Influence of Ionic Strength on the Kinetics of Sulfite Oxidation in
           the Presence of Mn(II)

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      Abstract: The paper considers available published data on the effect of the ionic strength of solutions on the kinetics of oxygen oxidation of sulfite in acidic solutions (pH 1.3–4.5) in the presence of manganese(II) ions. It was found that a consistent picture of this effect arises when the process is considered within the framework of a degenerate-branched chain mechanism with the participation of trace iron ions as an initiator. This approach, in agreement with the experimental data, led to the identification of two different modes of this process and made it possible to obtain explicit expressions for the observed reaction rate constants. This paper presents new expressions to describe the negative effect of ionic strength (~10–3–1.5 M) on the reaction rate constants in both modes.
      PubDate: 2022-04-01
       
  • Methyl Acetate Synthesis by Dimethyl Ether Carbonylation in the Presence
           of Zeolites: A Review

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      Abstract: The review analyzes the specific features of methyl acetate synthesis by dimethyl ether carbonylation in the presence of zeolite catalysts. The structural characteristics of zeolites, in particular, mordenite and ferrierite, that affect carbonylation are discussed. The bridging hydroxyl groups (Al–OH–Si) of zeolites function as Brønsted acid sites and interact with dimethyl ether. The carbonylation reaction is characterized by an induction period, during which dimethyl ether molecules interact with Brønsted acid sites to form methoxy groups. The incorporation of CO into the methoxy group leads to the formation of an acetyl intermediate. Methyl acetate is formed due to the interaction between a dimethyl ether molecule and an acetyl intermediate. The reaction is facilitated by the confinement effect characteristic of small zeolite pores, in particular, eight-membered pockets of mordenite. Methyl acetate is synthesized at moderate temperatures (about 200°C) in a CO–dimethyl ether mixture at a high selectivity and a significant dimethyl ether conversion. The occurrence of hydrocarbon formation side reactions, along with the methyl acetate synthesis target reaction, is observed; the side reactions decrease the on-stream stability of the catalyst. In the case of mordenite, these reactions are attributed to the sites present in the twelve-membered channels. The on-stream stability of the catalysts can be increased by using special techniques for neutralizing the deactivating sites of the zeolite. The effect can be achieved by pyridine adsorption or ion exchange of the respective protons of the mordenite structure for organic or metal cations. The introduction of zinc ions and, additionally, copper ions significantly inhibits the activity of the mordenite sites on which the side reactions occur. A new area of research is the use of multifunctional catalysts that mediate methyl acetate synthesis directly from synthesis gas.
      PubDate: 2022-04-01
       
  • Estimation of the Integral Toxicity of Photocatalysts Based on Graphitic
           Carbon Nitride in a Luminescent Test

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      Abstract: A ternary heterosystem consisting of crystalline graphitic carbon nitride, zinc oxide, and zinc sulfide (g-C3N4/ZnO/ZnS) was obtained by the one-stage decomposition of a mixture of thiourea and zinc acetate. The integral toxicity index of the resulting material was estimated in a luminescent test with a genetically modified Escherichia coli strain as a test object. The effect of quenching the luminescence of E. coli was noted both under exposure to UV radiation due to photocatalytic reactions on the surface of g-C3N4/ZnO/ZnS leading to the formation of highly oxidative radical ions interacting with cell membranes and without irradiation due to mechanical interactions with bacterial cells. At a 0.3 g/L concentration of g-C3N4/ZnO/ZnS in aqueous solution, the toxicity index T reached 75.6% under UV irradiation. In this case, an increase in the toxicity index T of the ternary heterosystem in a test concentration range from 0.1 to 0.3 g/L was 6 or 10–11% under UV radiation or without illumination, respectively, as compared with that of the pure graphite-like carbon nitride obtained under identical conditions.
      PubDate: 2022-04-01
       
  • Comparison of the Activities of Pd(0) and Pd(I) in Low-Temperature
           Oxidation of Carbon Monoxide on the Pd/γ-Al2O3 Catalyst

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      Abstract: Low-temperature oxidation of carbon monoxide on the Pd/γ-Al2O3 catalyst has been studied at room temperature and atmospheric pressure of air containing 100 mg/m3 CO. The catalyst became gradually deactivated during the process. Storage of the partially deactivated catalyst in air for 10–12 h resulted in a complete recovery of activity. According to XPS data, the material obtained by depositing Pd3(OAc)6 on γ-Al2O3 before contact with CO contains palladium compounds in the oxidation states I and 0. The specific catalytic activity of palladium compounds in different oxidation states was evaluated based on the correlation between the catalytic activity and the content of Pd(I) and Pd(0) compounds, and it was shown that the activity of the former is higher than that of the latter.
      PubDate: 2022-04-01
       
  • para-Substituent Effect on the Decay Kinetics of the Isomeric Forms of
           Aromatic Nitroso Oxides

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      Abstract: Flash photolysis of aromatic azides 4-R–C6H4N3 (where R = Ph, OPh, CH2Ph) in aerated acetonitrile solutions led to the intermediate formation of cis and trans isomers of the corresponding aryl nitroso oxides, which then presumably transformed via the aromatic ring opening into R-substituted unsaturated nitrile oxides. The electronic spectra of the cis and trans isomers of 4-R–C6H4NOO were recorded; the effective rate constants of the monomolecular decay of the isomers were determined, and the activation parameters of the rate constants were found. The rate constants ktrans are significantly lower than kcis, slightly varying in the series of nitroso oxides in the range 0.15–0.22 s–1 (295 K). The rate constants kcis for phenyl- (2.5 s–1) and benzyl- (2.8 s–1) substituted aryl nitroso oxides coincide within the experimental error, whereas the phenoxy substituent leads to an increase in kcis by a factor of ~1.5 (4.3 s–1). The decay of 4-R–C6H4NOO is represented by a system of three elementary reactions, including reversible isomerization of the cis and trans isomers and ortho-cyclization of cis-nitroso oxides into the corresponding nitrile oxide. Solving the system of differential equations describing the decay kinetics of 4-R–C6H4NOO led to an analytical time dependence of optical density of the reaction mixture, which coincides with the empirical dependence found earlier. This made it possible to reveal the physical meaning of the effective rate constants and calculate the elementary rate constants of the decay of aromatic nitroso oxides. The DFT calculations of activation barriers for cis-trans isomerization and irreversible ortho-cyclization of cis-4-R–C6H4NOO are in good agreement with experiment.
      PubDate: 2022-04-01
       
  • Biocatalytic Heterogeneous Processes of Low-Temperature Synthesis of Diol
           Monoesters

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      Abstract: A study was made of the low-temperature synthesis of esters of heptanoic (enanthic, C7:0) acid and various diols using heterogeneous biocatalysts prepared by the adsorptive immobilization of the recombinant lipase rPichia/lip on macroporous carbon aerogel. The substrates were diols differing in length of the carbon skeleton (2 to 6 C atoms), position of the OH group, and isomerism of the carbon skeleton, namely, 1,2-ethanediol (ethylene glycol) and its oligomers (dimers and trimers), 1,2-propanediol (propylene glycol), 1,3‑propanediol, 1,4-butanediol, 1,6-hexanediol, and 2-ethyl-1,3-hexanediol. The esterification and synthesis of monoesters of heptanoic acid were carried out in batch reactors under very mild conditions (20 ± 2°C, 1 bar). The properties of the prepared biocatalysts, such as enzymatic activity, substrate specificity, and operational stability, were investigated depending on the structure of the diol molecule and the nature of the organic solvent (chloroform, hexane, acetone). It was found that C2–C4 short-chain diols irreversibly inhibited the immobilized lipase, and the biocatalyst was completely inactivated within 1–3 reaction cycles. The maximum activity (83 U/g) and the conversion of acid (94% in 24 h) were observed in the esterification of heptanoic acid with 1,6-hexanediol; under the studied conditions, the fraction of monoester was more than 99%. A correlation was found between the biocatalytic activity and the molecular length of symmetric diols: the esterification reaction rate increased with increasing distance between the terminal OH groups. Because chloroform inactivated the adsorbed rPichia/lip, the conditions for the reactivation of the biocatalysts were selected by replacing the reaction medium: the solvent by hexane and the diol by butanol.
      PubDate: 2022-04-01
       
  • Experimental Studies and Simulation of Methane Pyrolysis and Oxidation in
           Reflected Shock Waves Accompanied by Soot Formation

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      Abstract: An experimental and computational study of methane pyrolysis and oxidation and formation of soot particles in reflected shock waves has been performed using a previously proposed unified kinetic model. The model makes it possible to describe the consumption of initial methane molecules and formation of products during pyrolysis and oxidation of various methane–oxygen–argon mixtures. The results of experiments in shock tubes of various designs, equipped with different means of detection of the initial components and secondary products, were compared with the predictions of kinetic simulations. In general, the kinetic model demonstrated good predictive power.
      PubDate: 2022-04-01
       
  • In Memoriam: R. A. Buyanov—A Scientometric View

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      Abstract: A bibliometric and subject analysis of more than 800 scientific publications (including ~90 patents and Inventor’s Certificates) of Corresponding Member of the RAS Roman Alekseevich Buyanov (1927–2020), one of the founders of the Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia, was performed using the Institute’s SciAct CRIS system and the Chemical Plus, Web of Science, Scopus, and Russian Science Citation Index databases. Buyanov’s main scientific activities were discussed, and his most cited works were identified.
      PubDate: 2022-02-01
       
  • Nonlinear Phenomena during CO Oxidation over Nickel

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      Abstract: The paper is devoted to the experimental and theoretical studies of self-sustained oscillations and wave phenomena during CO oxidation on Ni foil. A new type of spatial structures arising due to the redox processes of the catalyst and observed under isothermal conditions at atmospheric pressure were studied. A 3D distributed mathematical model was constructed, which describes the color change and the propagation of kinetic waves of nickel oxidation–reduction in a flow-through reactor. The main reason for the wave phenomena and their propagation during CO oxidation on nickel was shown to be the presence of an oxygen concentration gradient in the flow-through reactor due to the effect of mass transfer on the reaction rate.
      PubDate: 2022-02-01
       
  • Nickel as a Promising Electrocatalytic Material for Electrooxidation of
           Hydrogen and Borohydride: State-of-the-Art and Future Challenges

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      Abstract: Nickel is widely used in heterogeneous catalysis of hydrogenation, reforming, methanation, and other processes. Utilization of nickel in heterogeneous electrocatalysis is less wide-spread, but has evidenced considerable growth in last decades. Herewith we present a brief review of Ni-based electrocatalysts for electrooxidation of hydrogen and borohydride with a special emphasis on electrode materials comprising metallic nickel—nickel oxide (hydroxide) heterostructures.
      PubDate: 2022-02-01
       
  • Technology for Producing Hydrogen and Carbon Nanofibers from Natural Gas

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      Abstract: A technology for producing hydrogen and carbon nanofibers from natural gas is considered. A catalyst that actively and stably operated at temperatures of 700–750°C was developed to achieve high conversions of methane. The genesis of its phase composition was investigated using electron microscopy and X-ray diffraction analysis. The modification of a 75%Ni–12%Cu/Al2O3 catalyst with iron oxide led to the formation of a ternary Ni–Cu–Fe alloy. The method developed for producing hydrogen effectively worked with the use of not only methane but also natural gas as a feedstock. An installation with a rotating reactor for producing hydrogen and carbon nanofibers from natural gas made it possible to carry out the process on a 70%Ni–10%Cu–10%Fe/Al2O3 catalyst for 20–30 h. The hydrogen concentration at the reactor outlet was higher than 70 mol %. The yield of hydrogen reached 590 L per gram of the catalyst.
      PubDate: 2022-02-01
       
  • Coking of Catalysts: Mechanisms, Models, and Influence

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      Abstract: This review considers the mechanism of multilayered coke formation on catalysts of various types and analyzes its possible variants. A detailed derivation of equations of the dynamics of accumulation for different types of coke and the kinetics of its deactivating effect is given. The substantiated dependences of the relative activity of a catalyst on the concentration of coke are derived. Specific examples of these dependences are presented. They confirm the advantages of rigorous models based on the mechanism of the phenomenon in comparison with the formal description of experiments, which does not have predictive power.
      PubDate: 2022-02-01
       
  • Synthesis and Structure of a New Ruthenium(II) Clathrochelate and the Use
           of a Highly Porous Ceramic Material with an Immobilized Complex in the
           Oxidative Conversion of Methane

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      Abstract: A new ruthenium(II) cage complex with polar terminal groups in the apical substituents has been synthesized; the molecular design of the complex contributes to the effective immobilization of it due to the adsorption on the surface of a heat-resistant highly porous silicate fibrous material used as a support. The complex has been synthesized by the template condensation of cyclohexanedione-1,2-dioxime (nioxime) and 4-(hydroxymethyl)phenylboronic acid on the ruthenium(II) ion using a [Ru(CH3CN)3(COD)Cl](BF4) solvatocomplex as a source of Ru2+ cations. The composition and structure of the synthesized macrobicyclic compound have been determined using data of elemental analysis, MALDI-TOF mass spectrometry, 1H and 13C{1H} NMR spectroscopy, and X-ray diffraction analysis. It has been shown that the synthesized hybrid material with immobilized ruthenium clathrochelate catalyzes the dry reforming of methane. The productivity of the catalyst system at 900°C achieves 9437 mol CO and 11797 mol H2 per gram-atom of ruthenium per hour.
      PubDate: 2022-02-01
       
  • A Study of the Electrochemical Characteristics of Single-Chamber Solid
           Oxide Fuel Cells Based on Platinum and Strontium-Doped Lanthanum Manganite
           Electrodes and Fed with a Methane–Air Mixture

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      Abstract: The properties of single-chamber solid oxide fuel cells (SC SOFCs) composed of an electrolyte based on yttria-stabilized zirconia (YSZ), a platinum anode, and a strontium-doped lanthanum manganite (LSM) cathode and fed with a methane–air mixture in a temperature range of 500–750°C have been studied. It has been shown that, in the presence of LSM, the methane conversion in the oxidation reaction at 650°C does not exceed 10%; therefore, LSM can be used as a cathode material in SC SOFCs. It has been shown that a Pt YSZ LSM cell makes it possible to generate electricity. The maximum specific power (36 mW/cm2), voltage (0.85 V), and short-circuit current density (132 mA/cm2) are achieved at 700°C, a [CH4]/[O2] ratio of ~1.0, and a reaction mixture feed rate of 330 cm3/min. The study has shown that it is possible to design SC SOFCs fed with a methane–air mixture, which are capable of generating electrical power. The methane remaining after the operation of SC SOFCs can be used to generate heat or converted to synthesis gas, which is used as a feedstock, for example, in the production of ammonia, methanol, or hydrocarbons by the Fischer–Tropsch process.
      PubDate: 2022-02-01
       
  • Comparative Analysis of the Dehydrogenation of Hydrocarbons and Alcohols
           in a Membrane Reactor

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      Abstract: Membrane technologies are widely used in various modern technological processes. In the chemical industry, membranes are used to solve several problems from increasing the efficiency of targeted processes to ensuring strict environmental legislation. A special synergistic effect is expected in the field of membrane catalysis when it becomes possible not only to accelerate the main reaction using a catalyst affecting the kinetics of the process but also shift the reaction equilibrium toward the products due to the membrane separation of one or more products from the main reaction volume. This advantage of membrane catalytic technologies is especially in demand for endothermic processes. This mini review is devoted to the dehydrogenation of hydrocarbons exemplified by the production of the high demand monomers ethylene, propylene, and styrene and the dehydrogenation of alcohols exemplified by methanol as a key compound of the C1 chemistry.
      PubDate: 2022-02-01
       
 
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