На главную              К списку выставок

Гомогенный катализ в окислении (окислительной функционализации)алканов (насыщенных углеводородов)

Журнальные статьи

1.
Amini M., Haghdoost M.M., Bagherzadeh M. Oxido-peroxido molybdenum(VI) complexes in catalytic and stoichiometric oxidations // Coordination Chemistry Reviews. 2013. Vol. 257, № 7-8. P. 1093–1121.

This review mainly discusses the application of oxido-peroxido Molybdenum(VI) complexes as catalysts or mediators in homogeneous or heterogeneous catalytic systems for oxidations of olefins, sulfides, alcohols, alkanes, and amines toward the synthesis of a variety of organic compounds, such as epoxides, sulfoxides, aldehydes and ketones, carboxylic acids, alcohols and nitroso compounds.

2.
Araghi M., Bokaei F. Manganese(III) porphyrin supported on multi-wall carbon nanotubes: A highly efficient and reusable biomimetic catalyst for oxidative decarboxylation of alpha-arylcarboxylic acids and oxidation of alkanes with sodium periodate // Polyhedron. 2013. Vol. 53. P. 15–19.

In the present work, the highly efficient oxidative decarboxylation of carboxylic acids and also the oxidation of alkanes with sodium periodate catalyzed by tetrakis(p-aminophenyl)porphyrinatomanganese(III) chloride, [Mn(TNH2PP)Cl], supported on functionalized multi-wall carbon nanotubes, MWCNT, is reported. The catalyst, [Mn(TNH2PP)Cl@MWCNT], was used as an efficient and heterogeneous catalyst for hydroxylation of alkenes with NaIO4 at room temperature, in the presence of imidazole as an axial ligand. Also, in this system, carboxylic acids were converted to their corresponding carbonyl compounds. This heterogenized catalyst could be reused several times without significant loss of its catalytic activity.

3.
Bauer F. et al. Hydroisomerization of long-chain paraffins over nano-sized bimetallic Pt-Pd/H-beta catalysts // Catalysis Science & Technology. 2014. Vol. 4, № 11. P. 4045–4054.

The hydroisomerization of long-chain n-paraffins was studied in the temperature range of 205-230 degrees C at p(H2) = 50 bar using a pilot-scale trickle-bed continuous-flow reactor over bimetallic catalysts consisting of mixtures of platinum and palladium supported on commercially available nano-sized zeolite beta (n(Si)/n(Al) = 12.5 and 25, respectively) extruded with an alumina binder. For n-hexadecane conversion, high yields of isomers (25 and 45 wt.% of mono-and multibranched isomers, respectively) without extensive cracking (>10 wt.%) were obtained at a conversion of 80%. Long-term tests with n-hexadecane and blends of solid n-paraffins for 30-60 days on-stream clearly indicate that a minor loss in catalyst activity can easily be compensated for by increasing the reaction temperature from 220 degrees C to 225 degrees C. The zeolite with a "mild acidity" exhibits a low hydrocracking activity with isomerization yields of up to 70 wt.% and high stability over more than 60 days on-stream. Carbonaceous deposits formed during n-paraffin hydroisomerization were investigated by elemental analysis, TGA, ATR-FTIR and C-13 MAS NMR spectroscopy, showing the formation of hydrogen-rich coke which leads to pore blocking.

4.
Biomimetic Based Applications / ed. George A. InTech, 2011.

Biomimetic Based Applications The interaction between cells, tissues and biomaterial surfaces are the highlights of the book "Biomimetic Based Applications". In this regard the effect of nanostructures and nanotopographies and their effect on the development of a new generation of biomaterials including advanced multifunctional scaffolds for tissue engineering are discussed. The 2 volumes contain articles that cover a wide spectrum of subject matter such as different aspects of the development of scaffolds and coatings with enhanced performance and bioactivity, including investigations of material surface-cell interactions. Edited by Anne George, ISBN 978-953-307-195-4, 572 pages

5.
Cai F. et al. CO oxidation on supported platinum group metal (PGM) based nanoalloys // Science China-Chemistry. 2015. Vol. 58, № 1. P. 14–28.

The oxidation of carbon monoxide is widely investigated for realistic and potential uses in energy production and environmental processes. As a probe reaction to the surface properties, it gives an insight into the relationship between the structure of active phase and catalytic performance. Noble metals alloyed with certain transition metals in the form of a nanoalloy exhibit enhanced catalytic activity for various reactions, especially when simultaneous activation of oxygen and CO is involved. This article highlights some of these insights into nanoalloy catalysts in which platinum group metal (PGM) is alloyed with a second and/or third transition metal (M/M'=Co, Fe, V, Ni, Ir, etc.), for catalytic oxidation of carbon monoxide in a gas phase. Recent studies have provided important insights into how the atomic-scale structures of the nanoalloy catalysts operate synergistically in activating oxygen and maneuvering surface oxygenated species. The exploration of atomic-scale chemical/structural ordering and coordination in correlation with the catalytic oxidation properties based on findings from ex- and in-situ synchrotron X-ray techniques is emphasized; for example, high-energy X-ray diffraction coupled to atomic-pair distribution function and X-ray absorption fine-structure spectroscopic analysis. The understanding of the detailed active sites of the nanoalloys has significant implications for the design of low-cost, active, and durable catalysts for sustainable energy production and environmental processes.

6.
Chepaikin E.G. Oxidative functionalization of alkanes under dioxygen in the presence of homogeneous noble metal catalysts // J. Mol. Catal. A-Chem. 2014. Vol. 385. P. 160–174.

Basic approaches to design of catalytic systems for homogeneous oxidative functionalization of alkanes in the presence of noble metals are overviewed. Special attention was given to catalytic systems for oxidation of C1-C4 alkanes with dioxygen as a green oxidant and to methods for dioxygen activation with reducing agents. The mechanisms of the relevant reactions are considered.

7.
Donazzi A. et al. Synergy of Homogeneous and Heterogeneous Chemistry Probed by In Situ Spatially Resolved Measurements of Temperature and Composition // Angewandte Chemie International Edition. 2011. Vol. 50, № 17. P. 3943–3946.

Ultrafast catalytic processes for converting hydrocarbons at short contact times are characterized by extremely severe operating conditions. In situ sampling and detailed modeling of surface and gas-phase kinetics allowed the elucidation of the complex interplay between heterogeneous and homogenous pyrolytic routes to H2 and CO in the catalytic partial oxidation (CPO) of C3H8.

8.
Ferreira G.K.B. et al. Manganese porphyrin in solution and heterogenized in different materials mediates oxidation of hydrocarbons by iodosylbenzene // Journal of Molecular Catalysis A: Chemical. 2013. Vol. 378. P. 263–272.

We prepd. a free base porphyrin (HP) contg. hydroxy and methoxy groups in the mesophenyl substituents of the porphyrin ring. We then inserted Mn(III) ion into the resulting HP, to obtain MnP. We used silica synthesized by the sol-?gel process to immobilize the MnP in either acidic or basic medium, which afforded the solids MnPA and MnPB, resp. We also conducted the solvothermal Mn(III) ion insertion into HP, which furnished the self-?structured solid MnPS. Because the MnP was catalytically active in homogeneous medium, we investigated the activity of all the prepd. solids as heterogeneous catalysts in the oxidn. of various hydrocarbons. MnPA, MnPB, and MnPS presented similar or higher activity than the homogeneous MnP in the oxidn. of cyclooctene, cyclohexene, cyclohexane and n-?heptane. Concerning alkane oxidn., the heterogeneous catalysts were more selective for the alc. than the MnP in homogeneous soln. Moreover, the solid catalysts favored the oxidn. of linear alkane, with selectivity toward the primary alc. We were able to recover all the solids at the end of the reaction and reuse them.

9.U15097
Fortman G.C. et al. Selective Monooxidation of Light Alkanes Using Chloride and Iodate // J. Am. Chem. Soc. 2014. Vol. 136, № 23. P. 8393–8401.

We describe an efficient system for the direct partial oxidation of methane, ethane, and propane using iodate salts with catalytic amounts of chloride in protic solvents. In HTFA (TFA = trifluoroacetate), >20% methane conversion with >85% selectivity for MeTFA have been achieved. The addition of substoichiometric amounts of chloride is essential, and for methane the conversion increases from <1% in the absence of chloride to >20%. The reaction also proceeds in aqueous HTFA as well as acetic acid to afford methyl acetate. C-13 labeling experiments showed that less than 2% of methane is overoxidized to (CO2)-C-13 at 15% conversion of (CH4)-C-13. The system is selective for higher alkanes: 30% ethane conversion with 98% selectivity for EtTFA and 19% propane conversion that is selective for mixtures of the mono- and difunctionalized TFA esters. Studies of methane conversion using a series of iodine-based reagents [I-2, ICl, IC3, I(TFA)(3), I2O4, I2O5, (IO2)(2)S2O7, (IO)(2)SO4] indicated that the chloride enhancement is not limited to iodate.

10.
Garcia T. et al. The significance of the order of impregnation on the activity of vanadia promoted palladium-alumina catalysts for propane total oxidation // Catalysis Science & Technology. 2011. Vol. 1, № 8. P. 1367–1375.

The increased activity of alumina-supported palladium catalysts promoted with vanadium oxide has been investigated. Three different vanadium promoted Pd/Al(2)O(3) catalysts with the same composition but synthesized employing sequential and co-impregnation were tested for the total oxidation of propane. The order of impregnation was critical to produce high activity catalysts. Vanadium and palladium co-impregnation on the Al(2)O(3) support led to the most active catalyst, whereas the step-wise impregnated catalysts show a catalytic performance similar to or slightly better than unpromoted palladium catalysts. The high activity of the co-impregnated catalysts is related to the particle size and oxidation state of the palladium particles; and to the redox properties of vanadium species. The most active catalyst presents relatively large palladium particles in combination with increased reducibility of vanadium species and a relatively high amount of V(4+) within the bulk of the catalyst and on the surface. STEM shows that, compared to catalysts containing only Pd or V, co-addition of the Pd and V species drastically altered the particle size distribution and morphology of the PdO(x) particles, and simultaneously caused the monolayer dispersion of the VO(x) species to become much patchier in nature. It also showed that the microstructure of the catalysts was similar for the different orders of impregnation, but some differences between the morphology of PdO(x) particles were observed.

11.
Gunsalus N.J. et al. Discrete Molecular Catalysts for Methane Functionalization // Israel Journal of Chemistry. 2014. Vol. 54, № 10. P. 1467–1480.

The implementation of selective, energy efficient, direct alkane oxidation chemistry could lead to a new paradigm in materials and energy technologies for the 21(st) century that is environmentally and economically superior to current processes. Such processes would allow the vast reserves of natural gas to be directly employed as feedstocks for fuels and chemicals. Molecular catalysts that activate and functionalize the CH bonds of unactivated hydrocarbons are of particular interest, from both a scientific and economic viewpoint. This results from the unique properties of these engineered materials, which allow them to carry out oxidative hydrocarbon functionalization, with high atom and energy efficiency, under relatively mild conditions. Despite the large body of work on the activation of CH bonds over the last three decades, relatively few catalyst systems based on this approach present a viable route to functionalize hydrocarbons. This dilemma is largely due to the large gaps in our fundamental knowledge to allow rational design of such catalysts. Addressed in this paper are some of the key challenges and approaches to the de novo design of alkane functionalization molecular catalysts based on the CH activation reaction, with an emphasis on our own research.

12.
Hashiguchi B.G. et al. Designing Catalysts for Functionalization of Unactivated C-H Bonds Based on the CH Activation Reaction // Accounts Chem. Res. 2012. Vol. 45, № 6. P. 885–898.

In an effort to augment or displace petroleum as a source of liquid fuels and chemicals, researchers are seeking lower cost technologies that convert natural gas (largely methane) to products such as methanol. Current methane to methanol technologies based on highly optimized, indirect, high-temperature chemistry (>800 degrees C) are prohibitively expensive. A new generation of catalysts is needed to rapidly convert methane and O-2 (ideally as air) directly to methanol (or other liquid hydrocarbons) at lower temperatures (similar to 250 degrees C) and with high selectivity. Our approach is based on the reaction between CH bonds of hydrocarbons (RH) and transition metal complexes, LnM-X, to generate activated LnM-R intermediates while avoiding the formation of free radicals or carbocations. We have focused on the incorporation of this reaction into catalytic cycles by integrating the activation of the CH bond with the functionalization of LnM-R. to generate the desired product and regenerate the LnM-X complex. To avoid free-radical reactions possible with the direct use of O-2, our approach is based on the use of air-recyclable oxidants. In addition, the solvent serves several roles induding protection of the product, generation of highly active catalysts, and in some cases, as the air-regenerable oxidant. We postulate that there could be three distinct classes of catalyst/oxidant/solvent systems. The established electrophilic class combines electron-poor catalysts in acidic solvents that conceptually react by net removal of electrons from the bonding orbitals of the CH bond. The solvent protects the CH3OH by conversion to more electron-poor [CH3OH2](+) or the ester and also increases the electrophilicity of the catalyst by ligand protonation. The nucleophilic class matches electron-rich catalysts with basic solvents and conceptually reacts by net donation of electrons to the antibonding orbitals of the CH bond. In this case, the solvent could protect the CH3OH by deprotonation to the more electron-rich (CH3O](-) and increases the nudeophilicity of the catalysts by ligand deprotonation. The third grouping involves ambiphilic catalysts that can conceptually react with both the HOMO and LUMO of the CH bond and would typically involve neutral reaction solvents. We call this continuum base- or acid-modulated (BAM) catalysis. In this Account, we describe our efforts to design catalysts following these general principles. We have had the most success with designing electrophilic systems, but unfortunately, the essential role of the acidic solvent also led to catalyst inhibition by CH3OH above similar to 1 M. The ambiphilic catalysts reduced this product inhibition but were too slow and inefficient. To date, we have designed new base-assisted CH activation and LnM-R fuctionalization reactions and are working to integrate these into a complete, working catalytic cycle. Although we have yet to design a system that could supplant commercial processes, continued exploration of the BAM catalysis continuum may lead to new systems that will succeed in addressing this valuable goal.

13.U26496
Hashiguchi B.G. et al. Main-Group Compounds Selectively Oxidize Mixtures of Methane, Ethane, and Propane to Alcohol Esters // Science. 2014. Vol. 343, № 6176. P. 1232–1237.

Much of the recent research on homogeneous alkane oxidation has focused on the use of transition metal catalysts. Here, we report that the electrophilic main-group cations thallium(III) and lead(IV) stoichiometrically oxidize methane, ethane, and propane, separately or as a one-pot mixture, to corresponding alcohol esters in trifluoroacetic acid solvent. Esters of methanol, ethanol, ethylene glycol, isopropanol, and propylene glycol are obtained with greater than 95% selectivity in concentrations up to 1.48 molar within 3 hours at 180 degrees C. Experiment and theory support a mechanism involving electrophilic carbon-hydrogen bond activation to generate metal alkyl intermediates. We posit that the comparatively high reactivity of these d(10) main-group cations relative to transition metals stems from facile alkane coordination at vacant sites, enabled by the overall lability of the ligand sphere and the absence of ligand field stabilization energies in systems with filled d-orbitals.

14.
Jaenicke L. Biomimetic Oxidation // Chemie in Unserer Zeit. 2013. Vol. 47, № 2. P. 75–75.

15.
Ji H.-B., Zhou X.-T. Biomimetic Homogeneous Oxidation Catalyzed by Metalloporphyrins with Green Oxidants // Biomimetics Learning from Nature / ed. Mukherjee A. InTech, 2010.

16.
Jiang G., Liu Q., Guo C. Biomimetic Oxidation of Hydrocarbons with Air over Metalloporphyrins // Biomimetic Based Applications / ed. George A. InTech, 2011.

17.
Kipnis M. Gold in CO oxidation and PROX: The role of reaction exothermicity and nanometer-scale particle size // Applied Catalysis B-Environmental. 2014. Vol. 152. P. 38–45.

Gold is a promising catalyst for various processes. There have been extensive studies in catalysis using Au-containing catalysts, but their results are ambiguous, prompting researchers to revise the data available from the literature. In this work, we analyze publications on CO oxidation and PROX (preferential CO oxidation) over various supported gold catalysts, focusing on two important aspects: effect of high exothermicity of the reaction and of nanometer-scale particle of gold. Under certain conditions, exothermicity brings the reaction into the external diffusion control regime, causing the so-called ignition of the catalyst surface. The transition of the reaction to this regime is accompanied by a number of effects (sharp increase in conversion as a result of increasing temperature, CO conversion hysteresis, appearance of a hot spot in the catalyst bed, change in activation energy, and precursor self-activation), which are misinterpreted by researchers sometimes. The behavior of the catalyst in the steady-state external diffusion control regime and on return from this regime is discussed. In the synthesis of gold catalysts by conventional methods (precipitation, deposition precipitation, impregnation), the precursors dried at 100 degrees C have gold mostly in its cationic form. The gold cations turn into Au-0 as the calcination temperature is raised or as the catalyst is kept in a reductive atmosphere. This yields gold metal particles on the support surface. Their size distribution is usually asymmetric, with the maximum shifted to smaller sizes, which is typical of lognormal distribution. A critical review is made of the data concerning the size effect, specifically, the existence of an extremum of catalytic activity as a function of the mean particle size. It is demonstrated that the variation of gold content from one sample to another is often disregarded in the interpretation of these data, while catalytic activity and particle size correlate with gold content.

18.
Kirillov A.M., Kirillova M.V., Pombeiro A.J.L. Multicopper complexes and coordination polymers for mild oxidative functionalization of alkanes // Coordination Chemistry Reviews. 2012. Vol. 256, № 23-24. P. 2741–2759.

Alkanes (main components of natural gas and oil) are rather inert compounds and their functionalization under mild conditions, toward the synthesis of added value organic products, constitutes a challenge to modern chemistry. A promising approach concerns the development of bioinspired metal complex catalysts which, with an appropriate oxidizing agent and under tuned reaction conditions, are capable of converting alkanes into valuable functionalized products. In view of the well recognized biological function of copper, which is present in the active sites of many oxidation enzymes including the multicopper particulate methane monooxygenase (pMMO), the current contribution summarizes recent advances in the oxidative functionalization of alkanes catalyzed by multicopper systems. The main types of polynuclear copper complexes and coordination polymers applied in homogeneous alkane transformations are classified, and the critical analysis of the most efficient catalytic systems in two different reactions is presented. These reactions include the mild oxidation of alkanes (typically cyclohexane as a model substrate) by hydrogen peroxide into alkyl hydroperoxides, alcohols, and ketones, as well as the hydrocarboxylation of gaseous and liquid C-n (n = 2-9) alkanes, by carbon monoxide, water, and potassium peroxodisulfate into the corresponding Cn+1 carboxylic acids. The important effects of various reaction parameters are highlighted and the preferable requirements for a prospective homogeneous Cu-based catalyst in oxidative transformations of alkanes are identified. Emphasis is given on the use of hydrosoluble copper catalysts with an N,O-environment, acid co-catalysts, H2O/MeCN mixed solvent, under mild reaction conditions.

19.
Kirillov A.M., Shul’pin G.B. Pyrazinecarboxylic acid and analogs: Highly efficient co-catalysts in the metal-complex-catalyzed oxidation of organic compounds // Coordination Chemistry Reviews. 2013. Vol. 257, № 3-4. P. 732–754.

The development of new metal complex catalysts and efficient protocols for the mild and selective oxidation of alkanes, arenes, olefins, alcohols, and other organic substrates is a challenging topic in areas of homogeneous catalysis, coordination, and organic chemistry. In these oxidation reactions, the activity of many metal complex catalysts is dramatically improved upon addition of certain co-catalysts or promoters, which can also act as ligands in simple catalytic systems generated in situ. Given the fact that 2-pyrazinecarboxylic acid (Hpca) and analogous heteroaromatic acids such as 2,3-pyrazinedicarboxylic (H(2)pdca), picolinic (Hpic), and dipicolinic (H(2)dipic) acids are remarkably efficient and versatile co-catalysts in a high diversity of oxidation systems, the present review summarizes the state-of-the-art knowledge in this field. In particular, this contribution focuses on the use of Hpca as the most active co-catalyst and describes its coordination chemistry with regard to the oxidative transformations of various organic substrates, providing an overview of isolated vanadium, iron, and some other transition metal complexes derived from Hpca. The review also summarizes the applications of Hpca-assisted and related systems in the oxidation of various organic substrates by different oxidants, and highlights the main selectivity, kinetic, and mechanistic features of these oxidative transformations. The paper covers the application of catalytic systems wherein Hpca, H(2)pdca, Hpic, and H(2)dipic are used either as co-catalysts (additives) or as ligands within a metal complex catalyst. A special emphasis has been made on the oxidation of alkanes as very inert substrates, and the use of simple and highly efficient [VO3](-)/Hpca/H2O2 system. The multifaceted roles of Hpca and analogous co-catalysts have been identified and the analysis of main mechanistic pathways and possible intermediates has been performed.

20.
Konnick M.M. et al. A Mechanistic Change Results in 100 Times Faster CH Functionalization for Ethane versus Methane by a Homogeneous Pt Catalyst // J. Am. Chem. Soc. 2014. Vol. 136, № 28. P. 10085–10094.

The selective, oxidative functionalization of ethane, a significant component of shale gas, to products such as ethylene or ethanol at low temperatures and pressures remains a significant challenge. Herein we report that ethane is efficiently and selectively functionalized to the ethanol ester of H2SO4, ethyl bisulfate (EtOSO3H) as the initial product, with the Pt-II "Periana-Catalytica" catalyst in 98% sulfuric acid. A subsequent organic reaction selectively generates isethionic acid bisulfate ester (HO3S-CH2-CH2-OSO3H, ITA). In contrast to the modest 3-5 times faster rate typically observed in electrophilic CH activation of higher alkanes, ethane CH functionalization was found to be 100 times faster than that of methane. Experiment and quantum-mechanical calculations reveal that this unexpectedly large increase in rate is the result of a fundamentally different catalytic cycle in which ethane CH activation (and not platinum oxidation as for methane) is now turnover limiting. Facile Pt'-Et functionalization was determined to occur via a low energy,beta-hydride elimination pathway (which is not available for methane) to generate ethylene and a Pt-II-hydride, which is then rapidly oxidized by H2SO4 to regenerate Pt-II-X2. A rapid, non-Pt-catalyzed reaction of formed ethylene with the hot, concentrated H2SO4 solvent cleanly generate EtOSO3H as the initial product, which further reacts with the H2SO4 solvent to generate ITA.

21.
Labinger J.A. Alkane Functionalization via Electrophilic Activation // Alkane C-H Activation by Single-Site Metal Catalysis / ed. Perez P.J. Dordrecht: Springer Netherlands, 2012. Vol. 38. P. 17–71.

22.
Lanucara F., Crestoni M.E. Biomimetic Oxidation Reactions of a Naked Manganese(V)-Oxo Porphyrin Complex // Chemistry-a European Journal. 2011. Vol. 17, № 43. P. 12092–12100.

The intrinsic reactivity of a manganese(V)-oxo porphyrin complex, a typically fleeting intermediate in catalytic oxidation reactions in solution, has been elucidated in a study focused on its gas-phase ion-chemistry. The naked high-valent Mn(V)-oxo porphyrin intermediate 1 ([(tpfpp)Mn(V)O](+); tpfpp=meso-tetrakis(pentafluorophenyl) porphinato dianion), has been obtained by controlled treatment of [(tpfpp)Mn(III)]Cl (2-Cl) with iodosylbenzene in methanol, delivered in the gas phase by electrospray ionization and assayed by FT-ICR mass spectrometry. A direct kinetic study of the reaction with selected substrates, each containing a heteroatom X (X = S, N, P) including amines, sulfides, and phosphites, was thus performed. Ionic products arising from electron transfer (ET), hydride transfer (HT), oxygen-atom transfer (OAT), and formal addition (Add) may be observed, with a predominance of two-electron processes, whereas the product of hydrogen-atom transfer (HAT), [(tpfpp)Mn(IV)OH](+), is never detected. A thermochemical threshold for the formation of the product radical cation allows an evaluation of the electrontransfer ability of a Mn(V)-oxo complex, yielding a lower limit of 7.85 eV for the ionization energy of gaseous [(tpfpp)Mn(IV)O]. Linear free-energy analyses of the reactions of para-substituted N, N-dimethylanilines and thioanisoles indicate that a considerable amount of positive charge is developed on the heteroatom in the oxidation transition state. Substrates endowed with different heteroatoms, but similar ionization energy display a comparable reaction efficiency, consistent with a mechanism initiated by ET. For the first time, the kinetic acidity of putative hydroxo intermediates playing a role in catalytic oxidations, [(tpfpp)Fe(IV)OH](+) and [(tpfpp)Mn(IV)OH](+), has been investigated with selected reference bases, revealing a comparatively higher basicity for the ferryl, [(tpfpp)Fe(IV)O], with respect to the manganyl, [(tpfpp)Mn(IV)O], unit. Finally, the neat association reaction of 2 has been studied with various ligands showing that harder ligands are more strongly bound.

23.
Largeron M., Fleury M.-B. Bioinspired Oxidation Catalysts // Science. 2013. Vol. 339, № 6115. P. 43–44.

24.
Li H., Lia B.-J., Shi Z.-J. Challenge and progress: palladium-catalyzed sp(3) C-H activation // Catalysis Science & Technology. 2011. Vol. 1, № 2. P. 191–206.

Palladium-catalysis has been broadly applied to sp(2) C-H activation. Recently, palladium-catalyzed sp(3) C-H activation has also been considered as an important strategy to construct synthetically useful C-C/C-X bonds. Allylic sp(3) C-H bonds can be successfully activated by Pd(II) species to produce eta(3)-coordinated palladium species for further transformations, while activation of general sp(3) C-H bonds mainly proceeds through directed pathways with the assistance of proper directing groups or initiated by oxidative addition. Various catalytic mechanisms were extensively investigated through either Pd(II)/Pd(0), Pd(II)/Pd(IV) or Pd(0)/Pd(II) catalytic cycles. The challenges faced in this area have also been addressed in this perspective article.

25.
Liu H. et al. Noble metal-based composite nanomaterials fabricated via solution-based approaches // Journal of Materials Chemistry A. 2015. Vol. 3, № 7. P. 3182–3223.

One of the key frontiers in nanomaterial fabrication is the integration of different materials within the same structure to increase functionality. In particular, interactions between nanoscale materials with distinctly different physical and chemical properties can greatly improve the overall application performance of the nanocomposites and can even generate new synergetic properties. Within the last decade, the development of wet-chemistry methods has led to the development of research in to composite nanomaterials. The efforts of many leading research groups have led to a rich variety of composite nanomaterials. However, the design and synthesis of composite nanomaterials with controlled properties remain a significant challenge. We devote this review for summarizing the solution-based methods used for the preparation of noble metal-based nanocomposites, their characterization and their potential applications in diverse areas to provide readers with a systematic and coherent overview of the field.

26.
Mac Leod T.C.O. et al. Mild oxidation of alkanes and toluene by tert-butylhydroperoxide catalyzed by an homogeneous and immobilized Mn(salen) complex // Applied Catalysis A: General. 2010. Vol. 372, № 2. P. 191–198.

Mild oxidations with t-BuOOH of linear (n-pentane, n-hexane, n-heptane and n-octane) and cyclic (1,2-dimethylcyclohexane) alkanes to the corresponding secondary alcohols and ketones, as well as of toluene to benzaldehyde, catalyzed by homogeneous and immobilized Mn(salen) (on a polydimethylsiloxane (PDMS) based membrane, Mn(salen)-PM) systems [Mn(salen) = {(R,R)-N,N-bis(3,5-di-tert-butylsalicylidenato)-1,2-cyclohexanediamine(2-)}chloro manganese(III)], have been studied. These oxidations are markedly promoted by the addition of various acids, namely nitric, pyrazine-2-carboxylic, acetic, benzoic and oxalic acids. Regio- and stereoselectivity parameters are dependent on the immobilization of the catalyst on the support and on the type of acid promoter, and correlate with the sorption values of alkane substrates on the PDMS membrane. The oxidation was shown to proceed with participation of t-BuOradical dot and alkylperoxyl (ROOradical dot) radicals. The toluene oxidation systems feature a high selectivity towards the formation of benzaldehyde (mainly in the case of the supported catalyst) and remarkably high catalyst turnover numbers (up to 1.7 ? 103).

27.
Martinez-Arias A. et al. Characterization of Active Sites/Entities and Redox/Catalytic Correlations in Copper-Ceria-Based Catalysts for Preferential Oxidation of CO in H-2-Rich Streams // Catalysts. 2013. Vol. 3, № 2. P. 378–400.

This article reviews work done at authors' laboratories about catalysts based on combinations between copper and ceria for preferential oxidation of CO in H-2-rich streams (CO-PROX). The main focus of this review is the characterization of active sites for the process on the basis of spectroscopic analysis of the systems under reaction conditions (operando techniques). On such a basis, it is exposed the state of the art in this field in connection with results obtained in other laboratories.

28.
Meier G., Braun T. Hydrogenation of a Rhodium Peroxido Complex by Formate Derivatives: Mechanistic Studies and the Catalytic Formation of H2O2 from O-2 // Angew. Chem.-Int. Edit. 2012. Vol. 51, № 50. P. 12564–12569.

29.
Mishra G.S., Kumar A. Immobilized Pd complexes over MCM-41 as supported catalysts for effective reformation of hydrocarbons // Catalysis Science & Technology. 2011. Vol. 1, № 7. P. 1224–1231.

The ethylthio alkane ligands i.e. di(ethylthio) ethane, I, and di(ethylthio) propane, II, have been used for the synthesis of Pd(II) complexes. These complexes were covalently anchored to the modified MCM-41 matrix as supported hybrid catalysts (MCM-41/I as Pd-I and MCM-41/II as Pd-II). Remarkable catalytic effects were observed when these supported catalysts act in n-hexane and n-heptane reformation reactions in the presence of H-2. Catalyst Pd-I provided the high TONs of 2325 with 91% selectivity for n-hexane and high TONs of 2145 with 88% selectivity for n-heptane under optimized and relatively mild conditions. A carbenium-based mechanism has been included to explain the product formation. TGA analysis indicates that these catalysts were thermally stable up to the reaction temperature and recyclable for further utilization.

30.
Mishra G.S., Kumar A., Tavares P.B. Single site anchored novel Cu(II) catalysts for selective liquid-gas phase O-2 oxidation of n-alkanes // Journal of Molecular Catalysis a-Chemical. 2012. Vol. 357. P. 125–132.

The pentacoordinate schiff-base trialkoxysilane Cu(II) complexes, i.e. Cu[Sal(PMeOSi)DPTA], (III-a) and Cu[Cl-Sal(PMeOSi)DPTA], (III-b) were synthesized and covalently anchored on SiO2 and Al2O3 matrixes as supported hybrid catalysts (i.e. III-a/SiO2 as Catal.-1, III-b/SiO2 as Catal.-2, III-a/Al2O3 as Catal.-3 and III-b/Al2O3 as Catal.-4). The characterization of supported Cu(II) complexes were performed with SEM-EDX, TGA,ICP, FT-IR and EPR analysis. Catalytic tests were conducted in the oxidation (O-2) of n-alkanes under relatively mild conditions, in a batch rocking type reactor. Remarkable high catalytic TONs, from 1468 up to 2422, were observed. Catal.-2 provided the best overall yield, 25.2% with 92% selectivity for n-hexane and 20.1% with 75% selectivity for n-heptane. A 20% improvement in the yields was obtained with PCA as co-catalyst. The impact of both C- and O- centred radical traps were also assessed in order to establish a radical mechanism.

31.
Molinari R. et al. Membrane contactors operating in mild conditions for liquid phase partial oxidation of methane // Journal of Membrane Science. 2011. Vol. 366, № 1-2. P. 139–147.

An integrated catalytic membrane system for liquid phase partial oxidation of light hydrocarbons such as methane in mild operating conditions has been studied and tested. On the basis of tests on methane solubility and chemical stability of some candidate solvents, water was chosen as the reaction medium. The low methane solubility in water was enhanced by working under moderate pressure (0.4 MPa) and then integrating the catalytic system with a gas-liquid membrane contactor. Catalytic tests, using the Fenton reagent (Fe(2+), H(2)O(2)), were carried out in a batch system to study the influence of some operating conditions on system performance. Best results were obtained under the following operating conditions: [Fe(2+)] = 2.70 mmol L(-1); [H(2)O(2)] =

32.
Munz D. et al. ortho-Phenylene bridged palladium bis-N-heterocyclic carbene complexes: synthesis, structure and catalysis // Dalton Trans. 2013. Vol. 42, № 20. P. 7297–7304.

33.
Munz D., Strassner T. Catalytic Hydrocarbon Oxidation by Palladium-bis-NHC-Complexes // Top. Catal. 2014. Vol. 57, № 17-20. P. 1372–1376.

We report density functional theory studies on the CH-activation and functionalization of methane and propane by palladium (II) complexes with chelating bis(NHC) ligands. The combined experimental and computational results indicate that a palladium tetrahalogenido complex is the resting state of the reaction, while the CH-activation constitutes the rate-determining step of the catalytic cycle.

34.
Munz D., Strassner T. On the Mechanism of the Palladium Bis(NHC) Complex Catalyzed CH Functionalization of Propane: Experiment and DFT Calculations // Chem.-Eur. J. 2014. Vol. 20, № 45. P. 14872–14879.

We report a detailed mechanistic study on the CH functionalization of alkanes by palladium complexes with chelating bis(N-heterocyclic carbene) (NHC) complexes. The experimental results are complemented by detailed DFT calculations, which allow us to rationalize the regioselectivity and the catalytic activity. The study includes a library of catalysts with different electronic and steric properties, kinetic data, and isotope effects. The combined experimental and computational results favor a mechanism involving organometallic palladium(IV) intermediates. Furthermore, it is shown that at high halide loadings a different mechanism is operative.

35.
O’Reilly M.E. et al. Reductive functionalization of a rhodium(III)-methyl bond by electronic modification of the supporting ligand // Dalton Trans. 2014. Vol. 43, № 22. P. 8273–8281.

Net reductive elimination (RE) of MeX (X = halide or pseudo-halide: Cl-, CF3CO2-, HSO4-, OH-) is an important step during Pt-catalyzed hydrocarbon functionalization. Developing Rh(I/III)-based catalysts for alkane functionalization is an attractive alternative to Pt-based systems, but very few examples of RE of alkyl halides and/or pseudo-halides from Rh-III complexes have been reported. Here, we compare the influence of the ligand donor strength on the thermodynamic potentials for oxidative addition and reductive functionalization using [(t)Bu(3)terpy]RhCl (1) {(t)Bu(3)terpy = 4,4',4 ''-tri-tert-butylpyridine} and [(NO2)(3)terpy]RhCl (2) {(NO2)(3)terpy = 4,4',4 ''-trinitroterpyridine}. Complex 1 oxidatively adds MeX {X = I-, Cl-, CF3CO2- (TFA(-))} to afford [(t)Bu(3)terpy]RhMe(Cl)(X) {X = I- (3), Cl- (4), TFA(-) (5)}. By having three electron-withdrawing NO2 groups, complex 2 does not react with MeCl or MeTFA, but reacts with MeI to yield [(NO2)(3)terpy]RhMe(Cl)(I) (6). Heating 6 expels MeCl along with a small quantity of MeI. Repeating this experiment but with excess [Bu4N]Cl exclusively yields MeCl, while adding [Bu4N]TFA yields a mixture of MeTFA and MeCl. In contrast, 3 does not reductively eliminate MeX under similar conditions. DFT calculations successfully predict the reaction outcome by complexes 1 and 2. Calorimetric measurements of [(t)Bu(3)terpy]RhI (7) and [(t)Bu(3)terpy]RhMe(I)(2) (8) were used to corroborate computational models. Finally, the mechanism of MeCl RE from 6 was investigated via DFT calculations, which supports a nucleophilic attack by either I- or Cl- on the Rh-CH3 bond of a five-coordinate Rh complex.

36.
Papafotiou F. et al. Covalent attachment of a biomimetic Ru-(terpy)(bpy) complex on silica surface: Catalytic potential // Polyhedron. 2013. Vol. 52. P. 634–638.

The Ru-containing modified silica [Ru-II(terpy)(4'Mebpy/4CONH(CH2)(3)SiO3/2)Cl](+)m center dot zSiO(2) has been prepared by covalent attachment on silica surface of biomimetic [Ru-II(terpy)(4-CO2H-4'-Mebpy)Cl](+). complex through the formation of a pseudo-peptide bond. The catalytic ability of bio-derived silica for alkene oxidation with (HOOBu)-Bu-t has been evaluated exhibiting significant efficiency and, in some cases, showing increased activity compared vs. the corresponding 'net' [Ru-II(terpy)(4-CO2H-4'-Mebpy)Cl](+) complex. The data supported that the covalently attached ruthenium complex preserves the catalytic behaviour of the 'net' ruthenium complex indicating that the presented grafting process was successful.

37.
Prat I. et al. The Mechanism of Stereospecific CH Oxidation by Fe(Pytacn) Complexes: Bioinspired Non-Heme Iron Catalysts Containing cis-Labile Exchangeable Sites // Chemistry-a European Journal. 2013. Vol. 19, № 21. P. 6724–6738.

A detailed mechanistic study of the hydroxylation of alkane CH bonds using H2O2 by a family of mononuclear non heme iron catalysts with the formula [FeII(CF3SO3)2(L)] is described, in which L is a tetradentate ligand containing a triazacyclononane tripod and a pyridine ring bearing different substituents at the and positions, which tune the electronic or steric properties of the corresponding iron complexes. Two inequivalent cis-labile exchangeable sites, occupied by triflate ions, complete the octahedral iron coordination sphere. The CH hydroxylation mediated by this family of complexes takes place with retention of configuration. Oxygen atoms from water are incorporated into hydroxylated products and the extent of this incorporation depends in a systematic manner on the nature of the catalyst, and the substrate. Mechanistic probes and isotopic analyses, in combination with detailed density functional theory (DFT) calculations, provide strong evidence that CH hydroxylation is performed by highly electrophilic [FeV(O)(OH)L] species through a concerted asynchronous mechanism, involving homolytic breakage of the CH bond, followed by rebound of the hydroxyl ligand. The [FeV(O)(OH)L] species can exist in two tautomeric forms, differing in the position of oxo and hydroxide ligands. Isotopic-labeling analysis shows that the relative reactivities of the two tautomeric forms are sensitively affected by the substituent of the pyridine, and this reactivity behavior is rationalized by computational methods.

38.U60637
Qiang L., CanCheng G. Theoretical studies and industrial applications of oxidative activation of inert C-H bond by metalloporphyrin-based biomimetic catalysis // Science China-Chemistry. 2012. Vol. 55, № 10. P. 2036–2053.

High costs and low catalytic efficiency of metalloporphyrins, which are an analogue of cytochrome P450 enzyme, are the bottlenecks in the industrialization of biomimetic hydrocarbon oxidation reactions. The basic principle and research technique of physical organic chemistry were applied to the process of biomimetic oxidation of hydrocarbon catalyzed by metalloporphyrins. This biomimetic technology could be adapted to bulk chemicals production by developing the new methods for efficient scale-up synthesis of metalloporphyrins, new pathways for molecular oxygen activation on an industrial scale and new approaches to elevate the catalytic efficiency of metalloporphyrins. This review mainly focuses on research carried out in our group.

39.
Rosales M. et al. Kinetics and Mechanisms of Homogeneous Catalytic Reactions. Part 12. Hydroalcoxycarbonylation of 1-Hexene Using Palladium/Triphenylphosphine Systems as Catalyst Precursors // Catalysis Letters. 2014. Vol. 144, № 10. P. 1717–1727.

Systems prepared in situ by addition of n equivalents of triphenylphosphine to palladium dichloride in the presence of m equivalents of para-toluenesulfonic acid (TSA), PdCl2/nPPh(3)/mTSA (n and m varying between 2 and 10), were used as precatalysts for the olefin carbonylation (1-hexene, cyclohexene and styrene) with alcohols (MeOH, EtOH, n-PrOH and i-PrOH) to generate the corresponding esters (hydroalcoxycarbonylation), under mild reaction conditions. For 1-hexene carbonylation in presence of methanol (1-hexene hydromethoxycarbonylation), the most active system was PdCl2/6PPh(3)/5TSA at P(CO) = 50 atm and T = 125 degrees C, which was also active for the hydromethoxycarbonylation of other olefins (1-hexene > styrene > cyclohexene). This system was regioselective towards the linear product for 1-hexene and towards the branched product for styrene. A kinetic study of 1-hexene hydromethoxycarbonylation catalyzed by PdCl2/6PPh(3)/5TSA showed that the initial reaction rate (r (o)) was first order on Pd and MeOH concentrations and fractional order with respect to CO concentration; for olefin concentration was found a saturation curve. These kinetic results, together with coordination chemistry and computational DFT studies, allow us to propose a catalytic cycle involving species of the type [Pd(H)(L)(PPh3)(2)](+n) (L = Cl, n = 0; L = CO, MeOH, olefin and PPh3, n = 1) as the catalytically active species and three sequential reactions: (1) olefin insertion into the Pd-H bond to yield Pd-alkyl species, (2) CO insertion into the Pd-C bond to generate Pd-acyl intermediates, and (3) the methanolysis of Pd-acyl species to produce the corresponding methyl esters, regenerate the active species and restart the cycle; the last reaction is considered the rate-determining step (rds) of the mechanism.

40.
Senanayake S.D., Stacchiola D., Rodriguez J.A. Unique Properties of Ceria Nanoparticles Supported on Metals: Novel Inverse Ceria/Copper Catalysts for CO Oxidation and the Water-Gas Shift Reaction // Accounts of Chemical Research. 2013. Vol. 46, № 8. P. 1702–1711.

Oxides play a central role in important industrial processes, including applications such as the production of renewable energy, remediation of environmental pollutants, and the synthesis of fine chemicals. They were originally used as catalyst supports and were thought to be chemically inert, but now they are used to build catalysts tailored toward improved selectivity and activity in chemical reactions. Many studies have compared the morphological, electronic, and chemical properties of oxide materials with those of unoxidized metals. Researchers know much less about the properties of oxides at the nanoscale, which display distinct behavior from their bulk counterparts. More is known about metal nanoparticles. Inverse-model catalysts, composed of oxide nanoparticles supported on metal or oxide substrates instead of the reverse (oxides supporting metal nanoparticles), are excellent tools for systematically testing the properties of novel catalytic oxide materials. Inverse models are prepared in situ and can be studied with a variety of surface science tools (e.g. scanning tunneling microscopy, X-ray photoemission spectroscopy, ultraviolet photoemission spectroscopy, low-energy electron microscopy) and theoretical tools (e.g. density functional theory). Meanwhile, their catalytic activity can be tested simultaneously in a reactor. This approach makes it possible to identify specific functions or structures that affect catalyst performance or reaction selectivity. Insights gained from these tests help to tailor powder systems, with the primary objective of rational design (experimental and theoretical) of catalysts for specific chemical reactions. This Account describes the properties of inverse catalysts composed of CeOx nanoparticles supported on Cu(111) or CuOx/Cu(111) as determined through the methods described above. Ceria is an important material for redox chemistry because of its interchangeable oxidation stabs (Ce4+ and Ce3+). Cu(111), meanwhile, is a standard catalyst for reactions such as.

41.
Shen D. et al. Efficient Benzylic and Aliphatic C-H Oxidation with Selectivity for Methylenic Sites Catalyzed by a Bioinspired Manganese Complex // Organic Letters. 2014. Vol. 16, № 4. P. 1108–1111.

A benzimidazole-based nonheme manganese complex efficiently catalyzes benzylic, aliphatic C-H as well as tertiary C-H oxidation with hydrogen peroxide as the oxidant in the presence of acetic acid as additive. O-18 labeling experiments suggest the reaction may proceed via a high-valent manganese-oxo intermediate.

42.
Shul’pin G.B. C-H functionalization: thoroughly tuning ligands at a metal ion, a chemist can greatly enhance catalyst’s activity and selectivity // Dalton Trans. 2013. Vol. 42, № 36. P. 12794–12818.

This brief essay consists of a few "exciting stories" devoted to relations within a metal-complex catalyst between a metal ion and a coordinated ligand. When, as in the case of a human couple, the rapport of the partners is cordial and a love cements these relations, a chemist finds an ideal married couple, in other words he obtains a catalyst of choice which allows him to functionalize C-H bonds very efficiently and selectively. Examples of such lucky marriages in the catalytic world of ions and ligands are discussed here. Activity of the catalyst is characterized by turnover number (TON) or turnover frequency (TOF) as well as by yield of a target product. Introducing a chelating N,N- or N,O-ligand to the catalyst molecule (this can be an iron or manganese derivative) sharply enhances its activity. However, the activity of vanadium derivatives (with additionally added to the solution pyrazinecarboxylic acid, PCA) as well as of various osmium complexes does not dramatically depend on the nature of ligands surrounding metal ions. Complexes of these metals are very efficient catalysts in oxidations with H2O2. Osmium derivatives are record-holders exhibiting extremely high TONs whereas vanadium complexes are on the second position. Finally, elegant examples of alkane functionalization on the ions of non-transition metals (aluminium, gallium etc.) are described when one ligand within the metal complex (namely, hydroperoxyl ligand HOO-) helps other ligand of this complex (H2O2 molecule coordinated to the metal) to disintegrate into two species, generating very reactive hydroxyl radical. Hydrogen peroxide molecule, even ligated to the metal ion, is perfectly stable without the assistance of the neighboring HOO- ligand. This ligand can be easily oxidized donating an electron to its partner ligand (H2O2). In an analogous case, when the central ion in the catalyst is a transition metal, this ion changing its oxidation state can donate an electron to the coordinated H2O2 fragment. This provokes the O-O bond rupture in the hydrogen peroxide molecule as is assumed for the role of Fe2+ ions in the Fenton system.

43.
Tordin E. et al. Synthesis and characterisation of cobalt, nickel and copper complexes with tripodal 4N ligands as novel catalysts for the homogeneous partial oxidation of alkanes // Inorganica Chimica Acta. 2013. Vol. 402. P. 90–96.

Four new compds. [M(L)?(CH3COO)?]?[PF6]?, where L is a tetradentate tripodal ligand such as tris[2-?(dimethylamino)?ethyl]?amine (L1) or (2-?aminoethyl)?bis(2-?pyridylmethyl)?amine (L2) and M is Co(II)?, Ni(II) or Cu(II)?, were prepd. employing a simple two-?step synthesis. The compds. were characterized by elemental anal., mass spectroscopy, IR spectroscopy and x-?ray diffraction. The catalytic properties of the derivs. contg. the aliph. ligand L1 were studied in particular toward the oxidn. of cyclohexane and adamantane in the presence of the sacrificial oxidant m-?CPBA (meta-?chloroperbenzoic acid)?. Good TONs and selectivity were detd. for the Co and Ni compds.

44.
Vanelderen P. et al. Cu-ZSM-5: A biomimetic inorganic model for methane oxidation // Journal of Catalysis. 2011. Vol. 284, № 2. P. 157–164.

The present work highlights recent advances in elucidating the methane oxidation mechanism of the inorganic Cu-ZSM-5 biomimic and in identifying the reactive intermediates that are involved. Such molecular understanding is important in view of upgrading abundantly available methane, but also to comprehend the working mechanism of genuine Cu-containing oxidation enzymes.

45.
Vinogradov M.M. et al. Alkane oxidation with peroxides catalyzed by cage-like copper(II) silsesquioxanes // New J. Chem. 2015. Vol. 39, № 1. P. 187–199.

Isomeric cage-like tetracopper(II) silsesquioxane complexes [(PhSiO1.5)(12)(CuO)(4)(NaO0.5)(4)] (1a), [(PhSiO1.5)(6)(CuO)(4)(NaO05)(4)(PhSiO15)(6)] (1b) and binuclear complex [(PhSiO1.5)(10)(CuO)(2)(NaO0.5)(2)] (2) have been studied by various methods. These compounds can be considered as models of some multinuclear copper-containing enzymes. Compounds 1a and 2 are good pre-catalysts for the alkane oxygenation with hydrogen peroxide in air in an acetonitrile solution. Thus, the 1a-catalyzed reaction with cyclohexane at 60 degrees C gave mainly cyclohexyl hydroperoxide in 17% yield (turnover number, TON, was 190 after 230 min and initial turnover frequency, TOP, was 100 h(-1)). The alkyl hydroperoxide partly decomposes in the course of the reaction to afford the corresponding ketone and alcohol. The effective activation energy for the cyclohexane oxygenation catalyzed by compounds 1a and 2 is 16 +/- 2 and 17 +/- 2 kcal mol(-l), respectively. Selectivity parameters measured in the oxidation of linear and branched alkanes and the kinetic analysis revealed that the oxidizing species in the reaction is the hydroxyl radical. The analysis of the dependence of the initial reaction rate on the initial concentration of cyclohexane led to a conclusion that hydroxyl radicals attack the cyclohexane molecules in proximity to the copper reaction centers. The oxidations of saturated hydrocarbons with tert-butylhydroperoxide (TBHP) catalyzed by complexes 1a and 2 exhibit unusual selectivity parameters which are due to the steric hindrance created by bulky silsesquioxane ligands surrounding copper reactive centers. Thus, the methylene groups in n-octane have different reactivities: the regioselectivity parameter for the oxidation with TBHP catalyzed by 1a is 1:10.5: 8 :7. Furthermore, in the oxidation of methylcyclohexane the position 2 relative to the methyl group of this substrate is noticeably less reactive than the corresponding positions 3 and 4. Finally, the oxidation of trans-1,2-dimethylcyclohexane with TBHP catalyzed by complexes 1a and 2 proceeds stereoselectively with the inversion of configuration. The 1a-catalyzed reaction of cyclohexane with (H2O2)-O-16 in an atmosphere of O-18(2) gives cyclohexyl hydroperoxide containing up to 50% of O-18. The small amount of cyclohexanone, produced along with cyclohexyl hydroperoxide, is O-18-free and is generated apparently via a mechanism which does not include hydroxyl radicals and incorporation of molecular oxygen from the atmosphere.

46.
Wang J. et al. A Review on the Pd-Based Three-Way Catalyst // Catalysis Reviews-Science and Engineering. 2015. Vol. 57, № 1. P. 79–144.

The application of Pd in three-way catalyst represents a significant technology breakthrough for the removal of pollutants from gasoline powered vehicle exhaust gas. Pd shows superior catalytic activity for hydrocarbon (HCs) oxidation and thermal stability to the conventional Pt/Rh catalyst. However, Pd catalysts are more susceptible to chemical poisoning. This work summarizes the progress of the Pd-based three-way catalyst and its related technologies. The state of Pd in the reaction, the support and oxygen storage material, the promoters, and preparation methods on the catalytic performance are reviewed. The process and catalyst configurations, e.g., close-couple (CCC), dual bricks, layered, and zone-coated catalysts, are described and compared. The advances in the understanding of the reaction and deactivation mechanisms in the three-way catalysis systems are also discussed.

47.
Widmann D., Behm R.J. Activation of Molecular Oxygen and the Nature of the Active Oxygen Species for CO Oxidation on Oxide Supported Au Catalysts // Accounts of Chemical Research. 2014. Vol. 47, № 3. P. 740–749.

Although highly dispersed Au catalysts with Au nanoparticles (NPs) of a few nanometers in diameter are well-known for their high catalytic activity for several oxidation and reduction reactions already at rather low temperatures for almost 30 years, central aspects of the reaction mechanism are still unresolved. While most studies focused on the active site, the active Au species, and the effect of the support material, the most crucial step during oxidation reactions, the activation of molecular oxygen and the nature of the resulting active oxygen species (O-act), received more attention just recently. This is topic of this Account, which focuses on the formation, location, and nature of the O-act species present on metal oxide supported Au catalysts under typical reaction conditions, at room temperature and above. It is mainly based on quantitative temporal analysis of products (TAP) reactor measurements, which different from most spectroscopic techniques are able to detect and quantify these species even at the extremely low concentrations present under realistic reaction conditions. Different types of pulse experiments were performed, during which the highly dispersed, realistic powder catalysts are exposed to very low amounts of reactants, CO and/or O-2, in order to form and reactively remove O-act species and gain information on their formation, nature, and the active site for O-act formation. Our investigations have shown that the active oxygen species for CO oxidation on Au/TiO2 for reaction at 80 degrees C and higher is a highly stable atomic species, which at 80 degrees C is formed only at the perimeter of the Au oxide interface and whose reactive removal by CO is activated, but not its formation. From these findings, it is concluded that surface lattice oxygen represents the O-act species for the CO oxidation. Accordingly, the CO oxidation proceeds via a Au-assisted Mars-van Krevelen mechanism, during which surface lattice oxygen close to the Au NPs is removed by reaction with CO, resulting in a partially reduced TiO2 surface, which is subsequently reoxidized by O-2. We demonstrate that this is the dominant reaction pathway for Au catalysts based on reducible metal oxides in general, at typical reaction temperatures, while for less active Au catalysts based on non reducible metal oxides, this reaction pathway is not possible and the remaining activity must arise from another pathway, most probably a Au-only mechanism. At lower reaction temperature, reactive removal of O-act becomes increasingly inhibited, leading to a change In the dominant reaction pathway.

48.
Wu H. et al. Mesoporous Silica Based Gold Catalysts: Novel Synthesis and Application in Catalytic Oxidation of CO and Volatile Organic Compounds (VOCs) // Catalysts. 2013. Vol. 3, № 4. P. 774–793.

Gold nanoparticles, particularly with the particle size of 2-5 nm, have attracted increasing research attention during the past decades due to their surprisingly high activity in CO and volatile organic compounds (VOCs) oxidation at low temperatures. In particular, CO oxidation below room temperature has been extensively studied on gold nanoparticles supported on several oxides (TiO2, Fe2O3, CeO2, etc.). Recently, mesoporous silica materials (such as SBA-15, MCM-41, MCM-48 and HMS) possessing ordered channel structures and suitable pore diameters, large internal surface areas, thermal stabilities and excellent mechanical properties, have been investigated as suitable hosts for gold nanoparticles. In this review we highlight the development of novel mesoporous silica based gold catalysts based on examples, mostly from recently reported results. Several synthesis methods are described herein. In detail we report: the modification of silica with organic functional groups; the one-pot synthesis with the incorporation of both gold and coupling agent containing functionality for the synthesis of mesoporous silica; the use of cationic gold complexes; the synthesis of silica in the presence of gold colloids or the dispersion of gold colloids protected by ligands or polymers onto silica; the modification of silica by other metal oxides; other conventional preparation methods to form mesoporous silica based gold catalysts. The gold based catalysts prepared as such demonstrate good potential for use in oxidation of CO and VOCs at low temperatures. From the wide family of VOCs, the oxidation of methanol and dimethyldisulfide has been addressed in the present review.

49.
Wu X. et al. Total oxidation of propane on Pt/WOx/Al2O3 catalysts by formation of metastable Pt delta+ species interacted with WOx clusters // Journal of Hazardous Materials. 2012. Vol. 225. P. 146–154.

A series of Pt/Al2O3 catalysts with various tungsten oxide loadings were prepared by a stepwise wet impregnation method. The catalysts were characterized by X-ray diffraction, nitrogen physisorption, Raman, UV-vis diffuse reflectance, transmission electron microscopy and infrared spectroscopy of adsorbed probe molecules (CO, NH3 or C3H8). The propane oxidation activity of Pt/Al2O3 catalyst is significantly improved by the addition of tungsten oxide. The tungsten oxide overlayer is presented as monomeric/polymeric WOx clusters and WO3 crystals depending on the loading amount. The most active catalyst occurs at an intermediate surface tungsten density corresponding to the maximum of polytungstate species. The electronic interactions between Pt and WOx clusters lead to the generation of more reducible PO delta+ species which are suggested to be active sites for propane oxidation. Basically, a simple model is proposed involving the initial C-H bond activation at the platinum-tungsten oxide interface.

50.
Xiong H. et al. Low-temperature aqueous-phase reforming of ethanol on bimetallic PdZn catalysts // Catalysis Science & Technology. 2015. Vol. 5, № 1. P. 254–263.

Bimetallic PdZn catalysts supported on carbon black (CB) and carbon nanotubes (CNTs) were found to be selective for CO-free H-2 production from ethanol at low temperature (250 degrees C). On Pd, the H-2 yield was low (similar to 0.3 mol H-2/mol ethanol reacted) and the CH4/CO2 ratio was high (similar to 1.7). Addition of Zn to Pd formed the intermetallic PdZn beta phase (atomic ratio of Zn to Pd is 1) with increased H-2 yield (similar to 1.9 mol H-2/mol ethanol reacted) and CH4/CO2 ratio of <1. The higher H-2 yield and low CH4 formation was related to the improved dehydrogenation activity of the L1(0) PdZn beta phase. The TOF increased with particle size and the CNTs provided the most active and selective catalysts, which may be ascribed to pore-confinement effects. Furthermore, no significant changes in either the supports or the PdZn beta particles was found after aqueous-phase reforming (APR) indicating that the metal nanoparticles and the carbon support are hydrothermally stable in the aqueous phase at elevated temperatures and pressures (>200 degrees C, 65 bar). No CO was detected for all the catalysts performed in aqueous-phase reaction, indicating that both monometallic Pd and bimetallic PdZn catalysts have high water-gas shift activity during APR. However, the yield of H-2 is considerably lower than the theoretical value of 6 H-2 per mole ethanol which is due to the presence of oxygenated products and methane on the PdZn catalysts.

51.
Xu L. et al. Catalytic CO2 reforming of CH4 over Cr-promoted Ni/char for H-2 production // International Journal of Hydrogen Energy. 2014. Vol. 39, № 19. P. 10141–10153.

The objective of the study is to investigate the catalytic performance of Cr-?promoted Ni?/char in CO2 reforming of CH4 at 850°. The char obtained from the pyrolysis of a long-?flame coal at 1000° was used as the support. The catalysts were prepd. by incipient wetness impregnation methods with different metal precursor doping sequence. The characterization of the composite catalysts was evaluated by XRD, XPS, SEM-?EDS, TEM, H2-?TPR, CO2-?TPD, CH4-?TPSR, and CO2-?TPO. The results indicate that the catalyst prepd. by co-?impregnation of Ni and Cr possess higher activity than those by sequential impregnation. The optimal loading of Cr on 5 wt?% Ni?/char is 7.8 wt?%. Moreover, the molar feed ratio of CH4/CO2 has a considerable effect on both the stability and the activity of Cr-?Ni?/char. The main effect of Cr is the great enhance of the adsorption to CO2. It is interesting that the conversions of CH4 and CO2 over Cr-?promoted Ni?/char and Ni?/char decrease initially, following by a steady rise as the reaction proceeds with time-?onstream (TOS)?. In addn., cyclic tests were conducted and no distinct deterioration in the catalytic performance of the catalysts was obsd. On the basis of the obtained results, nickel carbide was speculated to be the active species which was formed during the CO2 reforming of CH4 reaction.

52.
Xue T. et al. Graphene-Supported Hemin as a Highly Active Biomimetic Oxidation Catalyst // Angewandte Chemie-International Edition. 2012. Vol. 51, № 16. P. 3822–3825.

Using synthetic systems to mimic natural enzymes with high catalytic activity and distinct substrate selectivity has been a challenge for the last decades. Hemin, the catalytic center for many protein families including cytochromes, peroxidases, myoglobins, and Hbs, can catalyze a variety of oxidn. reactions like peroxidase enzymes. Here we report the synthesis of a hemin-?graphene conjugate through ?-?? stacking interactions. Spectroscopic characterizations show that hemin retains the catalytic-?active monomer form as in natural enzymes. The catalytic studies show that the hemin-?graphene conjugates can function as effective catalysts in the oxidn. reaction of pyrogallol with exceptionally high catalytic activity (km) and substrate binding affinity (kkat) approaching that of natural enzymes.

53.
Xuereb D., Dzierzak J., Raja R. Biomimetic Single-Site Heterogeneous Catalysts: Design Strategies and Catalytic Potential // Heterogenized Homogeneous Catalysts for Fine Chemicals Production / ed. Barbaro P., Liguori F. Springer Netherlands, 2010. P. 37–63.

Enzymes catalyze the most fundamental reactions in organic chemistry from simple oxidations of straight chain alkanes to complex C–C bond forming reactions with exceptional selectivity. Mimicking the active site of an enzyme by immobilising a well defined amino acid containing transition-metal centre on a robust inorganic framework, provides a powerful catalyst that can be utilized in the production of fine chemicals and complicated drug molecules. Porous aluminosilicates and mesoporous silicas offer suitable supports for single-site bio-derived catalysts. These materials can be created from a range of methodologies and the different strategies used for immobilisation can greatly affect the nature of the active catalyst. The routes by which these catalysts are immobilised have also given the potential to derivatize inorganic structures with amino acids, not just for complexation to metal centres but for use as organocatalysts as well. These metal free bio-derivatized frameworks offer advantages over their homogeneous counterparts and can carry out stereoselective reactions with great effectiveness. Herein, the routes to heterogenizing biomimetic catalysts will be critically assessed and depending on the methods used, suitable active catalysts for use in chemo- and stereoselective transformations can be developed.

54.
Xuereb D.J., Dzierzak J., Raja R. From zeozymes to bio-inspired heterogeneous solids: Evolution of design strategies for sustainable catalysis // Catalysis Today. 2012. Vol. 198, № 1. P. 19–34.

Bio-derived transition-metal complexes containing well-defined and well-characterized active sites can be anchored, in a site-isolated fashion, on to the inner walls of porous inorganic supports, for generating highly active and selective single-site heterogeneous catalysts, which can serve as effective functional mimics of metalloenzymes. The nature of an active site in an enzyme and its ability to harness a particular catalytic function with remarkable selectivity, via its protein tertiary structure, could be judiciously transposed to zeolitic architectures with specifically engineered active sites. Throughout this article we follow the progress and evolution of engineering enzymatic activity and selectivity in synthetically designed catalysts, emphasizing the importance and the advantages of the different synthesis methodologies in immobilizing bio-inspired catalytically active single-sites on varying solid supports. The benefits of such systems are highlighted in terms of their environmental impact by reduction of waste, mitigating the generation of greenhouse gases, boosting the enantioselectivity in heterogeneously catalyzed reactions and in the utilization of 'greener' oxidants; with conclusions drawn on how specific supports affect catalytic properties via modification of the local environment of the active site. The seminal contributions of Dr. Ratnasamy in this field have paved the way for a more fundamental understanding of how the support environment, and its interactions with the active site at a molecular level, can lead to development of structure-activity relationships, which in the future can provide avenues for specifically tailoring catalytic outcomes from a mechanistic standpoint.

55.
Zaltariov M.-F. et al. Tetranuclear Copper(II) Complexes with Macrocyclic and Open-Chain Disiloxane Ligands as Catalyst Precursors for Hydrocarboxylation and Oxidation of Alkanes and 1-Phenylethanol: Tetranuclear Cu(II) Complexes for Hydrocarboxylation and Oxidation // European Journal of Inorganic Chemistry. 2014. Vol. 2014, № 29. P. 4946–4956.

Tetranuclear Copper(II) Complexes with Macrocyclic and Open-Chain Disiloxane Ligands as Catalyst Precursors for Hydrocarboxylation and Oxidation of Alkanes and 1-Phenylethanol: Tetranuclear Cu(II) Complexes for Hydrocarboxylation and Oxidation.

56.009823
Арутюнов В.С., Стрекова Л.Н. КИНЕТИЧЕСКИЕ ОСОБЕННОСТИ И ТЕХНОЛОГИЧЕСКИЕ ПЕРСПЕКТИВЫ ПАРЦИАЛЬНОГО ОКИСЛЕНИЯ ЛЕГКИХ АЛКАНОВ // Химическая физика. 2012. Т. 31. № 8. С. 18.

Обсуждаются характерные особенности кинетики парциального окисления легких алканов основных компонентов природных газов в среднетемпературной (300 < Т < 1200°С) области и перспективы создания на базе этих реакций новых технологических процессов.

57.009823
Басевич В.Я., Беляев А.А., Фролов С.М. МЕХАНИЗМЫ ОКИСЛЕНИЯ И ГОРЕНИЯ НОРМАЛЬНЫХ АЛКАНОВЫХ УГЛЕВОДОРОДОВ: ПЕРЕХОД ОТ С1-С5 К С6Н14 // Химическая физика. 2010. Т. 29. № 7. С. 71-78.

Предложенный ранее алгоритм построения оптимального механизма низко- и высокотемпературного окисления и горения нормальных парафиновых углеводородов с главными процессами, определяющими скорость реакции и образование основных промежуточных и конечных продуктов, применен к н-гексану. Механизм имеет статус неэмпирического детального механизма, так как все элементарные реакции имеют кинетическое обоснование. Механизм характеризуется двумя особенностями: 1) в нем отсутствуют реакции двойного присоединения кислорода (сначала к перекисному радикалу, а затем к его изомеризованной форме) и 2) в нем не рассматриваются в качестве промежуточных частиц изомерные соединения и их производные. Применение алгоритма к н-гексану привело к созданию нового, достаточно компактного кинетического механизма. Проведено сопоставление расчетов с опытными данными. Показано, что новый механизм позволяет правильно описать стадийность низкотемпературного самовоспламенения в виде последовательного появления холодных и голубых пламен.

58.004641
Герзелиев И.М., Усачев Н.Я., Попов А.Ю., Хаджиев С.Н. ПАРЦИАЛЬНОЕ ОКИСЛЕНИЕ НИЗШИХ АЛКАНОВ АКТИВНЫМ РЕШЕТОЧНЫМ КИСЛОРОДОМ ОКСИДНОМЕТАЛЛИЧЕСКИХ СИСТЕМ. СООБЩЕНИЕ 2. СИНТЕЗ КОНТАКТОВ-ОКСИДАНТОВ И ПОЛУЧЕНИЕ СИНТЕЗ-ГАЗА НА ПИЛОТНОЙ УСТАНОВКЕ С ЛИФТ-РЕАКТОРОМ // Нефтехимия. 2012. Т. 52. № 5. С. 339.

Синтезированы и охарактеризованы оксиднометаллические системы с высоким содержанием решеточного кислорода, которые обладают обратимостью окислительно-восстановительных переходов. Приготовлены контакты-оксиданты с использованием активных компонентов разработанных систем. Установлены закономерности взаимодействия метана с циркулирующим микросферическим твердым контактом в сквознопоточном лифт-реакторе. Изучено влияние температуры и времени пребывания углеводородов в реакторе на показатели процесса. Определены оптимальные условия получения синтез-газа, при которых конверсия метана достигает 9599%, отношение H2/CO в продуктах реакции находится в пределах 2.02.2.

59.004641
Герзелиев И.М., Усачев Н.Я., Попов А.Ю., Хаджиев С.Н. ПАРЦИАЛЬНОЕ ОКИСЛЕНИЕ НИЗШИХ АЛКАНОВ АКТИВНЫМ РЕШЕТОЧНЫМ КИСЛОРОДОМ ОКСИДНО-МЕТАЛЛИЧЕСКИХ СИСТЕМ: 1. ЭКСПЕРИМЕНТАЛЬНЫЕ МЕТОДЫ И УСТАНОВКИ // Нефтехимия. 2011. Т. 51. № 6. С. 420.

Проведен краткий обзор процессов производства cинтез-газа одного из наиболее важных и крупнотоннажных продуктов газохимии. Показаны тенденции развития используемых катализаторов и технологий процесса. Одним из наиболее перспективных по технологичности, экономичности и безопасности является процесс, основанный на окислительной конверсии низших алканов в синтез-газ с циркулирующим оксиднометаллическим микросферическим контактом. Предложены экспериментальные методы и установки для изучения контактов и создания технологии процесса. На примере оксиднометаллического микросферического NiCo контакта показано, что предложенные методы и установки дают обширную информацию и применимы в исследованиях по получению синтез-газа в системе с раздельной подачей сырья и окислителя соответственно в зону реакции и регенерации.

60.003757
Коваленко Г.А. и др. СИНТЕЗ КАТАЛИТИЧЕСКОГО ВОЛОКНИСТОГО УГЛЕРОДА НА КАТАЛИЗАТОРЕ Ni/ГРАФИТ И ИССЛЕДОВАНИЕ ПОЛУЧЕННЫХ КОМПОЗИТНЫХ УГЛЕРОД-УГЛЕРОДНЫХ МАТЕРИАЛОВ В МИКРОБНЫХ ТОПЛИВНЫХ ЭЛЕМЕНТАХ // КИНЕТИКА И КАТАЛИЗ. 2011. Т. 52. № 4. С. 574-582.

Проведены систематические исследования композитных углерод-углеродных материалов, полученных путем синтеза каталитического волокнистого углерода (КВУ) на нанесенном катализаторе Ni/графит в процессе пиролиза С3-С4-алканов в присутствии водорода. Исследовано влияние следующих условий на каталитическую активность, выраженную величиной выхода углерода (г КВУ/г Ni), и на характер синтеза КВУ на графитовых стержнях: 1) способы нанесения соединений Ni(II) пропитка и гомогенное осаждение, 2) концентрация компонентов в растворе при нанесении нитрата никеля, мочевины и этилового спирта, 3) условия обработки (окисления) графита перед нанесением соединений Ni(II), 4) температура пиролиза С3-С4-алканов в интервале 400?600°С. Подобраны оптимальные условия получения композитных углерод-углеродных материалов КВУ/графит, перспективных для использования в качестве электродов в микробных топливных элементах (МиТЭ). Изучены электрохимические характеристики МиТЭ, сконструированного с использованием электрода (анода) КВУ/графит и глицеринокисляющих бактерий Gluconobacter oxydans. Методом сканирующей электронной микроскопии исследованы морфология поверхности графита и синтезированного КВУ, а также адсорбированных на аноде бактериальных клеток.

61.001770
КУСТОВ Л.М., КУЧЕРОВ А.В., ФИНАШИНА Е.Д. ОКИСЛИТЕЛЬНОЕ ДЕГИДРИРОВАНИЕ ЛЕГКИХ АЛКАНОВ С2 - С4 В АЛКЕНЫ: ТРАДИЦИОННЫЕ СИСТЕМЫ И СВЧ-КАТАЛИЗ // ЖУРНАЛ ФИЗИЧЕСКОЙ ХИМИИ. 2013. Т. 87. № 3. С. 357.

Рассмотрены каталитические системы для получения алкенов C2 - C4 из соответствующих алканов путем их неокислительного или окислительного дегидрирования. Проанализированы немногочисленные данные по СВЧ-активации этого процесса и возможности и преимущества СВЧ-технологий в сравнении с традиционными подходами.

62.00612X
Лобачев В.Л., Матвиенко Я.В., Рудаков Е.С. АКТИВАЦИОННЫЕ ПАРАМЕТРЫ И МЕХАНИЗМ ОКИСЛЕНИЯ АЛКАНОВ КИСЛОТОЙ HOONO В ВОДЕ: МЕДЛЕННАЯ СТАДИЯ - РЕАКЦИЯ С ОН-РАДИКАЛАМИ // Теоретическая и экспериментальная химия. 2010. Т. 46. № 2. С. 108-113.

Найдены относительные константы скорости (kRH/kEtH), их температурные зависимости в интервале 5-55 оС и активационные параметры реакций алканов С3Н8, n-C4H10, n-C5H12, n-C6H14, i-C4H10, c-C5H10 и c-C6H12 с пероксиазотистой кислотой (HOONO) в воде. Сходство этих характеристик с данными для реакций алканов с ОН-радикалами подтверждает, что активными частицами в реакциях HOONO с углеводородами в воде являются радикалы ОН, образующиеся при гомолизе связи HO-ONO.

63.00612X
Лобачев В.Л., Матвиенко Я.В., Рудаков Е.С. КИНЕТИКА И МЕХАНИЗМ ОКИСЛЕНИЯ АЛКАНОВ ПЕРОКСИАЗОТИСТОЙ КИСЛОТОЙ В ГАЗОВОЙ ФАЗЕ: МЕДЛЕННАЯ СТАДИЯ - РЕАКЦИЯ С ОН-РАДИКАЛАМИ // Теоретическая и экспериментальная химия. 2010. Т. 46. № 2. С. 114-119.

Кинетическим распределительным методом в интервале 15-55 оС измерены относительные константы скорости (kRH/kEtH) и найдены активационые параметры реакций алканов С3Н8, n-C4H10, n-C5H12, n-C6H14, n-C7H16, i-C4H10, c-C5H10 и c-C6H12 с пероксиазотистой кислотой (HOONO) в газовой фазе. Сходство этих характеристик с данными для реакций RH + .ОН подтверждает, что активными частицами в реакциях HOONO с углеводородами являются радикалы ОН.

64.003757
Лякин О.Ю., Штейнман А.А. ОКСО-КОМПЛЕКСЫ ВЫСОКОВАЛЕНТНОГО ЖЕЛЕЗА В КАТАЛИЗЕ ОКИСЛИТЕЛЬНЫХ РЕАКЦИЙ // Кинетика и катализ. 2012. Т. 53. № 6. С. 738.

В обзоре рассмотрены оксо-комплексы высоковалентного железа (оксоферрильные, или просто феррильные комплексы), играющие важную роль в селективном окислении углеводородов и других органических соединений. Эффективность и высокая селективность природных оксигеназ стимулирует интерес исследователей к созданию химических аналогов этих систем. В связи с тем, что преимущества биологического и биомиметического окисления обусловлены участием феррильных интермедиатов, рассмотрены способы получения относительно устойчивых оксо-комплексов высоковалентного железа, их геометрическое и электронное строение и реакционная способность.

65.008036
Майорова Н.А., Жигалина О.М., Жигалина В.Г., Хазова О.А. PT/PD/C-КАТАЛИЗАТОР С УЛЬТРАМАЛЫМ КОЛИЧЕСТВОМ ПЛАТИНЫ ДЛЯ РЕАКЦИИ ВОССТАНОВЛЕНИЯ КИСЛОРОДА // Электрохимия. 2014. Т. 50. № 3. С. 251.

Исследование катализаторов Pt/Pd/C ЕТЕК типа ядрооболочка с ультрамалым количеством платины (0.515 мкг см-2) на основе коммерческого палладиевого катализатора показало, что их активность в реакции восстановления кислорода выше, чем у коммерческих Pt/C ETEK-катализаторов. Было установлено, что эта активность резко возрастает при уменьшении количества платины до значений, эквивалентных монослою и субмонослою платины на палладии. Подобная зависимость не наблюдалась при осаждении таких же количеств платины на углеродный носитель Vulcan XC-72. Это позволяет сделать вывод, что причиной высокой каталитической активности Pt/Pd/C ЕТЕК является, скорее всего, влияние палладия на электронные свойства платины, а не влияние изменения структуры осадка платины с уменьшением ее количества при осаждении на другой металл или углеродный носитель.

66.002311
Мельникова Н.Б., Кочетков Е.Н., Соловьева С.Е., Попова Е.В., Антипин И.С., Большакова А.Е., Жильцова О.Е., Коновалов А.И. МОНОСЛОИ ТРЕТ-БУТИЛТИАКАЛИКС[4]АРЕНА КАК БИОМИМЕТИЧЕСКАЯ МОДЕЛЬ ОКИСЛЕНИЯ АНТИОКСИДАНТОВ ЦИТОХРОМ С // Известия Академии наук. Серия химическая. 2011. № 9. С. 1915-1921.

67.000513
Наджафпур М.М., Гхобади М.З., Хагхигхи В., Итон-Рай Д.Д., Томо Т., Шен Д.Р., Аллахвердиев С.И. НАНОРАЗМЕРНЫЙ МАРГАНЕЦ-КАЛЬЦИЕВЫЙ КЛАСТЕР ФОТОСИСТЕМЫ II (ОБЗОР) // Биохимия. 2014. Т. 79. № 4. С. 413-428.

Процесс фотосинтеза, происходящий в цианобактериях, водорослях и растениях, приводит к окислению воды и высвобождению молекулярного кислорода. В связи с истощением запасов ископаемого топлива, в настоящее время исследователями предпринимаются активные попытки использовать природный каталитический центр, обнаруженный в фотосистеме II у оксигенных фотосинтетических организмов, для синтеза биомиметического суперкатализатора окисления воды. Успехи в этой области позволят преодолеть узкое место в разработке путей конверсии энергии солнечного света. В обзоре рассматриваются вопросы структуры и функции водоокисляющего комплекса (ВОК), обнаруживаемого в живой природе, с особым акцентом на последних достижениях Международного научного сообщества, работающего над решением проблемы искусственного расщепления воды на основе ВОК фотосистемы II.

68.001770
Насирова У.В., Гасанова Л.М., Нагиев Т.М. МОНООКСИДИРОВАНИЕ ЭТИЛЕНА ПЕРОКСИДОМ ВОДОРОДА НА БИОМИМЕТИКЕ PER-FTPHPFE3+OH/AL2O3 // Журнал физической химии. 2010. Т. 84. № 6. С. 1050-1054.

Процесс газофазного монооксидирования этилена пероксидом водорода на биомиметическом гетерогенном катализаторе (per-FTPhPFe3+OH/Al2O3) исследован в относительно мягких условиях. Показано, что биомиметическое окисление этилена пероксидом водорода когерентно-синхронизировано с реакцией разложения H2O2, и в зависимости от условий реакционной среды преимущественно образуется один из двух целевых продуктов этиловый спирт или ацетальдегид. Изучены кинетические закономерности и вероятный механизм реакции превращения этилена.

69.001770
Насирова У.В., Нагиева И.Т., Гасанова Л.М., Нагиев Т.М. КИНЕТИЧЕСКАЯ МОДЕЛЬ КОГЕРЕНТНО-СИНХРОНИЗИРОВАННОЙ РЕАКЦИИ МОНООКСИДИРОВАНИЯ ЭТИЛЕНА ПЕРОКСИДОМ ВОДОРОДА НА БИОМИМЕТИЧЕСКОМ КАТАЛИЗАТОРЕ FTPHPFE3+OH/AL2O3// Журнал физической химии. 2011. Т. 85. № 12. С. 2267.

На основе наиболее вероятного механизма окисления этилена пероксидом водорода над биомиметическим катализатором перфторированным тетрафенилпорфирином железа (III), нанесенным на оксид алюминия (per-FTPhPFe3+OH/Al2O3), исследована адекватная экспериментальным данным кинетическая модель. Найдены эффективные константы скорости для каталазной и монооксигеназной реакций и их эффективные энергии активации.

70.003757
Никитенко Н.Г., Шестаков А.Ф. КВАНТОВО-ХИМИЧЕСКОЕ МОДЕЛИРОВАНИЕ АКТИВАЦИИ И ОКИСЛЕНИЯ ЛЕГКИХ АЛКАНОВ В МЯГКИХ УСЛОВИЯХ КОМПЛЕКСАМИ AU(I) С БИОФЛАВОНОИДАМИ // Кинетика и катализ. 2013. Т. 54. № 2. С. 177.

С использованием метода функционала плотности рассмотрены реакции расщепления СН-связи в алканах ряда С1 - С3 биядерными аквакомплексами Au(I) с рутином и кверцетином по механизму электрофильного замещения с эстафетным переносом протона от алкана на атом О биофлавоноидного лиганда через молекулу воды. Учтено влияние факторов среды на энергетический профиль процессов. На основании результатов исследования энергетики взаимодействия промежуточного метильного комплекса с молекулярным кислородом предложена схема каталитического цикла окисления метана до метанола в мягких условиях.

71.003757
Чепайкин Е.Г., Безрученко А.П., Менчикова Г.Н., Моисеева Н.И., Гехман А.Е. ГОМОГЕННОЕ КАТАЛИТИЧЕСКОЕ ОКИСЛЕНИЕ ЛЕГКИХ АЛКАНОВ. РАЗРЫВ СВЯЗЕЙ СС В МЯГКИХ УСЛОВИЯХ // Кинетика и катализ. 2010. Т. 51. № 5. С. 691-696.

Совместное окисление СО и алканов С2 - С4 (компонентов попутного нефтяного и природного газов) под действием кислорода в растворах трифторуксусной кислоты в присутствии хлоридов родия и меди сопровождается окислительной деструкцией связей СС углеводородной цепи с образованием карбонильных соединений, спиртов и их эфиров. Для бутана и изобутана направление реакции с разрывом связи СС является доминирующим. Кривые накопления продуктов окисления изобутана (как с сохранением, так и с деструкцией цепи) имеют S-образную форму, характеризуются одинаковым индукционным периодом и не проходят через максимум. Предложена схема реакции, отражающая основные особенности механизма превращений, происходящих в окислительной системе O2/Rh/Cu/Cl-.

72.004641
Чепайкин Е.Г., Безрученко А.П., Менчикова Г.Н., Моисеева Н.И., Гехман А.Е. ПРЯМОЕ КАТАЛИТИЧЕСКОЕ ОКИСЛЕНИЕ НИЗШИХ АЛКАНОВ В СРЕДЕ ИОННЫХ ЖИДКОСТЕЙ // Нефтехимия. 2014. Т. 54. № 5. С. 380.

Иммобилизация родий (палладий)?медь?хлоридных каталитических систем в ионных жидкостях (ИЖ) как высококипящих растворителях, влияет на распределение продуктов окисления пропана: увеличивается выход ацетона и снижается выход спиртов. Пропан окисляется в ацетон, минуя стадию образования изопропанола. Метан, окисляясь в более жестких условиях, чем пропан, дает основной продукт метилтрифторацетат. Механизмы действия каталитических систем на основе родия и палладия близки и, по-видимому, включают оксо- или пероксокомплексы в качестве интермедиатов.

73.006651
Шилов А.Е., Штейнман А.А. ПРОБЛЕМА ГИДРОКСИЛИРОВАНИЯ МЕТАНА: БИОМИМЕТИЧЕСКИЙ ПОДХОД // Успехи химии. 2012. Т. 81. № 4. С. 291-316.

Обзор посвящен прямому окислению метана - важной фундаментальной проблеме, в последние годы привлекающей внимание исследователей. На основе анализа достигнутых результатов по биомиметическому и биоинспирированному оксигенированию метана показано, что освоение опыта Природы в окислении метана и других алканов существенно обогащает арсенал химической науки и может кардинально изменить облик всего химического производства, а также позволит решить многие материальные, энергетические и экологические проблемы. Библиография - 310 ссылок.

На главную              К списку выставок