The project is aimed at research of fundamental problems of catalysis of reactions of polyfunctional organic substances, development of new selective catalysts and catalytic processes. Polyfunctional compounds include heterocyclic and acyclic compounds that have several functional groups in their molecules and can react in different directions to form different products. Polyfunctional reagents play an important role in the industrial synthesis of medicines, plant protection products, dyes, and functional materials.
One of the Central problems of chemical processes based on transformations of polyfunctional organic substances is the problem of low selectivity of reactions. An effective approach to solving this problem can be the use of so-called Naz. nanoscale catalysts whose active particles are in the range that borders between bulk solid-state structures and individual molecules. In this area of dimensions, unique physical and chemical properties are shown, in particular, high catalytic activity and, in some cases, high selectivity. However, the prospects for the use of nanoscale catalysts for the synthesis and modification of polyfunctional organic substances have not been sufficiently investigated. There are a number of important problems – the instability of nanoparticles, their tendency to aggregation or transformation into molecular homogeneous complexes, the appearance of several active forms of the catalyst with different catalytic activity ("cocktail of catalysts"), the formation of strong non-reactive complexes with heteroatomic reagents or products.
Since polyfunctional reagents are of great importance for laboratory and industrial organic synthesis, an urgent task is to study the fundamental problems of catalysis of reactions of polyfunctional organic reagents involving nanoscale catalysts and other types of catalysts, to develop new catalytic systems and approaches to selective synthesis of organic substances based on polyfunctional reagents. Results for 2014:
- Analysis of modern methods for controlling the selectivity of catalytic reactions of polyfunctional organic substances – C-amino-1,2,4-triazoles, getarilazoles, azoloazines, 5-hydroxymethylfurfural and various types of catalysts (homogeneous, heterogeneous nanoscale). Shown a rapid increase in the role of organocatalysis, heterogeneous catalysis and nanocatalysis (including the so-called. adaptive catalytic systems containing both purely homogeneous forms of the catalyst and nanoparticles), as well as electrocatalysis in the creation of new selective processes for processing polyfunctional organic substances.
- Methods of synthesis of polyfunctional nitrogenous heterocycles necessary for further research: 1,4-disubstituted 3-amino - and 3,5-diamino-1,2,4-triazoles, 3-substituted 5-amino-1,2,4-triazoles, derivatives of 2-(2-thienyl)Acento[1,2-d]oxazole, 2-(2-hetaryl)naphtho[1,2-d] and [2,1-d]oxazoles, 2 - (furan-2-yl)-1(3)N-imidazo[4,5-b]pyridine, 2 - (2-furyl)oxazolo[4,5-b]pyridine. Samples of these substances, as well as other polyfunctional heterocycles that are necessary for conducting research at the subsequent stages of the project, have been developed.
– A comprehensive analysis of the structure-reactivity relationship of key polyfunctional nitrogen heterocycles with respect to electrophilic and nucleophilic reagents was performed using computational methods and experimental research of model reactions. It was found that the position of the endocyclic substituent R has a strong influence on the global and especially local reactivity of C-amino-1,2,4-triazoles. Static indices of reactivity, energy of transition States, and velocity constants for attacking electrophiles at different positions of molecules of isomeric C-amino-1-R-1,2,4-triazoles are calculated. A new approach to managing the selectivity of reactions of functionally substituted 1,2,4-triazoles is proposed. "fixation" of tautomeric forms by introducing a substituent at the nitrogen atom of a hydrazine fragment. On the example of typical electrophilic reactions (protonation, alkylation, acylation, nitration, halogenation, etc.), the mutual influence of heterocyclic fragments of polyfunctional bigetaryl molecules (isomeric pyridyl-substituted C-amino-1,2,4-triazoles, getarylnaftoxazoles, furilimidazopyridines, furiloxazolopyridines) and reaction conditions on the direction of the electrophile attack is analyzed.
- The influence of the shape and size of platinum particles, as well as the morphology of the carbon carrier on the adsorption and kinetics of electrocatalytic oxidation of aliphatic alcohols (methanol, ethanol) and polyfunctional compounds with symmetrical functional groups (ethylene glycol, glyoxal, dimethyl ether) on Pt/C nanocatalysts was studied. It was found that the filling of the surface of platinum nanoparticles with adsorbate formed as a result of destructive chemosorption of alcohols or glycol exceeds the filling of polycrystalline platinum with the same adsorbate and practically does not depend on the content of platinum in the catalyst and the size of its particles, as well as the method of obtaining these particles.
- It is shown that for deposited platinum-carbon catalysts, the most important factor determining the electrocatalytic activity of the material is the structure of the active component, i.e., platinum nanoparticles. The catalytic activity of Pt/C catalysts in the processes of electrocatalytic oxidation of aliphatic alcohols, aldehydes and dimethyl ether increases with the growth of Pt crystallites in the range of 2-10 nm. The most active catalysts are those whose particles have the shape of a cube (truncated cube), i.e. they are cut mainly by Pt(100) planes. The effect of the influence of the crystallographic orientation of platinum particles is more evident in the oxidation of molecules with a C-C bond(ethanol, ethylene glycol), which is due to the geometry and adsorption energy on the Pt (100) plane.
- The influence of the morphology of the carbon carrier of Pt/C catalysts on the oxidation kinetics has been established by the example of the dimethyl ether oxidation reaction. It is shown that carbon carriers with anisotropic 1D and 2D particle shapes (graphite, carbon nanotubes) do not provide equal access to the particles of the active component of the catalyst – platinum – for the molecules of the reacting substance. This leads to a lower rate of oxidation of the ether compared to a similar process on a catalyst, the carrier of which has a soot structure (spherical 3D particles comparable to platinum particles).
- A method of electrochemical synthesis of materials for heterogeneous and electrocatalysis has been developed. The method is based on the phenomenon of oxidation and dispersion of metals under conditions of non-stationary electrolysis. The process of oxidation/partial reduction of the formed oxides is periodic and is accompanied by intense gas release (oxygen to the anode pulse, hydrogen to the cathode pulse), which together with the high frequency of the current used causes the formation of highly dispersed oxide structures. The influence of the main technological parameters (current density and asymmetry, electrolyte composition and temperature) on the speed of the process is established.
- It is shown that the main technological parameters that determine the structural characteristics and composition of nanodisperse composite materials based on copper, tin and Nickel oxides are the electrolyte composition and current density. Highly dispersed metal oxides (Cu2O, SnOx, NiO) are formed in electrolytes based on chlorides (copper, tin) and hydroxides (Nickel) of alkali metals. As the current density increases in the range of 0.1-1 A/cm2, the unsteadiness of the process increases, which leads to the formation of more disordered defective structures with a high degree of dispersion. Temperature variation in the range of 30-80 °C does not affect the structure of the forming materials; current asymmetry determines the speed of the process, but not the structural characteristics of the oxides.
-Electrocatalytic properties of composite catalytically active materials based on the obtained oxides and nanoscale particles of platinum Pt/MeOx – C (Me=Sn, Ni) are studied on the example of oxidation reactions of aliphatic alcohols (methanol and ethanol) - promising fuels for low-temperature fuel cells. The oxide component of the composite carrier MeOx-C facilitates the adsorption of oxygen-containing particles on the catalyst and promotes the oxidation reaction of adsorbed alcohol molecules by the Langmuir-Hinshelwood mechanism at a speed 20 % higher than on the Pt/C catalyst and at lower anode potentials, which reduces the overvoltage of the anode process in a low-temperature fuel cell.
- A review of the current state of research on the mutual influence of heat and mass transfer on the main indicators of energy-stressed catalytic processes, including the synthesis of hydrocarbons from CO and H2 (Fischer-Tropsch synthesis). It is shown that in addition to the chemical and phase composition, porosity and surface morphology of the catalyst, heat and mass transfer parameters have an extremely important influence on the selectivity of the Fischer-Tropsch process in flow reactors. Solving the problem of efficient heat removal from the reaction zone is of paramount importance for increasing selectivity for linear limit hydrocarbons C5+.
- A new laboratory method for studying the parameters of heat and mass transfer of the Fischer - Tropsch process has been developed, which simulates the conditions of an industrial reactor. The method is based on the use of a laboratory flow-circulation unit, which is a reactor in the form of a shell-and-tube heat exchanger. A mathematical apparatus for analyzing experimental data has been developed that allows calculating heat and mass transfer coefficients.
- A fully automated laboratory facility has been developed to study the Fischer-Tropsch process. The unit allows a continuous synthesis process at fictitious linear flow rates of reagents up to 10 m / s under a pressure of up to 3.0 MPa in a quasi-isothermal mode and provides the ability to determine the radial and longitudinal temperature gradients in the reaction zone.
- Samples of heterogeneous cobalt catalysts (cobalt on silica gel and gamma-Al2O3) were synthesized. The optimal technological parameters of synthesis were found to provide the necessary physical and chemical parameters, elemental and phase composition, adsorption and desorption properties, parameters of the porous structure, strength, recoverability, etc.. Physical and chemical properties and catalytic activity of the obtained catalyst samples were studied. It was found that the introduction of a promoter-aluminum oxide-within the mass ratios of Co-Al2O3 from 100-2 to 100-50 has a significant effect on the surface area, the recoverability of cobalt, and the strength of the CO bond with the surface of the active component. Publications:
Alexandrov A. A., Yelchaninov M. M. Synthesis, properties and relative reactivity of 2-(2-getaryl)naphto[1,2-d] and [2,1-d]of oxazolo IZVESTIYA vuzov. NORTH CAUCASUS REGION. TECHNICAL SCIENCES, no. 6, Pp. 110-116 (year of publication-2014).
Alexandrov A. A., Yelchaninov M. M. Synthesis and properties of 2-(2-thienyl) acenafto [1,2-d] oxazole IZVESTIYA VUZOV. NORTH CAUCASUS REGION. TECHNICAL SCIENCES, no. 6, Pp. 88-91 (year of publication-2014).
Yelchaninov M. M., Alexandrov A. A., Illenseer E. V. Synthesis and properties of 2-(2-furyl)oxazolo[4,5-b]pyridine Journal of organic chemistry, Vol. 50, No. 12, Pp. 1844-1846 (year of publication-2014).
Yelchaninov M. M., Achkasova A. A., Yelchaninov I. M. Synthesis and Reactivity of 2-(Furan-2-yl)-1(3)H-imidazo[4,5-b]pyridine Russian Journal of Organic Chemistry, Vol. 50, No. 11, P. 1663-1666 (year of publication — 2014).
Kuryanov B. A., Kubanova, M. S., Smirnova N. In. ON THE CHEMISORPTION OF ETHYLENE GLYCOL AT NANOSTRUCTURED CATALYSTS PLATINOCHLORIDE NEWS OF HIGHER EDUCATIONAL INSTITUTIONS. NORTH CAUCASUS REGION. SERIES: NATURAL SCIENCES, Vol. 183, No. 5, Pp. 58-62 (year of publication-2014).
Kuriganova A. B., Smirnova N. V. Pt / SnOx-C composite material for electrocatalysis Mendeleev Communications, Vol. 24, No. 6, P. 351-352 (year of publication — 2014).
Savostyanov A. P. Courier G. B., Yakovenko, R. E., Lapidus, A. L., Fischer–Tropsch Process for the Synthesis of Hydrocarbons in Flow and Flow Circulation Modes Solid Fuel Chemistry, Vol. 48, No. 6, P. 404-405 (year of publication — 2014).
Chernyshev V. M., Astakhov A.V., Rybakov V. B., Chernysheva A.V., Tarasova E. V. Theoretical and experimental study of the structure of protonated forms of 3-pyridyl substituted 5-amino-1H-1,2,4 triazoles proceedings of the Academy of Sciences. Chemical series, no. 12, pp. 2591-2598 (year of publication-2014).
Chernyshev V. M., Vlasova A. G., Astakhov A.V., Shishkina S. V., Shishkin O. V. Reactivity of C-amino-1,2,4-triazoles towards electrophiles: a combined computational and experimental study of alkylation by halogen alkanes The Journal of Organic Chemistry, 80, 1, 375-385 (year of publication — 2015).
Yakovenko, R. E., Courier G. B., Bakun, V. G., Astakhov A. V., Savostyanov A. P. CATALYSTS FOR OBTAINING microcrystalline wax by the METHOD of FISCHER-Tropsch IZVESTIYA vuzov. NORTH CAUCASUS REGION. TECHNICAL SCIENCES, No. 6, pp. 92-95 (year of publication-2014).
Results for 2015:
- Developed new synthesis methods and new representatives of 2-aminotoluene 4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidines, 1,2,4-triazoles and (benzo)imidazoline salts (precursors of heterocyclic Kurbanov), and also new nitro and halogen derivatives, aldehydes and ketones 2-furyl - and 2-dienylbenzene, phenanthro[9,10-d]oxazole of benzoxazole, oxazolo[4,5-b]pyridine (potential reagents for the synthesis of catalysts photoreactive). Synthesis methods are based on catalytic and non-catalytic reactions of addition, substitution, and cyclocondensation of polyfunctional azageterocycles of the 1,2,4-triazole, imidazole, and oxazole series.
- A complex analysis of the structure – reactivity relationship of 2-amino-1,2,4-triazolo[1,5-a]pyrimidines with different saturation of the pyrimidine fragment in relation to electrophiles was performed using quantum chemical methods and experimental research of model reactions. Selective methods of synthesis of new polycondensed heterocycles – imidazo-have been developed[2',1':3,4][1,2,4]triazolo [1,5-a]pyrimidines, triazolodipyrimidines with various annelation cycles, based on catalytic reactions of 2-amino-1,2,4-triazolo[1,5-a]pyrimidines with bielectrophilic reagents. A new cascade rearrangement was discovered, which is realized during acid-catalyzed cyclocondensation of 2-amino-4,7-dihydro - [1,2,4]triazolo[1,5-a]pyrimidines with 1,3-dicarbonyls, including successive recyclizations of two pyrimidine cycles annelated with a 1,2,4-triazole core.
- New Ni (II)and Pd(II) complexes with N-heterocyclic carbenes(NHC) were synthesized on the basis of 1,2,4-triazolium and (Benz) imidazolium salts. their structure and catalytic activity were studied using examples of Hake, Suzuki, alkyne hydrothyolation, etc. It was first discovered that Ni(NHC)2x2 (X = Cl, Br, I) complexes, widely used as catalysts for many reactions, are easily hydrolyzed in the presence of water with the cleavage of the C(carbine)-Ni bond, forming the corresponding N,Nʹ-dialkylimidazolium salts and Nickel (II) hydroxide. The relationship between the structure of the complex and hydrolytic stability is studied. The hydrolysis reaction with a break in the Ccarbene-metal bond was considered uncharacteristic for most metal complexes with N-heterocyclic carbenes. The ability of Ni(II)-NHC complexes to hydrolyze should be taken into account during their synthesis and application in catalysis.
- New "One pot" methods for electrochemical synthesis of two-component Pt/MeOx catalytic systems (Me = Ti, Al, Sn, Ni) under non-stationary electrolysis conditions by sequential or simultaneous dispersion of Pt and corresponding metals have been developed. These methods allow for wide variation in the nanostructural characteristics of catalysts depending on the electrolysis conditions, and, unlike conventional "impregnation" methods, do not require the use of expensive platinum compounds and calcination and recovery operations. It is shown experimentally that the obtained Pt/MeOx systems are active in the processes of CO and NO oxidation and can be used in the production of exhaust gas afterburning catalysts.
— The regularities of electrocatalytic oxidation and reduction of a number of polyfunctional organic substances-5-hydroxymethylfurfural (GMF), 2,5 – diformylfuran (DFF) and some alcohols on various electrodes-Pt, Pt/C, Pt/MeOx-C were studied . It is shown that direct oxidation of GMF on most electrodes proceeds with low selectivity even in the presence of the TEMPO/halide anion mediator system (TEMPO – 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxyl). It was found that for selective oxidation of GMF to DFF (a valuable monomer), the process should be carried out in a two – phase system "organic solvent-water electrolyte" using a TEMPO/KI mediator. A new preparative method for the synthesis of DFF with a yield of 55-60% by electrochemical oxidation of HMP in a two – phase system "methylene chloride-an aqueous solution of sodium bicarbonate" during TEMPO and KI catalysis using a pulse mode of electrolysis has been developed. The method allows multiple recycling of the electrolyte.
- A mathematical model of Fischer–Tropsch synthesis (FT) in a tube reactor has been developed, which allows calculating performance and selectivity based on the specified process parameters and characteristics of catalysts, or selecting synthesis conditions to ensure the specified parameters for the selectivity of hydrocarbons. The adequacy of the model was tested using experimental data at synthesis pressures of 1-2 MPa. An experimental data set was obtained and a database of parameters of the FT process in a tube reactor using Co/SiO2 catalysts was created.this database can be used for technological calculations and automation of the synthesis reactor control processes. Based on the developed mathematical model, the parameters of the Fischer-Tropsch synthesis process are calculated to provide increased selectivity for C5+hydrocarbons.
- The technological parameters of FT synthesis with the target production of C60+ (ceresin) ulevorodov in a tube reactor using Co/SiO2 catalysts doped with aluminum oxide are theoretically and experimentally justified. It is shown that the synthesis must be carried out in a deep intradiffusion region, the necessary effect is provided by the creation of a porous structure of the catalyst, which has a bi - or polydisperse pore distribution over radii.
- Complex of physical and chemical methods (BET, TPV/TPD, XRD, SEM, TEM, RFA) investigated the influence of the promoter-aluminum oxide, on the nanostructural characteristics and catalytic activity of Co/SiO2 catalysts. It is shown that Al2O3 additives in the range of 0.4-1.0% lead to the formation of smaller cobalt particles with a size of 5-12 nm, among which the maximum size distribution corresponds to about 8 nm. It is this size of cobalt nanoparticles that contributes to the highest selectivity and performance of the catalyst for C5+hydrocarbons. Publications:
Alexandrov A. A., Illenseer E. V., Yelchaninov M. M. Synthesis and Some transformations of trans-2 - [β - (2-furyl)vinyl]benzoxazole Russian Journal of Organic Chemistry, 51, 8, 1111-1113 (year of publication-2015).
Astakhov A.V., Sokolov A. N., Pyatakov D. A., Shishkina S. V., Shishkin O. V., Chernyshev V. M. Reactivity of 2-amino [1,2,4]triazolo[1,5-a]pyrimidines with different saturation of the pyrimidine cycle in relation to electrophiles Chemistry of heterocyclic compounds, 51(11/12), 1039-1047 (year of publication — 2015).
Astakhov A.V., khazipov O. V., Degtyareva E. S., Khrustalev V. N., Chernyshev V. M., Ananikov V. P. Facile Hydrolysis of Nickel(II) Complexes with N-Heterocyclic Carbene Ligands Organometallics, 34 (24), pp 5759-5766 (year of publication — 2015).
Doronkin D. E., Kuriganova A. B., Leontiev I. N., Bayer S., Lichtenberg H., Smirnova N. V., Grunwaldt J.-D. Electrochemically Synthesized Pt/Al2O3 Oxidation Catalysts Catalyst Letters, 146, 2, 452-463 (year of publication — 2015).
Yelchaninov M. M., Alexandrov A. A. Synthesis and reactivity of 2-(2-thienyl)oxazolo[4,5-b]pyridine Russian Journal of General Chemistry, Vol. 85, No. 4, pp. 858-860 (year of publication — 2015).
Yelchaninov M. M., Alexandrov A. A. Synthesis and reactivity of 2-(2-thienyl)phenanthro[9,10-d]oxazole Russian Journal of General Chemistry, Vol. 85, No. 8, pp. 1862-1865 (year of publication-2015).
Yelchaninov M. M., Alexandrov A. A. Synthesis and reactivity of 2-(2-furyl)phenanthro[9,10 — d]oxazole Russian Journal of Organic Chemistry, Vol.51, No. 5, pp. 657-659 (year of publication-2015).
Yelchaninov M. M., Alexandrov A. A., Yelchaninov I. M. Synthesis of aldehydes and ketones of 1-methyl-2-(5-methyl-2-hetaryl)-1H — benzimidazole series Russian Journal of General Chemistry, Vol. 85, No. 4, pp. 841-843 (year of publication-2015).
Kashparova V. P., Kashparov I. A., Zhukova I. Yu., Astakhov A.V., Kagan E. sh. Salt Effects in the Reaction of Alcohols Oxidation with a Nitroxyl Radical-Iodine Catalytic System Russian Journal of General Chemistry, Vol. 85, No. 3, pp. 567-570 (year of publication — 2015).
Kashparova V. P., Khokhlova E. A., Galkin K. I., Chernyshev V. M., Ananikov V. P. single-Reactor method for obtaining 2,5-diformylfuran-a promising synton of organic materials in biomass conversion proceedings of the Academy of Sciences — chemical Series, no. 5, Pp. 1069-1073 (year of publication — 2015).
Klushin V. A., Bogdanova E. Yu., Zemlyakov N. D., Savostyanov A. P. Investigation of the process of fructose dehydration to 5-hydroxymethylfurfural in a two-phase system Izvestiya Vuzov. North Caucasus region. Technical Sciences, no. 4, Pp. 123-127 (year of publication-2015).
Krasnyakova T. V., Mitchenko S. A., khazipov O. V., Chernyshev V. M. platinum acid Complexes in the catalysis of C-C reactions, YURSPU publishing house(NPI), Novocherkassk,- (year of publication-2015).
Kuriganova A. B., Leontieva D. V., Smirnova N. V. on the mechanism of electrochemical dispersion of platinum under the action of alternating current proceedings of the Academy of Sciences — chemical Series, no. 12, Pp. 2769-2775 (year of publication — 2015).
Kuriganova A. B., Alexandrin A. S., Smirnova N. V. Electrochemical dispersion method for TiO2 nanoparticles preparation Key Engineering Materials, Vol. 683, pp 419-423 (year of publication — 2015).
Leontiev I. N., Leontieva D. V., Kuriganova A. B., Popov Y. V., Maslova O. A., Glebova N. V., nechitailov A. A., Zelenina N. K., tomasov A. A., Hennet L., Smirnova N. V. Characterization of the electrocatalytic activity of carbon-supported platinum-based catalysts by thermal gravimetric analysis Mendeleev Communications, 25, 468-469 (year of publication — 2015).
Leontieva D. V., Smirnova N. V. on the kinetics of electrochemical oxidation of 5-hydroxymethylfurfural and 2,5-diformylfuran on a platinum electrode in an aqueous medium Izvestiya Vuzov. North Caucasus region. Technical Sciences, no. 4, pp. 91-95 (year of publication-2015).
Narochny G. B., Yakovenko R. E., Savostyanov A. P. Investigation of the heat transfer process in a tube reactor under conditions of intensive synthesis of hydrocarbons from CO and H2 Engineering Bulletin of the don, no. 4 (2015) (year of publication — 2015).
Novikova K. S., Kuriganova A. B., Smirnova N. V. Influence of the carbon carrier type on the process of electrochemical oxidation of carbon monoxide on Pt/C catalysts Engineering Bulletin of the don, no. 4 (2015) (year of publication — 2015).
Pyatakov D. A., Sokolov A. N., Astakhov A.V., Chernenko A. Yu., Fakhrutdinov A. N., Rybakov V. B., Chernyshev V. V., Chernyshev V. M. Diversity Oriented Synthesis of Polycyclic Heterocycles through the Condensation of 2-Amino[1,2,4]triazolo[1,5-a]pyrimidines with 1,3-Diketones The Journal of Organic Chemistry, 80 (21), PP 10694-10709 (year of Publication — 2015). Savostyanov A. P., Bakun V. G., Yakovenko R. V., Sulima S. I., Narochny G. B., Chernyshev V. M. Catalysts and technology of synthesis of hydrocarbons from CO and H2 YURSPU publishing house(NPI), Novocherkassk — - (year of publication-2015).
Savostyanov A. P., Yakoveko R. E., Narochny G. B., Lapidus A. L. Effect of the dilution of synthesis gas with nitrogen on the Fischer-Tropsch process for the production of hydrocarbons Solid Fuel Chemistry, Vol. 49, No. 6, pp. 356-359 (year of publication — 2015).
Chernyshev V. M., Pyatakov D. A., Astakhov A.V., Sokolov A. N., Fakhrutdinov A. N., Rybakov V. B., Chernyshev V. V. Partially hydrogenated 2-amino[1,2,4]triazolo[1,5-a]pyrimidines as synthons for the preparation of polycondensed heterocycles: reaction witha-bromoketones Tetrahedron, 71 (2015) 6259-6271 (year of Publication — 2015).
Yakovenko, R. E., At B. G., Savostyanov, A. P., Kirsanov V. A. Feasibility of using a tube reactor in high-intensity Fischer–Tropsch synthesis Chemical and Petroleum Engineering, Vol. 51, No. 3-4, pp. 159-163 (year of publication — 2015).
Results for 2016:
- Metal complexes with N-heterocyclic carbenes (NHC) are widely used as homogeneous catalysts for organic reactions. According to the General opinion, the activity and stability of catalytic systems in solutions is provided by the high strength of the metal-NHC bond. However, at the previous stage of the project, we discovered the ability of Ni(II)-NHC complexes to undergo hydrolysis with a metal-NHC bond break under mild conditions (10.1021/acs.organomet.5b00856). This reaction, previously considered uncharacteristic for most M-NHC complexes, can significantly affect the catalytic properties. Therefore, we have studied the stability of m-NHC complexes (M = Ni, Pd, Pt) to solvolysis in media with different acidity. It was found that Pd(II) and Pt(II) complexes are more resistant to hydrolysis than Nickel complexes. At the same time, palladium complexes in alkali solutions can undergo redox transformations with the breaking of the metal-NHC bond and the reduction of Pd(II) to Pd (0). When studying the ability of Pt-NHC complexes to solvolysis in alcohols, using the example of a model compound — Na2PtCl4, a new C-O cross-combination catalytic reaction with the formation of esters was discovered, which occurs with the participation of platinum alkylcarbene complexes. The obtained results suggest alternative mechanisms of catalytic reactions involving so-called "NHC-free" forms of metals and open up new ways to control the catalytic process.
- A detailed study of the transformations of Pd-NHC complexes of various types (more than 20 complexes including NHC ligands of the 1,2,4-triazole, imidazole and benzimidazole series, various soligands) under standard conditions of the Mizoroki-Heck reaction was performed. A new mechanism for catalysis of cross-combination reactions in the presence of metal-NHC complexes has been identified. It was found that the catalytic activity of Pd-NHC complexes is mainly determined by the break of the metal-NHC bond with the generation of cocktail-type systems, in which the dominant role of active centers is played by "NHC-free" forms of palladium. This mechanism is fundamentally different from the generally accepted mechanism, in which the active centers are PD(0)-NHC molecular complexes. The efficiency of Pd-NHC complex catalysis depends on two main factors: the rate of metal – NHC bond break and the stabilization of atomic clusters and Pd(0) nanoparticles in solution. Based on DFT calculations, it is shown that the main way to generate "NHC-free" forms of palladium is the reduction elimination of NHC ligands. The decomposition of Pd-NHC complexes during the catalytic reaction is irreversible, since NHC ligands gradually turn into 2-R substituted azo salts (R = aryl, alkyl), losing the ability to coordinate according to the "carbene" type. It is shown that the rate of decomposition significantly depends on the structure of NHC ligands and soligands. Thus, varying the structure of M-NHC complexes can be considered as an effective way to regulate the rate of release of active forms of palladium in a catalytic reaction.
-The efficiency of catalytic systems based on ionic liquids for carbohydrate dehydration (fructose, glucose, sucrose, cellulose) has been studied and an improved method for producing 5-hydroxymethylfurfural (HMF) with a yield of 70-80% from glucose or sucrose has been developed. The scale of HMF synthesis up to 1 kg per month (product purity is not lower than 99%) was performed in a batch laboratory unit. The efficiency of the synthesis of 2,5-diformylfuran or 2,5-furandicarboxylic acid from glucose or sucrose by HMF oxidation without purification after extraction from reaction mixtures of carbohydrate dehydration is shown.
- A new effective method for the synthesis of nanodisperse photo - and electrocatalysts based on transition metals and their oxides (Pt/TiO2-C, Pt/Cu2O-C, Cu2O, Cu2O/TiO2, NiO/TiO2, SnO2/TiO2) by non-stationary electrolysis has been developed. It is shown that sequential dispersion of Pt and Ti or Cu electrodes, in contrast to simultaneous dispersion, provides a narrow range of sizes of Pt nanoparticles and their uniform distribution over the surface of the hybrid carrier (TiO2-C or Cu2O-C). Varying the synthesis parameters (electrolyte composition, current character) allows forming materials characterized by different structure, size distribution of nanoparticles, and the ratio of components. The General technological scheme, design of the electrolyzer and technological recommendations for the production of oxide (TiO2, CuOx, NiO, SnO2) and hybrid (TiO2-C, SnO2-C, NiO-C) carriers and catalysts based on them (Pt/Al2O3, Pt/TiO2-C, Pt/SnO2-C, Pt/NiO-C, Cu2O/TiO2, SnO2/TiO2 and NiO/TiO2) "OPE-pot" method of non-stationary electrolysis. Using the method of oxidative photodegradation of organic dyes, it is shown that the high photocatalytic activity in the reactions of oxidative degradation of organic substances under the action of visible (CuOx) and ultraviolet (TiO2, SnO2 and two-component systems) radiation is due to the disordered crystal structure, the presence of oxygen vacancies and a large number of defects on the surface of nanoscale metal oxide particles that are formed under non-stationary electrolysis under the action of pulsed alternating current. It was found that under the conditions of operation of low-temperature fuel cells, platinum-carbon catalysts, which include titanium oxides (Pt/TiO2-C), exhibit high electrocatalytic activity and stability of catalytic properties in the processes of alcohol oxidation, which is due to the presence of highly dispersed crystalline titanium oxide in the hybrid carrier. Copper oxide in the composition of the catalyst carrier Pt/Si2o-C has a strong inhibitory effect on the process of electrooxidation of methanol, due to the blocking of the active centers of platinum by copper adatoms due to its electrochemical dissolution and re-deposition.
- At the previous stage of research, the effectiveness of using aluminum oxide as a promoter of cobalt-silica catalysts for the synthesis of hydrocarbons by the Fischer-Tropsch method (FT) was shown, which leads to the stabilization of the activity of catalysts and an increase in selectivity for C5+ hydrocarbons. At the current stage of the project, the developed co–1Al2O3/SiO2 catalyst (25% Co, 1% Al2O3) was studied in a wide range of technological parameters of FT synthesis (pressure from 0.1 to 6.0 MPa, temperature from 195 to 238 °C, various CO ratios:H2 and gas loads) in a flow-circulation unit with a continuous operating time of 1000 h. It should be noted that Co/SiO2 catalysts promoted by aluminum oxide in the synthesis of FT were first studied at a high pressure of 6 MPa. As a result, an unusual phenomenon was found – at a pressure of 6 MPa with an increase in temperature in the range of 195-225 °C there is a significant increase in selectivity for C5 + hydrocarbons (from 40 to 80%) with a symbiotic decrease in selectivity for C1-C4 hydrocarbons. The observed trend is completely opposite to the patterns typical for medium (2-3 MPa) and low pressures. It is shown that the implementation of FT synthesis on Co-1Al2O3/SiO2 catalysts at a pressure of 6 MPa in the flow-circulation mode is a promising approach to the intensification of industrial production of long-chain hydrocarbons, which can be used for the production of liquid motor fuel.