Description
Main areas of research
Heterogeneous catalysis of transition metals, as well as their sulphides, oxides, phosphides and phosphates, deposited on traditional and non-traditional carriers. The development of new nanostructured catalysts for hydrogenation processes that underlie the production of environmentally friendly motor fuels.
Study of the formation and mechanisms of operation of the active sites of catalysts in hydrogenation, hydrogenolysis, oxidative dehydrogenation of organic compounds and other industrially important reactions.
Synthesis, as well as the study of the structure and mechanisms of transformation of organic and organometallic compounds using IR spectroscopy, plasma mass spectrometry and radioisotopes.
Main achievements
A concept was developed on the dynamic nature of the active centers (AC) of hydrodesulfurization catalysts based on transition metal sulfides, according to which different types of AC responsible for hydrogenolysis and hydrogenation reactions, which are formed and function under reaction conditions, can turn into each other as a result of oscillations of sulfur atoms and the promoter between layers of promoted molybdenum sulfide. The concept is confirmed by the EPR and radioisotope testing of sulfide catalysts. On the basis of the proposed concept, criteria were developed for evaluating the efficiency of catalysts in the processing of various types of raw materials and highly efficient catalysts for hydrotreatment of diesel fractions were synthesized (V. Kogan).
The effect of the intermediate carbon coating in catalysts based on transition metal sulphides prepared from heteropoly compounds on the catalytic activity in the reactions of thiophene hydrogenolysis, benzene hydrogenation and hydrotreating of the diesel oil fraction has been studied. It was found that the structure of the intermediate carbon coating changes depending on the presence or absence of the active phase. The specific catalytic activity increases in proportion to the carbon content of the catalyst. With an increase in the reaction temperature, the amount of hydrogen adsorbed on the surface decreases, the lack of which limits the formation of hydrogen sulfide in hydrogenolysis reactions, and, therefore, the reaction as a whole. The carbon coating plays the role of a hydrogen accumulator, which is necessary for the operation of active centers, which increases the catalytic activity. It has been established that the presence of an intermediate carbon coating contributes to an increase in the number of layers in molybdenum sulfide nanoclusters promoted by cobalt or nickel and, therefore, contributes to the formation of so-called. active phase CoMoS-II (second type), much more active than the phase CoMoS-I (first type) (V. Kogan, together with SamGTU).
The role of X (X — Co, Ni, Cr, Mn, Fe, Cu, Zn, Ga) heteroatoms in XMo6 (S) / Al2O3 and Ni3-XMo6 (S) / Al2O3 heteropoly compounds prepared from Anderson-type heteropoly acids has been studied. It is shown that the use of these heteropolyacids results in the formation of ultrafine molybdenum oxysulfides in the active phase of the synthesized catalysts. It has been established that the role of heteroatom X, which is part of heteropoly compounds, is, firstly, to optimize the electron density at the antibinding d-molybdenum orbitals in mixed sulfides, which causes an increase in the activity of both hydrogenation centers and desulfurization and, secondly, the ability to purposefully influence the number of layers of the MoS2 nanocluster, which determines the ratio between the hydrogenation and desulfurization centers, and thus the process selectivity (V. Kogan, together with SamGTU).
The physicochemical, structural, and catalytic properties of Ni-, Mo, W-phosphide catalysts, both unsupported and supported, on MCM-41 in the hydrodesulfurization of thiophene and dibenzothiophene were studied. Various methods for passivating and activating phosphide catalysts have been studied. Radioisotope testing of these catalysts in the thiophene hydrodesulfurization reaction was carried out. It has been established that the structure of the active phase of phosphide catalysts is different from that of sulfide catalysts. The catalysts have a higher catalytic activity in the desulfurization reactions of dibenzothiophene and middle distillates compared to traditional transition metal sulphides. Radioisotope testing data showed that the degree of sulfide sulfur coverage is very different for Ni, Mo, W phosphide catalysts. A new method of processing phosphide catalysts without loss of catalytic activity, in which, unlike the traditionally used oxygen, hydrogen sulfide is used, is proposed. In this case, the use of the catalyst does not require pre-reduction at high temperatures and the catalyst retains high activity for a long time. (Kogan V.M., Rozhdestvenskaya N.N., together with Dalian Technical University, Dalian, PRC).
For the first time, methods for introducing niobium into Mg-Al hydrotalcites — precursors of oxide catalysts for oxidative dehydrogenation (OD) of hydrocarbons and alcohols and synthesized samples of oxide catalysts containing niobium. The conditions for the preparation of catalysts were optimized and their catalytic properties were studied in the oxidative dehydrogenation of ethane, propane, ethylbenzene, and the conversion of sec-butanol to octane- (2) -one and octane to ethylbenzene and styrene. It is established that the V-Mo-Nb-Mg-Al-O catalyst performs the process of converting ethane to ethylene with high selectivity (92-97%) at low temperatures (450-500 ° C). The catalyst is effective at OD of sec-butyl alcohol in octane- (2) -one. The resulting catalysts in the reactions of OD work stably, the activity and selectivity after 50 hours of work does not decrease (Isagulyantz G.V., Belomestnykh I.P., together with IINSC RAS).
The state of metals in supported γ-Al2O3 bimetallic Pt-Sn and Pt-Pd catalysts was studied by IR spectroscopy of diffuse reflection of adsorbed CO. The adsorption of 13С18О + 12С16О mixtures on Pt supported on silica gel was studied for the first time. It was shown that the intermediate products of 13С18О adsorbed on platinum can be detected at its concentration in the mixture of ~ 3%. As a result, the frequency of the singleton and dipole-dipole shift of adsorbed CO can be determined in a single experiment. It has been established that on Pt and Pd deposited on Al2O3, CF2Cl2 and CF3CFCl2 molecules at room temperature in the presence of H2 are converted to CH4 and, accordingly, carbon2 formed on the surface of metals as a result of complete dissociation of CF2Cl2 molecules is an active intermediate product of CF2Cl2. When this occurs, the oxidation of metals to the divalent state and the formation of CO. It is spectrally determined that during the adsorption of CF3CFCl2, trifluoromethylcarbines are formed on the surfaces of supported Pt and Pd, which are intermediates of the conversion of CF3CFCl2 in the presence of H2 into CF3CH3, which is further hydrodefluorinated to form ethane. (Borovkov V.Yu.).
It has been established that in the reduced gallium-containing mordenite (Ga-MOR) there are exchangeable cations of both Ga3 + and Ga +. Ga3 + cations in Ga-MOR dissociatively adsorb hydrogen at elevated temperatures to form gallium hydride and acidic hydroxyl groups. It was shown that in the case of acidic carriers (Al2O3, TiO2, ZrO2), the concentration of surface Ga3 + cations active in hydrogen dissociation is significantly higher than in gallium catalysts supported on basic MgO and neutral SiO2 carriers (Gray A.I.).
A method has been developed for producing highly efficient catalysts for the hydroconversion of heavy oil feedstock into high-octane fuel. The method combines the method of microemulsions and cryotechnological techniques. With the help of the developed method, catalytic systems based on the Ti0.03Si0.97O2 mesoporous titanium silicate were obtained, in which highly dispersed crystalline NiO, obtained from a microemulsion using a cryoeffect, was incorporated. The textural and morphological features of the obtained composite systems of the general composition NiO × Ti0.03Si0.97O2 were studied. It is shown that the composite system obtained using cryoprocessing microemulsions exhibits several orders of magnitude higher catalytic activity in hydroconversion compared to similar, obtained directly from the microemulsion (Kogan V.M., together with Lab. 47 of the Institute of Organic Chemistry and Russian Academy of Sciences and IMET RAS) .
Catalysts based on mesoporous nanostructured titanium-silicate composite systems with a total gross formula NiO × Ti0.03Si0.97O2 have been developed. Synthesized molybdenum-free catalysts exhibit high activity in gas-phase and liquid-phase hydrodesulfurization of model (using thiophene) and technical petroleum oils with a sulfur content of 1.0-1.2%. The degree of desulfurization of mixtures reached 99.5% even under mild conditions. The process was accompanied by hydrogenolysis of a hydrocarbon substrate, which significantly increases at elevated temperatures. The resulting catalytic systems can be considered as the basis for the creation of catalysts for low-temperature and highly efficient production of low-sulfur motor fuels. (Kogan V.M., jointly with IMET RAS).
