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For the creation of new highly active and stable catalysts for the complete processing of coal methane, different methods for designing catalytic systems are being applied, including the use of the effects of mutual strengthening of the action of metals and modifying the composition of the supports. Different chemical synthesis approaches were considered for obtaining supported Ni nanoparticles with controllable compositions and sizes. For the citrate sol-gel method, it was found that with an increase in the citric acid/metals molar ratio from 0 to 1, the textural characteristics (specific surface area: 76-100 m2/g) of Ce0.2Ni0.8O12/Al2O3 catalysts, dispersion (average particle size: 10-5 nm) and reducibility (temperature of maximum H2 consumption: 580-530 °C) of the Ni-containing species improved. For calcined in air at 500 °C catalysts it was shown that Ni2+ cations stabilized in NiO or in the Ce-Ni-O solid solution. The proportion of the latter was maximum at a citric acid/metal molar ratio equal to 0.25, which was chosen as the optimal value in the investigated range of 0.25-1.0. An increase in the calcination temperature from 500 to 900 °C contributes to the stabilization of Ni2+ in the Al-Ni-O solid solution, which leads to a slight deterioration in the textural properties of the samples and a significant difficulty in their reducibility. After reductive activation at 800 °C of Ce0.2Ni0.8O12/Al2O3 samples, catalytically active metal Nio nanoparticles of -7 nm in size were formed for effective reforming of coal industry methane into synthesis gas. [ABSTRACT FROM AUTHOR]

Aerobic oxidative desulfurization of a model diesel fuel over MOx/CNTs catalysts (M = Ce, Cu, Mo) was studied to develop innovative technology for cleaning motor fuels to EURO-5 standard. It was shown that the thermal stability of catalysts improves in the following order of metal Cu < Ce < Mo. The disordering of the carbon matrix of support increases in the next row of M: Mo < Ce < Cu, which is accompanied by an increase in the specific surface area of the samples (40 → 105 m²/g). The forms of stabilization of the active component (CeO2, CuO/Cu2O/ Cu, or MoO3/MoO2) were revealed, indicating a partial reduction of the metal cations during the thermal decomposition of copper and molybdenum precursor compounds deposited on CNTs. In oxidative desulfurization of a model diesel fuel over MOx/CNTs catalysts at 150 °C the total conversion of dibenzothiophene increased in the next row of M: Ce < Cu < Mo. It was found that at 150 °C over the optimum MoOx/CNTs catalyst the highest dibenzothiophene conversion 95-99% is observed. It was assumed that the high activity of MoOx/CNTs is associated with both the oxidizing ability and the tendency of MoOx to chemosorption of sulfur compounds. [ABSTRACT FROM AUTHOR]

In this work, the introduction of modifying additives in the composition of catalysts is considered as an effective mode of improving functional characteristics of materials for two processes of methane conversion into valuable products - methane dehydroaromatization (DHA of CH4) into benzene and hydrogen and autothermal reforming of methane (ATR of CH4) into synthesis gas. The effect of type and content of promoters on the structural and electronic state of the active component as well as catalyst activity and stability against deactivation is discussed. For DHA of CH4 the operation mode of additives M = Ag, Ni, Fe in the composition of Mo-M/ZSM-5 catalysts was elucidated and correlated with the product yield and coke content. It was shown that when Ag serves as a promoter, the duration of the catalyst stable operation is enhanced due to a decrease in the rate of the coke formation. In the case of Ni and Fe additives, the Ni-Mo and Fe-Mo alloys are formed that retain the catalytic activity for a long time in spite of the carbon accumulation. For ATR of CH4, the influence of M = Pd, Pt, Re, Mo, Sn in the composition of Ni-M catalysts supported on La2O3 or Ce0.5Zr0.5O2/Al2O3 was elucidated. It was demonstrated that for Ni-M/La2O3 catalysts, Pd is a more efficient promoter that improves the reducibility of Ni cations and increases the content of active Nio centers. In the case of Ni-M/Ce0.5Zr0.5O2/Al2O3 samples, Re is considered the best promoter due to the formation of an alloy with anti-coking and anti-sintering properties. The use of catalysts with optimal promoter type and its content provides high efficiency of methane valorization processes. [ABSTRACT FROM AUTHOR]

A device is proposed for producing sulfur, in the form of a cylindrical reactor with several catalyst blocks consisting of heat exchange elements with an internal space for the passage of the coolant; the space between the elements is filled with a granular catalyst. The device additionally contains a steam heater for hydrogen sulfide-containing gas, a section for condensing sulfur vapors (surface condenser located below the catalyst units), and a thermosyphon device for removing reaction heat from the catalyst blocks. In this case, the catalyst units are equipped with devices for distribution of oxygen-containing gas over the cross section of the apparatus. The thermosyphon device is composed of a manifold distributor of the liquid heat carrier, a manifold-collector of the vapor-liquid mixture, and a separation space, which houses a steam heater of the hydrogen sulfide-containing gas. When highly concentrated hydrogen sulfide is oxidized (up to 90 vol. %) on the experimental apparatus, the sulfur removal is 4.0–4.1 kg/hr for every 1 liter of catalyst, the sulfur yield is 99.6% and a high-potential vapor is obtained (250°C, 4.0 MPa). [ABSTRACT FROM AUTHOR]

The effect of cobalt oxide content on the activity of NiO-Co2O3/γ-Al2O3 catalyst was investigated in process of dry reforming of methane (DRM) to synthesis gas. It was found that among the studied catalysts the highest activity is shown by the NiO-Co2O3/γ-Al2O3, where methane conversion is 89%. It was determined by the scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) there are oxides of Ni and Co in the form of nanosized particles on active NiO-Co2O3/γ-Al2O3 catalyst and Co-Ni alloys, formed after the reaction of DRM, the size of 17‒23 nm. Thermogravimetric Analysis (TGA)/Differential Thermal Analysis (DTA)/Differential Scanning Calorimetry (DSC) of catalyst showed that the highest weight loss (2.7%) is observed at a degree from 30 to 260 °C after DRM. After heating above 300 °C there is a slight increase in weight, accompanied by an exothermic effect on the DSC curve due to the gas adsorption used to purge the unit. The data indicate the absence of coke formation on NiO-Co2O3/γ-Al2O3 surface. According to TPR-H2 there are peaks at relatively low temperatures of Т¹mах = 205 °C and Т²mах = 497 °C on thermally programmed reduction (TPR) TPR-Н2 spectrum of NiO-Со2О3/γ-Al2O3, which are associated with the formation of easily reducible cobalt and nickel oxides, indicating the presence of active and mobile oxygen in the catalyst. These results confirm that the activity of NiO-Co2O3/γ-Al2O3 is due to the formation of nanophases, the presence of active oxygen, and the absence of coke on the catalyst surface. [ABSTRACT FROM AUTHOR]

Catalysts containing Mn, Mn–La and Mn–Ce oxides supported on ceramic honeycomb monoliths were prepared by excess-wet impregnation and solution combustion synthesis (SCS). In SCS, glycine was used as a fuel additive with variable concentration (fuel lean and fuel rich conditions). The catalysts were studied by BET, XRD, HRTEM, H2-TPR, and differential dissolution. Properties of the catalysts in the deep oxidation of butane were investigated. The best activity and stability were observed for the catalysts prepared by SCS under fuel rich conditions. Under these conditions, the active component is formed as highly dispersed particles of manganese oxides in the composition of simple and mixed oxides that are located in subsurface layers of the support. On the contrary, manganese oxides that are formed upon thermal treatment of the impregnation catalyst are located mostly in the bulk of the support. Reducing conditions of the SCS reaction lead to the formation of simple and mixed oxides where manganese is mostly in Mn3+ and Mn2+ oxidation states. The presence of reduced manganese species in the subsurface layers of support, which are accessible to reactants, provides high efficiency of SCS catalysts in the oxidation of butane. [ABSTRACT FROM AUTHOR]

In order to stabilize in the support matrix highly dispersed nickel forms of the active component, which are characterized by thermal stability and high resistance to carbonization under conditions of hydrocarbon raw material reforming, the synthesis of Ni–Ce–La–O catalysts was carried out with varying composition (La/Ce = 0, 0.25, 1, 4), the preparation technique (the method of polymer ester precursors and incipient-wetness impregnation) and the calcination temperature (300–900°C) of the samples. The patterns in the formation of materials are studied and a comparative study of the physicochemical properties of materials by a complex of methods (low-temperature nitrogen adsorption, X-ray phase analysis, Raman spectroscopy, transmission electron microscopy, and temperature-programmed reduction with hydrogen) is carried out. It is shown that at La : Ce = 0–4, the materials after calcination at 300–500°C are solid solutions based on ceria (Ni–Ce–La–O, Ce–La–O) with deposited nickel oxide particles. Compared with impregnation, the method of polymer ester precursors provides a higher specific surface area and the defect structure of material, a smaller average crystallite size of the solid solution, and nickel stabilization mainly in the composition of a ceria-based solid solution. After high-temperature calcination at 700–900°C, the differences in the textural and structural characteristics of the catalysts prepared by different methods become less pronounced, which is due to the partial destruction of the Ni–Ce–La–O solid solution. It is found that an increase in the dispersion and thermal stability of the Ni-containing phase and a decrease in the degree of carbonization of the Ni–Ce–La–O catalysts in the ethanol autothermal reforming is achieved by increasing the La : Ce molar ratio and using the method of polymer ester precursors for the synthesis. [ABSTRACT FROM AUTHOR]

The effect of preparation procedures (a polymer ester precursor method and incipient wetness impregnation) on the physicochemical and functional properties of Ni/CeO2 catalysts with different nickel contents (0–15 wt %) was studied in order to develop highly active and carbonization-resistant catalysts for hydrocarbon reforming. Based on the results of studying the samples by low-temperature nitrogen adsorption, X-ray phase analysis, Raman spectroscopy, transmission electron microscopy and temperature-programmed reduction with hydrogen, it was found that the textural, structural, and redox properties of the materials depend on the method of their synthesis. As compared with the samples prepared by impregnation, the Ni/CeO2 catalysts obtained by the polymer ester precursor method were characterized by different active component stabilization forms (a Ce1 –xNixOy solid solution phase and NiO particles <5 nm in size vs. a NiO phase with a particle size of 5–50 nm), a smaller average size of CeO2 crystallites (5.5 vs. 11 nm), a high specific surface area (105 vs. 75 m2/g), a defect structure, and a decreased reducibility. It was found that the samples of both series provided comparable yields of hydrogen (to 50% at 600°C) in an autothermal ethanol reforming reaction, but the Ni/CeO2 catalysts synthesized by the polymer ester precursor method were more resistant to the formation of carbonaceous deposits. [ABSTRACT FROM AUTHOR]

To elucidate the role of support composition in autothermal reforming of ethanol (ATR of C2H5OH), a series of Ni catalysts (Ni content 2-15 wt.%) supported on different ceria-based oxides (Ce1-xGdxOy, Ce1-xLaxOy and Ce1-xMgxOy; x = 0.1-0.9) were prepared. The synthetized materials were tested in ATR of ethanol at 200-700 °C. It was established that supports themselves show catalytic activity in ATR of C2H5OH and provide 10-15% yield of H2 at 700 °C. Upon the increase of Ni content from 2 to 15 wt.% the temperature of 100% ethanol conversion decreases from 700 to 300 °C, hydrogen yield increases from 25 to 60%, the inhibition of C2-C3 by-products formation, as well as the promotion of decomposition of acetaldehyde occur. The enhancement of catalyst performance in ATR of C2H5OH has been observed in the next series of supports: Ce1-xMgx Oy < Ce1-xGdxOy < Ce1-xLaxOy and with a decrease of x to an optimal value that correlates with the improvement of Ni active component reducibility. At 600 °C on 10Ni/Ce0.8La0.2O1.9 catalyst the H2 yield of 50% was achieved at C2H5 OH conversion of 100%. Stable and high performance of developed catalysts in ATR of C2\H5OH indicates the promise of their use in the production of hydrogen. [ABSTRACT FROM AUTHOR]

In recent decades, numerous reactions were shown to proceed efficiently with participation of uranium-containing catalysts. The present review considers physicochemical properties of uranium compounds employed in the catalyst synthesis. Methods for preparation and investigation of the catalysts containing depleted uranium compounds are analyzed and systematized. Special emphasis is made on possible applications of such catalysts in various chemical processes. [ABSTRACT FROM PUBLISHER]

Nanoparticle-doped mesoporous titania coatings were synthesized by incorporation of PdZn nanoparticles into support sol and deposition of the resulting sol on the inner surface of a fused silica capillary. This method allows controlling the chemical nature of the film, the porosity, metal dispersion and loading with an active species. The structural properties, chemical composition and morphology of the active component and the support were studied by means of TEM, EDS, ICP-AES, X-ray diffraction and N2 adsorption. Monodispersed PdZn bimetallic colloidal particles were prepared by polyol method in the presence of polyvinylpyrrolidone. The average particle size ranging from 1.8-4.3 nm was found to depend on the amount of PVP added and NaOH concentration. The bulk composition of nanoparticles depends on concentrations of the precursors and NaOH. The reaction mechanism is shown to involve the oxidation of ethylene glycol to mainly glyoxal and glycolic acid, while the metal Pd salts are reduced to form catalysts for Zn2+ ions reduction. Palladium-zinc-incorporated mesoporous TiO2 films were synthesized by a sol-gel method using a nonionic structure-directing agent Pluronic F127. The control of the pore size of the mesoporous titania was achieved by adding co-surfactants, such as n-butanol. The influence of the activation conditions on crystallite size and composition of metal particles was investigated. [ABSTRACT FROM AUTHOR]

Aspects are considered of providing safe oxidative conversion of acid gases directed in plant handling ethanolaminar purification of petroleum fetching gases in a fluidized bed of spherical catalyst. Details are established of an automated machine system for controlling the process in accordance with the current transformation from hazardous production objects. A unified approach is provided for analog and digital regulators with contours for maintaining the control by reference to perturbation in the reverse-coupling contour, which allows one to use a model to realize automatic regulation in a control computer. The basis is given for regulating the optimal relationship between volume flow rates for oxygen and hydrogen sulfide. [ABSTRACT FROM AUTHOR]

Abstract: The formation of carbon nanofibers (CNFs) doped with nitrogen was investigated during decomposition of C2H4/NH3 mixtures at 450–675°C over metal catalysts: 90Ni–Al2O3, 82Ni–8Cu–Al2O3, 65Ni–25Cu–Al2O3, 45Ni–45Cu–Al2O3, 90Fe–Al2O3, 85Fe–5Co–Al2O3, 62Fe–8Co–Al2O3, 62Fe–8Ni–Al2O3. It was found that the yield of CNFs, their structural and textural properties, as well as nitrogen content in CNFs are strongly dependent on the synthesis conditions such as: catalyst used, feed composition, temperature and duration. The 65Ni–25Cu–Al2O3 was proved to be the most efficient catalyst for the production of nitrogen-containing carbon nanofibers (N-CNFs) with nitrogen content up to 7wt.%. Ammonia concentration in the feed equal 75vol.%, temperature 550°C and duration 1h were found to be the optimum reaction parameters to reach the maximum nitrogen content in N-CNFs. TEM studies revealed that the nanofibers have a helical morphology and a “herringbone” structure composed of graphite sheets. According to the XPS data, the nitrogen incorporation in the N-CNF structure leads to the formation of two types of nitrogen coordination: pyridinic and quaternary, and their abundance depends on the reaction conditions. [Copyright &y& Elsevier]

The MoZSM-5 (4.0 wt % Mo) catalyst has been characterized by high-resolution transmission electron microscopy, EDXA, and EPR. Two types of molybdenum-containing particles are stabilized in the catalyst in the course of nonoxidative methane conversion at 750°C. These are 2-to 10-nm molybdenum carbide particles on the zeolite surface and clusters smaller than 1 nm in zeolite channels. According to EPR data, these clusters contain the oxidized molybdenum form Mo5+. The surface Mo2C particles are deactivated at the early stages of the reaction because of graphite condensation on their surface. Methane is mainly activated on oxidized molybdenum clusters located in the open molecular pores of the zeolite. The catalyst is deactivated after the 420-min-long operation because of coke buildup on the zeolite surface and in the zeolite pores. [ABSTRACT FROM AUTHOR]

Cu-ZSM-5 catalysts for the selective reduction of NO with propane were obtained by ion exchange between H-ZSM-5 zeolite and an aqueous or aqueous ammonia solution of a copper salt (acetate or nitrate). Their Cu/Al values (%) defined as 2 × 100 (Cu : Al), where Cu : Al is the copper-to-aluminum atomic ratio, were determined as a function of ion exchange pH, which was varied by changing the copper salt and solution concentration. Cu/Al is primarily determined by the chemical nature of the starting copper salt. For a given salt, it is governed by the salt concentration in the solution. At a fixed salt concentration, Cu/Al is always larger for copper acetate than for copper nitrate. It can be raised to ≫100% by using an aqueous ammonia solution of a copper salt. Furthermore, it increases with increasing Si/Al in the starting zeolite if the other ion exchange conditions are equal. Irrespective of preparation conditions, the catalytic activity of Cu-ZSM-5 grows in proportion to Cu/Al. It peaks at Cu/Al ∼ 100% and then remains constant up to Cu/Al ∼ 400%. In order to achieve Cu/Al ∼ 100%, it is most appropriate to use a copper acetate solution. [ABSTRACT FROM AUTHOR]

Valence and coordination states of molybdenum ions formed upon thermal treatment of Mo/H-ZSM-5 catalyst for methane dehydroaromatization in Ar and Ar/CH4 media at 573-973 K have been studied by ESR and UV-VIS spectroscopy. For comparison, the characteristic ESR spectra of thermolyzed bulk ammonium heptamolybdate have been studied and analyzed in detail. The nature of earlier observed Mo5+ ions has been verified, and new paramagnetic states of molybdenum in Mo/H-ZSM-5 catalysts have been detected: Mo3+ ions, and Mo5+ ions in tetrahedral coordination with delocalization of unpaired electron to Al and H or Al and N atoms. [ABSTRACT FROM AUTHOR]

The article presents information on the stabilization of Co2+ and Cu2+ by Extraframework Aluminum Ions in HZSM-5 Zeolite Channels. Considerable recent attention has been focused on the unusual catalytic properties of high-silicon zeolites modified by doubly charged cations, in particular, Cobalt ions. One popular viewpoint is that Magnesium ions are located in HZSM-5 zeolite channels at the charge-exchange sites of the oxygen environment of isolated Al atoms or Al-Al pairs included in the zeolite framework.

The phase composition of supported Mn–Al–O catalysts and their activity in the reaction of methane oxidation were studied depending on the composition of aluminum oxide supports (γ-Al2O3 with different χ-Al2O3 contents modified with individual Mg, La, and Ce oxides or Mg + La and Mg + Ce oxide mixtures) and calcination temperatures (500, 900, and 1300°C). It was found that the Mn–Al–O catalysts based on γ-alumina containing χ-Al2O3 and modified with Mg, La, or Ce additives are more active and thermally stable (up to 1300°C) than the samples based on pure γ-Al2O3. A conclusion was drawn that a higher degree of disorder of the structure of χ-Al2O3, compared to that of γ-Al2O3, is favorable for a deeper interaction of manganese and modifying additives with the support at the early stages of the synthesis and for the formation of Mn–Al compounds with complex composition (solid solutions and/or hexaaluminates) at 1300°C. These compounds are responsible for the stability and high activity of the catalysts in methane oxidation. [ABSTRACT FROM AUTHOR]

Review: 120 refs. [ABSTRACT FROM AUTHOR]

Steady and efficient decomposition of methane can be achieved at 625–675 °C over copper-promoted (8–15 wt.% of copper) nickel catalysts prepared from a Feitknecht compound precursor. Such catalysts permit one to increase the yield of catalytic filamentous carbon (CFC) and control both microstructural and textural properties of CFC by varying the copper concentration in the catalyst. The maximal conversion of methane into hydrogen and carbon reaches 40% at 675 °C at the carbon capacity not lower than 700 g/gNi under optimal conditions. The BET surface area of the CFC is 285.9 m2/g. The influence of promotion of nickel-containing catalysts with copper on the catalytic activity is discussed. [Copyright &y& Elsevier]

A number of Cu- and Fe-hydroxide containing catalysts, supported on oxide carriers, were prepared to provide the removal of 1,1-dimethylhydrazine from aqueous solutions via its oxidation by hydrogen peroxide and air oxygen. The Cu-containing samples as well as Fe/ZSM-5 are the most active catalysts in this reaction. The reaction products were analyzed by gas chromatography and UV–Vis spectroscopy. The effect of nature of the oxidizer and catalyst, pH and temperature on both the reaction rate and product composition was studied. [Copyright &y& Elsevier]

Catalysts containing platinum (1 and 10 wt.%) or cobalt oxide (10, 50 and 90 wt.%) and nitrogen doped carbon nanofibers (N-СNFs) were synthesized. X-ray photoelectron spectroscopy, CO chemisorption and temperature-programmed reduction methods were used to reveal that pyridine-like nitrogen of N-СNFs is involved in the anchoring of metal or oxide particles on the carbon surface and determines their size, electronic state and redox ability, thus changing the catalytic performance of the catalysts in the oxidation of carbon monoxide. Various models of particle stabilization on the surface of N-CNFs were proposed: (1) stabilization of nanoparticles with the retention of their metallic state by the pyridine-like site; (2) stabilization of electron deficient nanoparticles by a pair of pyridine-like nitrogen sites and (3) stabilization of electron deficient nanoparticles by the pyridine-like site near the carbon vacancy. [ABSTRACT FROM AUTHOR]