V. A. Drozdov

Chemical composition optimization and characterization of the NiO/B2O3-Al2O3 system as a catalyst for ethylene oligomerization

The samples of the NiO/B2O3-Al2O3 system with NiO contents from 0.48 to 38.30 wt % were synthesized by the impregnation of borate-containing alumina (20 wt % B2O3). It was found that nickel oxide occurred in an X-ray amorphous state in the samples containing to 23.20 wt % NiO. At a NiO content of 4.86 wt % or higher, the support was blocked by the modifier to cause a decrease in the specific surface area from 234 to 176 m2/g and in the amount of acid sites from 409–424 to 333 μmol/g. An extremal character of the dependence of catalyst activity in ethylene oligomerization on NiO content was found with a maximum in the range of 4.86–9.31 wt %. Based on spectroscopic data, it was found that ethylene activation on the NiO/B2O3-Al2O3 catalyst can be associated with the presence of Ni2+ cations, which chemically interact with the support. The catalyst containing 4.86 wt % NiO at 200°C, a pressure of 4 MPa, and an ethylene supply rate of 1.1 h−1 provided almost complete ethylene conversion at the yield of liquid oligomerization products to 90.0 wt %; the total concentration of C8+ alkenes in these products was 89.0 wt %.

Study of the effect of a number of oxidizers on variation of composition of surface functional groups, porous structure, and adsorption properties of composite carbon-carbon sorbent

The oxidation of a carbon-carbon composite sorbent by a number of oxidants results in the variations of the chemical nature of the surface, including an increase in the overall content of surface oxygen-containing groups and, in separate cases, increased variations in its structure-chemical characteristics, primarily in an increase in the percentage of large mesopores. The oxidative modification of the initial sorbent increases the hydrophilicity of its surface and enhances the specific sorption of water vapors.

Interaction of nickel hydroxocarbonate, ammonium paramolybdate, and ammonium metatungstate under mechanical activation

The interaction of nickel hydroxocarbonate, ammonium paramolybdate, and ammonium metatungstate (Ni: Mo: W = 3: 1: 1) is reported. Under mechanical activation conditions, nickel hydroxocarbonate particles undergo comminution and ammonium paramolybdate and ammonium metatungstate particles soften and aggregate. It is demonstrated by DTA, X-ray diffraction, and IR spectroscopy that heat treatment of the mechanically activated mixture at 400–450°C yields the salts NiMoO4 and NiWO4.

A study of the influence of the conditions of preparation of γ-aluminum oxide as a carrier for reforming catalysts on its physicochemical properties

The formation of highly imperfect γ-Al2O3 oxide prepared by calcining pseuodoboehmite and plasticized by organic acids was studied. The nature of the organic acid-aluminum hydroxide plasticizer was found to substantially influence the degree of γ-Al2O3 structure imperfection estimated qualitatively as the difference between the X-ray structural density and effective density with respect to helium and aluminum oxide. A high degree of imperfection caused an increase in the intensity of the absorption band at 3775 cm−1 corresponding to OH groups localized on five-coordinate Al3+ and the concentration of Lewis acid centers. The adsorption and catalytic properties of systems based on these carriers were studied.

Evolution of the Structures and Sorption Properties of Dehydrochlorinated Chloropolymers during Their Thermal Conversions

A microporous carbon material can be obtained by dehydrochlorination of the polymeric formulation poly(vinyl chloride)-poly(vinylidene chloride) in the presence of KOH followed by thermal treatment at a relatively low temperature (350°C in a nitrogen-oxygen gas mixture (10: 1 w/w)). This is because the chemical dehydrochlorination gives highly reactive chloro-containing polyconjugate systems. The conversion of chloropolyene systems into carbon structures is confirmed by Raman spectroscopy and TGA with MS analysis of volatile pyrolysis products. The resulting carbon material has a system of pores including ultramicropores 6.5 ± 0.5 Å), micropores (16 ± 1 Å), and mesopores (average pore size 150 ± 7 Å).

Synthesis of polychlorovinylenes as active conjugated polymers and their application for low-temperature formation of carbon structures

A low-temperature approach to the synthesis of carbon structures by dehydrochlorination of carbon-chain chlorine-containing polymers was suggested. The formation of carbon structures was observed in the temperature range of 200—400 °C, which was confirmed by Raman spectroscopy and transmission electron microscopy with X-ray microanalysis. This approach can be used in the processes of preparation of carbon materials with specified structures and in the development of dioxine-free methods for utilization of chlorine-containing polymers.

Structure and Composition of Aluminum Oxide Films in Contact with the Liquid In-Ga Eutectic

The oxide layers on the surface of aluminum metal and the aluminum alloys AD-1 and A-5 have been studied by attenuated total reflection infrared spectroscopy. The Al-O and Al-OH surface vibrational modes and A-O modes of the AlO4 and AlO6 groups have been identified. The structural inhomogeneity of the surface oxide layers is shown to contribute to their disruption when the sample is brought into contact with the liquid In-Ga eutectic. In situ scanning electron microscopy and X-ray microanalysis have been used to follow the dynamics of oxide layer disruption and the morphological and compositional changes in the eutectic alloy and the surface layer of aluminum.

Effect of pseudoboehmite peptization by organic acids on texture characteristics of obtained aluminum oxides

The texture characteristics of aluminum hydroxides peptized by organic acids and then calcined were studied. A decrease in the pore volume and pore diameter for aluminum hydroxide was studied as a function of the amount of a peptizer. The calcination causes basic aluminum salts obtained by peptization to decompose at different temperatures, depending on the strength of a peptizing acid. The observed regularities were explained in terms of the thermal decomposition of organic aluminum salts of varied composition.

Developing the synthesis of homogeneously microporous carbon membranes for selective extraction and accumulation of organic molecules with a carbon unit as a carrier

The composite carbon-carbon membranes (CMS membranes) obtained by polymer modification of a mesoporous carbon substrate through the formation of an activated carbon layer have microporous structures (specific micropore volume 0.11 ± 0.05 cm3/g). The size distribution of micropores shows two distinct peaks at 4.5 to 6.5 and 7.0 to 9.0 Å. The micropores with these widths adsorb well CO2 and CH4, respectively.

Studies of the effect of surface modification of carbon sorbents by poly-N-vinylpyrrolidone using a complex of physicochemical and microbiological methods

The surface of the VNIITU-1 carbon mesoporous sorbent was modified with poly-N-vinylpyrrolidone characterized by antibacterial activity. Synthesis was carried out in two stages: (1) impregnation of the carbon sorbent by an aqueous solution of poly-N-vinylpyrrolidone with the molecular mass of 10000 g/mol; and (2) impregnation of the carbon sorbent by an aqueous solution of the (N-vinylpyrrolidone) monomer and initiator with their further polymerization in an inert atmosphere. Carbon sorbent samples were studied using a complex of physicochemical methods: scanning electron microscopy, infrared spectroscopy, low-temperature nitrogen adsorption, nuclear magnetic resonance, and thermogravimetry. It was found that the polymer obtained on the carbon surface is free of the initial toxic VP monomer. Microbiological tests of modified sorbents with respect to pathogenic and opportunistic microflora were carried out.