Home – Home – Jornals – Chemistry for Sustainable Development 2007 number 6

The basic catalytic processes of hydrogen generation, which enclose the efficient use of hydrogen permeable membranes, are discussed. A variety of types of solid membranes are inspected for their suitability for hydrogen extraction from the gas mixture. The constructions of catalytic reformers with an integrated membrane module are given, and advantages of these devices relative to traditional reactors of fuel processor are discussed. The mathematical models of reaction vessels with the membrane release of hydrogen and certain of the simulation results are presented. The prospects for using catalytic reactors with membranes in the hydrogen energetics and transportation facilities are discussed.

Granulometry, morphology data and data on mineral composition of aerosol particles are given. These have been obtained with the use of scanning electronic microscope LEO 1430 VP that was furnished with energy dispersive spectrometer OXFORD. Mineral-geochemical indicators of local sources of aerosol pollution under conditions of a megacity have been determined using ICP-MS, ICP-AES, XRD-SI, atomic absorption, and phase X-ray diffraction methods. Mobility of toxic elements that were accumulated in a snow covering has been found. A comprehensive approach has allowed us to estimate the contribution of particular commercial manufacturers to the general ecological condition of Novosibirsk.

Composition and rheological behaviour of asphalt-resin-paraffin depositions that were excreted from high-wax oils under changes of temperature gradient of oil and adsorbing surface has been studied.
An effect of petroleum composition and temperature on the quantity, composition, and rheological behaviour of oil sediments has been demonstrated.

Methods of chromatography mass spectrometry and microcolumn high performance liquid chromatography have been used to study complex biological systems. Potentialities to apply these methods have been disclosed by the example of biochemical research of symbiotic community of the endemic Baikal sponge Lubomirskia baicalensis (Dybowsky, 1874) when it is kept both under natural and under simulated conditions. It has been demonstrated that the use of a complex of modern methods of biochemical analysis allows effective, rapid determination, high sensitivity detecting of changes in biologically active compounds in living organisms.

Original data that were obtained by means of microcolumn reversed-phase high performance liquid chromatography method have been presented on content of liposoluble vitamins (A, D, E, F) in muscles and liver of big golomyanka Comephoeng baicalensis.

Based on data for component composition of the source natural gas, external pressure, and temperature, the structure of hydrates of natural gas has been found for the main gas and oil fields of Yakutia. It has been determined that the total amount of gas in 1 L of gas hydrate ranges from 160 to 250 L.

Panzerina lanata subsp. argyracea (Kuprian.) Krestovsk. is a valuable drug plant that grows in Khakassia. It contains a complex of biologically active compounds including flavonoids. Resources of panzerina raw material steadily go down owing to anthropogenic load. Its domestication solves the problem of its preservation. A wild-growing cenopopulation with the greatest content of flavonoids in the aboveground part has been revealed that is of interest as a starting material for plant introduction. The content of flavonoids in particular members of plants Panzerina lanata subsp. argyracea that grows in various cenopopulations of Khakassia and under conditions of plant introduction has been examined. Dynamics of accumulation of flavonoids for strange silvery panzerina has been determined in various vegetation phases. It was found that plants in the crop exhibit a high level of variability in their content of flavonoids.

An environmentally sound method to produce microcrystalline cellulose (MCC) has been developed. Conditions have been adjusted that make it possible to produce top-quality MCC with a good yield. The produced MCC is highly competitive with commercial samples in its performance. By means of combined mechanical activation of piroxicam and MCC that was obtained following a new technology, compositions have been prepared that offer higher than usual speed of dissolving of a medicinal substance. It has been demonstrated that "graft complexes" are formed between MCC and piroxicam as a result of interaction of the ingredients to form hydrogen bonds.

The possibility to prepare bimetallic catalysts Fe-Ni, Fe-Co and Co-Cu through thermolysis of binary complex salts involving a complex cation of one metal and a complex anion of other one is discussed, and their catalytic properties in Fischer-Tropsch synthesis are presented. Our study revealed that deposition of binary complex salts having composition [Ni(NH₃)₆]₃[Fe(CN)₆]₂, [Co(NH₃)₆][Fe(CN)₆] and [Co(NH₃)₆]₂C₂O₄[Cu(C₂O₄)₂]₂ on to the surface of aluminium hydroxide and subsequent thermolysis of the obtained composition give the chance to have metallic particles of size 15-40 nm fixed on the surface of aluminium oxide. In the case of binary complexes Ni-Fe and Co-Fe, the formation of bimetallic particles of size 15-16 nm and respective structures FCC and BCC is observed. Break-up of complexes proceeds in several sequential exothermic stages. The catalytic properties of bimetallic particles Fe-Co of BCC structure, which are prepared by thermolysis of [Co(NH₃)₆][Fe(CN)₆] + Al(OH)₃ composition, differ essentially from the literature data for Co-Fe catalysts by the reduced activity of the prepared particles with respect to the secondary processes for hydrogenation of olefins. This feature manifests itself in the extremely high selectivity of the process in relation to olefines and its anomalous temperature dependence. A rise in the process pressure up to 10-20 atm leads to significant changes in catalytic properties of bimetallic Co-Fe catalysts, among them the loss of selectivity in relation to olefins and the decrease in the rate of secondary process of vapour conversion of CO. The pressure dependence of process passing character is caused by variation in structure of catalytically active component under the action of reagents.

Indirect electrochemical oxidation of benzene by intermediates has been studied. The intermediates were generated in situ from О₂, Н₂О, and Н₂О₂ with the use of anodes from platinum, lead dioxide, and ruthenium-titanium oxide anode in water solutions with various рН. Schemes with in situ generated Н₂O₂ from О₂ and with Н₂O₂ adding to electrolyte have been implemented. It was found that hydroxylation of benzene to produce phenol with a gas diffusion cathode from commercial-grade carbon that generates Н₂О₂ from О₂ in situ is ineffective because of the cathode passivation. On Н₂О₂ addition into the electrolyte, oxidation of benzene occurred with mineralization to yield СО2 and Н2O; the oxidation state could amount from 94.8 % (Pb/PbO₂, рН 2) to 63.5 % (Pt-anode, рН 2.8, С_Fe2+ = 7.1 ⋅ 10^-6 mg/L). Efficiency of oxidation drops owing to the formation difficult-to-oxidize carboxylated complexes of iron.

Thermal conversions of sapromixite from Barzas deposit in an inert medium, hydrogen medium, and that of synthesis gas have been studied in a flow-through reactor under atmospheric pressure and in an autoclave under a pressure of up to 7 MPa. A higher conversion level of brown coal as compared with sapromixite is determined by a low metamorphic degree of brown coal and by its high content of highly reactive oxygen-bearing fragments. However, the yield of resins from sapromixite in a temperature range of 450-850 ^oC is 3-4 times higher when compared to the yield from brown coal. It has been found that an increased yield of resins under variations in heat treatment conditions is caused for the most part by a decrease in the formation of gases and water. The yield of semicoke has no any significant changes. The process flow diagram has been suggested that explains the observed effects. It has been demonstrated that unlike heat treatment in an autoclave, when employing a flow-through reactor and atmospheric pressure, the composition of the gas medium has no tangible effect on the conversion level of combustible. Meanwhile, the liquid yield at a temperature of devolatilization of coal, 650 ^oC, in a current of hydrogen and synthesis gas is at least 1.5 times higher by comparison to the yield in devolatilization of coal in an inert medium. A procedure of devolatilization of sapromixite has been suggested that affords an enhanced liquid yield as compared with the conventional process by way of using the products of gasification of a fixed residue of the process as the gas heat carrier.

Results of mass spectrometer determination of the comprehensive group content and molecular-mass distribution of hydrocarbons of 30 various structural types in lower Cretaceous oils of East Gobi and Tamsag oil rich provinces of Mongolia have been presented. Hydrocarbon types of oils according to three current ways of classification have been determined; factors responsible for the distinctions in types of oils being determined by these ways have been found.

The role of the hydrodynamic cavitation for initiating and supporting chain-radical reactions of oxidation of organic substrates, among them 4-nitrophenol (4-NP), with Fenton's reagent (H₂O₂ + Fe²⁺) has been shown. Fe²⁺ ions were supplied into solution by dissolving split steel shot or steel chips in cavitation reaction vessel. At initial concentrations of 4-NP and H₂O₂ of 6.7 ⋅ 10^-5 and 4.02 ⋅ 10^-4 mol/L, respectively, the degree of phenol conversion at pH 3.4 reaches 98 %. The diagram of the set-up designed to treat sewage with productivity 0.5 m³/h and the description of the equipment for cavitation generation are presented.

The possibilities for sublimation of silicon and aluminium - basic components of refractory aluminium silicates - to gas phase have been demonstrated by way of thermodynamic computations and experiments with minerals of sillimanite tribe. The proposed method is founded on alternate action of chlorine on aluminium silicates in the presence of carbon-bearing reductant and aluminium subchloride as a reductant, with the results that low-boiling salts of aluminium and silicon are produced. This method was demonstrated to be economically feasible by direct expenditure of electric energy on the return of aluminium subchloride to the cycle solely in the case of joint production of aluminium and silicon from minerals of sillimanite tribe.

Content of toxic heavy metals (Ni, Cr, Cd, Co, Pb) in the rock-soil-plant system in forest steppe of Transbaikalia has been studied. It was found that it does not exceed percent abundance values and MPC of soils and plants.