Home – Home – Jornals – Chemistry for Sustainable Development 2013 number 3

Methodology of in situ investigations aimed at the studies of heterogeneous catalytic reactions is presented. The advantage of this approach in comparison with ex situ studies is demonstrated with a number of examples. The outlooks and possibilities of the application of various physical methods in the in situ mode are considered.

Modification of the oxide surface of aluminium oxide with oxalate complexes of aluminium was carried out, followed by thermal treatment for the purpose of varying the ratio between the functional groups on the surface (ОН groups, Lewis acid centres). It was established that the modification of γ–Al₂O₃ causes a 1.5-fold increase in the amount of adsorbed platinum (IV) complexes and the fraction of these complexes strongly bound with the surface of the support. The effect of γ–Al₂O₃ surface modification on the catalytic properties of the system Pt/Al₂O₃ was demosntrated. It was shown that an increase in the fraction of platinum forms strongly bound with the support causes an increase in the content of methylcyclopentane in the products of n–hexane isomerization and an increase in the selectivity of the formation of propylene in propane transformations.

Modern approaches to the development of ecologically and economically acceptable methods for obtaining a number of industrially essential products are considered. The promising character of the application of phase-transfer catalysis method for reactions proceeding in liquid two-phase systems with the use of ecologically favourable oxidizing agent – hydrogen peroxide – was demonstrated. Results of integrated studies of the structural characteristics of tungsten peroxopolyoxocomplexes formed in the interaction of the aqueous solutions of phosphotungstic heteropolyacid with hydrogen peroxide by means of EXAFS, Raman and IR spectroscopy are presented. The synthesized catalysts Q₃{PO₄[WO(O₂)₂]₄}, where Q₃ is a quaternary ammonium cation, were tested in the reactions of oxidation of organic substrates with 30–35 % H₂O₂ solutions.

The review is devoted base-catalyzed intramolecular cyclization of ammonium salts containing β,γ-unsaturated groups alongside with various enyne fragments. This process results in the formation of polynuclear isoindolinium salts and in the transformation (recyclization) of those containing the hydroxymethyl group at the position 4 in the aromatic ring.

There were investigated two variants of NaCl isolation from the solutions of human exometabolite mineralization and plant wastes, based on the fractional crystallization of salts via evaporation and the low solubility of NaCl in concentrated HCl, respectively. It has been established that owing to preferential dissolution of the impurities in the concentrated HCl, from the mineralized solutions one could recover 99 % of NaCl contained therein, whose purity of which is not worse with respect to the standard food grade salt. The methods for proposed processing the mineralized solutions allow one to involve NaCl and H₂O into the mass exchange within closed environments.

With the use of HPLC technique, studies on the amino acid composition of human bone tissue within the age range of 30–79 years were performed. Gender-features concerning the qualitative and quantitative amino acid content have been revealed. It is demonstrated that the clinical course of coxarthrosis does not lead to significant changes in amino acid composition of human bone tissue.

Organochlorine wastes generated in the production of epichlorohydrin, and lignin could be co-processed to obtain the sulphur-containing derivatives. For this purpose, the wastes of chloroorganic synthesis and hydrolytic lignin chlorinated under mild conditions should be entered into the reaction with sulphur in the form of sodium polysulphides. The overall process is cost-efficient due to the fact that it provides an almost complete conversion of organochlorine waste disposal, sulphur compounds as well as lignin binding. The condensation products obtained were tested as additives for modifying bitumen and demonstrated a good processability.

The dynamics of thermolysis was studied for the bituminous sandstone taken from the Bayan-Erkhet deposit (Mongolia). It has been demonstrated that the thermolysis procedure could be used for the isolation of bituminous component from these raw materials to obtain valuable intermediates for coal chemistry and motor fuels.

The results of research work are reported concerning the thermal decomposition of coal species from the Ulugh and Chadan beds of the Kaa-Khem site of the Tuva deposit as well as an effect of coal activation on the decomposition process. Potentiality is demonstrated for briquetting the coal after removing gaseous and light liquid fractions from the material.

An alternative gas phase nitration process was investigated wherein the reaction between an aromatic substrate (benzene/toluene) and a nitrating agent (either a 68 mass % HNO₃ aqueous solution, or a mixture of nitrous gases) occurs on a fixed-bed solid acidic catalyst. There have been studied physicochemical properties (elemental composition, pH, crystallinity) and catalytic properties inherent in the samples of naturally occurring zeolites taken from the deposits of Siberia and the Far East. An effect of zeolite preliminary treatment (calcination and acid extraction method) exerted on the activity thereof was investigated. It has been demonstrated that the highest activity is exhibited by a sample with the highest concentration of Bronsted acid sites (99 µmol/g according to NH₃ adsorption), taken from the Kulikovo deposit (the Amur Region). The productivity of the sample amounted to 161 mg/(g_cat · h).

Studies were performed concerning the features of soil ecological, microbiological and biochemical properties under influenced by the emissions of aluminum plants in Siberia. It has been found that the anthropogenically transformed soils of sub-taiga influenced by water-soluble fluoride species (10–20 MPC) cause the greatest inhibition of actinomycetes and chemoorganotrophic asporogenous bacteria. The steppe chernozem under the influence of fluorine (1–4 MPC) demonstrates a decrease in the level of biochemical activity.

Integrated studies of ion exchange extraction of tungsten was carried out in application to the carbonate solutions of autoclave leaching of raw material with low tungsten content. Anionite and desorbent for tungsten extraction were chosen. The integrated technology of processing tungsten-containing raw material was proposed, resulting in obtaining metal tungsten, with the possibility of regeneration of the treating reagent sodium carbonate.

The composition and structural features of the resin-asphaltene macromolecular fragments inherent in the substances from the Usinsk oilfield were investigated. It has been demonstrated that they contain ether and/or ester groups. Nitrogenous bases in the form of supramolecular structures are present only in the structure of the resinous components.

Changes of the quantitative and qualitative characteristics of peat components (bitumen, lignin, cellulose, humic acids) under cavitation action of aqueous alkaline media are considered. It was demonstrated that the cavitation treatment of peat in alkaline solutions involves the structural rearrangement, changes of separate fragments of macromolecules. As a result, additional amount of humic acids is formed. To obtain humic acids, it is preferable to use the aqueous solution of ammonia as the base. In water-ammonia medium, nitrogen fixation occurs with the participation of all the components of humate–carbohydrate complex.