Home – Home – Jornals – Chemistry for Sustainable Development 2016 number 1

Effect of the nature and content of secondary support, as well as the content and nature of palladium precursor on the catalytic activity in CO oxidation is considered for Pd/MeO _x /Ni-Al/SS catalysts where SS is stainless steel. It is demonstrated that the Ni-Al coating used to increase oxide adhesion to the metal substrate can serve as a catalyst and secondary support for palladium. It was determined that the best palladium precursor is [Pd(NH₃)₄](NO₃)₂. On the basis of the results of catalytic tests, the most active samples activated and not activated by palladium were revealed. All the catalysts are characterized by means of X-ray phase analysis and scanning electron microscopy with local microanalysis.

Results of field and laboratory studies of steam and gas assisted escape of elements from the material of sulphide-containing tailing dump (Komsomolsk settlement, Kemerovo Region) are presented. It was established that sulphur dioxide concentration in the ground layer of the atmosphere above the tailing dump exceeds the maximum permissible concentration more than 10 times. Due to emission from ground into the air, a broad range of chemical elements enters the atmosphere, though these elements are traditionally considered as non-volatile at low temperatures (Fe, Al, Mn and so on). The concentrations of As, Ni, Zn and Pb are substantially higher than the MPC for the air of populated areas. The coefficients of element distribution between the pore solution and the absorbing substance (alkaline load) were calculated. The mobility of elements in phase separation depends on the forms of their presence in pore solutions of the upper part of storage. The urgency of determining MPC and/or relatively safe level of emission was revealed for the elements for which the standard values have not been adopted yet.

The effect of mechanochemical action of aqueous alkaline media on the chemical composition and molecular mass distribution of lignin from upland peat was studied. It was shown that mechanochemical action leads both to hydrolytic destruction and to condensation processes in the molecular structure. These transformations are combined with oxidative processes. The accumulation of a noticeable amount of polar groups in lignin causes an increase in its hydrophilic properties and promotes a decrease in molecular mass due to the dissolution of low-molecular fraction in aqueous alkaline solution. As a consequence, complicated and deep lignin transformations combining destructive and condensation processes lead to gradual transformation of its chemical structure into humic substances. Lignin molecules subjected to sonolysis are composed of oxidized guayacyl and hydroquinone fragments connected through ether bonds or carbon bonds of methylene group. Some guayacyl fragments are oxidized to 2,3-dihydroxybenzoic acid. Along with carbon-carbon and ether bonds, they also include insignificant amount of nitrogen-carbon bonds formed as a result of oxidative ammonolysis of lignin during sonolysis. The stability of a part of lignocarbon bonds to hydrolytic action promotes the formation of not only framework but also the peripheral part of humic acids formed from polyose fragments as a result of sonolysis. The intensity of transformation of the lignocarbon complex into humic substances is due to the strength of the base used during sonolysis. It is assumed that the low molecular mass fractions of lignin participate in the formation of the framework part of humic substances during sonolysis of the secondary plant raw material in alkaline media.

The processes of phase formation and metal ion distribution in the systems without organic solvent were studied. The concentration parameters of the existence of two-phase systems water - polyethylene glycol esters of monoethanolamides of synthetic fatty acids (C _n H_{2 n + 1}CONHCH₂CH₂O(C₂H₄O) _m H, where m = 5-6, n = 10-16 (syntamide-5) - inorganic salting-out agent) were determined experimentally. Chlorides, fluorides, bromides, sulphates, nitrates, carbonates and acetates of alkaline, alkaline earth metals and ammonium, and some acids were used as salting-out agents. A comparison of salting-out capacity of salts and acids was carried out on the basis of the concentration boundaries of layering regions. The broadest concentration range of the existence of layering region is observed in the case of ammonium salts. The region of two-phase liquid equilibrium is conserved to water concentration 94 % in the system with ammonium sulphate and 93 % in the system with ammonium chloride. Extraction possibilities of the system water-syntamide-5-hydrochloric acid were evaluated. Quantitative extraction of thallium (III) from HCl solutions with the concentration of 2-3 mol/L was established.

Experiments on the enhancement of plant stability to oil pollution of soil were carried out for Vicia sativa as example. It was established that the positive effect on the probability of plant survival and an increase in the degree of destruction of oil pollution may be achieved due to the preliminary treatment of seeds by soaking them in potassium humate of salicylic acid solutions in different concentrations. With a 5 % addition of oil into soil, the best result on germ survival and the degree of destruction of oil pollution was obtained after seed soaking in the solution of salicylic acid with the concentration of 10^-4 mol/L, while for 10 % addition of oil - in the solution with the concentration of 10^-3 mol/L. Somewhat less efficient is seed treatment in humate solution. Baikal EM-1 preparation has insignificant positive effect only in the case of 5 % oil addition into soil. The degree of destruction of oil pollution exhibited good correlation with the survival of Vicia sativa ( K _corr = 0.9) in all experiments. A positive result of seed soaking in potassium humate is likely connected with its adaptogenic activity. Salicylic acid in low concentrations (10^-3-10^-4 mol/L) seems to be able to induce prooxidant processes participated by Н₂О₂. Due to this fact, first of all, the stability of plant organism to environmental stress factors increases as early as at the stage of seed soaking; second, Н₂О₂ and peroxidase secreted into the rhizosphere enhance the processes of oxidative oil destruction. Preliminary soaking of seeds in the solutions of salicylic acid with different concentrations depending on the level of oil pollution, or potassium humate may be recommended to increase the efficiency of revegetation of oil-polluted soil by means of phytoremediation.

Liquid-phase hydrogenation of acetylene into ethylene in a flow set-up with a steady catalyst layer at a pressure of 10 atm was investigated. N-methylpyrrolidone was used as a solvent. The effect of temperature and the presence of CO in the gas flow on the characteristics of selective hydrogenation of acetylene on Pd/Al₂O₃, Pd/Sibunite catalysts was studied. It was demonstrated that the selectivity of ethylene formation increases with an increase in CO content in the gas mixture H₂/CO, ethane content in reaction products decreases simultaneously, while the selectivity of the formation of C₄₊ oligomers remains practically unchanged. With an increase in reaction temperature, the degree of acetylene transformation increases, while the relations between reaction products change only insignificantly. The results provide evidence that liquid-phase hydrogenation of acetylene in the flow mode at a pressure of 10 amt and temperature of 120 °C and the presence of CO in the gas flow in the amount of 20 vol. % provide high conversion degree and selectivity of the formation of target product.

The effect of preliminary mechanochemical treatment of the mixtures of metal bismuth and the compounds of different composition on bismuth oxidation by atmospheric oxygen was studied by means of X-ray phase analysis and thermogravimetry. It was established that the oxidation of metal bismuth occurs at the stage of dispersion. It is shown that mechanochemical treatment of a mixture of metal bismuth with 10-30 % its oxide leads to a decrease in the temperature of the start of bismuth oxidation from 350 to 200 °C. It was established that complete transformation of bismuth into its oxide may be carried out by means of annealing of mechanochemically treated mixture of metal bismuth and its oxide (20 %) at 300 °C for 12 h, while at annealing temperature 400 °C - for 1 h. In the case of mechanochemical activation of the mixture of metal bismuth and sodium carbonate, followed by washing with water, the product is mainly bismuth oxide and oxo(hydroxo)carbonate and can be used at the stage of obtaining solutions of bismuth salts. It was shown that mechanochemical activation of a mixture of metal bismuth and sodium chloride followed by washing with water leads to the formation of a mixture of bismuth oxide and oxochloride. This mixture can be used at the stage of obtaining bismuth-containing hydrochloric solutions. It was established that bismuth oxide may be obtained by preliminary mechanochemical activation of metal bismuth with sodium or ammonium nitrate, as well as with stearic acid. The specific surface of bismuth oxide obtained as a result of mechanochemical activation of metal bismuth with different compounds was determined; it varies within the range 0.29-5.87 m²/g.

A method to obtain carbon nanofibres doped with nitrogen, with nitrogen content up to 8 mass %, was developed on the basis of the mechanism of carbide cycle of the synthesis of carbon nanomaterials. Within the framework of this mechanism, active dispersed nickel particle is a polyfunctional nanometre-sized system acting as a physicochemical robot and controlling the synthesis process.

Synthesis of layered double hydroxides (LDH) of MgAlSn with the ratio of Mg/(Al + Sn) = 3 and Sn/(Sn + Al), equal to 1, 5, 10 and 30 %, was carried out. The structural and acid-base properties of these compounds and the formation of the oxide phase were studied using a set of physicochemical methods (XPA, TA-DTG, СО₂ adsorption). It is shown that LDH obtained through co-precipitation have a single-phase composition for Sn/(Sn + Al) < 30 %. With an increase in tin content in the support, a side phase Mg(Sn(OH)₆) is formed. According to the data of СО₂ adsorption, the introduction of tin into LDH layers does not worsen their basic properties. Tin within the support promotes modification of the properties of platinum centres affecting the catalytic properties of Pt/MgAlSnO _x in the reaction of n- decane dehydrogenation. The dependence of n- decane transformation degree on tin content is extremal with the maximum at Sn/(Sn + Al) = 1 %, while the maximal yields of olefins and maximal selectivity are observed for the sample with Sn/(Sn + Al) = 5 %. The catalytic characteristics of the Pt/MgAl-5 % SnO _x sample are comparable with those for the industrial catalyst tested under similar conditions, which points to the promising character of further studies of the systems based on tin-containing LDH.

Results of the tests of platinum-containing catalysts on supports <>-ZrO₂-Al₂O₃, B₂O₃-Al₂O₃ and WO₃-Al₂O₃, as well Y-type, beta and mordenite zeolites mixed with aluminium oxide, within temperature range 200-375 °C are presented. It is shown that zeolite-containing catalysts ensure the maximal yield of methylcyclopentane - at a level of 14 mass % at a temperature of 275-300 °C. At higher temperature, the contribution from side reactions of cycle opening and hydrocracking increases on zeolite catalysts. Among anion-modified systems, the highest selectivity is demonstrated by the sample Pt/WO₃-Al₂O₃: the maximal yield of target methylcyclopentane and isoheptanes in the product mixture is 16.2 and 57 mass %, respectively. Almost complete benzene removal is provided, and the degree of heptane transformation is 80.6 %.

Effect of the modification of foamed polyurethane on extraction-sorption recovery of resorcinol from aqueous media was studied. The ratio of adsorbent/modifying agent phases was chosen. The conditions of adsorption-sorption concentrating of resorcinol were studied.

Under the conditions of inevitable depletion of the world resources of natural fossil fuel, in particular petroleum, an increase in oil recovery is an acute problem. The deposits of highly viscous heavy oil are increasingly actively involved in mining. The production of this kind of oil requires the action of steam and compositions containing chemical reagents. Not only the quantitative but also the qualitative composition of mined oil and investigation of the effect of different methods of oil recovery play essential part. In the present work we studied the effect of compositions pumped into productive deposits on the composition of mined heavy highly viscous petroleum from the Usinsk deposit (Republic of Komi, Russia). The introduction of oil-sweeping compositions into the stratum was carried out at the experimental plots through injection or producing wells, which provided a substantial increase in oil output. Using a set of physicochemical analysis methods (liquid adsorption chromatography, GC-MS), we studied the dynamics of the changes in the group composition of saturated and cyclic hydrocarbons, heterorganic compounds, individual composition of alkanes from oil subjected to the action of compositions. The most significant increase in the content of aromatic hydrocarbons and heterorganic compounds in oil was observed with the use of Zagushchennaya NINKA composition. The action of IKhN_PRO composition caused an increase in alkane content in the group composition of oil. It was shown that redistribution of light (C₁₀-C₁₅) and high molecular mass (more than С₁₆) homologues occurs among n- alkanes. The obtained results may promote deeper understanding of the processes occurring in the deposits as a result of the action of oil-sweeping compositions. Investigation of the effect of compositions on the composition of heavy highly viscous oil also allows one to control the quality of produced hydrocarbon raw material entering the processing facilities.

Modifiers of the properties of petroleum paving bitumen were developed on the basis of two kinds of acryl-nitrile rubbers BNKSС-18 AM (TU 38.30313-2006) and BNKS-28 AM (TU 38.30313-2006) and the fraction of liquid products of tyre pyrolysis without access of the air, with boiling point above 170 °C. Rubber content in the mixture did not exceed 30 mass %, the temperature of mechanical homogenization was 100-120 °C duration was 3 h. Preliminary studies showed that the mixtures prepared under these conditions do not get separated into phases when kept hot for 6 h. Addition of a modifier in the amount of 3-5 mass % per rubber improves the elasticity of bitumen and, which is especially important, causes a substantial decrease in brittle temperature. Due to this, resistance of paving asphalt concrete to frost and to cracks increases substantially. The composition of the fraction of liquid products of tyre pyrolysis was determined by means of IR spectroscopy and gas chromatography-mass spectrometry. This composition includes more than 100 individual compounds with content >0.1 % of the sum of all detectable peaks. These substances are represented mainly by aromatic hydrocarbons, mainly the derivatives of benzene and naphthalene containing aliphatic fragments with total number of carbon atoms 4 to 10 as substituents (43 rel. %). In addition, hydrocarbons with menthene structure were detected (31 rel. %), and aliphatic acyclic hydrocarbons with chains containing 16 to 27 carbon atoms (18 rel. %). Nitrogen-containing compounds are represented by hexahydro-2Н-azerin-2-one (caprolactam) - 0.5 rel. %, as well as 1,2,3-benzotriazol - 0.9 rel. %.

Results of theoretical studies of the thermal decomposition of substances present in the coke residue from primary coal processing are presented. On the basis of the molecular structure of coke residue represented by 1,3,5-triphenylbenzene, tetraphenylmethane, pentaphenylethane, hexaphenylethane, rubrene and benzoquinoline, the mechanism of thermal decomposition is proposed in the form of generalized chemical reactions. The possibility for reactions to proceed is substantiated by the calculated values of Gibbs energy, determined taking into account thermodynamic parameters of the structural fragments modelling the components of high-carbon coke residue. The changes of enthalpy and entropy of the proposed chemical reactions were calculated. The routes to the formation of the components of generator gas during the interaction of gaseous components with high-carbon substances allowing determination of the kinetic and thermal physical parameters of gasification process are shown.

For medical preparations of antidepressant class (amitriptyline, carbamazepine) as examples, experimental evaluation of the dependence of extraction extent on the parameters of alkaline destruction (concentration of potassium hydroxide, hydrolysis temperature, exposure) and organic solvent used to extract the target substances from hair hydrolyzate was carried out.. Relying on the results of the studies, a universal method of hair sample preparation within chemical toxicological analysis was proposed: hydrolysis of the sample in a 1.5 M KOH solution at 60 °C for 1.5 h, subsequent extraction with a mixture of hexane with ethyl acetate at the volume ratio of 5 : 1. The parameters of gas chromatographic-mass spectrometric detection of the target substances were optimized. A procedure for the analysis of amitriptyline and carbamazepine in hair by means of GC-MS was developed. Validation of this procedure was carried out, the working range of the procedure was determined to be 1-100 ng/mg; detection limits for amitriptyline and carbamazepine were determined to be 0.5 and 1 ng/mg, respectively. This procedure was successfully tested with heal hair samples.