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1.
Nanochemistry and Supramolecular Chemistry of Actinides and Lanthanides: Problems and Prospects A. Yu. Tsivadze, G. V. Ionova, and V. K. Mikhalko Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
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Received March 13, 2009 Abstract — The possibility of using unique properties of lanthanides in the nanotechnology is demonstrated. The origination of linear and nonlinear optical properties of lanthanide compounds with phthalocyanines, porphyrins, naphthalocyanines, and their analogs in solutions and condensed state and the prospects of obtaining novel materials on their basis are discussed. Based on the electronic structure and properties of lanthanides and their compounds, namely, optical and magnetic characteristics, electronic and ionic conductivity, and fluctuating valence, molecular engines are classified. High-speed storage engines or memory storage engines; photo conversion molecular engines based on Ln(II) and Ln(III); electrochemical molecular engines involving silicat and phosphate glasses; molecular engines whose operation is based on insulator–semiconductor, semiconductor–metal, and metal–superconductor types of conductivity phase transitions; solid electrolyte molecular engines; and miniaturized molecular engines for medical analysis are distinguished. It is shown that thermodynamically stable nanoparticles of LnxMy composition can be formed by d elements of the second halves of the series, i.e., those arranged after M = Mn, Tc, and Re. Prospects of using lanthanide superconductors in nanotechnology are considered. DOI: 10.1134/S2070205110020012
11/05/2010 | 952 Hits | Print
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2.
Adsorption of Gases, Vapors, and Solutions: I. Thermodynamics of Adsorption A. M. Tolmachev Department of Chemistry, Moscow State University, Moscow, Russia
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Received April 14, 2009 Abstract — The review considers methods of describing and preliminarily calculating the equilibrium characteristics of the adsorption of gases, vapors, and vapor–liquid mixtures of substances on adsorbents of different structures based on semiempirical, thermodynamic, and molecular models of adsorption systems. Based on the performed analysis, the systems of equations are obtained that allow one to fully describe the corresponding equilibriums and perform a theoretical study of highly selective adsorption systems for practically important engineering processes. DOI: 10.1134/S2070205110020024
11/05/2010 | 968 Hits | Print
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3.
Adsorption of n-Pentane on a Microporous Carbon Adsorbent with a Narrow Pore Size Distribution A. V. Shkolin*, A. A. Fomkin, and V. A. Sinitsyn Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
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Received April 14, 2009 Abstract — A model of thermochemical synthesis of a microporous carbon adsorbent of silicon carbide is developed. Isotherms of absolute adsorption of n-pentane on an AUK microporous carbon adsorbent of SiC with a narrow pore size distribution are measured in the pressure range of 1 Pa to 50 kPa and in the temperature interval of 243–393 K. The parameters of adsorption equilibrium of the adsorption isostere calculated in the same range are adequately approximated by straight lines. The differential molar isosteric heat of adsorption of n-pentane on the AUK adsorbent decreases of 58–46 kJ/mol in the whole region of micropore filling; this fact counts in favor of energetic heterogeneity in the micropores, which presumably appears in the process of thermochemical synthesis of the microporous carbon adsorbent of silicon carbide. DOI: 10.1134/S2070205110020036
11/05/2010 | 935 Hits | Print
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4.
Determination of Parameters of Porous Structure of Carbon Adsorbent during Analysis of Vapor Adsorption Isotherms in Region of Polymolecular Adsorption V. V. Guryanov, G. A. Petukhova, and L. A. Dubinina Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
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Received April 14, 2009 Abstract — The methods for determining the parameters of the porous structure for adsorbents based on considering the polymolecular adsorption range are analyzed. Advantages of the  method are shown compared to the methods of normalization of the adsorption isotherms, as it does not require knowing standard adsorption isotherms. The determination of the parameters of the porous structure can be performed based on the analysis of the adsorption isotherms for different adsorptives used directly in the sorption processes, which considerably extends the possibilities and importance of adsorption research methods. The analysis of extensive experimental materials on the sorption of different substances on nonporous and microporous carbon adsorbents is evidence of the reliability of results of the methods for determining the overall surfaces of mesopores and macropores and the external surface of adsorbent, as well as the volume of the macropores. DOI: 10.1134/S2070205110020048
11/05/2010 | 911 Hits | Print
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5.
Molecular Theory of Adsorption in Meso- and Macropores and Kelvin Equation Yu. K. Tovbin Karpov Research Institute of Physical Chemistry, Moscow, Russia
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Received June 14, 2009 Abstract — The molecular theory of adsorption is used to estimate the upper bound of the validity of the Kelvin equation for calculating the saturated vapor pressure in meso- and macroporous adsorbents. The values of saturated vapor pressure are compared according to the theoretical adsorption isotherms obtained in terms of the lattice gas model and the Kelvin equation for atoms of argon and molecules of nitrogen and tetrachloride carbon. As the temperature increases, the agreement between the two methods improves. It is shown that the validity of the results obtained using the Kelvin equation for problems of absorption porometry is even limited for pores as small as 50 nm. DOI: 10.1134/S207020511002005X
11/05/2010 | 926 Hits | Print
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6.
Fluctuation Formation Model and Operation Mechanism of Inhibiting Layers on Metals: II. Interaction and Evolution of Inhibitor Nuclei Yu. A. Popov, N. A. Koval’chukov, and V. N. Chistokhvalov Karpov Institute of Physical Chemistry, ul. Vorontsovo pole 10, Moscow, 105064 Russia
Russian People’s Friendship University, ul. Miklukho-Maklaya 6, Moscow, 117198 Russia Received March 15, 2009 Abstract — The formation kinetics of inhibitor nuclei during the origination of the primary layer at the metal interface is considered. A model of interactions that change the equilibrium state is presented. An equation of the process referred to as the evolution of nuclei is derived. DOI: 10.1134/S2070205110020061
11/05/2010 | 938 Hits | Print
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7.
Bridged Polysilsequioxane Adsorption Materials Containing Phosphonic Acid Residues I. V. Mel’nika, N. V. Stolyarchuka, O. A. Dudarkoa, Yu. L. Zuba*,
A. Dabrowskib, M. Barczakb, and B. Alonsoc a Chuiko Institute of Surface Chemistry, Ukrainian National Academy of Sciences,
ul. Generala Naumova 17, Kiev 03164, Ukraine
b Faculty of Chemistry, University of Maria Curie-Sklodowska, pl. M. Curie-Sklodowskiej 3, Lublin 20-031, Poland
c Institute Charles Gerhardt - UMR 5253 (CNRS/ENSCM/UM2/UM1),
8 rue de I’Ecole Normale, 34296 Montpellier Cedex 5, France
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Received June 5, 2009 Abstract — Reactions of hydrolytic polycondensation of bis(triethoxysilane) [(C2H5O)3Si]2C2H4 (or
[(C2H5O)3Si]2C6H4) and functional agent (C2H5O)3Si(CH2)2P(O)(OC2H5)2 (alkoxysilanes molar ratio of 2: 1
and 4 : 1, fluoride ion catalyst and ethanol solvent) yielded powder-like xerogels that contained phosphonic acid
residues in the surface layer. Their treatment with boiling concentrated hydrochloric acid resulted in transfor-
mation of functional groups  Si(CH2)2P(O)(OC2H5)2 into acid groups Si(CH2)2P(O)(OH)2. The methods of
IR, 1H MAS NMRm and 13C, 29Si, 31P MAS NMR spectroscopy showed the following (1) The surface layer in the initial xerogels contains not only phosphorus functional groups, but also some nonhydrolyzed ethoxysilyl groups as well as silanol groups. (2) The hydrochloric acid treatment of the initial xerogels causes the hydrolysis of not only ethoxy groups in the phosphonic acid residues, but also most residual ethoxysilyl groups. (3) Vacuum drying of xerogels after acid treatment forms Si(CH2)2P(O)(OH)–OSi links in their surface layer (not more than 20% of phosphorus-containing groups). (4) According to 29Si CP MAS NMR spectroscopic data, boiling acid treatment relatively enriches the xerogel structure T2 and T3 units and accounts for the higher rigidity of the hybrid framework. These units also account for retention of the porous structure in these xerogels over time, while most initial xerogels have porous structures that collapse in 12–18 months of storage. The acid-
treated xerogels were attributed to microporous adsorbents (having specific surface area of 620 to 760 m2/g). According to the AFM data, both initial and acid-treated xerogels contain almost spherical aggregates of the primary particles (globules). DOI: 10.1134/S2070205110020073
11/05/2010 | 953 Hits | Print
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8.
Comparing Factors that Affect Kinetics of Oxygen Electroreduction on Platinum- and Palladium-Containing Catalysts G. V. Zhutaeva and M. R. Tarasevich Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences,
Leninskii pr. 31, Moscow, 119991 Russia
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Received June 15, 2009 Abstract — The effect of blocking species, namely, oxygen-containing species adsorbed from water and blank electrolyte anions, on the kinetics of oxygen electroreduction on 40% Pt ETEK (denoted as 40Pt/C) and 20% Pd ETEK (20Pd/C) commercial catalysts, as well as on 20% Pd ETEK 6% Co (denoted as 20Pd6Co/C) and 20% Pd ETEK 5% Pt 2.9% Co (20Pd5Pt2.9Co/C) catalysts synthesized at the laboratory, is studied in sulfuric and perchloric acid solutions. It is shown that on a monopalladium catalyst, the first inhibiting factor prevails, whereas, on a monoplatinum catalyst, a substantial role in decelerating the reaction is played by the adsorption of HS anions. In the case of a trimetal catalyst, the adsorption curve of oxygen-containing species is noticeably shifted toward the curve typical of platinum. When perchloric acid is replaced with sulfuric acid, the potential of the kink point of the Tafel dependence of the oxygen electroreduction (on going from the low to high polarization) is shifted toward the less positive potentials. This shift of the kink potential is most clearly pronounced in the case of a monoplatinum catalyst. DOI: 10.1134/S2070205110020085
11/05/2010 | 970 Hits | Print
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