The Mechanism of Action of a Multicomponent Co-Mo-Bi-Fe-Sb-K-O Catalyst for the Partial Oxidation of Propylene to Acrolein: II. Changes in the Phase Composition of the Catalyst under Reaction Conditions

The structures of a complex multicomponent Co-Mo-Fe-Bi-K-Sb-O catalyst for the oxidation of propylene to acrolein and simpler catalysts from which some catalyst components were absent were studied by X-ray diffraction analysis. The phases of α-CoMoO₄, β-CoMoO₄, Fe₂(MoO₄)₃, Bi₂O₃ ⋅ MoO₃, Bi₂O₃ ⋅ 2MoO₃, Bi₂O₃ ⋅ 3MoO₃, oxidized molybdenum oxide, and reduced molybdenum oxide are the main components of the catalyst. Ternary compounds were not detected. Under catalytic reaction conditions, the relative amounts of the phases changed; this change suggests the occurrence of redox transformations with the participation of these phases, probably, at the interface.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 580–584.Original Russian Text Copyright © 2005 by Shashkin, Udalova, Shibanova, Krylov.     

Formation of Ferrite-Chromites BaFe10Cr2O19 and SrFe10Cr2O19 in the Solid-Phase Reaction of Fe2O3 and Cr2O3 with Barium or Strontium Carbonate

X-ray phase analysis and the thermomagnetic method were applied to study solid-phase reactions in mixtures of powders 5Fe₂O₃ + Cr₂O₃ + BaCO₃ and 5Fe₂O₃ + Cr₂O₃ + SrCO₃, yielding, respectively, barium and strontium ferrite-chromite solid solutions BaFe₁₀Cr₂O₁₉ and SrFe₁₀Cr₂O₁₉.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 357–361.Original Russian Text Copyright © 2005 by Bashkirov, Kostyushko.     

Transients of the Open-Circuit Potential Observed during the Interaction of Formic Acid with Preliminarily Adsorbed Oxygen on a Platinized Platinum Electrode

Transients of the open-circuit potential, which are observed during the interaction of formic acid with preliminarily adsorbed oxygen (O_ads) on a Pt/Pt electrode in 0.5 M H₂SO₄, are measured. It is established, by means of the method of cathodic potentiodynamic pulses, that the slowest interaction of formic acid with O_ads occurs in the region of large coverages of the electrode surface by oxygen (θ_O ∼1–0.8). A presumption is put forward that the process rate in this region is defined by a direct reaction of O_ads with molecules of formic acid from the bulk solution. It is shown that the interaction of formic acid with O_ads in the region of intermediate coverages (θ_O ∼ 0.8–0.2) proceeds via a mechanism of “conjugated reactions.” Transients of the open-circuit potential for formic acid are compared to transients for carbon monoxide obtained in analogous conditions. The substantially shorter overall time of potential decay in the case of CO (at the same concentrations) is caused by a faster reaction of CO with adsorbed oxygen in the region of large θ_O. The difference is explained by assuming that the HCOOH adsorption as opposed to CO bears a dissociative character.__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 936–942.Original Russian Text Copyright © 2005 by Manzhos, Maksimov, Podlovchenko.     

Structure of the Potassium Hydroxide-Dibenzo-18-crown-6 Complex

Dibenzo-18-crown-6 reacts with potassium hydroxide in methanol to give the C₂₀H₂₄O₆ ⋅ KOH ⋅ MeOH complex which was characterized by the ¹H NMR, UV, and IR spectra. Depending on the conditions, the reaction of the same compounds in toluene gave products with the compositions 4 C₂₀H₂₄O₆ ⋅ KOH ⋅ 3 H₂O (3 h, reflux) and 11C₂₀H₂₄O₆ ⋅ KOH (1 h, 80°C, 1 h).__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 4, 2005, pp. 620–625.Original Russian Text Copyright © 2005 by Nosyreva, Mal’kina, Sinegovskaya, Trofimov.     

Effect of the Nature of the Oxidizing Agent on Conversion of Finely Dispersed Carbon on Binary Oxide Catalysts

We have studied the process of catalytic oxidation of finely dispersed carbon on the surface of the designed soot filters, prepared by successive deposition of a second support (γ-Al₂O₃) and a catalytic coating (CuCr₂O₄ or CuCo₂O₄) on ceramic honeycomb monoliths of synthetic cordierite, using different oxidizing agents: O₂, O₃, NO, NO₂, H₂O. Using ozone as the oxidation initiator allows us to solve the problem of comprehensive purification of automobile exhaust gases at fairly low temperatures (“cold start”). __________ Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 307–312, September–October, 2005.     

Physicochemical and surface properties of alumina modified with rare earth oxides, III. Dispersion of supported platinum

The effect of various amounts of lanthanides on the dispersion of Pt on Al₂O₃ — Ln₂O₃ (where Ln = La, Ce) has been studied by hydrogen chemisorption in a pulse chromatographic system.This revised version was published online in December 2005 with corrections to the Cover Date.     

Behavior of the Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-ZrO<Subscript>2</Subscript> System at High Temperatures

The system Al₂O₃-ZrO₂ at temperatures of up to 2100°C was studied by differential thermal analysis.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 353–356.Original Russian Text Copyright © 2005 by Kamaev, Archugov, Mikhailov.     

Potentiometric investigations of some catechol derivatives of scandium

The equilibrium reactions of scandium(III) with some triprotic catechol derivatives (H₃L) were studied. The selected ligands that are 2,3-dihydroxybenzoic acid (2,3-DHBA), 3,4-dihydroxybenzoic acid (3,4-DHBA), 3.4-dihydroxyhydrocinnamic acid (3,4-DHHCA), and 3,4-dihydroxyphenylacetic acid (3,4-DHPA) were investigated in aqueous solution by means of potentiometry in 0.1 M ionic medium at 25°C. The stability constants are reported for the ScL and ScL(H₂L)^– mononuclear complexes. 2,3-DHBA can bind to Sc³⁺ ion strongly and the salicylate mode (COO^–, O^–) is effective over the acidic pH range. But in higher pH range, 3,4-DHBA, 3,4-DHHCA, and 3,4-DHPA act more efficiently through catecholate groups (O^–, O^–).Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 3, 2005, pp. 229–233.Original Russian Text Copyright © 2005 by Türkel, Özer.This revised version was published online in April 2005 with a corrected cover date.This revised version was published online in April 2005 with a corrected cover date.     

Binuclear Ruthenium(III) μ-Oxocarboxylates of the Nonelectrolyte Type. Molecular Structure of the Complex [Ru

Binuclear ruthenium μ-oxocarboxylates of the nonelectrolyte type [Ru ₂ ^III (μ-O)(μ-O₂CR)₂Py₄(O₂CR)₂] (R = C(CH₃)₃, CH₃, Ph, CH₂Cl, CCl₃, and CF₃) were obtained and studied by electronic absorption and IR spectroscopy and FAB mass spectrometry. The carboxylate ions RCO ₂ ⁻ are symmetrically arranged (trans with respect to the bridging μ-O atom) and coordinated in a monodentate fashion. According to X-ray diffraction data, the crystals of [Ru ₂ ^III (μ-O)(μ-O₂CCF₃)₂Py₄(O₂CCF₃)₂] ⋅ (CH₃)₂CO are monoclinic; the unit cell parameters are a = 11.705(2) Å, b = 16.166(3) Å, c = 20.917(4) Å, β = 103.47(3)°, space group C2/c, Z = 4. The RCO ₂ ⁻ groups that are trans to the μ-O atom can be easily replaced by pyridine or acetonitrile. __________ Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 11, 2005, pp. 803–809. Original Russian Text Copyright ? 2005 by Eremin, Belyaev, Simanova.     

Study of the activation of molecular oxygen in the presence of manganese(II) complexes

The electronic structures of the systems [Mn(phen)₂]²⁺ (I), Mn(HCO₃ ⁻)₂(H₂O)₃ (II), [Mn(phen)₂(H₂O)O₂]²⁺ (III) and [Mn(phen)₂O₂]²⁺ (IV) have been calculated by the IEHM method. The change in the energy barrier for the activation of O₂ (−4.59 eV (III), −4.69 eV (IV) for the elementary step has been calculated using the vibronic activation theory. The formation of an adduct of molecular oxygen with II is shown to be unlikely. Deceased. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 192–195, May–June, 1997.     

Redox Equilibria in the System Fe(OH)3(H2SO4)-Na2SO3-H2O Involving Precipitation of Iron(II) Sulfite as a Fe2O3 Precursor

Experimental data on the equilibria Fe²⁺/Fe³⁺ and SO₃ ²⁻/SO₄ ²⁻ in the system Fe(OH)₃(H₂SO₄)-Na₂SO₃-H₂O are presented. The quantitative relations between the reduction of Fe(III) and the precipitation of FeSO₃·2.5H₂O as a Fe₂O₃ precursor have considered graphically.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 1, 2005, pp. 41–44.Original Russian Text Copyright © 2005 by Vasekha, Motov.     

Comparative Study of the Oxygen Storage Capacity of Pt/M<Subscript>x</Subscript>O<Subscript>y</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Systems

The oxygen storage capacity of 1% Pt/15% M_xO_y/Al₂O₃ systems containing a rare-earth or an alkaline-earth metal oxide or TiO₂ as the oxygen-storing component was studied. Oxygen storage capacity was evaluated as the amount of C₃H₈ reacting at 400°C with oxygen that was taken up by the catalyst during oxidative treatment. The systems containing a rare-earth metal oxide or TiO₂ possess the highest oxygen storage capacity among the catalysts examined (80 and 75 µmol C₃H₈/g Cat, respectively). Of the BaO and SrO systems, the latter is of interest, although its oxygen storage capacity (∼27 µmol C₃H₈/g Cat) is somewhat lower than the oxygen storage capacity of any rare-earth metal oxide or the TiO₂ system.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 585–589.Original Russian Text Copyright © 2005 by Sinel’nikov, Tolkachev, Stakheev.     

Chemisorption of SO<Subscript>2</Subscript> on the Zn-modified In<Subscript>2</Subscript>O<Subscript>3</Subscript> surface

Chemisorption of SO₂ and O₂ on the In₂O₃ surface containing a zinc additive (0.4–2.7 at.%) was studied in a temperature range of 22–200 °C. At least three forms of sorbed SO₂ exist on the modified In₂O₃ surface. The temperature affects the contribution of single forms of SO₂ sorption and, hence, the change in the electric conductivity. The preliminary sorption of O₂ favors the formation of a donor form of chemisorbed SO₂. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2228–2232, October, 2005.     

The Mechanism of Selective NO<Subscript>x</Subscript> Reduction by Hydrocarbons in Excess Oxygen on Oxide Catalysts: III. Adsorption Properties of the Commercial STK Catalyst

According to X-ray diffraction data, the STK catalyst is a mixture of Fe₂O₃ and Cr₂O₃. The temperature-programmed reduction spectrum exhibited two reduction peaks: one, with T _max = 250°C, corresponds to the reduction process Cr₂O₃ → CrO and the other, with T _max = 360°C, corresponds to the reduction Fe₂O₃ → Fe₃O₄. The results of thermal desorption measurements suggest that the individual adsorption of oxygen on the surface of the STK catalyst is low; in this case (according to IR-spectroscopic data), an atomic form is the main species. Surface nitrite-nitrate complexes are formed upon the adsorption of NO. Nitrite and nitrate complexes desorbed at maximum rates at 105 and 160°C, respectively. Unlike the NTK-10-1 catalyst, the NO species, which desorbed at high temperatures (250–400°C), was absent from the surface of STK. Propane adsorbed at room temperature to form surface compounds containing an acetate group. The interaction of propane with the surface of the STK catalyst at reaction temperatures resulted in strong surface reduction.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 550–558.Original Russian Text Copyright © 2005 by Tret’yakov, Burdeinaya, Zakorchevnaya, Matyshak, Korchak.     

Decomposition in Prolonged Storage of KF · H<Subscript>2</Subscript>O<Subscript>2</Subscript> Stabilized with Carboxylic Acids

Decomposition of KF · H₂O₂ stabilized with carboxylic acids (maleic, fumaric, succinic, adipic) in storage for more than three years at 20°C was studied. Rate constants of decomposition of stabilized KF · H₂O₂ were determined in different time intervals. The chemical reactions in the system KF-H₂O₂-carboxylic acid in the stage of preparation of solid KF · H₂O₂ stabilized with carboxylic acid and those during prolonged storage of the final product are discussed.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 2, 2005, pp. 287–291.Original Russian Text Copyright © 2005 by Titova, Nikol’skaya, Buyanov, Pudova, Karzhavina.     

Electrocatalysis of the hydrogen evolution reaction by nanocomposites of poly(amidoamine)-encapsulated platinum nanoparticles and phosphotungstic acid

Poly(amidoamine) dendrimer (Generation-4) encapsulated platinum nanoparticles (PtNP-PAMAM) were prepared and used to fabricate nanocomposites with Keggin-type phosphotungstic acid (PW₁₂O₄₀³⁻) using a layer by layer electrostatic assembly technique. Indium tin oxide (ITO) electrodes, which were first modified with a monolayer of 3-aminopropyl triethoxysilane (3-APTES), were used as substrates for assembly of the PW₁₂O₄₀³⁻ monolayer. Nanocomposites were then fabricated by depositing PtNP-PAMAM on the monolayer of PW₁₂O₄₀³⁻. The amount of PtNP-PAMAM deposited was controlled by using different concentrations of PtNP-PAMAM diluted in 0.1 M H₂SO₄ solution. The hydrogen evolution reaction (HER) was used to test electrocatalytic activities of these nanocomposite modified electrodes. Modification of ITO|3-APTES with PW₁₂O₄₀³⁻ |PtNP-PAMAM showed significantly higher electrocatalytic activities toward the HER than electrodes modified with either PW₁₂O₄₀³⁻ or PtNP-PAMAM alone. The electrocatalytic activities were found to depend on the composition of PtNP-PAMAM and PW₁₂O₄₀³⁻ on electrode surfaces, which was attributed to an interaction between these species. Heat treatment of ITO|3-APTES|PW₁₂O₄₀³⁻ |PtNP-PAMAM electrodes at 200 °C produced significantly higher electrocatalytic activities, which supported the suggestion of an interaction. Presented at the 4th Baltic conference on Electrochemistry, Griefswald, March 13.−16., 2005.     

Interaction of Cl<Subscript>2</Subscript> and SO<Subscript>2</Subscript> with Finely Divided In<Subscript>2</Subscript>O<Subscript>3</Subscript>

The effect of O₂, Cl₂, and SO₂ on electrophysical and sorption properties of powdered In₂O₃ with a large specific area is studied at 23–200°C. The specimen is most sensitive to Cl₂ and SO₂ at near-room temperatures.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 529–536.Original Russian Text Copyright © 2005 by Vinokurova, Derlyukova.     

Reactions of 2-Butylsulfanyl-2-alkenals with Alcohols and Water

2-Butylsulfanyl-2-alkenals react with alcohols at room temperature in the presence of acid catalysts to give 45–90% of the corresponding acetals. Acetals derived from 2-butylsulfanylpropenal readily undergo hydrolysis at the vinylsulfanyl group (20°C, catalysis by HCl or TsOH) with formation of 2-oxopropionaldehyde O,O- or O,S-acetals in 70–90% yield. Unlike 2-butylsulfanyl-2-propenal O,O-dialkyl acetals, the initial aldehydes and 2,4-dinitrophenylhydrazones derived therefrom are stable to hydrolysis under analogous conditions: the vinyl sulfide moiety remains unchanged even under considerably more severe conditions (100°C, 3 h; HCl, H₂SO₄, CF₃SO₂OH, or TiCl₄).__________Translated from Zhurnal Organicheskoi Khimii, Vol. 41, No. 6, 2005, pp. 832–836.Original Russian Text Copyright © 2005 by Keiko, Chuvashev, Stepanova, Larina.     

Microstructure and Conduction of Composites Bi<Subscript>2</Subscript>CuO<Subscript>4</Subscript>-Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> Near the Eutectic Melting Point

Microstructure and conduction of ceramic composites Bi₂CuO₄ + xBi₂O₃ (x = 5, 10, 15, 20 wt %) near the eutectic melting point (770°C) are studied. Bismuth oxide, initially randomly distributed over the ceramics bulk, after quenching from temperatures exceeding the eutectic melting point, becomes localized at triple junctions and grain boundaries in Bi₂CuO₄, which is caused by wetting grain boundaries and forming a liquid-channel structure. The jumpwise change in the composites’ conductivity near 730 and 770°C caused by polymorphic transformation of Bi₂O₃ and the eutectic melting with simultaneous formation of a liquid-channel structure. Transport numbers of the oxygen ion are measured at 770°C by coulomb-volumetric method. The conduction by oxygen ions increases in the composites with decreasing average size of Bi₂CuO₄ crystallites.__________Translated from Elektrokhimiya, Vol. 41, No. 5, 2005, pp. 596–601.Original Russian Text Copyright © 2005 by Lyskov, Metlin, Belousov, Tret’yakov.     

Synthesis and Investigation of Indium Dodecatungstosilicate

Indium dodecatungstosilicate of the composition [In(OH)⋅5H₂O]₂ [SiW₁₂O₄₀]⋅H₂O is synthesized and studied by means of IR spectroscopy, thermogravimetry, and X-ray phase analysis. The crystals of this compound are triclinic, space group P1, a 13.079(3), b 13.795(3), c 13.967(3) Å, α 90.08(3)°, β 103.76(3)°, ψ107.76(3)°, Z 2, and π_calc 4.900 g cm⁻³.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 1, 2005, pp. 21–23.Original Russian Text Copyright © 2005 by Kaziev, Dutov, Quinones, Ita, Sychkin.