Hydrolysis of the uranyl ion in sodium nitrate medium

Studies on Nickel Oxide Mixed Catalysts. VIII. Catalytic Properties of NiO? Al₂O₃/SiO₂ Catalysts Catalytic properties of NiO? Al₂O₃/SiO₂ catalysts prepared by precipitation-deposition and impregnation have been investigated in dimerization of ethene and isomerization of but-1-ene. It was found that the catalytic activity is mainly determined by the interaction between the catalyst components where a X-ray amorphous nickel alumolayersilicate is formed. The dimerization of ethene proceeds by participation of coordinatively unsaturated nickel ions with aluminum ions in the neighbourhood. The catalytic activity in the isomerization of but-1-ene depends on the surface acidic properties of the catalyst.     

Synthesis of a gallosilicate analogue of high silica,large Port Mordenitel

A high silica (SiO₂/Ga₂O₃ = 42) crystalline mordenite containing gallium (III) in framework positions has been prepared by hydrothermal crystallization at 413 K in the presence of tetraethylammonium bromide. Evidence for the presence of framework gallium in the mordenite lattice is obtained from chemical analysis, XRD, framework IR, solid state MASNMR, thermoanalytical studies, sorption and catalytic activity studies. Chemical analysis and NMR data indicate the absence of significant amounts of aluminium (SiO₂/Al₂O₃ > 2400). An increase in the interplanar spacing and unit cell volume as well as a shift to lower wavenumbers of framework vibrations occurs on gallium incorporation in the mordenite lattice. Ga-mordenite exhibited significant ion exchange capacity. The gallium analogue of mordenite exhibited significant catalytic activity and shape selectivity in the isomerization reaction ofm-xylene.NCL communication No. 5317.     

Study of <Emphasis Type="Italic">n</Emphasis>-hexane isomerization on Pt/SO<Subscript>4</Subscript>/ZrO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts: Effect of the state of platinum on catalytic and adsorption properties

The state of surface Pt atoms in the Pt/SO₄/ZrO₂/Al₂O₃ catalyst and the effect of the state of platinum on its adsorption and catalytic properties in the reaction of n-hexane isomerization were studied. The Pt-X/Al₂O₃ alumina-platinum catalysts modified with various halogens (X = Br, Cl, and F) and their mechanical mixtures with the SO₄/ZrO₂/Al₂O₃ superacid catalyst were used in this study. With the use of IR spectroscopy (CO_ads), oxygen chemisorption, and oxygen-hydrogen titration, it was found that ionic platinum species were present on the reduced form of the catalysts. These species can adsorb to three hydrogen atoms per each surface platinum atom. The specific properties of ionic platinum manifested themselves in the formation of a hydride form of adsorbed hydrogen. It is believed that the catalytic activity and operational stability of the superacid system based on sulfated zirconium dioxide were due to the participation of ionic and metallic platinum in the activation of hydrogen for the reaction of n-hexane isomerization.     

Research on 1-azabicyclic compounds

1-(2-Furyl)-3-amino-4,4-dimethylpentane was used to obtain 3-tert-butyl-1,2-dihydropyrrolizine, the catalytic hydrogenation of which over Rh/Al₂O₃ at room temperature gives a mixture of cis- and trans-3,8-H-3-ter-butylpyrrolizidines with predominance of the cis isomer, whereas hydrogenation at 90–100 °C gives a mixture containing the trans isomer as the principal component. The three-dimensional structures of the isomers follow from data on the catalytic hydrogenation and isomerization and the IR, Raman, and PME spectra. A considerable percentage of the trans-fused form is characteristic for cis-3,8-H-3-tert-butylpyrrolizidine.     

Reactions of 2-and 3-methylbenzothiophenes in the presence of heterogeneous acid catalysts

In the presence of catalysts (Al₂O₃, Al₂O₃ activated by HCl, and 5, 10, and 20% ZnCl₂/Al₂O₃), 2- and 3-methylbenzothiophenes undergo mutual isomerization, dealkylation, and disproportionation to benzothiophene and 2,3-dimethylbenzothiophene at 250–450°C and space velocities of 0.1 and 0.8 h^–1. An ionic mechanism is proposed for the isomerization reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1079–1082, August, 1977.     

Effect of metals on the catalytic activity of sulfated zirconia for light naphtha isomerization

We studied on the function of the metal in the sulfated zirconia(SO₄^2–/ZrO₂) catalyst for the isomerization reaction of light paraffins. The addition of Pt to the SO₄^2–/ZrO₂ carrier could keep the high catalytic activity. The improvement in this isomerization activity is because Pt promotes removal of the coke precursor deposited on the catalyst surface. Though this catalytic function was observed in other transition metals, such as Pd, Ru, Ni, Rh and W, Pt exhibited the highest effect among them. It was further found that the Pd/SO₄^2–/ZrO₂–Al₂O₃ catalyst possessed a catalytic function for desulfurization of sulfur-containing light naphtha in addition to the skeletal isomerization. The sulfur tolerance of catalyst depended on the method of adding Pd, and the catalyst prepared by impregnation of the SO₄^2–/ZrO₂–Al₂O₃ with an aqueous solution of Pd exhibited the highest sulfur tolerance.Further, we investigated the improvement in sulfur tolerance of the Pt/SO₄^2–/ZrO₂–Al₂O₃ catalyst by impregnation of Pd. The results of EPMA analysis indicated that this catalyst was a hybrid-type one (Pt/SO₄^2–/ZrO₂–Pd/Al₂O₃) in which Pt/SO₄^2–/ZrO₂ particles and Pd/Al₂O₃ particles adjoined closely. This hybrid catalyst possessed a very high sulfur tolerance to the raw light naphtha that was obtained from the atmospheric distillation apparatus, although this light naphtha contained much sulfur. We assume that such a high sulfur tolerance in the hybrid catalyst is brought about by the isomerization function of Pt/SO₄^2–/ZrO₂ particles and the hydrodesulfurization function of Pd/Al₂O₃ particles. Besides, since the hybrid catalyst also provides high catalytic activity in the isomerization of HDS light naphtha, we suggest that the Pd/Al₂O₃ particles supply atomic hydrogen to the Pt/SO₄^2–/ZrO₂ particles by homolytic dissociation of gaseous hydrogen and also enhance the sulfur tolerance of Pt/SO₄^2–/ZrO₂ particles. Finally, we also propose the most suitable location of Pd and Pt in the metal-supported SO₄^2–/ZrO₂–Al₂O₃ catalyst.     

A Magnetically Separable Catalyst for Synthesis of 1‐Phenoxy‐2‐propanol Via Atom‐economic Reaction

A magnetically separable catalyst Al₂O₃‐MgO/Fe₃O₄ was prepared by Al₂O₃‐MgO supported on magnetic oxide Fe₃O₄ and charactered by FT‐IR, XRD and SEM. The mixed oxides afforded high catalytic activity and selectivity for synthesis of 1‐phenoxy‐2‐propanol from phenol and propylene oxide with 80.3% conversion and 88.1% selectivity to 1‐phenoxy‐2‐propanol. Especially, facile separation of the catalyst by a magnet was obtained and the catalytic performance of the recovered catalyst was unaffected even at the forth run.     

Roles of surface nitrogen oxides in propene activation and NO reduction on Ag/Al2O3

The activation of propene in selective catalytic reduction (SCR) of NO on 4% Ag/Al₂O₃ has been studied by in situ infrared (IR) spectroscopy. Distinctive propene activation products were detected in the SCR of NO, depending on the nature of surface oxygen and nitrogen oxide species on Ag/Al₂O₃. C₃H₆ was oxidized to acetate species in an O₂ + C₃H₆ atmosphere on Ag/Al₂O₃ above 573 K. The addition of NO to the C₃H₆ + O₂ feed gas suppressed the formation of acetate species but increased the proportion of acrylate species. Acrylate species were further confirmed to be formed preferentially from C₃H₆ oxidation without the O₂ atmosphere on Ag/Al₂O₃ or nitrate-adsorbed Ag/Al₂O₃. On the other hand, adsorption of NO led to the formation of nitrito species on Ag/Al₂O₃, but the nitrito was barely oxidized to nitrate species unless there was an O₂ atmosphere at 473–673 K. Thus, the oxidation of propene to acetate species, or the formation of nitrate from nitrito, is attributed to two competitive electrophilic reactions. The formation of nitrate from nitrito species decreased electrophilic oxygen species that oxidized propene to acetate. Nevertheless, the first dehydrogenation of propene to form acrylate species on nitrate-adsorbed Ag/Al₂O₃ is a nucleophilic reaction, as it is on Ag/Al₂O₃. Furthermore, there was no decrease in reaction activity for formation of acrylate species on nitrate-adsorbed Ag/Al₂O₃ compared to Ag/Al₂O₃. This led to the total reaction occurring easily through the propene nucleophilic oxidation branch because the presence of the adsorbed nitrogen oxides changed selectively the formation rates of the surface reductants. IR spectra data further demonstrate that acrylate and acetate species, as the surface reductants, reacted with nitrate to generate isocyanate intermediates in the SCR of NO. The effect of structures of different reductants on NO reduction is discussed.     

Catalytic Performance and Characterization of Pt‐Co/Al2O3 Catalysts for CO2 Reforming of CH4 to Synthesis Gas

Pt‐Co/Al₂O₂ catalyst has been studied for CO₂ reforming of CH₄ to synthesis gas. It was found that the catalytic performance of me catalyst was sensitive to calcination temperature. When Co/Al₂O₃ was calcined at 1473 K prior to adding a small amount of Pt to it, the resulting bimetallic catalyst showed high activity, optimal stability and excellent resistance to carbon deposition, which was more effective to the reaction than Co/Al₂O₃ and Pt/Al₂O₃ catalysts. At lower metal loading, catalyst activity decreased in the following order: Pt‐Co/ Al₂O₃ > Pt/Al₂O₃ > Co/Al₂O₃. With 9% Co, the Co/Al₂O₃ calcined at 923 K was also active for CO₂ reforming of CH₄, however, its carbon formation was much more fast man that of the Pt‐Co/Al₂O₃ catalyst. The XRD results indicated that Pt species well dispersed over the bimetallic catalyst. Its high dispersion was related to the presence of CoAl₂O₄, formed during calcining of Co/Al₂O₃ at high temperature before Pt addition. Promoted by Pt, Co/Al₂O₄ in the catalyst could be reduced partially even at 923 K, the temperature of pre‐reduction for the reaction, confirmed by TPR. Based on these results, it was considered that the zerovalent platinum with high dispersion over the catalyst surface and the zerovalent cobalt resulting from Co/Al₂O₄ reduction are responsible for high activity of the Pt‐Co/Al₂O₃ catalyst, and the remain Co/Al₂O₄ is beneficial to suppression of carbon deposition over the catalyst.     

Steam reforming of ethylene glycol over Ni-based catalysts: the effect of K

The effect of K on the activities of Ni/Al₂O₃ catalysts in steam reforming of ethylene glycol was investigated. Ni/Al₂O₃ catalysts were prepared by incipient wetness impregnation and co-precipitation methods. The addition of K was achieved using an incipient wetness impregnation method. The prepared catalysts were characterized by N₂ physisorption, inductively coupled plasma-atomic emission spectroscopy, X-ray diffraction, temperature-programmed reduction, and scanning electron microscopy. Irrespective of the preparation method, the promotional effect of K was observed and the optimum K content (~5 wt%) was verified for K-promoted Ni/Al₂O₃ catalysts. The addition of K to the Ni–Al₂O₃ catalyst prepared by co-precipitation led to higher catalytic activity than addition of K to the Ni/Al₂O₃ catalyst prepared by incipient wetness impregnation.     

Correlation between acidic properties of nickel catalysts and catalytic activities for ethylene dimerization and butene isomerization

Catalytic activities of NiO–SiO₂ for ethylene dimerization and butene isomerization run parallel when the catalysts are activated by evacuation at elevated temperatures, giving two maxima in activities. The variations in catalytic activities are closely correlated to the acidity of NiO–SiO₂ catalysts. Catalytic activities of NiO–TiO₂ catalysts modified with H₂SO₄, H₃PO₄, H₃BO₃, and H₂SeO₄ for ethylene dimerization and butene isomerization were examined. The order of catalytic activities for both reactions was found to be NiO–TiO₂/SO₄^2- >> NiO–TiO₂/PO₄^3-NiO–TiO₂/BO₃^3- > NiO–TiO₂/SeO₄^2-> NiO–TiO₂, showing clear dependence of catalytic activity upon acid strength. The high catalytic activity of supported nickel sulfate for ethylene dimerization was related to the increase of acidity and acid strength due to the addition of NiSO₄. The asymmetric stretching frequency of the S=O bonds for supported NiSO₄ catalysts was related to the acidic properties and catalytic activity. That is, the higher the frequency, the larger both the acidity and catalytic activity. For NiSO₄/Al₂O₃–ZrO₂ catalyst, the addition of Al₂O₃ up to 5 mol% enhanced catalytic activity for ethylene dimerzation and strong acidity gradually due to the formation of Al–O–Zr bond. The active sites responsible for ethylene dimerization consist of a low-valent nickel, Ni⁺, and an acid, as evidenced by the IR spectra of CO adsorbed on NiSO₄/ -Al₂O₃ and Ni 2p XPS.     

Homogenous and heterogenous catalytic hydrogenation and isomerization of hex-1-ene by palladium(II) Schiff base complexes

Summary Pd^II complexes of Schiff bases with N₂O₂ donor sets were tested for their catalytic activity towards the reductive hydrogenation of hex-1-ene. During the hydrogenation, trans- and cis-hex-2-ene isomers were formed which generally react more slowly than hex-1-ene, hence the rate of hydrogenation tends to slow down with increasing conversion. The rates of hydrogenation and isomerization were studied in relation to the catalyst structure, time, type of catalysis and amount and nature of solvents. The solubility of H₂ and the polarity of reaction medium play a significant role in the hydrogenation yield and selectivity. Hydrogenation and isomerization are parallel reactions; a mechanism for the isomerization is proposed.     

The solution photochemistry of αβ-unsaturated sulphones

1-Phenyl-2-(benzenesulphonyl)-ethylene and 1-phenyl-2-(benzenesulphonyl)-prop-1-ene have been shown to undergo $\text{Z}$,$\text{E}$-photoisomerisation, whereas 2-benzenesulphonylindene readily forms [_π2 + _π2] photoadducts with 2,3-dimethylbut-2-ene, cyclopentene, and cyclohexene.     

The Metal–Support Interaction Concerning the Particle Size Effect of Pd/Al2O3 on Methane Combustion

The particle size effect of Pd nanoparticles supported on alumina with various crystalline phases on methane combustion was investigated. Pd/θ, α‐Al₂O₃ with weak metal‐support interaction showed a volcano‐shaped dependence of the catalytic activity on the size of Pd particles, and the catalytic activity of the strongly interacted Pd/γ‐Al₂O₃ increased with the particle size. Based on a structural analysis of Pd nanoparticles using CO adsorption IR spectroscopy and spherical aberration‐corrected scanning/transmission electron microscopy, the dependence of catalytic activity on Pd particle size and the alumina crystalline phase was due to the fraction of step sites on Pd particle surface. The difference in fraction of the step site is derived from the particle shape, which varies not only with Pd particle size but also with the strength of metal–support interaction. Therefore, this interaction perturbs the particle size effect of Pd/Al₂O₃ for methane combustion.     

Nature of condensation products in but-1-ene aromatization on high-silica zeolite catalyst

The aromatization of but-1-ene on the H-form of pentasil-type zeolite catalyst (SiO₂/Al₂O₃ = 54) is studied in the temperature range from 573 to 723 K. It is shown that in the range of 623 to 723 K, the liquid phase consists mainly of aromatic hydrocarbons. The results from differential thermal and X-ray diffraction analyses show that graphite-like depositions can form in zeolite channels during the conversion of but-1-ene on the H-form of zeolite catalyst at 673 K and more than 20 h. The activity of the catalyst remains virtually the same.     

Selective Catalytic Reduction of NO with Propene over Au/Fe2O3/Al2O3 Catalysts

A series of Au/Fe₂O₃/Al₂O₃ catalysts were prepared by the homogeneous deposition-precipitation method. The catalytic activity of the catalyst samples for selective catalytic reduction of NO by propene under oxygen-rich atmosphere was evaluated. The results showed that 2%Au/10%Fe₂O₃/Al₂O₃ exhibited good low-temperature activity. The maximum of NO conversion reached 43% at 300 °C, while it was only 21% over the 2%Au/Al₂O₃ catalyst at the same temperature. The addition of 2% steam to the feed gas had little effect on the catalytic activity. X-ray diffraction results indicated that both Au and Fe₂O₃ particles were highly dispersed over Al₂O₃. H₂-temperature-programmed reduction results indicated that there was strong interaction between Au and Fe₂O₃, which made the reduction of Fe₂O₃ easy. The synergistic effect between Au and Fe₂O₃ was probably responsible for the good catalytic performance of the Au/Fe₂O₃/Al₂O₃ catalyst at low temperature.     

Co-Mo/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Ni-W/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts: Potential and prospects for use in hydrotreating of light cycle oil from catalytic cracking

Со-Мо/Al₂O₃ and Ni-W/Al₂O₃ catalysts were tested in hydrotreating of light cycle oil from catalytic cracking, of the straight-run gasoil, and of their mixture under typical hydrotreating conditions used in industry. The catalysts prepared using PMo₁₂ and PW₁₂ heteropoly acids exhibit high catalytic activity. The Со-Мо/Al₂O₃ catalyst is more active in hydrodesulfurization and hydrogenation of olefin and diene hydrocarbons, whereas the Ni-W/Al₂O₃ catalysts are more active in hydrogenation of mono- and polycyclic aromatic hydrocarbons. Comparison of the quality characteristics of the hydrogenizates obtained with the requirements of the technical regulations shows that the required levels of the sulfur content and cetane number of the hydrogenizates at practically accessible process parameters can be reached for mixtures of the straight-run gasoil and light cycle oil from catalytic cracking with high content of the latter component only when the process with the Со-Мо/Al₂O₃ system and Ni-W/Al₂O₃ catalysts is performed in two steps.     

Photochemical Reactions of Benzo[b]Thiophene-2,3-Diones with 2,3-Dimethylbut-2-Ene

Abstract

Photochemical reactions of benzo[b]thiophene-2,3-diones with 2,3-dimethylbut-2-ene gave dioxene derivatives in excellent yields.     

Direct Oxidation of Methane to Methanol Over Cu-Based Catalyst in an AC Dielectric Barrier Discharge

In this paper, the conversion of methane to methanol on CuO/Al₂O₃ and Mo–CuO/Al₂O₃ catalysts in a plasma reactor was tested. A comparison between catalytic and plasma-catalytic systems had been made in tested temperature range of 50–300°C. Experimental results showed that plasma-catalytic system demonstrated a much better methane conversion than catalytic system in tested temperature range and Mo–CuO/Al₂O₃ revealed a higher catalytic activity than CuO/Al₂O₃ for methanol synthesis. Furthermore, an Arrhenius plot was made in order to deduce the mechanism of plasma activation, which revealed that the presence of plasma decreased the activation energy for both catalysts. In the case of Mo-CuO/Al₂O₃ catalyst, the enhanced activity for methanol synthesis was assumed due to the oxygen vacancies on Mo–CuO/Al₂O₃ catalyst, which can utilize plasma-induced species to improve the catalytic efficiency.     

Reaction of a triazolinedione with simple alkenes. Isolation and characterization of hydration products

The reaction of N-phenyltriazolinedione with three simple alkyl-substituted alkenes in water/alcohol or water/acetone solution was found to give a mixture of the corresponding ene and water addition products. The new hydration products were characterized by spectroscopy, and in one case, also by X-ray diffraction analysis. Thermodynamic parameters were determined for the reactions involving 2-methylbut-2-ene, TriME, and 2,3-dimethylbut-2-ene, TetraMe, in accordance with an ‘S_N2-like’, nucleophilic attack on a closed aziridinium imide (AI) intermediate by water.