Nonlinear Energy Transfer over the Wave Spectrum in Water Covered by Solid Ice

On the basis of the hydrodynamic equations for nonlinear elastic-gravity waves beneath a solid ice cover and their Hamiltonian representation, a three-wave kinetic equation for the time evolution of the wave spectrum is formulated. The properties of the kernel of the kinetic integral describing the nonlinear interactions between wave triplets are investigated. An algorithm for numerically calculating the kinetic integral is developed. The rate of nonlinear energy transfer over the wave spectrum is estimated quantitatively and its most important characteristics are found.     

Type “salt-in-a-porous-matrix” sorbents in hydrocarbon processing

The information on the preparation and physicochemical properties of composite water sorbents of the type “salt in a porous matrix” is summarized. Comparative analysis of the kinetic and dynamic features of drying gas and liquid media on such sorbents is performed. Separate attention is given to the possibility of the possible use of “salt-in-porous-matrix” sorbents in hydrocarbon processing. Original Russian Text E.A. Buluchevskii, A.V. Lavrenov, V.K. Duplyakin, 2007, published in Russkii Khimicheskii Zhurnal, 2007, Vol. 51, No. 4, pp. 85–91.     

Hydroisomerization of benzene-containing gasoline fractions on a Pt/SO 42? -ZrO2-Al2O3 catalyst: II. Effect of chemical composition on acidic and hydrogenating and the occurrence of model isomerization reactions

The acidic and hydrogenating of Pt/SO₄²⁻-ZrO₂-Al₂O₃ samples containing from 18.8 to 67.8 wt % Al₂O₃ as a support constituent were studied by the IR spectroscopy of adsorbed CO and pyridine, and the model reactions of n-heptane and cyclohexane isomerization on these catalysts were examined. The total catalyst activity in the conversion of n-heptane decreased with the concentration of Al₂O₃; this manifested itself in an increase in the temperature of 50% n-heptane conversion from 112 to 266°C and in an increase in the selectivity of isomerization to 94.2%. In this case, the maximum yield of isoheptanes was 47.1 wt %, which was reached on a sample whose support contained 67.8 wt % Al₂O₃. A maximum yield (69.6 wt %) and selectivity (93.7%) for methylcyclopentane formation from cyclohexane were also reached on the above catalyst sample. This can be explained by lower concentrations of Lewis and Br?nsted acid sites in the Pt/SO₄²⁻-ZrO₂-Al₂O₃ system, as compared with those in Pt/SO₄²⁻-ZrO₂. The experimental results allowed us to make a preliminary conclusion that the Pt/SO₄²⁻-ZrO₂-Al₂O₃ catalyst whose support contains 67.8 wt % Al₂O₃ is promising for use in the selective hydroisomerization of benzene-containing gasoline fractions in the thermodynamically favorable process temperature range of 250–300°C.     

Synthesis of 1-N-(β-D-Glucopyranosyl)- and 1-N-(1-Deoxy-2,3,4,5,6-penta-O-acetyl-D-galactit-1-yl)ascorbigens

The 1-N-carbohydrate-containing ascorbigens 1-N-(-D-glucopyranosyl)ascorbigen and 1-N-(1-deoxy-2,3,4,5,6-penta-O-acetyl-D-galactit-1-yl)ascorbigen were synthesized.     

Chemical composition optimization and characterization of the NiO/B<Subscript>2</Subscript>O<Subscript>3</Subscript>-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> system as a catalyst for ethylene oligomerization

The samples of the NiO/B₂O₃-Al₂O₃ system with NiO contents from 0.48 to 38.30 wt % were synthesized by the impregnation of borate-containing alumina (20 wt % B₂O₃). It was found that nickel oxide occurred in an X-ray amorphous state in the samples containing to 23.20 wt % NiO. At a NiO content of 4.86 wt % or higher, the support was blocked by the modifier to cause a decrease in the specific surface area from 234 to 176 m²/g and in the amount of acid sites from 409–424 to 333 μmol/g. An extremal character of the dependence of catalyst activity in ethylene oligomerization on NiO content was found with a maximum in the range of 4.86–9.31 wt %. Based on spectroscopic data, it was found that ethylene activation on the NiO/B₂O₃-Al₂O₃ catalyst can be associated with the presence of Ni²⁺ cations, which chemically interact with the support. The catalyst containing 4.86 wt % NiO at 200°C, a pressure of 4 MPa, and an ethylene supply rate of 1.1 h⁻¹ provided almost complete ethylene conversion at the yield of liquid oligomerization products to 90.0 wt %; the total concentration of C⁸⁺ alkenes in these products was 89.0 wt %.     

Mechanochemical synthesis of nanocrystalline nickel-molybdenum compounds,their morphology and application in catalysis: I. Effect of the Ni: Mo atomic ratio on the structure and properties of nickel-molybdenum compounds prepared under mechanochemical synthesis conditions

Mechanochemical activation in high-energy planetary activators was used for the preparation of highly dispersed nickel-molybdenum compounds. Nickel hydroxocarbonate [NiCO₃ · 2Ni(OH)₂ · nH₂O] and ammonium paramolybdate [(NH₄)₆Mo₇O₂₄ · 4H₂O] were chosen as starting compounds. The effect of the Ni: Mo atomic ratio on the composition and structure of products formed in the process of mechanochemical activation followed by calcination was studied. It was found that, at the Ni: Mo atomic ratios of 1.0 and 1.4, the mechanically activated product after calcination at 520°C contained 70–100% β-NiMoO₄, which is a stable phase at temperatures lower than 180°C.     

Oligomerization of butenes on borate-containing alumina

The effects of the chemical composition of borate-containing alumina on its physicochemical properties, catalytic activity, and selectivity in the oligomerization of butenes are reported. The preparation of catalysts containing 2.6–12.4 wt % B₂O₃ by modifying γ-alumina with orthoboric acid leads to a 9–60 m²/g decrease in the specific surface area and to a 0.02–0.14 cm³/g decrease in the pore volume relative to the same parameters of the initial support. At boron oxide contents of ≥8.8 wt %, these changes are due to the buildup of B₂O₃ on the catalyst surface. This is accompanied by a decrease in the number of surface B-OH groups, which are active sites of oligomerization. This finding correlates well with the results of catalytic measurements. The catalyst containing 4.5 wt % B₂O₃ is the most active. It was found by experimental design methods that the most favorable combination of catalytic activity (total butene conversion of 77.8–86.8%) and selectivity (butene oligomer concentration of at least 90 wt % in the liquid product) is attained at T = 150°C, P = 8.0 MPa, and a butene WHSV of 0.5–1.0 h^?1. Under these conditions, the butene conversion decreases by no more than 13% from the initial level in 14 h. The activity of the catalyst can be restored by oxidative regeneration.     

On askey-wilson algebra

The ladder representations of Askey-Wilson algebra (AWA) is investigated and the over-lap problem is discussed. The full class of exactly solvable potentials for one-dimensional ordinary Schrödinger equation with the AWA as an algebra of dynamical symmetry is found for creation-annihilation operators of third order. The generating spectrum algebra for latticeSchrödinger equation as AWA is examined. All exactly solvable potentials with this dynamical symmetry are found. Some generalizations of obtained results are discussed.