Liquid-Phase Heterogeneous Oxidation of Hydroxypivalaldehyde with Oxygen in Alkaline Aqueous Solution in the Presence of Supported Palladium Catalyst

The kinetics of a model reaction of hydroxypivalaldehyde oxidation with molecular oxygen in alkaline aqueous solution in the presence of 4% Pd/Al2O3 was studied with the aim of searching for promising heterogeneous catalysts for D-glucose oxidation.     

Dehydrogenation of methanol on low Cu and Re—Cu catalysts supported on sibunite

The activity and selectivity of mono- and bimetallic catalysts containing copper and rhenium on sibunite were studied in the decomposition of methanol to methyl formate (MF), water, H₂, CO, and CO₂at 200—400 °C. Methane is also formed on rhenium-containing catalysts at 300—400 °C. The dehydrogenating activity and selectivity to form MF are higher on the copper-sibunite catalysts than on the rhenium-sibunite samples. The introduction of 0.25% Re into the 4% copper-containing catalyst enhances its total activity and stability.     

Adsorption properties of cermet and track-etched poly(ethylene terephthalate) membranes

The adsorption properties of cermet and track-etched poly(ethylene terephthalate) (PET-TM) membranes are compared with respect to proteins and water-soluble dyes. It is shown that the cermet membranes have a noticeably higher adsorption capacity (calculated per unit surface area) than the PET-TM. In this case, the character of adsorption of these substances on both types of membranes is quite similar and determined by the combination of ionic and hydrophobic interactions. The adsorption values of basic dyes are considerably higher than acid one because of the negative charge at the membrane surfaces. The isotherm of adsorption of the basic dye rhodamine 6G on PET-TM from aqueous solution is characterized by the inflection in the concentration range of lower than 1 µmol/l due to the presence of highly active adsorption sites on the surface. The adsorption of dyes considerably lowers on adding isopropanol to the aqueous solution. Using basic protein cytochrome C as an example, it is established that its adsorption on cermet membranes can be prevented by increasing solution ionic strength.Translated from Kolloidnyi Zhurnal, Vol. 67, No. 1, 2005, pp. 124–127. Original Russian Text Copyright © 2005 by Khataibe, Khokhlova, Trusov, Mchedlishvili.     

A Magnetooptical Effect in a Rotating Field in the Case of a Polymorphic Colloid

Magnetooptical methods are used to study particle polymorphism in colloids and suspensions. Electrooptical methods of studying disperse systems make it possible to determine the average value of the shape factor of colloidal particles approximated by ellipsoids of revolution. However, they do not enable one to solve the problem of the particle shape distribution in real disperse systems, because the orientation of particles in an electric field always depends on their size as well as shape. The use of a magnetic field makes it possible to create the conditions under which the orientation of particles is determined by their shape irrespective of the size.     

Tuning the morphology and magnetic properties of single-domain SrFe8Al4O19 particles prepared by a citrate auto-combustion method

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IR luminescence of bismuth-containing centers in materials prepared by impregnation and thermal treatment of porous glasses

The properties of bismuth-containing luminescent materials prepared by impregnating a porous glass with an aqueous solution of bismuth and aluminum salts followed by thermal treatment are studied. The formation of a variety of bismuth-containing centers luminescent in the near infrared range of the spectrum is revealed, one of which is the Bi⁺ monocation. At high temperatures, along with it, bismuth-containing cluster-type luminescent centers are apparently formed.     

Determination of the size of particles of highly dispersed materials by low temperature nitrogen adsorption

The average size of particles of highly dispersed materials (Al₂O₃, TiO₂, Y₂O₃) is calculated from their specific surface areas. The latter is determined with the analysis of sorption capacity of materials with nitrogen at ?196°C in the ranges of relative equilibrium pressures of 0.05–0.35 (the Brunauer-Emmett-Teller method, BET) and 0.4–0.7 (the comparative method). Good agreement is obtained between results produced with the comparative method and familiar methods of analysis such as scanning and transmission electron microscopy and small-angle X-ray scattering.