Structure and composition of the surface layer of Zr-containing fiberglass materials

The chemical composition and structure of Zr-containing fiberglass materials were studied by Infrared spectroscopy, X-ray photoelectron spectroscopy, and nuclear magnetic resonance spectroscopy. The domains built of three-dimensional network of silicon–oxygen tetrahedrons connected through zirconium were revealed in the bulk of fiber. The space between these domains was found to be filled with sodium silicates and carbonates (in subsurface layers). It was shown that the leaching of fiberglass materials resulted in the formation of a SiO₂ layer on the fiber surface, which was almost zirconium free.     

Mobility and reactivity of lattice oxygen in Gd-doped ceria promoted by Pt

Summary For samples of the Ce_1-xGd_xO_2-y system prepared by the Pechini route and promoted with Pt, the mobility and reactivity of lattice oxygen were found to correlate with the density of surface and bulk anion vacancies.     

Isopropanol diffusion and dehydration in zeolite Hzsm-5. Spectrokinetic study

The isopropanol diffusion and dehydration in zeolite HZSM-5 were studied by FTIR spectroscopy. The alcohol dehydration was shown to start at the temperature above 60°C. It was found that at temperatures above 350°C, the isopropanol dehydration was limited by diffusion in the mesopores of zeolite. The method developed allows studying the kinetics of interactions of the reagent molecules with the OH-groups at the external surface of the zeolite and inside its channels.     

Reactivity and transformation routes of surface nitrates in the reaction of NOx reduction by C3H8 over cation-exchanged zeolites

FITRS combined with¹⁵N and¹⁸O isotope substitution and TPD have revealed that nitrates are the most abundant ad-NO_x species on over-exchanged Cu- and Co-ZSM-5 zeolites. the transformation rates of such species under the action of a propane—oxygen mixture were found to be comparable and sufficiently high to afford steady-state catalytic activities. A scheme of the reaction mechanism including C, N-containing intermediates detected in work is suggested.     

Carbonization of alumina-based catalysts in propionitrile ammonolysis

Summary The asymmetric hydrogenation of ethyl 2-acetoxyacrylate (EtA) by cinchonidine modified Pd/Al2O3 and Pt/Al2O3 catalyst is described (ee up to 60 %). This is the first example of asymmetric hydrogenation of an enol esters in heterogenized conditions.     

Adsorption and conversion of ethylene glycol on the surface of Ag-containing catalyst modified with phosphate

The interaction of ethylene glycol with the surface of Ag-containing catalysts modified with phosphates was studied by IR spectroscopy. It was found that ethylene glycol was adsorbed at the surface phosphate groups; the presence of water vapor increased the stability of adsorbed ethylene glycol to a temperature of 400°C. A study of the kinetics of oxidation of ethylene glycol showed that it was consecutively converted into glycolaldehyde and glyoxal at 400°C. At 500–550°C, glyoxal was formed upon both the consecutive and direct conversion of ethylene glycol. The presence of a stage of the consecutive conversion of ethylene glycol into glycolaldehyde and glyoxal was caused by the participation of surface phosphate groups in the adsorption of alcohol molecules to be oxidized.     

State of components in PdCu/Al2O3 catalysts obtained via anchored metal complexes

IRS and XPS data have shown that the reduction of pdCu/Al₂O₃ catalysts is followed by the formation of 30–40 Å homogeneous bimetallic particles with a surface enriched in copper atoms.     

Acid-base and catalytic properties of iron-antimony oxide catalysts

Iron antimonate, whose strongest acidic sites (Fe³⁺) are blocked by weak acidic aprotic centers Sb³⁺, is an active and selective catalyst for the ammoxidation of propylene.

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, (Fe⁺³) Sb⁺³, .

     

Estimation of proton donor ability of surface hydroxy groups in terms of proton affinity

A method to estimate the proton donor ability of hydroxy groups in terms of proton affinity (PA) is suggested. The PA of hydroxy groups of aerosil and of decationated zeolite type Y have been determined.

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(PA). PA .

     

Studying the Interaction between Water Vapor and a γ-Al2O3 Surface by IR Spectroscopy

Russian Journal of Physical Chemistry A - The interaction between a γ-Al2O3 surface and vapors of H2O and D2O is studied via IR spectroscopy. It is shown that surface hydroxyl groups of...