Heterogeneous reactions of tropospheric trace-gases on solid model aerosol surface : a laboratory study

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One-step hydroxylation of benzene to phenol by N2O has been performed over structured catalytic beds made of ZSM-5 coatings on stainless steel grids. The catalysts demonstrated high activity with a selectivity toward phenol formation of 98%. A detailed kinetic study was carried out with a variation in reactant concentrations, benzene/N2O ratio, and residence time. The results obtained suggest a surface reaction between benzene and nitrous oxide adsorbed on two different active sites.

The catalytic cracking of methane over nickel gauze is proposed as an attractive alternative for the prodn. of CO-free hydrogen. The catalyst deactivates due to intensive coke deposition. Therefore, the reactor was operated periodically with the reaction followed by the catalyst regeneration by burning of coke in oxidative atm. The optimal reaction performance was found to consist of reaction periods of 4 min followed by 4 min regeneration periods. [on SciFinder (R)]

The Cl2 evolution reaction was studied at highly boron-doped diamond thin film electrodes. The comparison of this carbonaceous material with graphite and glassy carbon points out the similar behavior in terms of diagnostic parameters and related mechanisms, without the mech. fragility of these materials. Tafel slopes at different chloride concns. in soln. (from 0.1-4 M NaCl in 0.01 M HClO4) and at different pHs were detd., together with the reaction orders with respect to Cl- and H+. All measurements were c

Nickel-aluminium intermetallics constitute interesting systems for the study of irradiation-induced phase transformations (order → disorder, amorphization) and production of defects. Irradiation of ordered intermetallics may induce disorder or amorphization depending on the projectile characteristics, irradiation conditions and chemical and physical properties of the target. The behavior of the various intermetallic compounds of the nickel-aluminium system with respect to electron and ion irradiation has be

Metalation/trapping sequences applied to relatively inert, tert-alkyl substituted arenes tend to give poor yields unless the reagent is used in high concns. Under optimized conditions, even 1,4-bis(tert-butyl)benzene, 1,1,3,3-tetramethylindane and 1,1,2,2,3,3-hexamethylindane can be smoothly converted into derivs. Competition expts. enable the quant. assessment of tert-alkyl substituent effects on the metalation rates at arom. ortho, meta and para positions. Unlike alkyl groups, hetero elements generally ac

The electrochemical promotion of heterogeneous catalytic reactions is a new development which draws the attention of the scientific community as much to fundamental research as to the possible direct applications of this phenomenon in automotive and in industrial catalysis. We have chosen to study the electrochemical promotion of the complete ethylene oxidation on metallic oxides catalysts. The principal oxides which we used has been the iridium oxide (IrO2) and iridium and titanium oxide mixtures (IrO2+TiO

Pb1-xCaxTiO3 thin films with x = 0-0.3 for pyroelectric applications were deposited on platinized silicon wafers by chemical solution processing. Ca-substitution for Pb in PbTio(3) results in a reduced cia ratio of the unit cell, which, in turn, leads to better pyroelectric properties. Control of nucleation and growth during rapid thermal annealing to 650 degrees C allowed the formation of either highly porous or dense (111) oriented films. The inclusion of pores creates a matrix-void composite with the low

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

Chem. ligation methods in combination with regioselective addressable templates have allowed the prepn. of well defined complex monomol. films tethered to gold surfaces. The supramol. monolayers exposed artificial recognition sites, here for monoclonal antibodies. SPR, FTIR spectroscopies, and TOF-SIMS were ideally suited surface sensitive techniques to enable the essential control of the individual reaction steps. The concept presented here for the functionalization of gold surfaces may be easily applied t

The measurements obtained were used to investigates the methanol synthesis reaction from pure carbon dioxide and hydrogen over binary (CuO/ZrO2) and ternary supported catalysts (CuO/ZnO/Al2O3). A comparison of different catalysts is presented. The influence of the most important reaction parameters, i.e. temperature, pressure, space velocity and feed gas composition is examined at moderate temperatures (≤ 300 °C) and pressures (≤ 20 bar). The influence of the partial pressures of hydrogen, carbon dioxide, c

The kinetics of condensation of D218O water vapor on D216O ice was studied in the temp. range 140-220 K. The measurements have been performed in real time using the pulsed valve technique in a low-pressure flow reactor. Ice samples were prepd. by several different methods. The uptake coeff. (g) was obsd. to decrease with increasing surface temp., and varied from g = 0.06 to 0.8. A significant dependence of g on the method of prepn. of the ice has been found. At 180 K, g = 0.13 for single-crystal ice, 0.18 f

The large quantities of reactor-grade (RG) and weapons-grade (WG) Pu accumulated worldwide could be reduced by employing 100% mixed-oxide (MOX) cores in light water reactors. The buildup of new Pu from the U present in the MOX, however remains disadvantageous from the viewpoint of inventory reduction and also enhances the need for multiple recycling. A more effective way would be to use U-free fuel so that no new Pu is produced. A comparison is made, from the physics design viewpoint, between the potential

Heterogeneous reactions of tropospheric trace-gases on solid model aerosol surface : a laboratory study

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ZSM-5 coatings on stainless steel grids in one-step benzene hydroxylation to phenol by N2O: Reaction kinetics study

Hydrogen production by catalytic cracking of methane over nickel gauze under periodic reactor operation

Chlorine evolution at highly boron-doped diamond electrodes

The order-disorder transformation and microstructure evolution in nickel-aluminium intermetallics after heavy-ion irradiation

The rate retarding effect of alkyl groups on arene metalation quantified

Etude de la promotion électrochimique de l'oxydation catalytique de l'éthylène sur des oxydes métalliques

Microstructural evolution of dense and porous pyroelectric Pb1−xCaxTiO3 thin films

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Functional molecular thin films: topological templates for the chemoselective ligation of antigenic peptides to self-assembled monolayers

Carbon dioxide hydrogenation to methanol at low pressure and temperature

Real-Time Kinetic Measurements of the Condensation and Evaporation of D2O Molecules on Ice at 140 K < T < 220 K

Comparison of pressurized water reactor core characteristics for 100% plutonium-containing loadings