We show that coverage fluctuations on catalyst particles can drastically alter their macroscopic catalytic behavior. Scrutinizing the occurrence of kinetic bistabilities, it is demonstrated by molecular beam experiments on model catalysts that macroscopically observable bistabilities vanish completely with decreasing particle size, as previously predicted by theory. The effect is attributed to ...

Supported Ru and Pt nanoparticles are synthesized by the method of strong electrostatic adsorption and subsequently treated under different steaming-reduction conditions to achieve a series of catalysts with controlled particle sizes, ranging from 1 to 8 nm. While in the case of oxidation-reduction conditions, only Pt yielded particles ranging from 2.5 to 8 nm in size and a loss of Ru was obser...

Formation and properties of Pd nanoparticles have been investigated in situ in the temperature range between 186 and 483 K by X-ray absorption fine structure (XAFS) spectroscopy and by ex situ electron microscopy. Results of the experiments conducted under hydrogen and helium atmospheres were compared, in order to illuminate and explain the changes in bond length of Pd particles as a result of ...

A green, efficient, chemoselective, facile and clean procedure is described and discussed for the synthesis of α, α'-bis (substituted-benzylidene) cycloalkanones in solvent-free conditions. The condensation reaction was carried out through the reaction of aromatic aldehydes with cycloalkanones in the presence of Fe3O4@WO3 (Fe3O4@WO3</s...

in suspension polymerization, particle size distribution of polymer is the outcome of dynamic equilibrium between the break up and coalescence phenomena. the rates of break up and coalescence and consequently polymerization stability depend on several parameters, the most important of which are type and concentration of stabilizer. in this study, the effects of type and concentration of stabili...

In this research work, the dissolution of chalcopyrite was investigated under atmospheric pressure, with sulfate media at low temperatures, in 30°C to 50°C. In the galvanic interaction between chalcopyrite and pyrite, pyrite is used as a leaching catalyst. Effects of different parameters such as temperature, stirring speed, pyrite to chalcopyrite ratio, particle size, and solution potential wer...

Pd catalysts with varying particle size supported on a high-surface-area (600 m2/g) SiO2 were prepared by wet impregnation. The kinetics of vinyl acetate (VA) synthesis at atmospheric pressure was investigated in a fix-bed microreactor. With transmission electron microscopy (TEM), the average diameter of the Pd particles was estimated to be 4.0 ± 0.2 and 2.5 ± 0.1 nm over the reduced Pd(5.0 wt%...

The fluidization characteristics of a prototype-fluidized bed laboratory reactor were understudied in order to investigate the suitable conditions at which the dehydrogenation reaction of butane could be carried out. To achieve this, a reactor with an effective volume of 1100ml was fabricated and coupled with temperature and pressure accessories. Zeolites were obtained from the market and clay ...

Using a quite small but suitable amount of Nafion as stabilizer, iridium colloids with well controlled particle size were synthesized and directly used for fuel cells or water electrolyzers without further removal or addition of Nafion, meanwhile, a strategy for fabrication of supported catalyst with high utilization was also proposed.