Ball Milling of Copper Powder Under Dry and Surfactant-Assisted Conditions-On the Way Towards Cu/Cu2O Nanocatalyst.

Samples of copper powder was milled with varied grinding frequencies in the presence of various organic agents (oleylamine, ethylene glycol or dimethyl sulfoxide) or without additives. The effects of experimental conditions were investigated by X-ray diffractometry, scanning electron microscopy and dynamic light scattering measurements. The aggregation of particles were supressed by added organics. The catalytic activities of the variously treated samples were measured in the Ullmanntype reaction of iodobenzene and 1H-pyrazole.

The Synthesis and Use of Nano Nickel Catalysts.

The hydrazine reduction method was applied for the synthesis of nickel nanoparticles without using inert atmosphere and added surface active agents. The effect of the preparation temperature and the chemical quality of the metal sources as well as the solvents were studied. The generation of nanoparticles were studied primarily by X-ray diffractometry, but scanning and transmission electron microscopies as well as dynamic light scattering measurements were also used for the better understanding of the nanoparticles behaviour. The elevation of temperature was the key point in transforming Ni(OH)2 into metallic nickel. By selecting the metal source, the obtained crystallite sizes could be tailored between 7 nm and 15 nm; however, the SEM and DLS measurements revealed significant agglomeration resulting in aggregates with spherical or Ni(OH)2 resembling morphologies depending on the solvent used. The catalytic activities of the nanoparticles prepared were tested and compared in a Suzuki-Miyaura cross-coupling reaction.

Ultrasound-Assisted Hydrazine Reduction Method for the Preparation of Nickel Nanoparticles, Physicochemical Characterization and Catalytic Application in Suzuki-Miyaura Cross-Coupling Reaction.

In the experimental work leading to this contribution, the parameters of the ultrasound treatment (temperature, output power, emission periodicity) were varied to learn about the effects of the sonication on the crystallization of Ni nanoparticles during the hydrazine reduction technique. The solids were studied in detail by X-ray diffractometry, dynamic light scattering, thermogravimetry, specific surface area, pore size analysis, temperature-programmed CO2/NH3 desorption and scanning electron microscopy. It was found that the thermal behaviour, specific surface area, total pore volume and the acid-base character of the solids were mainly determined by the amount of the nickel hydroxide residues. The highest total acidity was recorded over the solid under low-power (30 W) continuous ultrasonic treatment. The catalytic behaviour of the nanoparticles was tested in a Suzuki-Miyaura cross-coupling reaction over five samples prepared in the conventional as well as the ultrasonic ways. The ultrasonically prepared catalysts usually performed better, and the highest catalytic activity was measured over the nanoparticles prepared under low-power (30 W) continuous sonication.