Papers by Keyword: Polyol Reduction

Abstract: Nanocrystalline Co₈₂Ni₁₈ alloy was synthesized by polyol reduction of cobalt-nickel hydroxide precursor. X-ray diffraction results indicated the formation of fcc phase alloy and the crystallite size was found to be about 19 nm. Scanning electron microscopy and transmission electron microscopy images showed the morphology of particles close to spheres and stoichiometry of the precursor and the alloy was obtained by the energy dispersive X-ray analysis. Selected area electron diffraction pattern indicated the polycrystalline nature of the alloy particles. The saturation magnetization of the nanocrystalline alloy was about 107 (emu/g) at room temperature and the M-H measurements at 300 K and 5 K indicated that the nanocrystalline alloy exhibits close to superparamagetic behaviour.

Abstract: Novel catalytic systems based on PdZn alloys have been synthesized by polyol reduction over the entire compositional range [1, 2] and characterized by means of HRTEM, EDS and ICP. The expected bulk compositions were reproducible to within a 2 mol% margin and the purified particle suspensions stable for several months after preparation. The EDS results indicated the presence of considerable amounts of oxygen, especially in those samples containing high fractions of zinc. The particle size distributions were shown to be narrow and the mean sizes slightly decreased with higher molar fractions of palladium (diameter range 2.6 to 3.2 nm). In the catalytic hydrogenation of phenylacetylene, a strong dependence of the substrate conversion time on the Pd concentration was established, and selectivity towards the semihydrogenation product (styrene) was found to be close to 100 %. The selectivity dropped only shortly before the initial substrate was fully depleted.