[Show abstract][Hide abstract] ABSTRACT: Herein, we report the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite (Ca10(OH)2(PO4)6, HAP) and their catalytic use in the hydrolysis of hydrazine-borane, which attracts recent attention as promising hydrogen storage materials. Hydroxyapatite supported rhodium(0) nanoparticles were readily prepared by the hydrazine-borane reduction of rhodium(III)-exchanged hydroxyapatite in situ during the hydrolysis of hydrazine-borane at room temperature. Characterization of the resulting material by ICP–OES, TEM, SEM, EDX, XRD, XPS spectroscopies and N2 adsorption–desorption technique, which shows the formation of rhodium(0) nanoparticles well dispersed on hydroxyapatite support. The catalytic performance of these new supported rhodium(0) nanoparticles in terms of activity, lifetime and reusability was tested in the hydrolysis of hydrazine-borane. They were found to be highly active, long-lived and reusable catalyst in this important catalytic reaction even at low temperatures and high initial [substrate]/[catalyst] conditions. This report also includes the detailed kinetic study of the hydrolysis of hydrazine-borane catalyzed by hydroxyapatite supported rhodium(0) nanoparticles depending on the catalyst concentration, substrate concentration, and temperature.
Full-text · Article · Mar 2012 · International Journal of Hydrogen Energy
[Show abstract][Hide abstract] ABSTRACT: Pentacarbonyl(2-methylpyrazine)chromium(0) [Cr(CO)(5)(2mpyz)], complex was isolated from its n-hexane solution as orange plate-like crystals which were characterized by IR, NMR spectroscopies and X-ray crystallography. The crystallographic results show that the complex was crystallized in the monoclinic system with the unit cell parameters of a=7.176 (5), b=12.045 (3), c=14.461 (3)Å, β=90.44 (3)° and space group 2/M. The single crystal structure of the complex shows the bonding of chromium metal to 2-methylpyrazine through the less sterically hindered nitrogen-4 lone pair. The pyrazine ring plane makes an angle of 179.58° (19) with COCrN bond axis. The four carbonyl groups are slightly bent away from pyrazine with the angle of 91.28° (17) for C(5)CrN1 bond axis. The DFT calculations run out using the Gaussian 03 PC program show good agreement with the experimental results. The thermal properties of the complex were also investigated by differential thermal analysis and thermogravimetry techniques.
No preview · Article · Feb 2012 · Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy
[Show abstract][Hide abstract] ABSTRACT: Among the hydrogen storage materials, ammonia-borane and sodium borohydride appear to be promising candidates as they can release hydrogen on hydrolysis in aqueous solution under mild conditions. Here, we report the development of a cost-effective and highly active nickel(0) nanoparticles catalyst for the hydrolysis of ammonia-borane and sodium borohydride. Nickel(0) nanoparticles confined in zeolite framework were prepared by using our previously established procedure and characterized by ICP-OES, XRD, TEM, HR-TEM, SEM, EDX, XPS, Raman spectroscopy and N(2) adsorption-desorption technique. All the results show that nickel(0) nanoparticles are formed within the framework of zeolite-Y. Nickel(0) nanoparticles confined in zeolite framework are highly active catalyst in the hydrolytic dehydrogenations of sodium borohydride and ammonia-borane. This catalyst is isolable, bottleable, redispersible and reusable. The report also includes the detailed kinetic study of the catalytic hydrolysis of both substrates, ammonia-borane and sodium borohydride depending on the catalyst concentration, substrate concentration, and temperature.