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Rhodium(0) nanoparticles supported on hydroxyapatite: preparation, characterization and catalytic use in hydrogen generation from hydrolysis of hydrazine borane and ammonia borane
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2012
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Çelik, Derya
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This dissertation presents the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite, and investigation of their catalytic activity in hydrogen generation from the hydrolysis of hydrazine-borane and ammonia-borane. Rh+3 ions were impregnated on hydroxyapatite by ion-exchange; then rhodium(0) nanoparticles supported on hydroxyapatite were formed in-situ during the hydrolysis of hydrazine-borane at room temperature. The rhodium(0) nanoparticles supported on hydroxyapatite were isolated as black powders by centrifugation and characterized by ICP-OES, SEM, TEM, EDX, XRD, XPS, and N2 adsorption-desorption spectroscopy. Rhodium(0) nanoparticles supported on hydroxyapatite have a mean particle size of 2.7±0.7 nm. The catalytic activity of rhodium(0) nanoparticles supported on hydroxyapatite was tested separately in the hydrolysis of hydrazine-borane and ammonia-borane. The hydrolysis of hydrazine-borane was started by adding the precatalysts, Rh+3-exchanged hydroxyapatite into the aqueous solution of hydrazine-borane; whereas, the hydrolysis of ammonia-borane was initiated by adding the catalyst rhodium(0) nanoparticles supported on hydroxyapatite which have been isolated from the first run of hydrolysis of hydrazine-borane. Rhodium(0) nanoparticles supported on hydroxyapatite provide a turnover frequency value of 6700 h-1 in the hydrolysis of hydrazine-borane at room temperature. The reuse experiments reveal that these supported nanoparticles are isolable, bottlable, and redispersible in solution. Furthermore, they retain 62 % of their initial activity at the fifth run in the hydrolysis of hydrazine-borane with release of 3 equivalents hydrogen. Activity of rhodium(0) nanoparticles supported on hydroxyapatite is maintained after the redispersion of the sample and 3 equivalents hydrogen generation from the hydrolysis of ammonia-borane confirms the activity of preformed catalyst. Rhodium(0) nanoparticles supported on hydroxyapatite provide a turnover frequency value of 3990 h-1 in the hydrolysis of ammonia-borane at room temperature.
Subject Keywords
Inorganic Chemistry.
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http://etd.lib.metu.edu.tr/upload/12614070/index.pdf
https://hdl.handle.net/11511/21306
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Graduate School of Natural and Applied Sciences, Thesis
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D. Çelik, “Rhodium(0) nanoparticles supported on hydroxyapatite: preparation, characterization and catalytic use in hydrogen generation from hydrolysis of hydrazine borane and ammonia borane,” M.S. - Master of Science, Middle East Technical University, 2012.
