Ruthenium(0) nanoparticles supported on graphene: preparation, characterization and catalytic use in hydrogen generation from hydrolysis of ammonia borane

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2015

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Acar, Fatma Asiye

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The development of new storage materials will facilitate the use of hydrogen as a major energy carrier in near future. In hydrogen economy, chemical hydrides have been tested as hydrogen storage materials for supplying hydrogen at ambient temperature. Among these chemical materials, ammonia borane having a high content of hydrogen (19.6 wt.%) seems to be an ideal hydrogen storage material since it is stable under ordinary conditions and releases hydrogen gas in a safe and controllable way in aqueous solutions. However, hydrolysis of ammonia borane requires a suitable catalyst. In this thesis, the preparation, characterization and investigation of the catalytic activity of the ruthenium(0) nanoparticles supported on graphene were reported. In order to obtain ruthenium(0) nanoparticles supported on graphene, first graphene oxide was prepared from graphite by using modified Hummers’ method. Then Ru3+ ions were impregnated onto graphene oxide. Finally, ammonia borane was used to reduce ruthenium(III) ions to ruthenium(0) nanoparticles supported on graphene. The ruthenium(0) nanoparticles were characterized by ICP-OES, XRD, SEM, SEM/EDX and TEM. Ruthenium(0) nanoparticles supported on graphene were used to catalyze the hydrolysis of ammonia borane releasing 3 equivalent of hydrogen per mole of ammonia borane. They are highly active catalyst providing 200,000 turnovers in hydrogen generation from the hydrolysis of ammonia borane at 25.0 ± 0.1 °C with an initial turnover frequency value of 150 min-1. The kinetics of the catalytic hydrolysis of ammonia borane was studied depending on the catalyst concentration, substrate concentration, and temperature. The kinetic study shows that the ruthenium(0) nanoparticles-catalyzed hydrolysis of ammonia borane is first order with respect to catalyst concentration and zero order with respect to substrate concentration. The activation parameters of this reaction were determined from the evaluation of the kinetic data.

Subject Keywords

Ruthenium., Hydrolysis., Ammonia., Boranes., Catalysts., Nanoparticles.

URI

http://etd.lib.metu.edu.tr/upload/12618351/index.pdf
https://hdl.handle.net/11511/24355

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

F. A. Acar, “Ruthenium(0) nanoparticles supported on graphene: preparation, characterization and catalytic use in hydrogen generation from hydrolysis of ammonia borane,” M.S. - Master of Science, Middle East Technical University, 2015.