The main focus of the present work is the recovery process for spent fuels based on catalytic hydrogenation of liquid organic hydrides (LOH). To gain the knowledge about the possible hurdles of hydrogen loading process, the hydrogenation of 9-ethylcarbazole as a model compound was elected to be studied in more detail. The structures of the intermediates and products of this reaction were characterized for the first time using combined GC-MS and NMR analysis with reference to DFT calculations. The fully saturated product was found to be a mixture of stereoisomers. A reaction model was developed which agreed well with the experimental results. The combined theoretical and experimental approaches were also undertaken to identify catalytic sites on the metal surface and their role in the hydrogenation of 9-ethylcarbazole. Kinetically stable intermediate (Plus 8 [H]) containing a central unsaturated “pyrrole” ring was found to be accumulated in the solution over a ruthenium black catalyst. Its further hydrogenation was found to involve its unusual shuttling from terraced sites to higher indexed sites. The stability of Plus 8 [H] was found to be influenced by the type of active sites present on the surface of the catalyst, as well as by the electronic structure of the metal. In addition, the kinetics of the hydrogenation was analyzed experimentally and the activation energies were obtained for all of the intermediate steps. Further understanding of how the molecules interact with the catalyst surface was provided by examining the hydrogenation activity and selectivity of a series of LOH. The general factors involved in LOH structure- catalyst –activity trend were outlined. Overall, due to a number of defined challenges in the LOH spent fuel recharging, it is believed that this complex H2 storage strategy is not likely to meet the targets for wide scale applications.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:572651 |
| Date | January 2011 |
| Creators | Morawa Eblagon, Katarzyna Anna |
| Contributors | Tsang, S. C. Edman ; Ramirez-Cuesta, Timmy |
| Publisher | University of Oxford |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://ora.ox.ac.uk/objects/uuid:eca70cd1-68cb-48c2-b505-852b11876774 |
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