Sökning: "rhodium"
Visar resultat 11 - 15 av 67 avhandlingar innehållade ordet rhodium.
11. Development of a regeneration procedure for commercial automotive three-wy catalysts
Sammanfattning : Car exhaust catalysts were introduced in the early 1980’s, to limit the release of pollutants such as hydrocarbons, carbon monoxides and nitrogen oxides. These catalysts contain noble metals such as palladium (Pd), platinum (Pt) and rhodium (Rh) and are able to simultaneously abate all three of the above-mentioned pollutants, hence the name three-way catalyst (TWC). LÄS MER
12. Asymmetric transfer hydrogenation of ketones : Catalyst development and mechanistic investigation
Sammanfattning : The development of ligands derived from natural amino acids for asymmetric transfer hydrogenation (ATH) of prochiral ketones is described herein. In the first part, reductions performed in alcoholic media are examined, where it is found that amino acid-derived hydroxamic acids and thioamides, respectively, are simple and versatile ligands that in combination with [RhCp*Cl2]2 efficiently catalyze this particular transformation. LÄS MER
13. Experimental Studies of NOx Catalysts; Storage, Reduction and Sulphur Deactivation
Sammanfattning : The aim of this thesis work was to investigate how different gaseous compounds, present in an automotive exhaust from lean-tuned combustion, interact with so-called NOx storage catalysts containing Al2O3 as a support, BaO as the NOx storage compound and noble metals to provide oxidation and reduction functions. The investigations included model sample preparations, flow reactor studies with various gas mixtures and spectroscopic experiments (FTIR and XPS). LÄS MER
14. Transition metal-catalyzed reduction of carbonyl compounds : Fe, Ru and Rh complexes as powerful hydride mediators
Sammanfattning : A detailed mechanistic investigation of the previously reported ruthenium pseudo-dipeptide-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones was performed. It was found that the addition of alkali metals has a large influence on both the reaction rate and the selectivity, and that the rate of the reaction was substantially increased when THF was used as a co-solvent. LÄS MER
15. Platinum Group Elements in Birds of Prey
Sammanfattning : The environmental concentrations of Pd, Pt and Rh (three of the platinum group elements, PGE) have increased since the introduction of exhaust catalysts on automobiles. A limited understanding of the environmental distribution and effects of the platinum group elements has raised concern over their potential biological availability. LÄS MER