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Rhodium in the environment
Ondreášová, Klára ; Nevrlá, Jana (referee) ; Komendová, Renata (advisor)
This bachelor thesis focuses on the characteristic of rhodium, its use in the automotive industry, the occurrence in environmental compartments (air, soil, vegetation, water), accumulation and transformations. In this thesis there are also described methods of sampling for determination, the types of sample preparation, separation and preconcentration techniques necessary prior to instrumental analysis. The work also focuses on the most commonly used analytical methods of rhodium determination, which are spectrophotometric methods, AAS, ICP-AES and ICP-MS.
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Single Atomic Catalysts
Závodný, Adam ; Švec,, Martin (referee) ; Čechal, Jan (advisor)
Single atom catalysts are prospective class of materials, which holds promises to reach the ultimate limit of improvement in catalyst performance, selectivity, lifetime and cost reduction. The ability to efficiently capture the adsorbates at the active sites is the key prerequisite for catalytic transformation to the products. In this respect, our experimental study aims to describe the interaction of gas molecules (H2O, CO, O2 and NO) with single metal atoms (Rh, Ir, Cu) on the magnetite surface employing scanning tunneling microscopy.
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Investments of the Automotive Industry in Precious Metals as Strategic Materials
Dvořáček, Martin ; Plíhal, Tomáš (referee) ; Rejnuš, Oldřich (advisor)
The subject of the thesis is the investment recommendations of companies operating in the automotive industry to purchase strategic raw materials, such as in particular platinum, palladium and rhodium. Thesis include a theoretical description of the topic, respectively certain forms of hedging, instruments used to hedge and brief characteristics of precious metals. Analytical and proposed section of the thesis contains specific methods, procedures and its own approach used to meet the global target of thesis.
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Platinum group elements in waste and surface waters
Novotný, Matěj ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This assignment provides a detailed description of platinum metals, their occurrence in surface and waste water and their determination options. Currently, platinum metals are widely used in the automotive industry as a part of a catalyst, as well as in medicine and jewelery. Release of these metals in pure form and the form of oxides leads to their subsequent accumulation, which directly affects fauna and flora. Due to that, the living conditions and health status of some organisms are petting worse.
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Study of contamination of river sediments with platinum metals
Novotný, Matěj ; Řezáčová, Veronika (referee) ; Komendová, Renata (advisor)
This work deals with the characteristics of platinum metals and problems related to their toxicity and mobility in the environment, especially in the aquatic environment. These metals are released into the environment due to the use of automotive catalysts. Their function is based on the catalytic properties of platinum metals. Because of the high temperatures, these metals can be oxidized in the catalyst and subsequently emitted together with the combustion products into the surrounding atmosphere. The aim of the thesis is to measure real samples of river sediments of the river Svratka on the territory of the city of Brno and to find the possibility of contamination of the aquatic environment with these metals.
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Study of gas molecule - surface interaction
Kettner, Miroslav ; Nehasil, Václav (advisor) ; Johánek, Viktor (referee)
Title: Study of gas molecule - surface interaction Author: Miroslav Kettner Department: Department of surface and plasma science Supervisor: doc. RNDr. Václav Nehasil, Dr., Department of surface and plasma science Abstract: In this work, we examined the suitability of rhodium deposited on a plasma sprayed substrate of titanium dioxide for catalysis reactions. With X-ray photoelectron spectroscopy method, the thermal stability of TiO2 prepared with plasma spray technology on aluminum plate was tested at first. Then, rhodium was evaporated on substrate and thermal stability of the whole system Rh/TiO2 was determined. Further methods of thermal desorption spectroscopy and molecular beam were used to study adsorption and desorption of CO and reaction of CO with oxygen. It was verified that the system Rh/TiO2 ceases to adsorbing CO after heating above 620 K, also the CO reaction with oxygen exhibits considerably lower intensity after heating above 620 K. After calibrating on rhodium plate, it was determined that the intensity of CO2 creation on Rh/TiO2 is four times lower than intensity on the rhodium plate. Unprompted adsorption and desorption passivation of the system, however, seems to be the most significant problem. Therefore, the system was assessed as unsuitable for further research. Keywords: Rh, TiO2,...
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Study of CeOx / Rh inverse catalyst
Kettner, Miroslav ; Nehasil, Václav (advisor) ; Johánek, Viktor (referee)
Title: Study of CeOX / Rh inverse catalyst Author: Bc. Miroslav Kettner Department: Department of Surface and Plasma Science Supervisor: doc. RNDr. Václav Nehasil, Dr., Department of Surface and Plasma Science Abstract: Inverse catalysts of cerium oxide deposited on polycrystalline and monocrystalline (111) rhodium substrates were studied by means of surface science experimental methods. Growth characteristics of cerium oxide were investigated in dependence on deposition conditions and different thickness determination methods were compared. Acording to oxidizing or reducing exposition conditions changes in degree of oxidation of CeOX were observed. Further spectra analysis showed additional Ce-Rh alloy formation. Adsorption positions CO on-top and CO hollow on Rh (111) surface were differentiated by spectra fitting procedures. Oxygen absorption and reverse desorption in CeOX was confirmed. Performed experiments indicate that this process occurs through oxide-metal interface. CO oxidation reaction mechanisms at room temperature were proposed. Cerium oxide presence is necessary for reaction occurrence. Significant influence of deposited CeOX on proposed CO oxidation reaction mechanisms was proved by this way. Keywords: Rhodium, cerium oxide, alloy, inverse catalyst, CO oxidation.
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Reactivity of transition metals - influence of the degree of oxidation of active substrate
Kettner, Miroslav ; Nehasil, Václav (advisor) ; Jiříček, Petr (referee) ; Lykhach, Yaroslava (referee)
The impacts of fluorine doping of ceria are studied by means of surface science experimental methods. Fluorine-doped and fluorine-free ceria layers are epitaxially grown on rhodium single crystals and their properties are compared in regular and inverse catalyst configurations. A procedure for epitaxial growth of CeO2(110) and CeOxFy(110) layers on Rh(110) single crystal is developed and described in detail. Shape alterations of Ce 3d spectrum brought about by fluorine doping are explained and a suitable deconvolution method is proposed. Special attention is focused towards stability of fluorine in ceria. Presented data show that fluorine incorporation in ceria lattice causes stable reduction of ceria, which withstands up to 200řC in near-ambient pressure conditions. Morphological changes are observed due to elongation of surface lattice constant of reduced ceria. Oxygen storage capacities and hydrogen oxidation reaction rates of four different studied systems are compared and discussed. The twofold nature of oxygen exposure of fluorinated ceria is discovered and explained. Oxygen repels fluorine from the surface, while the remaining part of fluorine is expelled to adsorbate positions, where its electronic state is altered. Moreover, such fluorine is prone to interact with atomic hydrogen. This reaction is...
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Reactivity of a ferrocene distibane
Antala, Jakub ; Štěpnička, Petr (advisor) ; Gyepes, Róbert (referee)
5 Title: Reactivity of ferrocene distibane Author: Jakub Antala Department: Department of Inorganic Chemistry Supervisor: prof. RNDr. Petr Štěpnička, Ph.D., DSc. Consultant: RNDr. Jiří Schulz, Ph.D. Abstract: The aim of this bachelor thesis is preparation of 1,1'-bis(diphenylstibino)ferrocene (L), an antimony analogue of the widely studied ligand 1,1'-bis(diphenylphosphino)ferrocene and study into its coordination properties. Two ruthenium(II) (1, 3) and two rhodium(III) complexes (2, 4) were prepaired, in which the ligand L coordinates as bridging or chelating ligand. Two ruthenium(II) and one rhodium(III) precursors with π-coordinated arene ligands were used for the preparation of complexes. When preparing chelate complexes, sodium hexafluorophosphate was also necessary. All complexes were characterised by NMR spectroscopy, mass spectrometry, elemental analysis and crystal structure was determined by X-ray structural analysis. The structures of the stibine complexes were compared with their analogs resulting from 1,1'-bis(diphenylphosphino)ferrocene. Key words: ferrocene, stibines, complexes, ruthenium, rhodium, structure elucidation
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Study of dependence of the metal-oxide electron structure on the reactivity of these systems
Ševčíková, Klára
Title: Study of dependence of the metal-oxide electron structure on the reactivity of these systems Author: Klára Ševčíková Supervisor: doc. RNDr. Václav Nehasil, Dr., Department of Surface and Plasma Science Abstract The presented thesis focuses on studying the interaction between rhodium and cerium oxide and its impact on the reactivity. We investigated two different systems, Rh/CeOx and Rh- CeOx, by means of the photoelectron spectroscopy and the temperature programmed reactions. Rh/CeOx stands for rhodium nanoparticles supported by cerium oxide thin film. We show that there is an electronic metal-substrate interaction between rhodium and cerium oxide. The type of the interaction depends on a degree of cerium oxide reduction and it has a tremendous impact on the reactivity of the system. On the other hand, Rh-CeOx represents cerium oxide thin films doped by rhodium. We characterized the properties of the films with various concentration of rhodium. We show that the morphology, chemical composition and reactivity of the samples strongly depend on the concentration of the rhodium dopant.
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