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Real-time study of reaction waves
Gazdík, Richard ; Pavera, Michal (referee) ; Bábor, Petr (advisor)
Táto bakalárska práca sa zaoberá heterogénnou katalytickou oxidáciou oxidu uhoľnatého, a hlavne reakčnými vlnami vyskytujúcimi sa pri určitých podmienkach, na povrchu platiny. Práca je rozdelená na dve hlavné časti – teoretickú a experimentálnu. Teoretická časť podáva informácie ohľadom rastrovacieho elektrónového mikroskopu, mikroskopu atomárnych síl a detailov reakcie. Pre experimentálnu časť boli vykonané pozorovania tejto reakcie v ultravysoko-vákuovom, ako aj vo vysoko-vákuovom rastrovacom elektrónovom mikroskope, a v oboch prípadoch boli identifikované reakčné vlny. Cieľom bolo tiež skúsiť vykonať korelatívne meranie reakčných vĺn sondou a elektrónovým mikroskopom (CPEM), ktoré, bohužiaľ, z veľa rôznych dôvodov popísaných v poslednej časti práce, nevyšlo.
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Study of CO oxidation on platinum by UHV-SEM
Jaroš, Antonín ; Kolíbal, Miroslav (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis is focused on the study of heterogeneous catalytic oxidation of CO on the surface of platinum, but also in the confined space between platinum and graphene. The thesis is separated into two parts – theoretical and experimental. In the theoretical part, there is a general explanation of important principles regarding this thesis, such as the stucture of scanning electron microscope, growth of graphene, evolution of the catalytic oxidation of CO and oscillatory mode of this reaction, and lastly evolution of the same reaction under the graphene. The experimental part is chronologically concerned about individual tasks of bachelor’s thesis.
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Study of catalytic reaction waves by SIMS
Jaroš, Antonín ; Willinger, Marc Georg (referee) ; Bábor, Petr (advisor)
Katalytické reakce jsou klíčové pro mnoho technologických oblastí. Abychom docílili jejich zlepšení, je potřeba porozumět jejich mechanismu, k čemuž je důležité vyvíjet nové in-operando techniky. Operando spektroskopie jsou obecně rozděleny do dvou kategorií: velkoplošné techniky, které poskytují zprůměrované informace z celé analyzované oblasti, přičemž nemusí zaznamenat signál z důležitých aktivních míst, a lokalizované techniky, které poskytují informace na atomární úrovni, ovšem nemusí relevantní aktivní místa obsahovat vůbec. V této práci je demonstrováno, že hmotnostní spektrometrie sekundárních iontů je bezprecedentní způsob, jak v reálném čase sledovat oscilační vlny během oxidace CO, poskytující mikro-spektroskopická data, která jsou klíčová pro rozluštění složitého katalytického mechanismu. Ukazuje se, že v nízkých tlacích jsou reakční vlny tvořeny střídajícími se vlnami oxidu platiny a adsorbovaného oxidu uhelnatého. Mechanismus reakce spočívá v redukci oxidu pomocí CO. Navíc jsou oxid platiny a CO adsorbáty nehomogenně rozloženy napříč vln, což je nejvíce patrné na reakční vlnoploše.
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Real-time study of reaction waves
Gazdík, Richard ; Pavera, Michal (referee) ; Bábor, Petr (advisor)
Táto bakalárska práca sa zaoberá heterogénnou katalytickou oxidáciou oxidu uhoľnatého, a hlavne reakčnými vlnami vyskytujúcimi sa pri určitých podmienkach, na povrchu platiny. Práca je rozdelená na dve hlavné časti – teoretickú a experimentálnu. Teoretická časť podáva informácie ohľadom rastrovacieho elektrónového mikroskopu, mikroskopu atomárnych síl a detailov reakcie. Pre experimentálnu časť boli vykonané pozorovania tejto reakcie v ultravysoko-vákuovom, ako aj vo vysoko-vákuovom rastrovacom elektrónovom mikroskope, a v oboch prípadoch boli identifikované reakčné vlny. Cieľom bolo tiež skúsiť vykonať korelatívne meranie reakčných vĺn sondou a elektrónovým mikroskopom (CPEM), ktoré, bohužiaľ, z veľa rôznych dôvodov popísaných v poslednej časti práce, nevyšlo.
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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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High pressure CO and methanol oxidation study over nanopowders Rare Earth Oxides and platinum thin film catalysts
Rednyk, Andrii ; Matolín, Vladimír (advisor) ; Lykhach, Yaroslava (referee) ; Šmíd, Břetislav (referee)
Title: High pressure CO and methanol oxidation study over nanopowder Rare Earth Oxides and platinum thin film catalysts Author: Mgr. Andrii Rednyk Department: Department of Surface and Plasma Science Supervisor: Prof. RNDr. Vladimír Matolín, DrSc. matolin@mbox.troja.mff.cuni.cz Abstract: This doctoral thesis focuses on reactivity study of nanopowder rare earth oxides (REOs) and platinum based thin film catalysts using microreactor with high pressure reaction cell. REOs nanoparticles were prepared by new approach based on sol-gel chemistry. Magnetron sputtering technique was used for preparation of thin film samples. In the first part of the thesis CO oxidation on REOs and on Pt, PtOx thin films were performed. Among prepared REOs catalyst better activity exhibited alumina stabilized ceria, due to higher surface area. Both Pt and PtOx deposited on silicon substrate exhibited similar activity. When carbon (G-foil or C interlayer) is used as support, activity of Pt thin film decreases while PtOx preserves high activity. In the second part of the thesis steam reforming of methanol (SRM) and partial oxidation of methanol (POM) were performed on Pt thin films. It was shown that PtOx thin film exhibited superior activity compared to other samples with the same thickness. It is due to the reduction of platinum...
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Study of CO oxidation on platinum by UHV-SEM
Jaroš, Antonín ; Kolíbal, Miroslav (referee) ; Bábor, Petr (advisor)
This bachelor’s thesis is focused on the study of heterogeneous catalytic oxidation of CO on the surface of platinum, but also in the confined space between platinum and graphene. The thesis is separated into two parts – theoretical and experimental. In the theoretical part, there is a general explanation of important principles regarding this thesis, such as the stucture of scanning electron microscope, growth of graphene, evolution of the catalytic oxidation of CO and oscillatory mode of this reaction, and lastly evolution of the same reaction under the graphene. The experimental part is chronologically concerned about individual tasks of bachelor’s thesis.
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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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Study of cerium oxide-metal interaction with gases - carbon monoxide oxidation and methanol decomposition
Kolářová, Tatiana ; Nehasil, Václav (advisor) ; Čech, Vladimír (referee) ; Jirka, Ivan (referee)
Title: Study of cerium oxide-metal intraction with gases - carbon monoxide oxidation and methanol decomposition Author: Tatiana Kolářová Department: Department of Surface and Plasma Science Supervisor: Doc. RNDr. Václav Nehasil, Dr., Department of Surface and Plasma Science Abstract: Dissertation thesis is focused on the study of two catalytic systems on the basis of cerium oxide-metal. The systems were characterized by various methods of surface analysis. The first part of the work concerns influence of the preparation parameters on the character of gold nanoparticles deposited onto the sputtered cerium oxide layers from a solution. Catalytic activity of prepared Au/CeOx/(C)/Si systems, containing particles with the mean sizes of 4- 10 nm, was tested toward CO oxidation at atmospheric pressure. The results show that with increasing amount of gold present on the samples, also the productivity of CO2 during the reactions grows. The work is further focused on the preparation of an inverse model CeOx/Pt(111) system. On this system, adsorption of methanol at low temeperatures and its decomposition during a heating was studied. It is apparent from presented results that the decomposition of methanol on the inverse CeOx/Pt(111) systems behaves in a different way than on a clean platinum sample or a thick...
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Study of dependence of the metal-oxide electron structure on the reactivity of these systems
Ševčíková, Klára ; Nehasil, Václav (advisor) ; Jiříček, Petr (referee) ; Plšek, Jan (referee)
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. Powered by TCPDF (www.tcpdf.org)
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