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The effect of reaction conditions and type of active sites on the kinetics of heterogeneously catalysed formylation of amines
Olšovská, Adéla ; Veselý, Ondřej (advisor) ; Kubička, David (referee)
Formamides are valuable compounds in pharmaceutical production and organic synthesis; however, their common synthesis methods suffer from number of drawbacks including low reaction rate and contamination with heavy metals leached from a catalyst. According to several articles, these problems could be overcome by using zeolite-based catalysts. Nevertheless, the mentioned articles provide somewhat conflicting results and also lack a clear description of which centres in zeolites are catalytic active. Therefore, we prepared a set of zeolite-based catalysts commonly described in the literature (zeolite Beta ion exchanged to H+ and Cu2+ form) in order to test them as catalysts and clarify their catalytic behaviour and nature of the active sites. We chose formylation of N-methylaniline by formic acid as the model reaction for our research and performed a series of experiments under varying conditions (solvents, concentration of reactants, temperature). In contrast to the published articles, none of the investigated materials demonstrated significant catalytic activity in our experiments. Moreover, we found that the often pronounced catalyst: zeolite Beta ion-exchanged into the copper form, is unstable in the presence of formic acid, which causes leaching of copper into the reaction mixture. At the same...
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Metal nanoparticles in zeolites
Zhang, Yuyan ; Čejka, Jiří (advisor) ; Zima, Vítězslav (referee) ; Kubička, David (referee)
Zeolites with encapsulated metal nanoparticles have attracted a wide attention in heterogeneous catalysis due to their high catalytic activity, selectivity, and stability. The PhD thesis was focused on design and synthesis of metal@zeolite catalysts with small and uniformly distributed metal nanoparticles. The main interests were encapsulation of metal nanoparticles into zeolites by co-crystallization strategy and 2-dimensional to 3-dimensional zeolite transformation approach. The PhD work was performed at the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry and Department of Physical and Macromolecular Chemistry, Faculty of Science at Charles University under the supervision of Prof. Jiří Čejka. Zeolites are inorganic crystalline aluminosilicates with microporous framework structures. The micropores of zeolites provide the ideal microenvironment to accommodate metal nanoparticles. During metal nanoparticles formation in zeolite micropores, they can be limited by a rigid framework, preventing the aggregation and leaching of metal during the reaction process. Furthermore, the diameters of zeolite micropores are usually in the range of 0.3-1.5 nm, which can be used to discriminate molecules depending on their size and shape, thus endowing the metal@zeolite...
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Design of sustainable catalysts by post-synthesis modification of germanosilicate zeolites
Zhang, Jin ; Shamzhy, Mariya (advisor) ; Hronec, Mlan (referee) ; Kubička, David (referee)
1 Abstract Due to the presence of small structural units (e.g., D4R, D3R), the frameworks of germanosilicate zeolites are generally characterized by high pore volumes and multidimensional/extra-large pore systems, making them especially suitable in processing bulky molecules (in particular, involved in biomass-derived compounds valorization). However, weak acidity, low hydrothermal stability and high cost of Ge significantly limit the practical use of Ge-containing zeolites. This thesis is aimed at design of sustainable germanosilicate zeolite-based catalysts of modifiable chemical composition and tunable porosity for relevant acid-catalyzed reactions, such as ketalization of polyols, epoxidation of olefins, Baeyer-Villiger oxidation of cyclic ketones and Meerwein-Ponndorf-Verley reduction of aldehydes. Germanosilicate zeolites of different structures, including medium-pore ITH, large pore IWW, extra-large pore UTL and *CTH, were thoroughly characterized using a combination of techniques (i.e., XRD, physisorption, electron microscopy, chemical analysis, among others) and subjected to different post-synthesis modifications to address synthesis-structure-activity relationships in the designed germanosilicate-zeolite based catalysts. In ketalization of glycerol to solketal, weak acid centers of IWW and UTL...
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Shape selectivity of ADOR zeolites in gas-phase m-xylene isomerisation
Remperová, Natália ; Mazur, Michal (advisor) ; Kubička, David (referee)
Zeolites are microporous crystalline aluminosilicates. They are used as catalysts due to their acidity, shape selectivity, high surface area, high thermal, and chemical stability. New types of zeolitic materials are of interests as catalysts for various reactions. Isomerisation of m-xylene is sensitive to shape and dimensionality of pores, thus it is excellent model reaction for zeolites characterisation. The aim of this thesis is to investigate shape selectivity effects of isoreticular zeolites on the catalytic performance in m-xylene isomerisation. Isoreticular zeolites have the same crystalline layers connected in various way resulting in different, tuneable pore systems. The catalytic behaviour of the studied zeolites was compared to commercial ZSM-5 zeolite catalysts. Isoreticular zeolites were prepared via ADOR method. This new method is a top-down approach for zeolite synthesis providing materials with preserved crystalline layers, but different channel systems. Parent Al-UTL (14- and 12-ring channels) zeolite was prepared via hydrothermal synthesis. This material was utilised for the synthesis of daughter zeolites with various channel systems: Al-IPC-7 (14- and 12-ring, as well as 12- and 10-ring channels), Al-IPC-2 (12- and 10-ring channels), Al-IPC-6 (12- and 10-ring, as well as 10- and...
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Market analysis for commercialization
Kukula, Jakub ; Procházka, David Anthony (advisor) ; Kubička, David (referee)
This Bachelor theses is analysing current global sterilization market with focus on vapour phase Hydrogen Peroxide sterilization (VPHP) and methods of its detection during sterilization process. The goal of this theses is to find optimal strategy for commercialization of new technology that provides online monitoring of Hydrogen peroxide concentration during sterilization process. Market is analysed by PESTLE analysis and Porters analysis. Findings are then synthesized by SWOT analysis, where strengths, weaknesses, threats and opportunities are introduced and optimal procedure for the technology commercialization is presented.
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