|
|
Synthesis and characterization of UZM-9 zeolite
Koreň, Branislav ; Kubů, Martin (advisor) ; Bulánek, Roman (referee)
UZM-9 zeolite of LTA framework holds significant importance due to its unique structure and properties, making it suitable for various industrial processes such as gas separation, ion exchange, and catalysis. Optimizing the synthesis process is crucial to enhance its performance and applicability. This research aims to contribute to develop efficient and cost- effective methods for its production, furthering its potential in industrial applications. The main objectives include the optimization of synthesis parameters, isomorphous substitution, and adsorption studies. Optimization involved the addition of seeding crystals, reducing structure-directing agents, and selecting reactant sources. Direct synthesis of Fe and Zr forms of the UZM-9 zeolite by isomorphous substitution was studied. Adsorption studies examined CO2 on different cation forms, while the texture properties were studied by nitrogen adsorption. Prepared zeolites were further characterised by XRPD, SEM, ICP-MS, and FT-IR. Results show significantly improved crystallization times, enhanced texture properties, and the effects of using various sources of reactants. Isomorphous substitution of Fe atoms was unsuccessful, while showing promising results for Zr. Various ion-exchanged forms of UZM-9 zeolite were shown to have their adsorption...
|
|
|
Synthesis and characterization of zeolites with controllable location of active sites
Dobiášová, Ivana ; Shamzhy, Mariya (advisor) ; Hulla, Martin (referee)
This bachelor thesis focusses on the synthesis, post-synthesis modification, and comprehensive characterization of two series of zeolites based on IWW and ITH topologies. The investigated zeolite structures were chosen because their frameworks contain d4r units preferentially occupied by Ge atoms, which can be substituted for various catalytically active metal sites such as Al, Ti, and Sn by post-synthesis degermanation/metallation. To study the influence of the chemical composition of the parent germanosilicate on the concentration and accessibility of the incorporated Al-, Ti- and Sn-associated acid sites, IWW and ITH were hydrothermally synthesized with different amounts of germanium in the reaction mixture (Si/Ge = 4 - 10 for IWW and Si/Ge = 10 - 30 for ITH) and used for post-synthesis Ge- for-metal substitution. X-ray diffraction (XRD) was used to verify the structure of the synthesized zeolites; chemical analysis identified their elemental composition; nitrogen physisorption was used to determine their textural characteristics (e.g., micropore volume, total pore volume pore, and external surface area), while scanning electron microscopy (SEM) was applied to visualize the shape and size of the zeolite particles. The coordination state of the incorporated Ti and Sn sites was studied using...
|
guest ::
