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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Návrh zeolitických materiálů s řízenou strukturou a texturními vlastnostmi / Design of zeolite materials with tailored interlayer structure and tunable textural properties

Kasneryk, Valeryia January 2018 (has links)
Germanosilicate zeolites attracted a lot of attention during the last decade. The reason for such interest is related to the unique structural properties of germanosilicates, which include zeolites of UTL, UOV, ITH, IWR, IWW, and CIT-13 types. The frameworks of these materials can be described as Si-rich layers connected by double four ring (D4R) units preferentially occupied by Ge atoms. Hydrolytic instability of Ge-O bonds in mentioned frameworks compared with Si-O bonds in conventional zeolites gives the opportunity for controllable chemically selective transformation of the germanosilicate frameworks towards novel types of zeolites including their 2D analogues. This PhD thesis focuses on modification of the structure and textural properties of germanosilicates using different ways of post-synthesis treatment: the ADOR (Assembly - Disassembly - Organization - Reassembly) transformation and post-synthesis degermanation and alumination. Presented work was carried out in the Department of Synthesis and Catalysis at J. Heyrovský Institute of Physical Chemistry in Prague under the supervision of Dr. Maksym Opanasenko and advising of Prof. Jiři Čejka. First way of post-synthesis treatment applied in this work was the recently developed method of zeolite synthesis - the ADOR transformation....
2

Synthèses de structurants organiques originaux pour la préparation de nouvelles structures zéolithiques / Synthesis of new zeolites directed by original organic structure directing agents

Bellet, Brice 25 November 2016 (has links)
L’obtention de nouvelles structures zéolithiques a été permise grâce à la diversification des conditions de synthèse, comme l’utilisation d’ions fluorures, la substitution partielle du silicium par du germanium ou l’ajout d’un agent structurant organique. Les travaux développés au cours de cette thèse se concentrent sur la synthèse de nouveaux solides microporeux zéolithiques possédants de larges à extra-larges pores (>10 unités TO4) à l’aide de nouvelles molécules organiques structurantes. Le travail de thèse se divise donc en deux étapes avec, dans un premier temps, la synthèse de molécules organiques originales (dérivées de la pyrrolidine) qui sont ensuite engagées en synthèse hydrothermale. Huit nouveaux structurants non commerciaux ont été élaborés qui ont permis d'obtenir divers matériaux déjà connus, parmi lesquels les zéolithes octadécasil (AST), ITQ-7 (ISV), ITQ-17 (BEC) et ITQ-21. L'utilisation des cations N,N-diméthylperhydro-dicyclopenta[b,d]pyrrolium et N,N-diméthyldicyclopentylammon-ium, ont permis la découverte de deux nouveaux silicogermanates dont l’un de topologie connue nommé clovérite (-CLO) et l’autre nommé Mu-43 présentant une topologie de charpente inédite. Chacun de ces deux matériaux possède un système tridimensionnel de canaux avec des ouvertures à 12 atomes T (Mu-43) ou à 20 atomes T (clovérite). / Several synthetic strategies have emerged such as the use of fluoride, the introduction of germanium and the development of new organic structure directing agents (SDAs) to obtain zeolites, which have led to significant structural diversity. Previous works at the laboratory enable us to develop a new range of non-commercial SDAs that have been designed to produce novel extra-large pores zeolites (>10 TO4 units). Elaborated organic structure directing agents (pyrrolidine derivatives) were first synthesized by a concise route and then engaged in hydrothermal synthesis. Eight non-commercial and original SDAs were produced which led to the synthesis of several known zeolites such as octadecasil (AST), ITQ-7 (ISV), ITQ-17 (BEC) and ITQ-21. The use of the cations N,N-dimethylperhydro-dicyclopenta[b,d]pyrrolium and N,N-dimethyldicyclopentyl-ammonium, allowed us to discover two new silicogermanates named cloverite of known topology -CLO and the novel one Mu 43. Each of these two materials possesses a three-dimensional channel system with 12-membered ring pores (Mu-43) or 20-membered ring pores (cloverite).
3

Open-framework Structures Built by Inorganic Clusters : Synthesis and Characterization

Chen, Hong January 2014 (has links)
Novel open-framework germanates and vanadoborates, which are constructed from typical types of clusters, have been synthesized based on different strategies. The crystal structures are solved by using single crystal X-ray diffraction (SXRD) technique or by combined techniques. Additionally, the structures of two open-framework materials, PKU-3 and PKU-16, are determined from nano-sized crystals by rotation electron diffraction (RED) combined with powder X-ray diffraction (PXRD). This thesis serves as an introduction to synthesis of open-framework germanates and vanadoborates based on different design strategies. Two germanates are obtained; SU-74 is achieved by employing a novel structure directing agent (SDA), SUT-8 is achieved by assembling the novel structure building units (SBUs) of Co@Ge14 with the introduction of cobalt ions in the synthesis. Four strategies are successfully used in construction of open-framework vanadoborates: using metal-oxo polyhedra as the linkages in SUT-6; applying the scale chemistry approach in SUT-7; employing metal-organic complexes as the linkages in SUT-12, SUT-13, SUT-14; and introducing covalent bond organic linkages into SUT-10 and SUT-11. Single crystal X-ray diffraction is used to conduct the structure determination in combination with other techniques. Furthermore, the structures of two open-framework materials, an aluminoborate PKU-3 and a germanosilicate PKU-16, are solved from nano-sized crystals using RED data. The structures are further confirmed by Rietveld refinement against PXRD data. The advantages of the RED techniques are demonstrated in two aspects. In PKU-3, the presence of seriously preferred orientation and light elements in the structure makes it difficult for structure determination by PXRD, but it is easier by RED. In PKU-16, the RED technique is used to determine its structure from the as-synthesized multi-phasic sample containing nano-sized crystals. After the structure of PKU-16 has been solved, the synthesis of this interesting phase can be optimized and pure PKU-16 can be obtained. Keywords: Open-framework, germanates, vanadoborates, aluminoborates, germanosilicates, crystal structure, hydrothermal synthesis, single crystal X-ray diffraction, rotation electron diffraction, powder X-ray diffraction

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