Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Coating of Spinel Layers on Alumina by Electrostatic Spray Deposition (esd)(01. Izmir Institute of Technology, 2023) Demirkol, İrem; Akkurt, Sedat; Akkurt, Sedat; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyMgAl2O4 spinel layer was coated on dense alumina pellets by advantageous ESD among the other deposition methods in terms of providing a simple, inexpensive setup and good control of the layer morphology. The main goals are successfull deposition of spinel layers on alumina pellets by ESD, to investigate the effect of ESD parameters (working distance, flow rate of precursors, applied voltage) on coating microstructure by conducting full factorial design experiments and to determine the best experimental conditions for a porous layer. Besides, MgCr2O4 layer was coated on dense alumina and MgAl2O4 layer was deposited on bisque-fired alumina pellet to extend the scope of the work. Alumina powders were compressed and sintered, respectively to obtain pellets. MgAl2O4 spinel precursor solution was sprayed on the alumina pellets by changing the parameters accordingly the full factorial design. MgAl2O4 and MgCr2O4 solutions were also sprayed on the bisque-fired and the dense alumina pellets with the parameters given the best porous layer. Elemental analysis of the residues obtained after evaporation of the solutions by energy dispersive X-ray spectroscopy (EDX), both unheated and post-heated residual powders of solutions by X-ray diffraction (XRD) and surface morphologies of coated pellets by scanning electron microscopy (SEM-EDS) were analyzed. Spinel layers on alumina pellets were successfully coated by ESD, which could provide variable surface morphologies. The optimum conditions for a porous layer were obtained as working distance of 15 mm, flow rate of 0.25 mL/h and applied voltage of 6 kV in this study. The coatings on the pellets before further heating were amorphous. Post-heating of the pellets were required to obtain crystalline spinel structure.Master Thesis Carbon Dioxide Hydrogenation on Alumina Supported Ruthenium Catalysts(Izmir Institute of Technology, 2019) Hamza, Gökmen Oğuzcan; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study the effect of basicity of catalyst is investigated using different metal oxide supported Nickel and Ruthenium catalyst. The basic strength of catalysts was orchestrated with using different types of metals and different composition of supports. In this study Al2O3-CaO, Al2O3-MgO, Al2O3-BaO supports were used with nickel and ruthenium catalyst, which synthesized with sol-gel method. Different mass ratios of supports were used such as; 100%, 70%/30%, %50/50%, 20%/80% respectively. For all metal oxides Nickel loadings are 1 %, 5% and Ruthenium loading is 0.5%. Calcination temperature was 500 0C with 6 hours. All catalysts were used in methanation reaction with conditions varies between 300-600 0C, inlet ratio of CO2/H2 1/4 to 1/6 and GSHV 5000h-1/10000h-1. The products were analyzed using GC and catalysts were analyzed using XRD NH3-TPD and BET. Nickel load selected as 1%, magnesium supported catalysts' the main crystallites were aluminum oxide and magnesium oxide for 30%,50%,80; respectively. Calcium supported catalyst had had alumina and calcium oxide crystallites for 30%,50% respectively. Barium supported catalysts had had alumina and barium mix oxide crystallites for 30%,50% respectively. For 5% Nickel loaded 70-30% alumina magnesia mix oxide catalyst magnesia and alumina crystallites are found. Aluminum magnesium mix oxide catalysts had higher basicity than aluminum barium mix oxide catalysts for 1% nickel catalysts. Ruthenium based magnesium alumina mix oxide catalyst had higher basicity than nickel-based magnesium alumina catalysts. Ruthenium catalysts had higher total performance towards both of the reverse water gas shift reaction and carbon dioxide methanation than nickel-based catalysts.