Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Chemical EngineeringSubject: search.filters.subject.Cobalt

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  • Master Thesis
    Co-ni Separation In Ix-sx Circuit
    (2023) Polat, Mehmet; Polat, Mehmet; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Eti Gübre stands out as the sole facility capable of reclaiming multiple metals from chalcopyrite flotation tails in Turkey. While the overall performance of the process has been deemed satisfactory, the cobalt and nickel products have yet to meet commodity standards. The objective of this project is to ascertain the feasibility of using a series of hydrometallurgical techniques, namely, solvent extraction and ion exchange resin technologies, for attaining premium-quality cobalt and nickel products from a compound comprising cobalt, nickel, and other assorted elements. Extracting cobalt and nickel selectively from impurities, reaching over 95% recovery in a solution containing various elements and steep concentration differences, presents a considerable challenge. Moreover, accomplishing this within an already operational process adds another layer of complexity, demanding alignment with the existing process's stability. The strategy involved selectively separating and refining cobalt and nickel from the sulfate solution through solvent extraction (SX) methods and employing the Ion Exchange (IX) method for further purification.
  • Master Thesis
    Effect of Sulfur on the Elementary Reactions of Fischer-Tropsch Synthesis on Cobalt Surfaces
    (Izmir Institute of Technology, 2020) Dağa, Yağmur; Kızılkaya, Ali Can; Kızılkaya, Ali Can; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Industrial observations indicate that sulfur acts a poison for Fischer-Tropsch Synthesis (FTS) and surface science studies show that sulfur blocks the adsorption sites for reactants on cobalt surfaces. However, various experimental studies have indicated conflicting results about the effect of sulfur on cobalt FTS catalyst activity and selectivity. This study aims to clarify the effect of sulfur on cobalt FTS catalysts by molecular modelling of the elementary reactions of FTS on surfaces that are present on sulfur covered cobalt surfaces that are present in fcc-Co nanoparticles, using Density Functional Theory (DFT). For 0.25 ML sulfur coverage, it is found that on bare, C and O covered surfaces, S is the main dissociation product, while HS can be present on low coverages. Atomic sulfur decreases the adsorption energies of all species investigated, while the decrease is more pronounced for CO compared to H2. The effect of S on the elementary FTS reactions direct and H-assisted CO dissociation, carbon hydrogenation, carbon coupling and oxygen removal are also investigated. The results indicate that S inhibits mainly the oxygen removal reaction, in terms of both H2O and CO2. CO dissociation is not inhibited but rather slowed down, due to increasing activation barriers. It is also found that carbon hydrogenation barriers are significantly decreased, while carbon coupling barriers are unaffected. These results indicate that the intrinsic effect of sulfur poisoning would be to increase methane selectivity, while decreasing the selectivity to long chain hydrocarbons.