Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
Browse
2 results
Search Results
Master Thesis Valorization of Biomass for Fuel and Chemicals Production(01. Izmir Institute of Technology, 2023) Yüksel Özşen, Aslı; Yüksel Özşen, Aslı; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRapidly increasing global energy demand resulting from the growing population and worldwide development increased consumption of limited fossil fuel usage that causes severe environmental deterioration by CO2 emission have sparked interest in finding green, renewable, and sustainable alternative sources for energy. Bio-oil, derived by several biomass via liquefaction, is a promising candidate to replace fossil fuels. Turkey is a country, 27% of which is covered with forests (mostly oak trees). Therefore, it has great potential for cheap lignocellulosic feedstock forest residues from industrial applications and harvesting. In the present study, the thermal liquefaction of oak wood particles (OWP) was performed using various solvents besides water, such as ethanol, 1-butanol, and 1,4-dioxane. The experiments were carried out in a batch reactor for 1 and 2 h residence time at different temperatures (210oC, 240oC, and 270oC). Bio-oil samples obtained at best reaction temperature, 270oC, optimum residence time, 1 h, were analyzed with TGA, CHNS elemental analyzer, FTIR, and GC-MS. Based on energy recovery calculations, the enhancement of pristine OWP's energy efficiency depends on bio-oil yield, and quality was confirmed for all solvent types. 1,4-dioxane showed the best performance in yielding the maximum bio-oil with 51.8%. The higher heating values of the bio-oils ranged from 22.1 to 35 MJ/kg. Phenolic groups were the predominant components of bio-oil produced from OWP, while intensity of alcohols, ketones, and acids varied based on using solvents.Master Thesis Development of Multi Metal Oxide Photo-Electrodes for Energy Applications(Izmir Institute of Technology, 2020) Karabudak, Engin; Karabudak, Engin; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyWater splitting via artificial photosynthesis uses only sunlight and water to produce hydrogen and oxygen. Hydrogen can be used as a green energy source. To be able this reaction to occur there is a catalyst needed as reaction center. Platinum and Iridium are the state-of-art catalyst used for water splitting reactions. The goal of this study is to develop an earth abundant, highly stable and efficient catalyst as an alternative to noble metal catalysts. For this purpose, ABO3 type perovskites was chosen to study for their abundancy and proven electrochemical efficiencies. BSCF was chosen as the starting point of this study because it is known for its great catalytic activity compared to state-of-art catalysts such as Iridium Oxide. To enhance the stability and catalytic activity of synthesized perovskite oxides, several foreign atoms (dopants) were introduced to their structure from B-site. Each perovskite was synthesized by the EDTA-Citrate complexing Sol-Gel method. Also, for dopants, cost-efficient and electron conductive elements was chosen in each study. As HER catalysts, manganese, zinc, and copper were introduced to BSCF structure as dopant, while for OER, silver was used as a dopant. In this study, catalytic activities and stabilities were tested by electrochemical methods. All electrochemical measurements were performed in alkaline media by three-electrode configurations. Perovskite oxides were prepared by the coating of their inks on Ni foam substrates by drop coating for HER and OER activity measurements by electrochemical methods. For the bulk and surface characterization of synthesized perovskite oxide powders, SEM, XRD, XPS, and BET analysis was performed.