Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Adsorption Kinetics of Methane Reformer Off-Gases on Aluminum Based Metal-Organic Frameworks(Izmir Institute of Technology, 2017) Angı, Deniz; Çakıcıoğlu Özkan, Seher FehimeOver the last decades, with the development in industrialization, the combustion of fossil fuels has generated an increasing level of emission of greenhouse gases into atmosphere. Considerable efforts have been endeavored to advance alternative cleaner energy source to relieve the stress on environmental concerns and depletion of oil reserves. Hydrogen is regarded as an ideal clean energy carrier. A great majority of ultrapure hydrogen is produced by hydrogen rich steam methane reformer (SMR) off-gas mainly composed of 60-80% H2, 15-25% CO2, 3-6% CH4 and 1-3% CO, which severely requires an efficient separation and purification process associated with gas adsorption principle. A novel class of porous adsorbents known as metal-organic frameworks (MOFs) represent outstanding separation performance due to possessing large surface area and tunable pore size. Aluminum based metal organic frameworks (Al-TPA) are widely utilized in gas separation/purification applications due to its breathing characteristics by adjusting cell volume reversibly. The highest surface area of Al-TPA was found to be 1270 m2/g by performing solvothermal synthesis route. Diffusion studies of SMR off-gas components on the Al-TPA were carried out at different flow rates (80, 168 and 175 mL/min), temperatures (34, 70 and 100 °C) and concentrations (15 and 28%). High value of parameter L demonstrated that system was under kinetic control. The diffusivity values were found to be ranging from 5.73 x 10-13-8.04 x 10-13 for CO2, 5.03 x 10-13-6.64 x 10-13 for CH4, 1.36 x 10-12-1.56 x 10-12 for H2 and 1.01 x 10-13- 5.03 x 10-13 m2/g for CO respectively with increasing temperature.Master Thesis Adsorption of Methane Reformer Off-Gas Components in a Column Packed With Cu, Al,ti and Zn Based Organic Frameworks(Izmir Institute of Technology, 2016) Kanaltı, Gaye; Çakıcıoğlu Özkan, Seher FehimeWithin the past decade, CO2 emissions from fossil fueled power plants has accelerated rapidly as a result of the increase in energy consumption associated with industrial development all over the world. Beyond the necessity of reduction in CO2 emissions, concerning on the crude oil reserves depletion induced the urgent need of transition to more efficient, renewable, cleaner and cheaper fuel, hydrogen. In the world, most of the hydrogen is produced by hydrogen-rich stream methane reformer (SMR) off gas streams composed of 80-60% H2, 15-25% CO2, 3-6% CH4 and 1-3% CO, thereby separation of SMR components became more of an issue. In this study, adsorption based separation of SMR components were investigated in a column packed with copper (CuTPA, (SLang: 776 m2g-1)), aluminum (AlTPA, (SLang: 1330 m2g-1)), titanium (TiTPA, (SLang: 1835 m2g-1)) and zinc (ZnTPA, (SLang: 1023 m2g-1)) based organic frameworks (MOFs). The pure gas adsorption studies on equimolar CO2/H2, CH4/H2 and CO/H2 systems and the equimolar mixture of CO2/CH4 system were carried out and the experimental breakthrough curves were obtained at three different feed flow rates (10, 20 and 30 mL/min) at three column pressure (1, 5 and 10 bar) at 303 K. The highest adsorption capacities of all MOFs were achieved at 30 mL/min of feed rate and 10 bar operating pressure, at these conditions the non-adsorptive behavior of hydrogen on the aforementioned MOFs was ensured. The amounts of CO2 adsorbed were calculated as 1.61, 5.54, 5.20 and 2.11 mmolCO2/g, while adsorbed CH4 amounts were 1.50, 3.16, 3.25 and 1.90 mmol CH4/g and the adsorbed CO amounts were 1.47, 2.59, 1.91 and 1.83 mmol CO/g on CuTPA, AlTPA, TiTPA and ZnTPA, respectively. The highest selectivity for CO2 over CH4 was attained on TiTPA as 8.0 at 10 mL/min feed rate of CO2/CH4 mixture at atmospheric column pressure and 303 K. The experimental adsorption isotherms of SMR components were fitted well with Langmuir and virial models and the best fitted model parameters were evaluated for each MOF.Master Thesis Synthesis of Copper Based Metal Organic Framework for Separation of Co2/H2 at High Pressure(Izmir Institute of Technology, 2014) Çiçek, Ahmet Uğur; Çakicioğlu Özkan, Seher FehimeIn this study, synthesis of Copper based metal organic framework (CuTPA) was achieved. Terephthalic acids were used as an organic linkers supplied from PETKİM A.Ş. Synthesis procedure was carried out in three steps; crystallization, purification and activation with different parameters. Crystallization time and temperature, purification method and solvent type , thermal activation rate are studied. MOFs were characterized by using SEM (Scanning Electron Microscopy), Fourier Transformer Infrared (FTIR), Thermal Gravimetric Analyzer (TGA), X-ray Diffractometer (XRD), and Volumetric Adsorption Instrument (ASAP 2010). The CuTPA with the highest specific surface area (SLang=776 m2/g) was synthesized after purification with methanol by soxhlet method in a schott bottle for 24 hours at crystallization temperature of 110 oC. Copper based MOF synthesized (SLang=776 m2/g) and Commercial NaX zeolite (SLang= 1359 m2/g) were packed in the column. Dynamic adsorption behavior of adsorbents was also studied; breakthrough of CO2/H2 and gases from the packed bed were carried out under total molar flow rate of 10, 20, and 30 mL/min gas mixture at 1, 5, and, 10 bars. It was conclude that the adsorption data results obtained from our system is reliable. As a result of breakthrough experiment both adsorbents (CuTPA and 13X zeolite) did not adsorbed H2. The break points are increased with increasing pressure and decreasing total flow rate. The amount to be adsorbed by the adsorbent in the column is increased indicating that the adsorption mechanism, controlling mechanism is changed with decreasing total flow rate.