Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Renewable natural gas production via Sabatier reaction(01. Izmir Institute of Technology, 2021) Çamlık, Cansu; Şeker, Erol; Şeker, Erol; 01. Izmir Institute of Technology; 03.02. Department of Chemical Engineering; 03. Faculty of EngineeringThis study attempts to understand the effect of support basicity on Sabatier reaction and improve the performance of Ni based catalysts by introducing calcium which is known for its basicity. In accordance with this purpose, Ni-Al2O3-CaO catalysts were synthesized with modified sol-gel method. Effect of Ni loading, calcination temperature and calcium content were investigated. Al2O3-CaO supports were synthesized at three ratios as follows; 70-30 wt.%, 40-60 wt.%, 10-90 wt.% wherein Ni/Al2O3 catalyst was used as reference catalyst. Based on thermodynamic analysis, reaction was conducted at 400oC and 1 atm with inlet composition of CO2/H2=1/4 and total volumetric flow rate of 100 ml/min. Reference catalyst calcined at 700oC was found to be inactive at used reaction conditions due to the presence of inactive NiAl2O4 phase. Increasing Ni loading from 1 wt.% to 10 wt.% increased both CO2 conversion and methane selectivity. Over the catalysts calcined at the temperature of 900oC, maximum methane yield was obtained over 10Ni-70Al-30Ca-900 as 8%. The influence of Ni loading was more pronounced for catalysts calcined at 700oC. In 10Ni-70Al-30Ca-700 catalyst, NiO particles were smaller than 5 nm. Therefore, it is conceivable that the alumina-calcium mixed oxide support could disperse higher loadings of Ni, which could result in higher CO2 conversion. Ca modification was found to have a prominent impact on both methane selectivity and yield. With 10Ni-10Al-90Ca-700, being best performing catalyst, CO2 conversion obtained as 76% and methane yield was 60%. The promotion of catalytic performance might arise from intensifying the CO2 chemisorption supported by XRD and TGA results.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.