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.Oxidation

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Now showing 1 - 3 of 3
  • Master Thesis
    The Production of Thymoquinone From Thymol and Carvacrol by Using Zeolite Catalysts
    (Izmir Institute of Technology, 2005) Güneş, Alev; Bayraktar, Oğuz; Bayraktar, Oğuz; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    In this thesis study, by using general flexible ligand method, Cr(III), Fe(III),Bi(III), Ni(II) and Zn(II) complexes of N,Nbis(salicylidene)propane-1,3-diamine (H2salpn) encapsulated in NaY-zeolite were prepared. All catalyst were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and Scanning electron microscopy (SEM) analyses to confirm the complex encapsulation. Activities of all prepared catalysts for the decomposition of hydrogen peroxide and oxidation of carvacrol were tested. Leaching test or heterogeneity test was also performed. The performances of all catalysts were compared based on the leaching test results and carvacrol conversion. Thymohydroquinone and benzoquinones were observed as by-products at high conversions of carvacrol. No product was formed in the absence of a catalyst. Fe(salpn)-NaY catalyst has shown the highest carvacrol conversion of 27.6% with a yield of 22.0% which was followed by Cr(salpn)-NaY catalyst with 23.5% carvacrol conversion with a yield of 17.6%. Other catalysts have shown relatively lower performances in terms of carvacrol conversion and leaching. The Cr(salpn)-NaY catalyst was found to be a more efficient catalyst than others based on leaching and activity tests. Selected catalyst was extra characterized by Brunauer Emmett and Teller (BET) and Thermal gravimetric (TGA) analyses. With selected catalyst Cr (salpn)-NaY, temperature, catalyst amount, reactant carvacrol to hydrogen peroxide molar ratio effects were investigated in carvacrol oxidation reactions. Increasing the temperature from 40 to 60C caused the increment of thymoquinone yield from 6.2 to 16.0%. In addition to that the yield of thymoquinone was increased from 7.4 to 20.7% by increasing catalyst amount from 0.05 to 0.2 g. And also thymoquione yield was increased from 3.7 to 23.0% by decreasing carvacrol to hydrogen peroxide molar ratio from 1 to 3. Moreover, Cr (salpn)-Y catalyst was also tested in thymol and essential oil oxidation reactions.
  • Master Thesis
    Oxidation of Ethanol and Carbon Monoxide on Alumina-Supported Metal/Metal Oxide Xerogel Catalysts
    (Izmir Institute of Technology, 2011) Ateş, Selcan; Şeker, Erol; Şeker, Erol; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    The main goal of the study is to investigate the effect of metal type, metal oxide type and metal/oxide loading on the conversion as a function of temperature for the complete combustion of ethanol and CO in air over single step sol-gel made Al2O3 supported metal and mixed metal oxides. Two types of catalysts, Pt/Al2O3 (1, 2, and 3 % Pt loaded) and CuO-Mn2O3/Al2O3, with Cu/Mn molar ratio of 1:1, 5:1 and 12:1, and 50, 70, and 90% metal loading, were synthesized by impregnation and single step sol-gel methods, respectively. In addition, by synthesizing CuO/Al2O3, Mn2O3/Al2O3 and Pd-Mn2O3/Al2O3, the catalytic activity relationship between metal and metal oxides were clarified. Characterization of the samples was performed by XRD, BET, and FT-IR techniques and it was observed that among the metal oxide catalysts, CuO-Mn2O3/Al2O3 (70 wt%; (Cu/Mn)molar=1) showed the highest activity due to the formation of Cu1.5Mn1.5O4 phase while 3% Pt loaded alumina was the catalyst demonstrated the highest catalytic activity among the noble metal catalysts. Also, Pd addition enhanced the activity of metal oxide catalyst by lowering the temperature at which ~99% ethanol conversion was obtained. Moreover, deactivation of CuO-Mn2O3/Al2O3 mixed oxides was observed due to the irreversible adsorption of CO2 on catalyst surface at low temperatures. Except for Pt containing catalysts, the catalysts that showed high catalytic activity in ethanol oxidation was also tested for CO oxidation and CO2 formation was detected qualitatively at varying operating temperatures.
  • Master Thesis
    Effects of Dimethyl Ether on N-Butane Oxidation
    (Izmir Institute of Technology, 2011) Bekat, Tuğçe; İnal, Fikret; İnal, Fikret; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Effects of dimethyl ether on the oxidation of n-butane were investigated using Detailed Chemical Kinetic Modeling approach. Oxidation process was carried out in a tubular reactor under laminar flow conditions. The formations of various oxidation products, especially toxic species were investigated for the addition of dimethyl ether in different mole fractions to n-butane. Pure dimethyl ether oxidation was also investigated for comparison. Pure dimethyl ether oxidation resulted in lower mole fractions of carbon monoxide, methane, acetaldehyde and aromatic species, but higher mole fractions of formaldehyde when compared to pure n-butane oxidation. The addition of dimethyl ether to n-butane in different mole fractions was observed to decrease mole fractions of acetaldehyde and aromatic species and increase the mole fraction of formaldehyde, while other toxic species investigated were not affected significantly. The effects of three important process parameters on the formations of oxidation products were also investigated. Inlet temperatures between 500 and 1700 K, pressures of 1 and 5 atm, and equivalence ratios of 2.6 and 3.0 were studied. Increasing pressure and equivalence ratio were observed to increase the mole fractions of toxic species in general. The effect of temperature was more complicated depending on the species and the temperature interval. Reaction path analysis indicated that the most important precursors playing role in the formation of the first ring benzene were acetylene, ethylene, propargyl, allene, allyl, propene and fulvene during n-butane/dimethyl ether oxidation. Finally, a skeletal chemical kinetic mechanism was developed and validated for the oxidation of n-butane/dimethyl ether mixture.