Master Degree / Yüksek Lisans Tezleri

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

Browse

Filters

2014 - 201912020 - 20221

Settings

Subject: search.filters.subject.Mesoporous catalysts

Search Results

Now showing 1 - 2 of 2
  • Master Thesis
    Biolubricant Production Over Sulfated Ti-Sba and Tio2-Sio2 Based Mesoporous Catalysts
    (01. Izmir Institute of Technology, 2022) Özperçin, Tuğçe; Yılmaz, Selahattin
    Production of ecofriendly biodegradable lubricants from vegetable oils is an attractive alternative to petroleum derived lubricants for environmental protection. This study presents an investigation for the production of biolubricants via ring opening reaction of epoxidized soybean oil using the mesoporous solid acid catalysts. SO4/SBA- 15, SO4/Ti-SBA-15, SO4/TiO2-SiO2 and SO4/La-TiO2-SiO2 catalysts were prepared and characterized. In addition, effect of increasing titanium content on SO4/Ti-SBA-15 (Si/Ti: 10, Si/Ti: 6) and effect of sulfation source (ammonium sulfate and chlorosulfonic acid) on Ti-SBA-15 and La-TiO2-SiO2 properties, activities and stabilities were studied. Activity and stability of all the catalysts were tested in the ring opening reactions of epoxidized soybean oil with 2-propanol at 80 oC with 10/1 alcohol-epoxide mol ratio. After determination of the two most stable and active catalysts, reactions were also performed with 2-ethylhexanol at 100 oC with 6/1 alcohol-epoxide mol ratio. Products were analyzed by titration, FTIR and H-NMR. Also, thermal stability and low temperature behavior of products were determined by thermogravimetric analysis and differential scanning calorimetry. Prepared catalsysts had mesoporous structure and stronger acid sites by attachment of sulfate groups The catalysts showed a serious leaching when they were sulfated with ammonium sulfate. On the other hand, chlorosulfonic acid treatment enhanced significantly stability of catalyst. Furthermore, increasing of titanium content and sulfation with chlorosulfonic acid increased the acidity of catalysts compared to ammonium sulfate. The SO4/Ti-SBA-15-6(CS) catalyst (Si/Ti:6 mole ratios and chlorosulfonic acid sulfated) was found as the most stable and active catalyst. It provided 62 % (12 h) and 90 % (18 h) conversion in the reactions with 2-propanol and 2-ethylhexanol, respectively. All products were found as thermally stable up to 300 oC showing that ring opening reaction did not affect thermal stability. Nevertheless, it affected positively low temperature properties and better low temperature properties were obtained from the products of reactions with 2-ethylhexanol. However, its influence on the products obtained from 2-propanol was not prominent.
  • Master Thesis
    Development of Tungsten Loaded and Zirconia Incorporated Mesoporous Catalysts for Esterification of Palmitic Acid With Cetyl Alcohol
    (Izmir Institute of Technology, 2014) Mutlu, Vahide Nuran; Yılmaz, Selahattin; Yilmaz, Selahattin
    In this study, it was pursued to develop acidic mesoporous catalysts for esterification of cetyl alcohol by palmitic acid. For this, Zr incorporated SBA-15 was prepared by hydrothermal synthesis. Zr-SBA-15 was used both as a catalyst support and as a catalyst itself. WO3 loading onto the Zr-SBA-15 was performed by incipient wetness impregnation. Additionally, WO3-ZrO2 catalyst was prepared by co-precipitation with two different contents of WO3 (15 wt% and 20 wt%). The reaction tests were carried out in mesitylene under reflux conditions. Zr was incorporated into SBA-15 successfully. The surface areas of Zr-SBA-15 and WO3/Zr-SBA-15 catalysts were significantly higher than that of WO3-ZrO2. Loading of WO3 decreased the surface area of Zr-SBA-15. The acidity of the WO3/Zr-SBA-15 with 15 wt% WO3 was higher than that of with 20 wt% WO3. Moreover, increasing the calcination temperature from 700 to 800 oC resulted in the increase of acidity. The activity of the catalysts differed. The only product obtained was cetyl palmitate. Under the test conditions it was found that the reaction rate was not limited by equilibrium. Zr-SBA-15 provided the highest conversion (64 %) which corresponded to cetyl palmitate yield of 63% among other mesoporous catalysts because of its high surface area (600.3 m2/g) and acidity (0.152 mmol NH3/g cat). This catalyst did not show leaching. WO3/Zr-SBA-15 based catalys tests showed that catalyst activity increased by increasing calcination temperature. This was atributed to better dispersion of W. The conversion of cetyl alcohol did not change much with more W loading.