Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2012
Thesis Language: Turkish
Student: Sultan YÜKSEL
Supervisor: Fatma Suna Balcı
Abstract:SBA-15 material, the first time synthesis of it was performed in 1998, having a one dimensional hexagonal structure, uniform pore dimension and distribution, high surface area, high mechanical and hydrothermal stability is a mesoporous structure with high microporous. These materials which can be used for several purposes show low catalytic activity because of neutral surface combination. Catalytic activities of SBA-15 can be improved with the modification of silica structure by use of metal/metal oxides or increasing the surface acidity (Lewis and Bronsted acidity) by processing sulfanation etc. In this study, increasing catalytic properties of SBA-15 was aimed by using the iron and vanadium metal sources and their characterizations were performed. For this aim, V-, Fe-, V+Fe-SBA-15 samples with different metal/silica mole ratios (metal/Si=0,06 and 0,09) were synthesized by direct hydrothermal synthesis and the surface sulfonation of the synthesized samples were performed. It was seen that, by XRD analysis, metal loading improved structure showing an increase in peak intensity and sulfonation did not change the structure of SBA-15. The EDS analyses results showed that high amount of iron source was incorporated to the structure than vanadium source and homogeneous distribution was achieved, after the sulfonation, decreases in metal/silica ratio in the samples were observed. With the nitrogen adsorption/desorption analysis, increase of BET surface area, from 800 m2/g upto 970 m2/g, decrease of mesopore volume from 31% to 21% over the total in addition approximately 20% increase in micropore volume were observed. Increases in BJH mean mesoporous size and SF mean microporous sizes were designated by the increase of metal/silica ratio in the synthesis solution. In addition to approximately 150 m2/g decreases in BET surface area, decreases in mesopore volume and partly increases in micropore volume, increases in mean micropore diameters and decreases in mesopore diameters were observed for each sulfonated materials. FTIR analysis performed after pyridine adsorption and then desorption at different temperatures showed that serious increases in especially peaks in Lewis acid region, in addition to this, prominence in Bronsted and Lewis-Bronsted sites region. More prominence especially in the intensities of peaks in Lewis acid site regions was seen for the surface sulfonated samples.