Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2014
Thesis Language: Turkish
Student: Filiz AKTI
Principal Supervisor (For Co-Supervisor Theses): Fatma Suna Balcı
Co-Supervisor: Timur Doğu
Abstract:SBA-15 is prefered as support material in the catalytic applications becasause of its one dimensional hexagonal structure, larger pore dimension, thicker pore wall, thermal and hydrothermal stability. Metal-SBA-15 catalysts were synthesized by using copper (Cu) and tin (Sn) active metals which are known as showing high activity in the selective oxidation of alcohols. By selecting 0.03-0.2 range of metal/Si molar ratio metals were loaded to structure in mono and dual combinations by means of hydrotermal method. In the synthesis of some tin loaded samples, metal sources were dissolved in alcohols and then added to the sytnhesis solution before or after silica source added. Some tin loaded catalysts were also synthesized by taking the Al/Si molar ratio as 0.001 or 0.005 in the presence of competitive metal salts. X-ray difraction patterns and TEM (Transmission Electron Microscopy) images showed that uniform hegzagonal structure of SBA-15 support did not change with metal loading. Surface area value of support material was increased from 800 m2/g to 1072 m2/g by metal loading. The average BJH (Barrett-Joyner-Halenda) mesopore diameters and SF (Saito-Foley) micropore diameters of samples showed changes between 64-72 Å and 5-10 Å, respectively. The meso and micro pore volume values were found within the range of 0.8-1.27 cm3/g and 0.17-0.28 cm3/g, respectively. XRD, EDX ( Energy Dispersive X-Ray Spectroscopy) and TEM images showed that the metal loading success was positively effected under competitive salt environment. In the FTIR (Fourier Transform Infrared Spectroscopy) spectrums obtained with pyridine and lutidine probe molecule, the remarkable increases in the intensities in the peaks of Bronsted and Lewis acid sites were observed with metal loading. Even at high temperature probe molecule desorption showed that the intensities of the Bronsted acid sites were preserved. The samples in which the support structures properties were preserved, getting better structures properties and high success of the metal loading were tested in the selective oxidation reaction of ethanol. Acetaldehyde was seen predominantly in studies were carried out in a differential flow reactor between 250-450oC, 0.5 ethanol/O2 molar ratio. Acetaldehyde selectivity that according to ethanol conversion was reached to a value of 0.51 at 350oC temperature with Sn009SBA-15 (EA-TÖ-Al/Si=0001) sample.