The room temperature photocatalytic oxidation of carbon monoxide in excess
air was examined over silica/titania and 0.1%palladium/silica/titania catalysts
under UV irradiation. The experiments were conducted in batch re-circulated
reactor with the initial 1000 ppm carbon monoxide in air and 0.5 g catalyst
charge and the conversion of carbon monoxide to carbon dioxide was
followed by FT-IR spectro-photometer. The change in gas composition in
dark and under 36 Watts of UV irradiation exposed to a catalyst area of 12.4
centimeter square indicated both adsorption of carbon monoxide and
conversion of carbon monoxide to carbon dioxide over the catalyst samples.
The effect of catalyst composition (silica/titania) ratio and the presence of
palladium oxide were investigated. The catalyst samples were synthesized
by sol-gel technique and all samples were hydrothermally treated before
calcination in air. The catalyst samples were characterized by XRD and
nitrogen adsorption techniques. XRD results indicated that titania is
comprised of pure anatase phase and palladium oxide preferantially
dispersed over titania. BET surface area of the samples were observed to
increase with silica loading and the BJH results showed isotherms of Type V
v
with H2 hysteresis loops. The highest carbon monoxide adsorption rate
constant was achieved with pure silica with the highest surface area.
Photocatalytic activity measurements indicated that carbon monoxide in
excess air can be successfully oxidized at room temperature over the titania
photocatalyts. Higher physisorption was observed over higher silica
containing samples and higher oxidation activity was observed with
increasing titania/silica ratio. The optimum titania/silica ratio was determined
by the titania content and surface area of catalyst. The activity tests were
also indicated that the addition of palladium oxide phase synergistically
increased the adsorption and oxidation activity of the catalysts.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12612466/index.pdf |
| Date | 01 September 2010 |
| Creators | Yetisemiyen, Pelin |
| Contributors | Karakas, Gurkan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for METU campus |
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