Gas-phase oxidation of 1-butene using nanoscale TiO{sub 2} photocatalysts
The effects of preparation methods, humidity, and calcination temperatures on the behavior on nanoscale TiO{sub 2} photocatalysts were investigated in this study. Application of these photocatalysts were investigated in this study. Application of these photocatalysts in the gas-phase decomposition of 1-butene demonstrated that the nanoscale catalysts, prepared y the acid-assisted sol-gel technique, showed higher photocatalytic reactivity than commercially available Degussa P-25 TiO{sub 2}, while lower photoactivity was obtained on TiO{sub 2} catalysts prepared without photoactivity was obtained available Degussa P-25 TiO{sub 2}, while lower photoactivity was obtained on TiO{sub 2} catalysts prepared without adding acid to titanium isopropoxide. Experimental results revealed that the oxidation rates of 1-butene decreased exponentially with increasing water concentrations in the flowing stream. However, a trace amount of water vapor was indispensable in maintaining the stability of the catalysts. Proper calcination temperature (300 C) could promote the resistance of catalysts against the poisoning effects of humidity. Higher calcination temperature (400 C) unfavorably lowered the photoactivity due to phase transformation occurring at such a temperature. Amorphous and futile-typed TiO{sub 2} showed less photocatalytic reactivity. XRD patterns and BET measurements indicated that moderate surface areas (from 100 to 160 m{sup 2}/g), appropriate crystallite sizes (5{approximately}6 nm), and crystallinity to anatase were beneficial to the photocavity of TiO{sub 2} catalysts. In situ FTIR studies indicated that catalyst surfaces contained large amounts of chemisorbed water and hydroxyl groups, which are considered to be active sites in photocatalytic reactions. The accumulation of carbonate species on active sites resulted in the deactivation of TiO{sub 2} catalysts under dry conditions. quantum size effects were thought to be responsible for the high photoactivity achieved on the nanoscale TiO{sub 2} catalysts prepared by sol-gel methods.
- Research Organization:
- Univ. of Connecticut, Storrs, CT (US)
- OSTI ID:
- 20003850
- Journal Information:
- Journal of Catalysis, Vol. 188, Issue 1; Other Information: PBD: 15 Nov 1999; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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