Transient studies of 2-propanol photocatalytic oxidation on titania
- Univ. of Colorado, Boulder, CO (United States)
Transient reaction techniques were used to study the room-temperature, photocatalytic oxidation (PCO) of 2-propanol on a thin catalyst film of titania (Degussa P25) in an annular reactor. Adsorbed 2-propanol was photocatalytically oxidized in the absence of gas-phase 2-propanol, and the species remaining on the TiO{sub 2} surface were characterized by temperature-programmed desorption (TPD) and oxidation (TPO). Nonphotocatalytic decomposition (TPD) and oxidation (TPO) of 2-propanol and acetone were also studied. The initial PCO of 2-propanol at room temperature rapidly forms acetone and water; water can displace acetone into the gas phase. Adsorbed acetone is subsequently oxidized photocatalytically to CO{sub 2} and H{sub 2}O at a slower rate than 2-propanol photocatalytically oxidizes to acetone and it may form a surface intermediate before complete oxidation. Thus, at steady-state, the TiO{sub 2} surface is expected to be covered with H{sub 2}O and strongly bound acetone or an intermediate. There are no indications that photoadsorbed oxygen was important for PCO; gas phase O{sub 2} is needed to replace lattice oxygen, but this may or may not be photoadsorbed. In the absence of near-UV light, titania is an oxidation catalyst only at much higher temperatures. Thermal oxidation of 2-propanol also proceeds through acetone formation, but acetone thermally oxidizes faster than 2-propanol. Methanol and ethanol also undergo PCO on TiO{sub 2} at room temperature to form aldehydes, CO{sub 2}, and H{sub 2}O. 46 refs., 12 figs., 3 tabs.
- OSTI ID:
- 224031
- Journal Information:
- Journal of Catalysis, Journal Name: Journal of Catalysis Journal Issue: 2 Vol. 157; ISSN JCTLA5; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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