Kinetics of the photocatalytic oxidation of gaseous acetone over platinized titanium dioxide

A. V. Vorontsov, I. V. Stoyanova, D. V. Kozlov, V. I. Simagina, E. N. Savinov

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Abstract

The photocatalytic oxidation of acetone was studied in a flow-circulating reactor over Pt/TiO2 prepared by deposition (Pt/TiO2-P) and by reduction with NaBH4 (Pt/TiO2-C). Compared with untreated TiO2, Pt/TiO2-P was less active and Pt/TiO2-C more active at 40°-120°C, water level of 4500 ppm, and light intensity of 1.10 x 10-6 E/min-sq cm. The increased activity of Pt/TiO2-C was due to the stronger adsorption of acetone and higher rate constant, as seen in the reaction rate's dependence on concentration. Adsorption constants obtained from adsorption isotherms were significantly lower than those taken from the dependence of the rate on acetone concentration, suggesting that acetone photoadsorption occurred during photocatalytic oxidation. Platinized samples did not exhibit the steady state deactivation seen over TiO2 at temperatures > 100°C. However, the oxidation rate was reduced while reaching steady state following a temperature rise to ≥ 80°C. Apparent activation energy of photocatalytic oxidation over platinized samples was 10-13 kJ/mole; the apparent activation energy of thermal acetone oxidation was 84 and 40 kJ/mole for Pt/TiO2-P and Pt/TiO2-C, respectively. Photoinduced oxidation could occur on Pt particles at 80°-140°, manifested by acetone photoinduced oxidation over Pt/α-Al2O3. The lack of deactivation of Pt/TiO2 above 100°C may be linked to the modification of the TiO2 surface during Pt deposition because TiO2 treated with NaBH4 showed a higher deactivation temperature. The dependence of activity on Pt content in Pt/TiO2-C peaked at Pt content of ~ 0.1 wt %.

Original languageEnglish
Pages (from-to)360-369
Number of pages10
JournalJournal of Catalysis
Volume189
Issue number2
DOIs
StatePublished - 25 Jan 2000
Externally publishedYes

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