Characteristics of photocatalytic oxidation of gaseous 2‐propanol using thin‐film TiO₂ photocatalyst

Abstract

This work presents a photocatalysis-based method to treat and purify air because of its broad applicability to common, oxidizable, air contaminants. The effect of oxygen content, temperature, water vapor, and 2-propanol concentration on the TiO 2 surface was investigated. The rate of 2-propanol decomposition increased with increasing the oxygen content, but was reduced at temperatures higher than 100• C. When water vapor concentration was in the range of 10-355 mmol m −3 , the rate of 2-propanol decomposition was proportional to the water content. However, an opposite result was observed at a higher concentration of water vapor. 2-Propanol was photooxidized to acetone, and eventually to carbon dioxide and water. The kinetic model of 2-propanol photooxidation was successfully developed by the competitive Langmuir-Hinshelwood rate form, incorporating the inhibition effect coming from the formation of acetone.  2004 Society of Chemical Industry Keywords: photocatalysis; titanium dioxide; kinetics; 2-propanol; acetoneReaction rate constant of acetone (mmol m

A surface science perspective on TiO2 photocatalysis

“…Several studies have shown the importance of gas phase O 2 in the conversion of 2-propanol to acetone [721,722,[898][899][900][901][902][903][904]. In particular, Brinkley and Engel [900][901][902] examined the photooxidation of 2-propanol on R TiO 2 (110) and (100) surfaces in UHV, and concluded that O 2 was necessary for photooxidation.…”

“…Isopropyl alcohol: Photooxidation of 2-propanol (isopropanol) presents an interesting case because the reaction exhibits near 100% selectivity toward acetone [721,722,[898][899][900][901][902][903][904]. Conversion of 2-propanol to acetone requires two oxidative steps, and the intermediate associated with the first step has not that been identified.…”

“…Numerous gas phase studies support the conclusions of Fu and coworkers in attributing the influence of water in photocatalysis on TiO 2 to the roles of promoter or inhibitor. Examples include the photooxidation reactions of propane [927], toluene [1311,1312], 1-butene [1313,1314], methanol [1312], 2-propanol [903], trichloroethylene [1006,1014,1315], triethylamine [1052], formaldehyde [1311,1316], formic acid [1316], stearic acids [743], and diethyl sulfide [1066]. In terms of RH, the point at which the conflicting influences of water transition depends on many factors (including those mentioned above).…”

“…More common are cases in which an intermediate from a particular reactant acts as an inhibitor. Examples including: acetate or condensation products from acetone: [701,1020], acetaldehyde from ethanol [890,893], benzaldehyde, benzoate and other aromatics from toluene [941][942][943]946,947,1318], acetone from isopropanol or propane [903,927], acetate from catechol or resorcinol [1467], sulfates/sulfites from sulfides or organosulfides [1067,1074,1082], and halides or halocarbon fragments from halocarbons [718,1006,1008,1009,1015]. Similarly, in systems in which a co-catalyst is employed, build-up of a strongly bound intermediate on the co-catalyst might have adverse effects on the overall reaction process.…”

Surface modification of titanium dioxide nanoparticles by polyaniline via an in situ method

“…Titanium dioxide (TiO 2 ) is a widely studied material because of its unique optical, electrical and chemical properties, high photocatalytic activity and high photoelectric conversion efficiency. It is well known for its photovoltaic and photocatalytic properties 1–4. Polyaniline (PANI) is one of the most intrinsically conducting polymers, with perfect conductivity, good environmental stability and relatively easy preparation.…”