EFFECT OF INERT SUPPORTS FOR TITANIUM-DIOXIDE LOADING ON ENHANCEMENT OF PHOTODECOMPOSITION RATE OF GASEOUS PROPIONALDEHYDE

Citation
N. Takeda et al., EFFECT OF INERT SUPPORTS FOR TITANIUM-DIOXIDE LOADING ON ENHANCEMENT OF PHOTODECOMPOSITION RATE OF GASEOUS PROPIONALDEHYDE, Journal of physical chemistry, 99(24), 1995, pp. 9986-9991
Citations number
51
Categorie Soggetti
Chemistry Physical
ISSN journal
00223654
Volume
99
Issue
24
Year of publication
1995
Pages
9986 - 9991
Database
ISI
SICI code
0022-3654(1995)99:24<9986:EOISFT>2.0.ZU;2-7
Abstract
Effects of the use of inert supports for TiO2 loading on photocatalyze d decomposition of propionaldehyde in the gas phase was investigated f or mordenite support with various amounts of TiO2 loading and for seve ral kinds of supports such as other zeolites, alumina, silica, and act ivated carbon. The adsorption constant and the amount of adsorption of propionaldehyde were evaluated for TiO2-loaded supports by obtaining Langmuir adsorption isotherms. By correlating these parameters to the photodecomposition rates of propionaldehyde, the involvement of the su pport in the photodecomposition reaction is clarified. The photocataly tic activity of TiO2 on mordenite having various amounts of TiO2 loadi ng increases with increase in the amount of loaded TiO2 up to an optim um value (ca. 50 wt %), beyond which a decreasing tendency of the acti vity appeared. In the region of ascending activity, plenty of adsorbed substrate is available and the activity is controlled by the content of TiO2, while in the region of descending activity, the decrease in t he amount of adsorbed substrate due to a decrease in the occupancy of the support by the TiO2 loading is responsible for the activity decrea se. The photocatalytic activities are greatly influenced by the kind o f inert supports used and show a volcano type dependence on the adsorp tion constant of the TiO2-loaded supports. In cases where the adsorpti on constant is low, the decomposition rate is determined by the amount of adsorbed substrate, while if the adsorption constant is very high, plenty of adsorbed substrate is available on the support, but it is n ot mobile to the loaded TiO2. We conclude that the use of an inert sup port having a medium adsorption constant is necessary to obtain the hi ghest activity, where a high amount of adsorbed substrate that can be supplied to TiO2 particles is available.