Home-prepared (HP) rutile TiO2 catalysts were prepared at room temperature by using H2O and TiCl4 in different ratios and without addition of additives. The catalysts were used for carrying outthe selective photocatalytic oxidation of 4-methoxybenzyl alcohol to 4-methoxybenzaldehyde inaqueous suspension, free from any organic co-solvent. The selectivities showed by the home prepared catalysts were in the 45–74% range, up to four times higher than that of a commercial rutile TiO2 sample, the reaction rates being comparable. By using the most selective photocatalyst, the oxidation of benzyl, 4-methylbenzyl, and 4-nitrobenzyl alcohols was also carried out in order to investigate the inﬂuence of the substituent group on the oxidation rate and selectivity. The presence of an –OCH3 group positively inﬂuenced the selectivity whereas a –NO2 group showed to have a detrimental effect. The Hammett relationship effectively describes the inﬂuence of substituent group on the kinetic constant of partial oxidation of aromatic alcohols to aldehydes.
|Numero di pagine||7|
|Stato di pubblicazione||Published - 2009|
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