The hydroxylation of phenol (a substrate containing an electron donor group) and of benzoic acid (asubstrate containing an electron withdrawing group) has been carried out by the photocatalytic method inaqueous suspensions containing commercial or home prepared TiO2 samples. The aim of the work was tostudy the distribution of hydroxylation products when different photocatalysts were used and to correlatethe selectivity to some physico-chemical features of the powders. The samples were characterized by Xraydiffraction, thermogravimetry, determination of crystalline phase percentage, specific surface areaand zero charge point. The photoreactivity results indicate that the products of the primary oxidation ofphenol are the ortho- and para-mono-hydroxy derivatives while those of benzoic acid are all the monohydroxyderivatives independently of the catalyst. The selectivity toward mono-hydroxy derivativesshows a strong dependence on catalyst hydroxylation and crystallinity degrees: the highest selectivityvalues were obtained by using the commercial samples that resulted the least hydroxylated and themost crystalline ones. A kinetic model, taking into account the mineralization and the partial oxidationreaction routes, is proposed by using the Langmuir–Hinshelwood model.
|Numero di pagine||11|
|Rivista||Applied Catalysis A: General|
|Stato di pubblicazione||Published - 2012|
All Science Journal Classification (ASJC) codes
- Process Chemistry and Technology