Enhancement of the ETS-10 titanosilicate activity in the shape-selective photocatalytic degradation of large aromatic molecules by controlled defect production.
In recent times, it has been shown that the microporous ETS-10 titanosilicate can be used as a shape-selective photocatalyst for the decomposition of aromatic molecules (Chem. Commun. 2001, 2131). Its actual use on practical grounds is however discouraged by its too low activity, when compared with that of TiO(2) photocatalysts. In the present work, we show how an ad hoc mild treatment with HF enhances the activity of ETS-10 toward the photodegradation of large aromatic molecules that are unable to penetrate inside the zeolitic pores, such as 2,5-dichlorophenol, 2,4,5-trichlorophenol, 1,3,5-trihydroxybenzene, and 2,3-dihydroxynaphthalene (DHN). The photoactivity of the acid-treated materials is comparable or even greater than that of the nonselective TiO(2) catalyst. Moreover, the enhancement of the photoactivity is accompanied by a remarkable parallel increase of the shape selectivity, particularly toward DHN (k(DHN)/k(P) = 127, where P = phenol). A complete characterization (by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and X-ray aborption spectroscopy techniques) of a set of ETS-10 samples which have undergone a progressively severe HF treatment allows us to propose an explanation of the photocatalytic activity and selectivity of the modified materials.
Llabrés I Xamena
Francesc X
FX
Dipartimento di Chimica IFM, Università di Torino, Via P. Giuria 7, I-10125 Turin, Italy.
Calza
Paola
P
Lamberti
Carlo
C
Prestipino
Carmelo
C
Damin
Alessandro
A
Bordiga
Silvia
S
Pelizzetti
Ezio
E
Zecchina
Adriano
A