Enhancement of the ETS-10 Titanosilicate Activity in the Shape-Selective Photocatalytic Degradation of Large Aromatic Molecules by Controlled Defect Production

Abstract

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.

Enhanced ammonia-borane decomposition by synergistic catalysis using CoPd nanoparticles supported on titano-silicates

“…1, 18 On the other hand, the use of an active support (under UV-Vis conditions), such as titania or a titano-silicate (Ti-SiO 2 ), is an available strategy to enhance the catalytic activity of the final catalytic system. 22,23 In the present work, Pd and Co x Pd 1-x NPs were prepared by the well-established procedure of the reduction by solvent method using PVP as capping agent and following an already reported procedure. 15,24 After their purification, the NPs were loaded on SiO 2 and Ti-SiO 2 (UV-Vis inactive and active supports, respectively) to study their catalytic activity in AB Fig.…”

Oriented TiO2 Nanostructured Pillar Arrays: Synthesis and Characterization

“…The first centers on tailoring of the size, shape, and threedimensional organization of TiO 2 particles [1,2,11,12] or of Ti-O-Ti wires with semiconductor character. [5,[13][14][15][16] The second strategy focuses on improving the photocatalytic properties: i) by incorporating metal cations and anions (mainly nitrogen, sulphur, iodine, and other elements) into the bulk; [6,14,[17][18][19][20][21][22][23] ii) by supporting metal particles (mainly Au, Ag, Pt, Ni). [1,3,[24][25][26][27][28][29][30][31] Interesting results are obtained when the two abovementioned research directions are combined to benefit from the sum of their advantages.…”

Environmental Catalysis over Zeolites

“…While microporous ETS-4 and ETS-10 exhibit significant selectivity in the photodegradation of various molecules using both UV and visible lights, TiO 2 (P25) selectivity is observed with visible light only. This means that besides the inverse shape-selectivity effect already observed for the microporous materials [132], selectivity may be achieved also by selecting the excitation light in accordance with the electronic transition of the adsorbed molecule. In such a case, the photodegradation may occur if the conduction band of the Ti-based material is opportunely matched with the lowest unoccupied molecular orbital (LUMO) level of the adsorbed molecule so that it can receive the electron of the excited adsorbate (concept of band alignment).…”

“…The classic example is the use of the microporous titanosilicate ETS-10 [131,132]. The photoactivated ETS-10 shows catalytic activity driven by the size and polarity of the substrates.…”