Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

PP-III-14A REACTOR FOR PHOTOELECTROCATALYTIC OXIDATIONOF AROMATIC ALCOHOLSGiovanni Palmisano a,b , Vittorio Loddo a , Sedat Yurdakal a,c , Vincenzo Augugliaro a ,Rosaria Ciriminna b , Agatino Di Paola a and Mario Pagliaro ba «Schiavello-Grillone» Photocatalysis Group – Dipartimento di Ingegneria Chimica deiProcessi e dei Materiali – Università degli Studi di Palermo – Viale delle Scienze,90128 Palermo (ITALY);b Istituto per lo Studio dei Materiali Nanostrutturati – CNR – Via Ugo La Malfa 153,90146 Palermo (ITALY);c Kimya Bölümü, Fen Fakültesi – Anadolu Üniversitesi – Yunus Emre Kampüsü,26470 Eskişehir (TURKEY). E-mail: gpalmisano@dicpm.unipa.itIn heterogeneous photocatalysis the charge recombination between the photogeneratedelectrons and holes is often a main limiting factor lowering the quantum yields of theprocesses. Recently, several efforts have been made to enhance the photocatalytic efficiencyof titanium dioxide, such as noble metal deposition, ion doping and electrochemically assistedmethod. Concerning this last opportunity, an external anodic bias is applied to force thephotogenerated electrons and holes in different directions so that the charge recombination isreduced to a large extent. 1-3Photoelectrochemical technology with external field appears to be a novel emergingresearch front in photocatalytic degradation of organic pollutants. As for any hybridtechnology, it is significant to take into account the advantages coming from higher oxidationrates and synergic factors coming from the combined system. The experimental phenomenonis considered as an indicator of synergetic effect originated from the interaction between thesingle technologies.It was recently developed by us a new photoelectrochemical reactor, used in the oxidationof p-methoxybenzyl alcohol. The Pyrex reactor is of cylindrical shape and graphite rods(diameter: 3 mm) play the role of anodes, while a gold sheet, that of cathode. A 125 Wmedium pressure Hg lamp (Helios Italquartz, Italy) was axially positioned inside the reactor;it was cooled by water circulating through a Pyrex thimble. The six anodes were placedaxially with respect to the lamp (Figure 1). The annulus of reactor was filled with Pyrexbeads, of 3 mm diameter. TiO 2 thin layers, obtained through a sol gel method from TiCl 4 ,were deposited either on the glass beads or on the graphite rods.Photoelectrocatalytic runs (with a constant bias in the 0-4 V range) were performed inrecirculation mode, with or without irradiation. The photoelectrocatalytic conversion for all329