Photocatalytic reforming of C3-polyols for H2 production Part II. FTIR study on the adsorption and photocatalytic reforming reaction of 2-propanol on Pt/TiO2

The adsorption behavior and the photocatalytic reforming (PR) process of 2-propanol over Pt (1 wt.%)/TiO2 (PT) photocatalyst have been investigated by Fourier transform infrared (FTIR) spectroscopy. Both the adsorption complexes and the reforming intermediates formed on the PT and the gas-phase were determined and identified by FTIR spectra. The results indicated that the first layer surface of the PT mainly consisted of chemisorbed 2-propanol (Ti-OCH(CH3)(2)) through the condensation of 2-propanol with surface Ti-OH or dissociative adsorption with undercoordinated Ti atoms, while the second layer consisted of physisorbed 2-propanol by interaction with the chemisorbed one or the formed H2O via hydrogen-bond. Under UV irradiation, a rapidly deprotonation of 2-propoxide occurred by the attack of holes (h(+)) and resulted in the formation of acetone, which was then slowly oxidized to acetate and formate species by the hydroxyl radicals ((OH)-O-center dot). The carboxylates finally decarboxylate over the PT to evolve CO2 and CH4 via the photo-Kolbe reaction. According to the results, a reforming mechanism was proposed. The role of the OH groups contained in 2-propanol and its intermediates were found to serve as anchors for their adsorption and to involve the formation of hi transport ways. (C) 2011 Elsevier B.V. All rights reserved.