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.%)/TiO 2 (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(CH 3 ) 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 H 2 O 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). The carboxylates finally decarboxylate over the PT to evolve CO 2 and CH 4 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 h + transport ways.