FTIR study of the surface complexes of β-picoline, 3-pyridine-carbaldehyde and nicotinic acid on sulfated TiO2 (anatase)

Surface complexes of beta-picoline, 3-pyridine-carbaldehyde and nicotinic acid on sulfated TiO2 (anatase) containing 0.12 and 6.9 wt.% SO42- were studied using FTIR spectroscopy. The water and beta-picoline were used as molecular probes for identification of surface acidity and sulfate species. Depending on SO42- content, FTIR spectra have revealed differences in the type, quantity and strength of acidic sites as well as in the composition and strength of surface complexes of beta-picoline, 3-pyridine-carbaldehyde and nicotinic acid. Both samples possess Lewis and Bronsted acidic sites. But only TiO2 (6.9) contains strong Bronsted sites. On this sample the dead-end nicotinates form during 3-pyridine-carbaldehyde transformation while the weakly bound nicotinates on TiO2 (0.12) surface transform into nicotinic acid. (C) 2013 Elsevier B.V. All rights reserved.