ADSORPTION AND DECOMPOSITION OF ALIPHATIC-ALCOHOLS ON TIO2 Academic Article uri icon

abstract

  • Methanol, ethanol, 1-propanol, and 2-propanol were adsorbed at ambient temperature on Ti02 anatase powders. Temperature-programmed desorption spectra were obtained by using two different experimental apparatuses: a carrier-gas flow reactor system and a high-vacuum microbalance system. Two adsorption states were observed: molecular alcohol and alkoxide. Molecular alcohols desorbed intact upon slight heating (at 350 K) while alkoxides were removed from the surface via two channels: recombination at 390 K and decomposition at higher temperatures. The concentration of alkoxide species was equal for all of the primary alcohols but was less for the secondary alcohol due to steric effects. Temperatures at which the maximum rate of alkoxide decomposition occurred decreased in the sequence methoxide > ethoxide > n-propoxide > isopropoxide. Both unimolecular and bimolecular reaction products were observed in the decomposition of the primary alkoxides; only unimolecular decomposition was observed for the isopropoxide. Dehydrogenation as well as dehydration products were obtained from the decomposition of each of the alcohols studied, with smaller alcohols favoring dehydrogenation. The patterns of sample weight change during TPD experiments also reflected the reaction selectivity: those species favoring dehydration produced smaller ultimate sample weight losses than those favoring oxidative dehydrogenation. The selectivity of alkoxide decomposition depended on both intramolecular bond energies and intermolecular interactions, suggesting that the interpretation of the selectivity in terms of surface acid-base properties alone is inadequate. 1988, American Chemical Society. All rights reserved.

published proceedings

  • LANGMUIR

author list (cited authors)

  • KIM, K. S., BARTEAU, M. A., & FARNETH, W. E.

citation count

  • 151

complete list of authors

  • KIM, KS||BARTEAU, MA||FARNETH, WE

publication date

  • May 1988