INSITU FTIR STUDIES ON THE ADSORPTION AND OXIDATION OF NORMAL-PROPANOL AND ISOPROPANOL AT A PLATINUM-ELECTRODE IN SULFURIC-ACID-SOLUTIONS

The adsorption and oxidation of n-propanol and isopropanol at a platinum electrode have been investigated mainly by in situ FTIR spectroscopy. Molecular structure effects due to the different bonding position of the hydroxyl group to the carbon chain of the two molecules studied were demonstrated clearly. n-Propanol can dissociate into linearly bonded CO and CH3CH3 species which block the platinum surface at lower potentials; however, for steric reasons no dissociative adsorption takes place with isopropanol at a Pt electrode. CO2 was detected as the final oxidation product for both reagents. The reactive intermediate in the oxidation of n-propanol was identified as H-bonded propionic acid, and the majority intermediate in the isopropanol oxidation was acetone. It is concluded that the oxidation of n-propanol takes place via a dual path mechanism; in the case of isopropanol, a successive dehydrogenation mechanism is suggested. © 1990.