CHARACTERIZATION OF THE HYDROGENATION PROCESS OF ALLYL ALCOHOL AT A PT ELECTRODE USING A DOUBLE GALVANOSTATIC PULSE TECHNIQUE

The adsorption properties of allyl alcohol and the kinetics of its hydrogenation at a Pt electrode are characterized by means of a double galvanostatic pulse technique. It is found that the adsorption of allyl alcohol on the Pt electrode follows a Langmuir isotherm with an adsorption constant K(ad) = 1.3 x 10(5) M-1. Hydrogenation of adsorbed allyl alcohol by cathodically generated H atoms proceeds on the Pt electrode. The hydrogenation process shows a saturation kinetics that can be analyzed in terms of active sites for allyl alcohol activation. The number of active sites for activation of allyl alcohol corresponds to 31% of a H atom monolayer with a surface density of 0.67 nmol/cm2. The rate constant for the hydrogenation of surface activated allyl alcohol corresponds to k(p) = 438 S-1. The amount of Pt-adsorbed allyl alcohol remains constant during the hydrogenation process, implying rapid exchange of bulk alcohol solute and the adsorbed species.