ELECTROCHEMICAL MODIFICATION OF CH3OH OXIDATION SELECTIVITY AND ACTIVITY ON A PT SINGLE-PELLET CATALYTIC REACTOR

It was found that the catalytic activity and selectivity of Pt for the oxidation of methanol to formaldehyde and CO2 can be altered signific antly and reversibly by depositing a Pt catalyst film on an yttria-sta bilized zirconia (YSZ) disc and by applying current or potential betwe en the catalyst film and a Ag film deposited on the other side of the O2--conducting YSZ disc. Both the catalyst film and the Ag counter and reference electrodes are exposed to the reacting CH3OH-O2 mixture. Th e observed increase in the rate of H2CO production was typically a fac tor of 100 higher than the rate of O2- supply to the catalyst with a c oncomitant 2-fold increase in selectivity. This demonstration of the e ffect of non-Faradaic electrochemical modification of catalytic activi ty (NEMCA) to reversibly modify catalyst activity and selectivity in a single-pellet flow reactor is a new result. It has considerable pract ical importance as it shows that the NEMCA effect can be utilized in c onventional flow-type catalytic reactors. The present study has also s hown the spontaneous generation of significant reaction-driven potenti al differences between the catalyst and the counter electrode. This ob servation is significant both for catalytic and also for sensor applic ations.