NON-FARADAIC ELECTROCHEMICAL MODIFICATION OF CATALYTIC ACTIVITY (NEMCA) OF PROPANE OXIDATION AT THIN-FILM CELL ON ALUMINA

Abstract

Non-faradaic electrochemical modification of catalytic activity (NEMCA) of propane oxidation has been studied. It is a potential phenomenon that could become a breakthrough in improvements on catalytic converters. Yttria-stabilized zirconia (YSZ, Y2O3:ZrO2) ionic conductors, was deposited on alumina substrates by sputtering technique carried out in vacuum in the form of a thin film deposited on a cheaper alumina support. NEMCA of propane oxidation was studied under a stoichiometric ratio of propane to oxygen at 200-500 °C in both open-circuit (i.e., with no current passing through the electrolyte) and closed-circuit conditions with wired configuration cell between wireless and conventional methods. The highest catalytic CO2 production rate is 1.98 x 10-8 mol/s by wireless method operated by sputtering at 400 W for 4 h while in case of conventional method, at 500 °C with YSZ thin film cells, the reaction rate exhibited the electrophobic type of NEMCA (i.e., the promoting effect at positive potentials) at closed-circuit condition. However, reversibility of reaction rates was observed during forward and reverse potential scans at 400°C for sputtering time 4 h and 200 °C for sputtering time 8 h. Moreover, screen-printing technique was also fabricated YSZ thin film on alumina. By wireless method, the maximum rate enhancement ratios was 2 times at 60wt% YSZ ink and by conventional method, the maximum rate enhancement ratios was 1.31 times.