Electrochemical promotion of NO reduction by C3H6 on Rh catalyst-electrode films supported on YSZ and on dispersed Rh/YSZ catalysts

The selective catalytic reduction of NO by C3H6 in the presence of O2 was investigated on porous polycrystalline Rh catalyst-electrode films deposited on YSZ (Y2O3-stabilized ZrO2) and dispersed Rh/YSZ (0.5 wt%) catalysts. In the former case, it was found that the application of current or potential between the Rh catalyst-electrode and an Au counterelectrode enhanced the rate of NO reduction and CO2 formation by factors of up to 55 and 200, respectively. These rate increases were strongly non-Faradaic with apparent Faradaic efficiencies, Λ, of up to 7000 for the formation of CO2, demonstrating a significant effect of electrochemical promotion or non-Faradaic electrochemical modification of catalytic activity. A comparison of the activity between the electropromoted Rh paste catalyst and the dispersed Rh/YSZ catalyst shows that the TOFs on the dispersed Rh/YSZ catalyst fall between the corresponding TOFs on the unpromoted and electropromoted Rh catalyst-electrode film.