Oxygen as promoter or poison in the catalytic dissociation of H 2, C 2H 4, C 2H 2, and NH 3 on Palladium

Abstract

The dissociation rates of H 2, C 2H 4, C 2H 4, and NH 3 have been studied on oxygen covered Pd surfaces by measuring the water desorption rates during exposure to each of the molecules. These results are correlated with the hydrogen response of a Pd-MOS structure. The measurements show a trend (at 473 K) where oxygen blocks H 2 dissociation, blocks C 2H 4 dissociation only above a certain oxygen coverage, has no influence on C 2H 2 dissociation, and promotes NH 3 dissociation.