Effect of presorption on platinum films on the catalytic oxidation of hydrogen; and area determinations by carbon monoxide/oxygen titration

Abstract

The effect of the presorption of water, methyl alcohol and ammonia on platinum films on the catalytic oxidation of hydrogen at 195 K has been examined. Substantial amounts of hydrogen molecules were associatively chemisorbed on the presorbed primary layer of dissociatively chemisorbed water, and were rapidly oxidized by O₂(g). A mechanism for this process is proposed and confirmation obtained by use of presorbed layers of methyl alcohol and of ammonia. It is suggested that the exceptionally high hydrogenation activity of platinum at lower temperatures might be associated with the presence of this molecularly chemisorbed hydrogen. The possiblity of determining the surface area of the metal catalyst by using the titration of chemisorbed oxygen with CO(g) has also been investigated.