Mechanism of the catalytic oxidation of hydrogen on copper

Abstract

The mechanism of water formation from H₂ and O₂ on copper at 393–423 K was studied using a closed circulating system and X-ray photoelectron spectroscopy. Under the whole pressure range of O₂ studied the surface was covered with a Cu₂O layer during the reaction. Where the partial pressure of O₂ was higher than ca. 9 × 10³ Pa, the reaction rate was expressed as follows: r=k[H₂]¹[O₂]⁰ and H₂–D₂ exchange did not proceed during the reaction. On the other hand, where the partial pressure of O₂ was lower than ca. 9 × 10³ Pa, the rate of water formation showed a maximum value at 1.3 × 10³ Pa and the H₂–D₂ exchange reaction proceeded gradually. From these results, a possible mechanism of the reaction is proposed.