Oxidation of Ethylene over Palladium and Palladium–Gold Alloys

Abstract

UNTIL recently, nearly all successful catalysts used for the partial heterogeneous oxidation of ethylene contained silver as the active component1. In 1962, however, Kemball and Patterson2 reported that ethylene could be oxidized to acetic anhydride and acetic acid over evaporated palladium films, and several applications have since then appeared in the patent literature3. Kemball2 suggested that the partial oxidation products (which amounted to only about 3 per cent of the total) were formed by a path parallel to that for the complete oxidation to carbon dioxide. Acetaldehyde was proposed as the intermediate in the partial oxidation reaction, but none was detected, presumably because of its rapid oxidation to acetic anhydride. The purpose of the present work was to isolate and identify the proposed intermediate, and to determine whether higher selectivities might be obtained under more favourable reaction conditions.