Studies of the heterogeneous oxidation of methanol in a pulsed-flow reactor

Abstract

Investigations have been made of the oxidation of methanol over palladium catalysts using a pulsed flow microreactor. In this way it is possible to prepare a catalyst in an accurately predetermined condition and to study reactions over it before any appreciable modification of the catalyst surface can take place. With a thoroughly pre-oxidized catalyst methyl formate is produced with high selectivity at low conversions, whereas with a reduced (metallic) catalyst complete oxidation to carbon dioxide and water takes place much more rapidly with the accompanying formation of formaldehyde in the early stages. The experimental results can be accounted for in terms of a mechanism involving the adsorption of methanol as methoxy species on sites which are different for the oxidized and reduced forms of the catalyst, followed in each case by rate-controlling surface reactions.