Kinetics and reaction pathways of methanol oxidation on platinum

Methanol oxidation kinetics were measured on Pt wires in a flow reactor at pressures between 30 and 130 Pa. The kinetics were measured as a function of oxygen-to-methanol equivalence ratio phi and wire temperature. In methanol-lean feeds (phi 1), CO, H/sub 2/, H/sub 2/CO, CO/sub 2/, and H/sub 2/O were observed. Experiments with /sup 18/O/sub 2/ showed that the principal methanol oxidation pathway does not involve C-O bond dissociation. However, the /sup 18/O/sub 2/ experiments, together with other features of the methanol oxidation data, also provided evidence for a minor oxidation pathway (accounting for less than 1% of the product CO/sub 2/) which proceeds through a carbon intermediate. A mathematical model is presented which describes the principal CH/sub 3/OH oxidation pathway as a series reaction involving adsorbed H/sub 2/CO and CO intermediates. Consistent with experimental results, the model predicts that inhibition by adsorbed CO should be weaker for CH/sub 3/OH and H/sub 2/CO oxidation than for CO oxidation. 34 references, 10 figures, 2 tables.