MOLECULAR ENGINEERING OF PT-BASED ELECTROCATALYSTS FOR HYDROCARBON FUEL CELL ELECTRODES.
Semiannual interim rept. no. 2, 1 May-31 Oct 67,
TYCO LABS INC WALTHAM MA
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The activity of practical high surface area Pt catalysts for the anodic oxidation of propane is strongly dependent on the method of preparation. An examination was made of changes in activity and attempt to correlate them with the changes in physical characteristics of the black. Positive correlations help elucidate what factors are responsible for the unique capability of Pt to oxidize propane electro-chemically at significant rates. The experimental approach was based on the preparation of Pt black under carefully controlled conditions. Most of the work was carried out on the formaldehype reduction of chloroplatinic acid. The physical characterization is based on the determination of surface area, pore volume distribution, bulk density, X-ray diffraction measurements, and electron microscopy. The activities of the Pt blacks were measured using TFE bonded electrodes. A complicating factor in the testing of a catalyst in its practical form is the requirement to distinguish between those changes in activity that can be attributed to mass transport limitations related to structure which results on an uneven utilization of Pt particles in a Pt-agglomerate and those due to changes in the intrinsic activity of the catalyst. Considerable effort is being devoted to an experimental method for measuring the intrinsic activity of the catalyst and for measuring the structural factors such as the macro-and microporosity of the electrodes which mask the intrinsic activity.
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