THE HYDROGEN STORAGE BEHAVIOUR OF PT AND PD LOADED TRANSITION METAL OXIDES

The catalytic properties of Pt and Pd deposited on commercial porous MnO2 and TiO2 powders for hydrogen adsorption were examined to determine whether hydrogen molecules and diffuse onto the support. Fluidised-Bed Metal-Organic Catalyst deposition was achieved using metal-organic Chemical Vapour Deposition. Scanning Electron Microscopy showed that the average diameter of metal particles was < 1 mu m. The amount of catalyst loading was determined from the deposition conditions and was < 1%wt. Hydrogen uptakes at 77K were determined volumetrically. Experiments were carried in 77K and measurements were performed for samples before and after deposition. Physically adsorbed hydrogen was determined form the uptake of metal oxides without catalyst loading and it was found that the hydrogen uptakes exceeded both the amount of physically adsorbed hydrogen and the theoretical capacity for Pt and Pd. From this it was inferred that some hydrogen had been transferred from the support although the mechanism for this process is still not clear.