Metal surface areas hydrogen-oxygen titrations

Supported platinum and palladium catalysts were prepared by soaking a preformed alumina support (Kaiser KC/SAF gel-derived alumina, 250 m2/g, %-inch spheres) in concentrated aqueous solutions of the appropriate metal chloride. The catalysts were calcined at 600 °C in air before use. Specific metal surface areas were measured by titration of chemisorbed oxygen with hydrogen (I, 2). Prior to the adsorption measurement, each sample was reduced 1 hr in H2 at 500°C, evacuated 1 hr at 500°C, and exposed overnight to 02 at room temperature. Elemental distributions in the catalyst pellets were determined by electron microprobe. 

The results of catalytic activity correlate very well with the free metal surface area (dispersion) obtained by hydrogen-oxygen titration cycles HOTC method. 

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