ABSTRACT
In the case of noble metal catalysts, calcination in air prior to reduction is necessary to avoid metal sintering. The presence of water vapors is generally avoided, in order to prevent metal sintering. By using an excess of hydrogen, the water formed during reduction can be swept away. The noble metal oxides can be readily reduced with hydrogen between 300°C and 500°C [l]. A variety of chemical reagents may also be used for reduction (e.g., hydrazine, formaldehyde).
