Catalysis by gold on ferric oxide

The selective oxidation of carbon monoxide in hydrogen on Au/a-Fe2C 3 (haematite) catalysts shows characteristics that differ from those of the oxidation of carbon monoxide by itself (Chapter 6). The presence of hydrogen, or perhaps more importantly, of the water formed from it, decreases the rate of activity loss by inhibiting formation of carbonate ion, and causes the rate of carbon monoxide oxidation to increase a little.7,18,21,22 

Catalysts used in this work7,18,21 22 were prepared either by deposition-precipitation or coprecipitation, and were pretreated in air at 673 K. Depending on the way in which the a-Fe2C 3 support was made, the precursor before calcination may have been either ferrihydrite ( 2-line or 6-line 6) or 7-Fe2C 3 (magehmite), the former giving the better results.6 

Oxidations of the two molecules appear to proceed almost but perhaps not quite wholly independently of each other the dissociative chemisorption of hydrogen is not much affected by the carbon monoxide, which, in view of what was said in Chapter 5, is somewhat surprising, as there it seemed that both interacted with lowly coordinated gold atoms. The dependence of kinetic parameters on the hydrogen concentration has not been 

Au/Fe203 has been formed within the pores of alumina pellets to facilitate their use in a prototype reactor.6 

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