A comparative study of Pt/γ-Al2O3, Au/α-Fe2O3 and CuO–CeO2 catalysts for the selective oxidation of carbon monoxide in excess hydrogen

Three different catalysts, namely Pt/γ-Al 2 O 3 , Au/α-Fe 2 O 3 and CuO-CeO 2 were prepared (by wet impregnation, coprecipitation and a sol-gel method, respectively) and their catalytic performance for the selective oxidation of carbon monoxide in the presence of excess hydrogen was evaluated and compared. The effects of the presence of CO 2 and H 2 O in the reactant feed on the activity and selectivity of these catalysts, as well as their stability under realistic reaction conditions were also investigated. Regardless of whether CO 2 or both CO 2 and H 2 O are present in the reactant feed, the Au/α-Fe 2 O 3 catalyst is superior to the other two for the selective CO oxidation at relatively low reaction temperatures (<80-120°C, depending on contact time and feed composition employed), while at higher reaction temperatures, best results are obtained with the CuO-CeO 2 catalyst, which proved to be more active and remarkably more selective than the Pt/γ-Al 2 O 3 catalyst. The Au/α-Fe 2 O 3 catalyst was the most sensitive, while the Pt/γ-Al 2 O 3 the most resistant towards deactivation caused by the presence of CO 2 and H 2 O in the feed. Finally, while the Au/α-Fe 2 O 3 catalyst lost a considerable portion of its activity during the first 80 h under reaction conditions, the CuO-CeO 2 and Pt/γ-Al 2 O 3 catalysts exhibited a stable catalytic performance, at least during the time period tested in this work (7-8 days).

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