Bimetallic catalysts platinum-rhodium alloys

Bimetallic catalysts, mostly combinations of platinum with other metals such as tin [331] and rhodium [324], are promising candidates for the preferential oxidation reaction. Platinum/tin oxide catalysts showed significant reaction rates even at 0 °C [214]. Similar with platinum/rhodium catalysts, an alloy is formed from both metals, which changes the properties of both source metals [214]. Other additive metals, which may improve the activity and selectivity of platinum catalysts, may well be ruthenium and cobalt [329]. 

Ethanol oxidation was studied under lean conditions on platinum/alumina catalysts modified by rhodium and/or lanthanum oxide. The results on alumina support suggest that the formation of bimetallic Pt-Rh particles enhances the production of acetaldehyde, particularly after oxidizing thermal aging of the Pt-Rh/alumina catalyst prepared by coimpregnation. The addition of lanthanum oxide to alumina allows to avoid the formation of Pt-Rh alloy after high temperature treatment and therefore induces a decrease of the production of acetaldehyde. 

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