Carbon heterogeneous oxidation

Surface Studies with the Vacuum Microbalance High-Temperature Reactions Earl A. Gulbransen The Heterogeneous Oxidation of Carbon Monoxide Morris Katz... 

The Heterogeneous Oxidation of Carbon Monoxide Morris Katz... 

Carbon monoxide oxidation is a relatively simple reaction, and generally its structurally insensitive nature makes it an ideal model of heterogeneous catalytic reactions. Each of the important mechanistic steps of this reaction, such as reactant adsorption and desorption, surface reaction, and desorption of products, has been studied extensively using modem surface-science techniques.17 The structure insensitivity of this reaction is illustrated in Figure 10.4. Here, carbon dioxide turnover frequencies over Rh(l 11) and Rh(100) surfaces are compared with supported Rh catalysts.3 As with CO hydrogenation on nickel, it is readily apparent that, not only does the choice of surface plane matters, but also the size of the active species.18-21 Studies of this system also indicated that, under the reaction conditions of Figure 10.4, the rhodium surface was covered with CO. This means that the reaction is limited by the desorption of carbon monoxide and the adsorption of oxygen. 

Washing for over 100 h in a solvent such as toluene before the reaction resulted in no significant loss of the catalytic activity, and recovery and reusability studies at high turnover number also indicated the catalyst stability. Same catalysts, H5[PV2Mo10O40] supported on fiber and fabric carbon materials, catalyzed 02-based oxidations of acetaldehyde and 1-propanethiols [113], This aerobic heterogeneous oxidation proceeded under mild reaction conditions. 

This review deals only with the heterogeneous oxidation of-carbon monoxide by solid materials which show some catalytic activity or a fast surface reaction. It does not include purely stoichiometric reagents used in detection and analysis, such as iodine pentoxide, mercuric oxide, palladium salts activated by molybdenum salts, or liquid-gas systems. A review of such agents has recently been presented elsewhere (11). Furthermore, no attempt has been made to provide complete coverage of the numerous patents in this field, although a number of the more important ones are mentioned. 

The study of the heterogeneous oxidation of carbon monoxide has been a fruitful field of research for many investigators in heterogeneous catalysis. Highly active catalysts have been prepared from simple oxides, multicomponent oxides, and salts of acidic metal anhydrides, derived... 

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