Bismuth uranates

The conversion of toluene to benzene was studied by Steenhof de Jong et al. (302—304), by both pulse and flow experiments. In the absence of oxygen, selectivities of up to 70% are obtained with bismuth uranate catalysts at 400—500° C. The best catalyst is Bi2U06. The catalyst is reduced in the oxidation process, as gas phase oxygen is absent. The reduction proceeds to metallic bismuth and U02. The activity decreases during reduction, but is completely restored by reoxidation with air. Therefore, a regenerative mode of operation is proposed for practical application of this process. 

The oxidahon of carbon monoxide to carbon dioxide using similar bismuth uranate catalysts has been reported by Derouane and coworkers [49]. The work on carbon monoxide oxidation confirmed that the bismuth uranate catalyst operated by a redox mechanism. These studies on bismuth uranates highlight the important role played by oxygen transfer via the lathee, and reinforce the importance of the ability of uranium to exhibit relatively facile redox behavior. 

TJranospheerite, a bismuth uranate of composition Bi20a.2U03. 3H2O, occurs in Saxony in orange-yellow half-gloliiilar aggregated forms, of hardness 2-3 and density 6-36. 

N. Bonanos [1989] High Oxide Ion Conductivity in Bismuth Uranate,... 

Ignites on contact with antimony, arsenic, boron, iodine, phosphorus, selenium. Ignites when warmed with bismuth, carbon, chromium, lead, sulfur. Incandescent reaction with aluminum, cadmium, cobalt, iron, molybdenum, nickel, potassium, sodium, thorium, titanium, tungsten, uran-... 

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