Bismuth ruthenium oxide

S. J. H. F. Arts, F. van Rantwijk, and R. A. Sheldon, Oxidation studies of carbohydrates using molecular oxygen and a bismuth-ruthenium oxide catalyst, J. Carbohydr. Chem., 15 (1996) 317-329. 

Iodine is also given off to a small extent in dissolving the uranium metal in nitric acid, but larger amounts may be obtained on steam distillation after dissolution (5). Ruthenium is often removed from the fission products by distillation of the volatile tetroxide formed by oxidation with potassium permangate, sodium bismuthate, periodic acid (38) etc. The distillation goes readily and gives a product of good purity. 

In comparison to the bismuth molybdate and cuprous oxide catalyst systems, data on other catalyst systems are much more sparse. However, by the use of similar labeling techniques, the allylic species has been identified as an intermediate in the selective oxidation of propylene over uranium antimonate catalysts (20), tin oxide-antimony oxide catalysts (21), and supported rhodium, ruthenium (22), and gold (23) catalysts. A direct observation of the allylic species has been made on zinc oxide by means of infrared spectroscopy (24-26). In this system, however, only adsorbed acrolein is detected because the temperature cannot be raised sufficiently to cause desorption of acrolein without initiating reactions which yield primarily oxides of carbon and water. 

A2Pt207, similar to those reported for tin, ruthenium, titanium, and several other tetravalent ions. Trivalent ions which form cubic platinum pyrochlores range from Sc(III) at 0.87 A to Pr(III) at X.14 A. Distorted pyrochlore structures are formed by lanthanum (1.18 A) and by bismuth (1.11 A). Platinum dioxide oxidizes Sb203 to Sb2(>4 at high pressure. The infrared spectra and thermal stability of the rare earth platinates have been reported previously and will not be repeated here, except to point out the rather remarkable thermal stability of these compounds decomposition to the rare earth sesquioxide and platinum requires temperatures in excess of 1200 °C. 

Any iron present in the leach solution is removed by precipitation as goethite (FeOOH). The solution is then purified by cementation with lead powder to remove copper, silver, bismuth, arsenic and antimony, leaving impurities such as zinc, which do not co-deposit with lead. The purified solution is electrolysed in a diaphragm cell, which uses a coated copper cathode and a titanium mesh anode coated with ruthenium and iridium oxides. An ion permeable membrane separates the cathode and anode compartments. The cathode is fabricated from a dimpled copper sheet coated with an inert adhesive sheet between the dimples, leaving numerous sites of high current density to promote dendritic growth of the lead deposit. The crystalline lead falls from the cathode and is collected in the base of the cell. 

Ruthenium pyrochlore oxides, mixed oxides of ruthenium and bismuth or lead with the general formula A2+xRu2.x07.y (A = Pb or Bi 0 < x < 1 0 < y < 0.5) catalyze the oxidative cleavage of vic-diols to the corresponding... 

The use of these ruthenium pyrocWoie oxides as catalysts for the aerobic oxidation of alcohols would seem to be worthy of further investigation. Presumably the function of the bismuth (or lead) is to facilitate the reoxidation of the ruthenium, by dioxygen, in these catalysts. 

In order to decrease the overpotential for cysteine oxidation in cysteine-containing peptides, graphite-epoxy resin or carbon paste electrodes with immobilized cobalt phthalocyanine have been employed in HPLC systems [53,87-89]. Glassy carbon electrodes modified with a mixed-valence ruthenium(I V,III) oxide film stabilized by cyano cross-links [61,62], indium ferricyanide [63], or a Prussian blue film [64], and a bismuth(V)-doped lead dioxide Pb02 film on gold [65] have also been used for detection following HPLC separation. In addition, a carbon fiber modified with a nfixed-valence ruthenium(IV,III) oxide film stabilized by cyano cross-links has been used in CE [46]. 

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