Oxygen adsorption spectroscopic study

Finkelstein, N. P., 1999. Addendum to The activation of sulphide minerals for flotation a review. Inter. J. Miner. Process, 55(4) 283 - 286 Fomasiero, D., Montalti, M., Ralston, J., 1995. Kinetics of adsorption of ethyl xanthate on pyrrhotite in situ UV and infiared spectroscopic studies. Langmuir, 11 467 - 478 Forssberg, K. S. E., Antti, B. M., Palsson, B., 1984. Computer-assisted calculations of thermodynamic equilibria in the chalcopyrite-ethyl xanthate system. In M. J. Jones and R. Oblatt (eds.). Reagents in the Minerals Industry. IMM, Rome, Italy, 251 - 264 Fuerstenau, M. C., Kuhn, M. C., Elgillani, D. A., 1968. The role of dixanthogen in xaomthate flotation ofpyrite. Trans. AIME, 241 437 Fuerstenau, M. C. and Sabacky, B. J., 1981. Inter. J. Miner. Process, 8 79 - 84 Fuerstenau, M. C., Misra, M., Palmer, B. R., Xanthate adsorption on selected sulphides in the presence of oxygen. Inter. J. Miner. Process... 

D. Stacchiola, G. Wu, M. Kalchev, W. T. Tysoe, A reflection-adsorption infrared spectroscopic study of the adsorption of ethylene and ethylene oxide on oxygen-covered Ag(lll), Surf. Sci. 486 (2001) 9. 

The adsorption of CO2 on metallic nickel films has been studied in both the presence and absence of oxygen. An i.r. spectroscopic study of the simultaneous adsorption of COg and O2 on nickel has shown the formation of carbonate-carboxylate structures on the nickel surface. The adsorption of CO2 on nickel in the temperature range —196 to 0 °C has been found to be irreversible, the molecules being adsorbed at two surface sites within the limits of the monolayer. Above 100 °C, dissociative adsorption of CO2 takes place with the formation of CO. ... 

Other X-ray spectroscopic studies include cadmium adsorption on aluminum oxides (Papelis et al. 1995), where it was found that Cd-O distances and coordination numbers (6 oxygens) on two aluminas agree with Cd-O distances and coordination in aqueous solutions. In low sorption density samples, absence of cadmium... 

GiameUo, E., Sojka, Z., Che, M., et al (1986). Spectroscopic study of superoxide species formed by low-temperature adsorption of oxygen onto cobalt oxide (CoO)-magnesium oxide solid solutions An example of synthetic heterogeneous oxygen carriers, J. Phys. Chem., 90, pp. 6084-6091. 

In the previous sections of this review, it has been shown that most effective catalysts for the selective oxidation of propylene contain at least two types of metal oxides—an amphoteric or low-valence oxide, such as bismuth, tin, iron, or cobalt, and an oxide of a high valence metal, such as molybdenum or antimony. Moreover, it has been suggested several times that each of these metal oxide components may give rise to an active site for example, propylene may adsorb on an active site associated with one of the metal oxide components, and oxygen may adsorb on an active site associated with another metal oxide component. This problem has been studied using spectroscopic, adsorption, and kinetic techniques. It now seems appropriate to consider some of these studies in detail, attempting to relate the solid structure of the catalyst to the active sites wherever possible. 

From the above discussion it becomes apparent that some conflicting experimental evidence exists on hydrocarbon adsorption and on surface intermediates. This arises primarily from the use of electrocatalysts of varying histories and pretreatments. It should be stressed that many adsorption studies were performed on anodically pretreated platinum. The removal of surfaces oxides from such electrodes may have not been always accomplished when the surface was cathodically reduced in some experiments, as outlined in Section IV,D. Obviously, different surface species could exist on bare or on oxygen-covered electrocatalysts. Characterization of surface structure and activity and of adsorbed species using modern spectroscopic techniques would provide useful information for fuel cell and selective electrocatalytic oxidations and reductions. 

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