Surface properties antimony formation

Because of the strong hydrolysis property of antimony salt, it is very difficult to prepare antimony xanthate salt to obtain its IR spectrums. Therefore, the formation of antimony xanthate is difficult to be identified by the UV and FTIR analysis, which has been determined by using XPS. Finally, it can be concluded that the interaction mechanism between ethyl xanthate and jamesonite are attributed to the formation of lead and antimony xanthate on the surface in the light of flotation results, voltammogram measurement, UV and FTIR as well as XPS analyses. 

At the higher metal level (2.0-4.5% Ni with up to 2% Sb) used to study artificially contaminated materials, XRD results have shown the formation of Ni-Sb alloys (NiSb x<0.08) whereas XPS data have indicated that a non-reducible antimony oxide, a well dispersed reducible Sb phase together with reducible Sb (that form an alloy with reducible Ni), were present. Selective chemisorption data for unsupported Ni-powders showed that one surface structure can effectively passivate 2-3 Ni atoms with respect to H2 chemisorption. XPS examination confirmed that Sb segregates at the surface of Ni particles where it can drastically affect the electron properties of neighboring Ni atoms thus reducing their activity. 

Pure lead has low creep and fatigue resistance, but its physical properties can be improved by the addition of small amounts of silver, copper, antimony, or tellurium. Lead-clad equipment is in common use in many chemical plants. The excellent corrosion-resistance properties of lead are caused by the formation of protective surface coatings. If the coating is one of the highly insoluble lead salts, such as sulfate, carbonate, or phosphate, good corrosion resistance is obtained. Little protection is offered, however, if the coating is a soluble salt, such as nitrate, acetate, or chloride. As a result, lead shows good resistance to sufuric acid and phosphoric acid, but it is susceptible to attack by acetic acid and nitric acid. 

A similar lack of clarity pervades other areas concerning the relationship between the catalytic performance and fundamental properties of the catalysts. Wakabayashl et al. (10) reported that the optimized conversion of propylene to acrolein (>7%) over alumina-supported tin-antimony oxide (3 1) was dependent on the sintering temperature of the catalyst and was maximized after heating at 10(X)°C for 3 hr. Further work (22) showed that both electrical conductivity and surface area were maximized in the material containing 3% antimony and a close association between acrolein production and solid solution formation was suggested. 

In view of these observations it would seem sensible that the influence of adjacent superficial antimony and tin ions should also be considered in terms of likely mechanisms. Immediately one would recall the suggestion (72) that the catalytic properties may be related to the blue color of the material, which has been associated with a possible Sb -Sb charge transfer process. Such an association may then be related to the kinetics of butene oxidation, which have been interpreted in terms of the formation of allylic intermediates at active centres containing Sn and Sb ions. Indeed, McAteer (76) has suggested that these active centers have acidic and basic functions and consist of surface oxide ions of different electron density as determined by the coordinated cations. McAteer described the pattern of selectivity for the formation of butadiene and a-ketone according to the depiction in Fig. 7a. The initial step was postulated as the formation at an acid center of a positively charged allyl ion which is ti or a bonded at an adjacent basic site. The formation of butadiene was attributed to proton abstraction from the zr-allyl intermediate, its facile desorption at surfaces... 

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