Reduction of tin oxides

Reduction of tin oxide, therefore, enhances corrosion by the melt and decreases significantly the lifetime of electrodes. 

The set of results from TPR is consistent with the interpretations made so far, based on other characterization techniques used. In aU cases, the reduction in tin oxides occurs at temperatures much lower than those in the literature, where values above 900 K are reported for Sn02 [59]. The selectivity of the preparation reaction leads to a close relationship between M and Sn atoms transition metal atoms generate atomic hydrogen by dissociative adsorption, these hydrogen atoms being able to reduce tin oxides closely related to transition metals. Thus, the reduction temperature of the transition metal is the one that controls the global reduction process. As Pt is the metal that can be reduced most easily, the PtSn-BM catalyst exhibits the highest reducibiUty (lower reduction temperature) of aU the bimetalUc systems studied. 

The reduction of tin(IV) oxide to (white) tin metal by graphite proceeds at moderately low temperatures. More commonly, tin(IV) oxide is reduced to the metal by an excess of carbon monoxide at temperatures above 980 K. (a) Write the two chemical equations for the reduction of SnOz. 

Direct chemical reduction of titanium oxide, titanium chloride, titanium sulfate, or titanium hydride with carbon, nitrogen, or ammonia or by both carbon and nitrogen to form TiC, TiN and TiCN.3-6 Titanium nitride can also be prepared in a plasma jet from titanium tetrachloride and nitrogen.7... 

Because of the high temperatures generated, sodium evaporated during the reaction and the product phase consisted of only solid TiN. Alternatively, instead of the metal, the corresponding metal oxide could be used as a reactant in this case magnesium metal was employed for the reduction of the oxide and the MgO in the product was subsequently leached out with HC1 17... 

Tin and Pb are obtained from the ores in various ways, commonly by reduction of their oxides with carbon. Further purification is usually effected by dissolving the metals in acid and depositing the pure metals electrolytically. 

Water-soluble polyether tin hydride and the bis(2-cardoxyethyl)tin hydroxide allowed reductions and cyclizations to be carried out in water with easy separation from organic soluble products. The latter tin reagent is generated in situ and has not been characterized, but may be a multiplicity of tin oxides and hydroxides. It is soluble in dilute alkali and catalyzes the reduction of alkyl and aryl bromides in the presence of NaBH4 and the water-soluble initiator 4,4 -azobis(4-cyanovaleric acid) (AVCA). 

Both TIN and TTA [Tl(OAc)3] have been known to act as electrophiles toward olefinic double bonds, enolizable ketones and nitrogen-containing compounds to afford a variety of natural products or their synthons. As already shown in Scheme 162, TIN was applied to phenolic oxidation by Yamamura and Nishiyama . In particular, this method which consists of TIN oxidation in MeOH followed by Zn reduction in AcOH is effective for the construction of macrocyclic diaryl ethers from the corresponding open-ring precusors, which are required to possess two o,o -dihalophenol moieties. 

The lower activation energy for the reduction of tin-antimony oxides with hydrogen as compared with that for the pure oxides has been confirmed by Saia and Trifiro (47), and, contrary to other studies, the activity reported to vary with calcination temperature. Some studies (50-52) have reported an increase in activity and selectivity for the oxidation of butene with increasing antimony content and to be maximized at an antimony concentration of about 20% (50). Saia and Trifiro also reported that materials calcined at 900°C showed peaks in activity for butadiene formation at antimony to tin ratios of 0.20 and 0.90 and that selectivity to butadiene increased with antimony content to 80% for the catalyst with a ratio of 0.40. 

Tin Oxide. - To our knowledge this system has been studied (with one exception) only by Thornton and Harrison at the University of Nottingham, who have produced seven papers on the subject. I.r. has been used to investigate the surface as a function of the evacuation temperature. Molecular H2O is largely removed at 320 K and fully removed at 473 K. H-bonded -OH groups are present, and the free -OH absorbs at 3640 cm . CO2 yields carbonates and bicarbonates. CO is not adsorbed as such, but forms carbonates by the partial reduction of Sn to Sn ". Adsorption of both NH3 and pyridine reveals Lewis basicity only. The adsorption of small organic molecules shows the oxidizing properties of tin oxide as indicated by CO. 

Although zinc oxide is comparatively easily reduced to free metal, it was obtained in a metal state much later than copper, iron, tin, and lead. The explanation is that reduction of zinc oxide with coal requires high temperature (about H00°C). The boiling point of the metal is 906°C therefore, highly volatile zinc vapour escapes from the reaction zone. 

TiN nanoparticles also have been prepared by various methods such as CVD (52), cathodic arc deposition (53), and electrochemical reduction of titanium oxide (54). Thus, TiN nanoparticles were deposited on epo resin by electrochemical reduction with high cathodic potential of-1.5 V at room temperature (54). 

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