Platinum sulfide PtS

The above two reactions result in the poisoning of the platinum sites. In other words, the adsorption of the sulfur on the platinum sites results in a smaller area for hydrogen adsorption. Thus, the above two reactions are in competition with the adsorption and electrooxidation reactions of hydrogen given in equation (7.106) and equation (7.107). The formation of the platinum sulfide (Pt-S) can either follow equation (7.108) and equation (7.109) or could be formed electrochemically as well, as suggested by Mohtadi et al. [112], according to the following equation ... 

Ruthenium(ll) sulfide, RuS2 (laurite) iridium(III) sulfide, It2S3 iridium(IV) sulfide, IrS2 palladium(ll) sulfide, PdS platinum(II) sulfide, PtS (braggite, cooperite) platinum(lV) sulfide, PtS2. 

The current work indicates that sulfided platinum catalysts are, in general, more active and selective than Pt, Pd, or sulfided Pd catalysts for reductive alkylation of primary amines with ketones. The choice of the catalyst preparation parameters, especially the support, plays a major role in determining the performance of the catalyst. Diamines, especially of lower molecular weight, tend to react with ketones even at room temperature to form heterocycles such as imidazolidine, diazepanes, and pyrimidines. Hence, a continuous reactor configuration that minimizes the contact between the amine and the ketone, along with a highly active catalyst is desired to obtain the dialkylated product. In general, sulfided Pt appears to be more suited for the reductive alkylation of ethylenediamine while unsulfided Pd or Pt may also be used if 1,3-diaminopropane is the amine. 

Procedure The irradiated molybdenum is dissolved in cone, sulfuric acid and technetium is distilled with the acid. The distillate obtained is diluted to 4 M H2SO4, heated to boiling and treated with bromic water. A platinum salt (1 mg of Pt/200 ml solution) is added to the solution as collector, and technetiiun is coprecipitated with the platinum sulfide. The precipitate is dissolved in NH OH/ HjOj mixture and the solution evaporated to dryness. The residue is dissolved in cone. HjSO or HCIO4 and technetium separated from platimun by distillation. The solution is diluted and the sulfide precipitated. 

Both sulfate and sulfide have been detected by XPS on sulfided Pt/Al203 and platinum black sulfide ions selectively eliminated aromatisation and hydrogenolysis of n-hexane, while sulfate ions stopped all processes except dehydrogenation. At high sulfur loadings, where both forms were present, activity was reduced by 95%. 

PuAl20gy Pt-asbestosy Pt-Cy Pt-silk PtyFe-C Pt02, Platinum rhodium oxide Platinum sulfide-carbon H tClg... 

The adsorbed sulfur deactivates Pt by blocking the access to a given number of Pt atoms and modifies the electronic properties of the neighboring atoms. For example, S not only decreases the amount of CO adsorbed but also decreases the binding energy between CO and Pt (138) and also with other adsorbates (87). It has been established that certain amount of sulfur remains adsorbed on the metal, even after 30 h at 500° C in H2 flow. This is called irreversible sulfur, and this amount does not depend on the sulfiding conditions (139). This amount is approximately 0.4 atoms of sulfur for each atom of accessible platinum, in Pt, Pt-Re, and Pt-Ir catalysts. 

Although estimates of their abundances vary considerably, Pd and Pt (approximately 0.015 and 0.01 ppm respectively) are much rarer than Ni. They are generally associated with the other platinum metals and occur either native in placer (i.e. alluvial) deposits or as sulfides or arsenides in Ni, Cu and Fe sulfide ores. Until the 1820s all platinum metals came from South America, but in 1819 the first of a series of rich placer deposits which were to make Russia the chief source of the metals for the next century, was discovered in the Urals. More recently however, the copper-nickel ores in South Africa and Russia (where the Noril sk-Talnakh deposits are well inside the Arctic Circle) have become the major sources, supplemented by supplies from Sudbury. 

Pyridine complexes of Pd- and Pt-pincer ligands are also suitable substrates for olefin metathesis [116]. The first-generation catalyst 9 efficiently mediates the RCM of diallylphosphines and diallyl sulfide when the heteroatom is com-plexed by a cationic [C5H5(NO)(PPh3)Re] moiety [117]. This principle has been exploited in the same study for tungsten, rhodium, and platinum complexes. 

Previously, we have developed several techniques for platinum supported zeolite catalysts to improve the benzene product purity, including on-line sulfiding [3], precoking [6], and dual-bed catalyst system [7]. We report herein an in-depth investigation on the synergism of proton zeolite and platinum supported ZSM-12 catalyst (Pt/Z12) in a cascade dual-catalyst system. 

Elemental composition (anhydrous salt) Pt 47.60%, H 0.49%, Cl 51.90%. The compound may be identified by its physical and chemical properties. Platinum in an aqueous solution of the compound can be analyzed by flame AA or ICP spectroscopy. Also, the compound can be measured by gravimetry following precipitation with ammonium chloride, hydrogen sulfide, or silver nitrate (see Reactions above). 

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