Particles palladium sulfide

Schultz and Matijevic (16) prepared nanoparticles of palladium sulfide (PdS) by the continuous double-jet mixing of PdCl2 or Na2(PdCl4) and Na2S. They found that the particle size was 20-30 nm in mean diameter obtained in acidic media (pH = 2-3), but 2-5 nm in alkaline media, probably due to the high equilibrium concentration of sulfide ions S2- by dissociation of H2S and HS in the alkaline media (pH = 10-12). A cationic surfactant, cetyl trimethyl ammonium bromide (CTAB), was found to be useful for stabilizing the small particles prepared in alkaline media. 

In another study, a poly4VP layer was grafted, which was further activated in a PdCl2 solution followed by reaction with CO or H2S to yield composite particles with metallic palladium or palladium sulfide nanoparticles in the shell. 

The structures of the palladium sulfides have been confirmed clearly by scanning electron microscopy (SEM) study [26]. When Pd(OAc)2 dissolved in alkyne in the presence of y-terpinene is allowed to react with cyclohexanethiol upon microwave heating, nanostructured Pd species (Pd nanobelts) is formed in 85% yield. y-Terpinene acts as an excellent radical trapper and suppresses the formation of anfi -Markovnikov addition product 3 by radical pathway. On the other hand, the addition of thiols to Pd(OAc)2 followed by addition of alkyne leads to amorphous particles in the pm-size region. The formed Pd nanobelts exhibits excellent catalytic activity toward the hydrothiolation of aUcynes. In particular, the hydrothiolation with aUcanethiols proceeds efficiently with excellent regioselectivity upon microwave heating (Scheme 6). 

Therefore, it appears clearly from all the observations that sulfur adsorption from thiophene onto palladium is restricted to the surface area of metal particles, with part of this surface being sulfided through the decomposition of the sulfur compound. 

Vazquez A, Pedraza F, Fuentes S. Influence of sulfidation on the morphology and hydrodesulfurization activity of palladium particles on silica. J Mol Catal. 1992 75(1) 63. Feuerriegel U, Klose W, Sloboshanin S, Goebel H, Schaefer JA. Deactivation of a ptilladium-supported alumina catalyst by hydrogen sulfide during the oxidation of methtme. Langmuir. 

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