Cobalt alloy synthesis catalysts

According to Farlow, Lazier, and Signaigo195 a cobalt poly sulfide catalyst is useful for synthesis of thiols from aldehydes by means of hydrogen sulfide under hydrogenating conditions the catalyst is obtained by treating a cobalt-aluminum alloy with sodium sulfide. 

Virtually all commercial HPHT synthesis of diamond uses iron, nickel, cobalt, manganese, chromium, and their alloys as catalyst-solvents. However, many other metals ean catalyze graphite-to-diamond formation at higher temperatures and pressures, as can water, silicates, and other minerals that are more akin to the environment in which natural diamonds grow in the earth. 

Tungsten alloyed with nickel, cobalt, or rhodium in thin layers on alumina supports, also sulfided, is used on an industrial scale as a catalyst in crude oil processing (hydrotreating, hydrocracking, reforming, hydrodesulfurization, and hydrodenitrogenation), as well as in Fischer-Tropsch synthesis (alcohol formation from CO + H2). 

Precaution Dust is flamm. attacked by dil. hydrochloric and sulfuric acids corrodes readily in air explosive reaction with ammonium nitrate + heat ignites on contact with bromine pentafluoride incandescent reaction with acetylene, nitryl fluoride Uses In alloys oxidizing agent lamp filaments in mfg. of cobalt steel, cobalt salts electroplating ceramics catalyst (sulfur removal from petrol., Oxo process, org. synthesis) trace element in fertilizers drier in inks, paints colors cermets in porcelain, glass, pottery, enamels pigment in paints food processing aid cemented carbides jet... 

For higher alcohols synthesis, the catalytic formulation includes a metal that does not dissociate CO (copper) as well as a metal able to perform this dissociation and ensure the chain growth (cobalt). The interest of starting with a perov-skite as catalyst precursor lies in the control of the position of both metals in the perovskite structure, favoring close interactions or alloy formation between the two metals after reducing treatment. 

In a previous paper, it was shown that there is a rough correlation between the catalytic activity in methanol synthesis and the whole chemisorption activity towards CO (35). Therefore, the low catalytic activity of copper-rich catalysts may be attributed to the segregation of much of the copper as well crystallized metallic particles (36). The further decrease in activity for Cat D and, especially. Cat E is in agreement with the hypothesis of the formation of alloys at the surface of the copper particles (26,27), taking into account the poisoning effect of small amount of cobalt (37). 

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