Rhodium-ruthenium catalysts temperature-dependence

Although the actual reaction mechanism of hydrosilation is not very clear, it is very well established that the important variables include the catalyst type and concentration, structure of the olefinic compound, reaction temperature and the solvent. used 1,4, J). Chloroplatinic acid (H2PtCl6 6 H20) is the most frequently used catalyst, usually in the form of a solution in isopropyl alcohol mixed with a polar solvent, such as diglyme or tetrahydrofuran S2). Other catalysts include rhodium, palladium, ruthenium, nickel and cobalt complexes as well as various organic peroxides, UV and y radiation. The efficiency of the catalyst used usually depends on many factors, including ligands on the platinum, the type and nature of the silane (or siloxane) and the olefinic compound used. For example in the chloroplatinic acid catalyzed hydrosilation of olefinic compounds, the reactivity is often observed to be proportional to the electron density on the alkene. Steric hindrance usually decreases the rate of... 

Precious metals such as platinum, palladium, rhodium and ruthenium on ceria supports are reported in the literature as formulations for a water-gas shift [164]. Certainly the most prominent formulation is platinum/ceria, which has the drawback of a particular activity towards methane formation [164] at temperatures exceeding 375-425 °C, depending on the catalyst formulation. Its long-term stability is usually limited to a maximum temperature of between 425 and 450 °C due to the sintering effects of platinum. 

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