Catalytic hydrogenation catalysts

The catalysts generally used in catalytic reforming are dual functional to provide two types of catalytic sites, hydrogenation-dehydrogenation sites and acid sites. The former sites are provided by platinum, which is the best known hydrogenation-dehydrogenation catalyst and the latter (acid sites) promote carbonium ion formation and are provided by an alumina carrier. The two types of sites are necessary for aromatization and isomerization reactions. 

The presence of soluble Rh nanoparticles after catalysis is demonstrated by TEM. The kinetic of the catalytic reaction was found to be zero-order in respect to the substrate and first order with respect to hydrogen and catalyst. Curiously, under the same conditions (60 °C, 7 bar H2), ethylcyclohexane is not detected at the end of phenylacetylene hydrogenation and the formation of methylcyclohexane from toluene was only obtained under drastic conditions 40 bar H2 and 80 °C. 

New approaches to catalyst recovery and reuse have considered the use of membrane systems permeable to reactants and products but not to catalysts (370). In an attempt to overcome the problem of inaccessibility of certain catalytic sites in supported polymers, some soluble rho-dium(I), platinum(II), and palladium(II) complexes with noncross-linked phosphinated polystyrene have been used for olefin hydrogenation. The catalysts were quantitatively recovered by membrane filtration or by precipitation with hexane, but they were no more active than supported... 

SELOP C4 A process for upgrading the C4 petroleum fraction by selective catalytic hydrogenation. Different catalysts, containing palladium on alumina, are used for different feedstock compositions. Developed by BASF and used in its Antwerp plant since 1994. 

Other examples of arene hydrogenation by Ziegler-type catalysts have been reported [35]. However, none of them is discussed at this point as they are generally poorly defined. Likewise, some hydrogenation catalytic systems in either oxo or water-gas-shift conditions are only reported in the list of references for sake of information [24, 36]. 

Hydroformylation (0.xo process). Production of aldehydes by catalytic reaction of an olefm with carbon monoxide and hydrogen. Cobalt catalysts are often used. 

In aqueous hydrochloric acid solutions, mthenium(II) chloride catalyzed the hydrogenation of water-soluble olefins such as maleic and fumaric acids [6]. After learning so much of so many catalytic hydrogenation reactions, the kinetics of these simple Ru(II)-catalyzed systems still seem quite fascinating since they display many features which later became established as standard steps in the mechanisms of hydrogenation. The catalyst itself does not react with hydrogen, however, the mthenium(II)-olefin complex... 

Iridium nanoparticles prepared in imidazolium-based ILs have been also used in the catalytic hydrogenation of ketones under mild conditions [50]. Firstly, cyclohexanone was chosen as the model substrate to optimize the reaction conditions (temperature, hydrogen pressure, catalyst concentration). Initially, isolated lr(0) nanoparticles were tested in a solventless system for the hydrogenation of cyclohexanone the prehminarily results are listed in Table 15.6. 

The structure of Ni3Os3(CO)9( /5-C5H5)3 has been established by X-ray diffraction.3 The complex behaves as an homogeneous catalyst for selective hydrogenation Hydrogenating catalytic activity is observed also when adsorbed on alumina.4... 

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