Hydrogenolysis of saturated hydrocarbons

It converts anthracene, however, into a mixture of partially and completely reduced products. 

It is possible to hydrogenate aromatics in the superacids HF-TaF5, HF-SbF5, or HBr-AlBr3 in the presence of hydrogen. The reduction of benzene was shown to give an equilibrium mixture of cyclohexane and methylcyclopentane.243 244 Reduction was postulated to proceed via initial protonation of benzene followed by hydride transfer  

It was found244 that a tertiary hydride ion source (isoalkanes formed under reaction conditions through isomerization) is necessary to yield the products. However, when isopentane and hydrogen pressures greater than 14.6 atm are used, the reduction becomes catalytic. The function of hydrogen under such conditions is to reduce the formed isopentyl cation, thereby regenerating isopentane and yielding a proton. 

An extreme case of the effectiveness of ionic hydrogenation is the HF-BF3 superacid-promoted hydrogenation of coals at 170°C with 36-atm hydrogen giving efficiently liquid products under these relatively mild conditions.245,246 

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HYDROGENOLYSIS OF SATURATED HYDROCARBONS 11.5.1. Metal-Catalyzed Hydrogenolysis... 

Catalytic Activity of Nickel-Loaded Titanates. A good test of the dispersion of the active metal is the activity and selectivity for the hydrogenolysis of n-butane. For example, it is well known (6) that the hydrogenolysis of saturated hydrocarbons, or the rupture of carbon-carbon bonds by hydrogen, are structure sensitive that is, their rates per surface metal atom (TOF s) vary with the percentage of metal exposed on the catalyst (i.e.. the dispersion). Typically,... 

CO2 hydrogenation, ammonia synthesis, hydrogenation of unsaturated organics, methane reforming, hydrogenolysis of saturated hydrocarbons, and wet oxidation of pollutants in waste waters have been tested, the main reactions taking place in the auto-exhaust converters have received special attention. Such is the case of CO and hydrocarbon oxidations, NO reduction, steam reforming, and water-gas shift reaction. 

Matsumoto, H. Saito, Y. and Yoneda, J. "Contrast between nickel and platinum catalysts in hydrogenolysis of saturated hydrocarbons."/. Catal. 19 101-112 1970. 

C. Leclcrq, L. Leclerq, and R. Maurcl. Hydrogenolysis of Saturated Hydrocarbons. III. Selectivity in Hydrogenolysis of Various Aliphatic Hydrocarbons on Platinum/Alumina. J. Catal. 50 87 (1977). 

Skeletal rearrangements of saturated hydrocarbons on CePd3 were studied by Le Normand et al. (1984). Hydrogenolysis of methylcyclopentane, isomerization of 2-methyl-pentane and aromatization of 3-methylhexane were performed at 350 or 360°C. The results were compared with those of classical Pd/Al203, Pd/Si02 or Pd/Ce02 catalysts. The activity of CePd3 itself was very low and palladium atoms seemed to play a minor role. For example, the initial reaction of methylcyclopentane was the selective formation of isopentane, which is not observed on classical palladium catalysts. Air treatment at... 

From a catalytic viewpoint, the material was tested for two commercially important reactions the Fischer-Tropsch process of CO hydrogenation and the hydrogenolysis and dehydrogenation of saturated hydrocarbons. 

The siHca-supported Zr(IV) hydrides 1 obtained by hydrogenolysis of the singlesite siHca-supported species [(=SiO)ZrNp3] are well-known catalysts for hydrogen/ deuterium exchange in saturated hydrocarbons [2, 3], olefin polymerization [4] and alkane or polyolefin hydrogenolysis [5, 6]. They also display a key role in stoichio-... 

Deoxygenation ofketones. Enol triflates, readily available by reaction of ketones and triflic anhydride catalyzed by this sterically hindered base, undergo rapid hydrogenolysis to the saturated hydrocarbon. Overall yields are 65-90%. ... 

Formation of hydroxyl quinoline must have been initiated by ionic reactions that involved and OH ions. Hydrogenation by Ha enables the heterocyclic ring to be saturated, and this can be followed by hydrogenolysis of C-N bonds that first open the hetero-ring and then convert the resultant aliphatic and aromatic amine intermediates to hydrocarbons and ammonia (24). Also direct attack of OH on quinoline may have led to formation of hydroxyl quinoline. It has been suggested that both ionic reaction and free radical capping are possible under supercritical conditions (25). 

In the work of the author and his associates on bimetallic catalysts comprising various combinations of Group VIII and Group IB metals, it was discovered that the activity of the Group VIII metal for hydrogenolysis reactions of hydrocarbons was decreased markedly by the presence of the Group IB metal (11-15). It was shown that the inhibition of hydrogenolysis leads to improved selectivity for alkane isomerization reactions (11) and for reactions in which saturated hydrocarbons are converted to aromatic hydrocarbons (12,14,15). Interest in bimetallic catalysts increased markedly with the discovery of this selectivity phenomenon. 

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