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Hydrogen ability

At low temperatures, cyclohexane is the only product observed at the beginning of the reaction, but benzene becomes the only product formed after about 100 min of reaction, which shows that the aromatic hydrogenation ability of Ni is suppressed (poisoning), probably through the deposition of As on the Ni surface. At higher temperatures, benzene is the main compound formed, regardless of the reaction time. [Pg.192]

Co/A1203 catalysts that contain higher amounts of less reactive polymeric carbon not only exhibited enhanced deactivation when tested in FTS when compared to the fresh catalyst, but also showed an increase in selectivity to olefinic products.31 The authors postulated that this was probably due to the reduction in hydrogenation ability of the carbon deposited catalyst to convert primarily formed olefins into the corresponding paraffins. [Pg.73]

Ionic Reduction. The remarkable hydrogenating ability of sodium borohydride-triflic acid was reported in the hydrogenation of C02.126 Methane as the sole... [Pg.95]

A Rh on Si02 catalyst promoted with V and Sm showed similar improvements in catalyst performance.522 Sm3+ ions improve the dispersion of Rh and increase CO and H2 uptakes, enhancing the formation of acetaldehyde and acetic acid. Lower-valence V ions have a good H2 storage capacity, thereby increasing the hydrogenation ability of the catalyst and promoting the formation of ethanol. [Pg.127]

Prevent deactivation. The increased hydrogenating ability of Co prevents accumulation of coke deposits. There is some merit in this proposal as Mo/Al catalysts appear to deactivate faster than CoMo/Al catalysts (100). However, initial activity of the sulfided catalyst was higher for the CoMo/Al catalyst (100). [Pg.303]

Schutz and Weitkamp (15) show product distributions for the hydrocracking of dodecane on several noble metals on zeolite catalysts. Product distributions are in general similar to those distributions previously reported for noble metals on ambrphous supports. These results show no major unexpected effect of the zeolitic support differences among the catalysts tested are related to changes in hydrogenation ability or acidity. [Pg.35]

Another model projection is the smallness of most activation barriers for hydrogenation of C2Ht species. In general, for all hydrogenation reactions, the calculated barriers decrease in the order Fe/W > Ni > Pt, which explains an increase in the hydrogenation ability of transition metals in the direction Fe/W < Ni < Pt, making Pt overall the best hydrogenation catalyst (119). [Pg.146]

The unique hydrogenating ability of a mixture of synthesis gas and a cobalt catalyst is intimately associated with the chemistry of the cobalt compounds formed under these conditions, namely dicobalt octacarbonyl and cobalt hydrocarbonyl. Before any mechanism for the hydrogenation reaction is discussed it is imperative to consider, if even briefly, the chemistry of the cobalt carbonyls. [Pg.402]

The addition of increasing amounts of iodine promoters accelerates the hydrocarbonylation of methanol, but at the same time detioriates the hydrogenation ability of the cobalt catalysis. To obtain a high ethanol selectivity under these conditions, catalysts active for hydrogenation in the presence of iodine have to be added. Ruthenium compounds have been proved to be most suitable, as was mentioned earlier. Althou no detailed studies on the ruthenium intermediates involved are available, it is well known that aliphatic aldehydes... [Pg.126]

As shown in Fig.5, gasohne fraction was produced with 65% selectivity in case of H-Ga-sdicate. Hydrogen inverse spdlover feature of Ga part in sdicate suppress hydrogenation ability to paraffin formation and promote ohgomerization of lower olefins to gasohne component. [Pg.27]

For practical applications, Ni-Mo catalysts generally have higher hydrogenation ability for saturating aromatic ring that is connected to thiophenic sulfur, while... [Pg.235]

Figures 6 and 7 show the hydrogenation of propene over MoH-mordenite (6.1 wt % Mo, 1.95 Mo/unit cell). The fully reduced form (Mo5+) exhibits significant hydrogenation ability, however the oxidised form (Mo6+) exhibits almost pure metathesis. It is generally accepted that the lower the oxidation state of Mo the greater the rate of hydrogenation (refs. 9,10). The rate must be significantly low over the fully oxidised form that the metathesis reaction predominates (some propane is observed), and hydrogen has the affect of inhibiting acid-catalysed secondary reactions. Figures 6 and 7 show the hydrogenation of propene over MoH-mordenite (6.1 wt % Mo, 1.95 Mo/unit cell). The fully reduced form (Mo5+) exhibits significant hydrogenation ability, however the oxidised form (Mo6+) exhibits almost pure metathesis. It is generally accepted that the lower the oxidation state of Mo the greater the rate of hydrogenation (refs. 9,10). The rate must be significantly low over the fully oxidised form that the metathesis reaction predominates (some propane is observed), and hydrogen has the affect of inhibiting acid-catalysed secondary reactions.
Reaction of propene with hydrogen over fully reduced (Mo ) MoH-mordenite produced mainly the hydrogenated product propane, with the presence of hydrogen appearing to suppress acid catalysed reactions. The fully oxidised (Mo6+) catalyst under the same conditions exhibited little hydrogenation ability, with products more like those of metathesis. [Pg.620]

In an earlier work Lazier and Vaughen (11) reported that amorphous chromia obtained by precipitation promoted the hydrogenation of olefin hydrocarbons. No details of conditions or yields were given in this work. Ipatieff, Corson, and Kurbatov (12) found no hydrogenation ability for pure chromia on either isopentene or benzene at atmospheric pressure and no hydrogenation of benzene at high pressures. [Pg.711]

By use of the catalyst possessing both acid and basic sites, the product diacetonealcohol undergoes dehydration to mesityl oxide. If hydrogenation ability is further added to the catalyst, mesityl oxide is hydrogenated to methylisobutylketone(M IBK). [Pg.42]


See other pages where Hydrogen ability is mentioned: [Pg.12]    [Pg.70]    [Pg.74]    [Pg.233]    [Pg.60]    [Pg.42]    [Pg.103]    [Pg.378]    [Pg.302]    [Pg.306]    [Pg.310]    [Pg.44]    [Pg.12]    [Pg.147]    [Pg.216]    [Pg.145]    [Pg.112]    [Pg.115]    [Pg.662]    [Pg.680]    [Pg.263]    [Pg.39]    [Pg.235]    [Pg.554]    [Pg.658]    [Pg.585]    [Pg.593]    [Pg.337]    [Pg.312]    [Pg.313]    [Pg.661]    [Pg.679]    [Pg.500]    [Pg.596]   
See also in sourсe #XX -- [ Pg.29 , Pg.46 , Pg.128 ]




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