Dehydrogenation metals active

We have found that the activity of nickel towards dehydrogenation and dehydrocyclization is increased on particles which contain zeolites relative to non-zeolitic particles of the same matrix composition and surface area. However, the coke and hydrogen making capability of vanadium does not depend on the presence or absence of zeolite. The increase in hydrogen and coke production by nickel when the zeolite is present in the matrix suggests that the zeolite increases the metal activity in catalyzing secondary... 

Different catalysts bring about different types of isomerization of hydrocarbons. Acids are the best known and most important catalysts bringing about isomerization through a carbocationic process. Brpnsted and Lewis acids, acidic solids, and superacids are used in different applications. Base-catalyzed isomerizations of hydrocarbons are less frequent, with mainly alkenes undergoing such transformations. Acetylenes and allenes are also interconverted in base-catalyzed reactions. Metals with dehydrogenating-hydrogenating activity usually supported on oxides are also used to bring about isomerizations. Zeolites with shape-selective characteristics... 

In spite of their high formal oxidation states, the polyhydrides behave as low-oxidation species because of the low charge on the metal, which is close to the charge found in the free metal. From the organometallic point of view, the most remarkable consequence of this reactivity is found in the reactions of polyhydrides with alkanes leading to alkane dehydrogenation. Alkane Activation or C-H Bond... 

Determination of Coke Deposition on Metal Active Sites of Propane Dehydrogenation Catalysts... 

Characterized of the nickel state on deactivated USY can contribute to answer one important question How dehydrogenation properties are affect by NiA7 ratio To develop an easy test to measure metal activity and its interaction on USY is also an objective of this work. 

It is also noted that in determining the heats of hydrogenation of unsaturated five- and seven-membered rings, Kistiakowsky performed the hydrogenations catalytically, using metals active in the dehydrogenation of cyc ohexane. 

In the dehydrogenation, the activity of the catalyst, TOF, is independent of the particle size of the metal or the catalyst used. Therefore, the reaction is insensitive to the structure. 

Fig. XVIII-17. Correlation of catalytic activity toward ethylene dehydrogenation and percent d character of the metallic bond in the metal catalyst. (From Ref. 166.)...

They represent an improvement over earlier platinum on alumina catalysts in their abiHty to resist coke fouling when operated at low pressures. Dehydrogenation and hydrogenation occur on the active metal sites isomerization takes place on the acidic alumina surface. 

Electroless reactions must be autocatalytic. Some metals are autocatalytic, such as iron, in electroless nickel. The initial deposition site on other surfaces serves as a catalyst, usually palladium on noncatalytic metals or a palladium—tin mixture on dielectrics, which is a good hydrogenation catalyst (20,21). The catalyst is quickly covered by a monolayer of electroless metal film which as a fresh, continuously renewed clean metal surface continues to function as a dehydrogenation catalyst. Silver is a borderline material, being so weakly catalytic that only very thin films form unless the surface is repeatedly cataly2ed newly developed baths are truly autocatalytic (22). In contrast, electroless copper is relatively easy to maintain in an active state commercial film thicknesses vary from <0.25 to 35 p.m or more. 

The chemistry of ethyl alcohol is largely that of the hydroxyl group, namely, reactions of dehydration, dehydrogenation, oxidation, and esterification. The hydrogen atom of the hydroxyl group can be replaced by an active metal, such as sodium, potassium, and calcium, to form a metal ethoxide (ethylate) with the evolution of hydrogen gas (see Alkoxides, metal). 

Metals are most active when they first deposit on the catalyst. With time, they lose their initial effectiveness through continuous oxidation-reduction cycles. On average, about one third of the nickel on the equilibrium catalyst will have the activity to promote dehydrogenation reactions. 

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