Group 10 VIII applications

Fischer-Tropsch Catalysts. - It is well known that all Group VIII transition metals are active for F-T synthesis. However, the only F-T catalysts, which have sufficient CO hydrogenation activity for commercial application, are composed of Ni, Co, Fe or Ru as the active metal phase. These metals are orders-of-magnitude more active than the other Group VIII metals and some characteristics of Ni-, Fe-, Co- and Ru-based F-T catalysts are summarized in Table 2. 

Catalysts. - Group VIII metals, conventional base metal catalysts (Ni, Co, and Fe) as well as noble metal catalysts (Pt, Ru, Rh, Pd) are active for the SR reaction. These are usually dispersed on various oxide supports. y-Alumina is widely used but a-alumina, magnesium aluminate, calcium aluminate, ceria, magnesia, pervoskites, and zirconia are also used as support materials. The following sections discuss the base metal and noble metal catalysts in detail, focusing on liquid hydrocarbon SR for fuel cell applications. 

D. Bauerle, Laser Chemical Processing. In Landolt-Bomstein New Series, Group VIII Advanced Materials and Technologies, Vol. 1 Laser Physics and Applications, Subvolume C Laser Applications, ed. by R. Poprawe, H. Weber, G. Herziger (Springer, Berlin 2004) pp 311-354... 

Tungsten carbide — WC, belongs to a class of Group IV B-VIB transition metal carbides and nitrides, often referred to as interstitial alloys, in which the carbon and nitrogen atoms occupy the interstitial lattice positions of the metal [i]. These compounds possess properties known from group VIII B precious metals like platinum and palladium [ii]. Thus, they show remarkable catalytic activities, attributed to a distinct electronic structure induced by the presence of carbon or nitrogen in the metal lattice. Tungsten carbide resembles platinum in its electrocatalytic oxidation activity (- electrocatalysis) and is therefore often considered as an inexpensive anode electrocatalyst for fuel cell [iii] and -> biofuel cell [iv] application. 

By contrast with the radiation-induced procedures, isotope exchange reactions catalyzed by Group VIII transition metals are applicable to both deuterium and tritium labeling of heterocyclic compounds. Because of recent mechanistic developments in this field, it is possible to predict with some degree of certainty the reactivity of a molecule for deuteration and also for moderate levels of tritiation. If compensation for additional radiation-induced interactions is made, then the theory also satisfactorily explains high specific activity tritiations. 

Synthetic Applications of Group VIII Transition Metal Complexes... 

Some of the Group VIII metals have uses as oxidation catalysts (5). All except platinum do however tend to oxidize under vigorous conditions, such as are used in ammonia oxidation and the Andrussow process, for which only platinum and its alloys are acceptable catalysts. Under milder conditions both platinum and palladium have somewhat limited applications in liquid-phase oxidation processes, as for example in the carbohydrate field. 

Selective chemisorptions of hydrogen and carbon monoxide have also been used to determine the surface area of other Group VIII metals, especially by Yates et al. (6). Development of methods applicable to other metals is only a matter of ingenuity and from now on every investigation of catalysis on supported metals must include a determination of the surface area of the metal. 

M. R. Buchmeiser, Homogenous metathesis polymerization by well-defined group VI and group VIII transition metal alkylidenes fundamentals and applications in the preparation of advanced materials, Chem. Rev., 100 (2000) 1565-1604. 

Complexes of the [SnCl3] anion and. to a lesser extent, the [GeCl3] anion have found extensive application in homogeneous catalysis.1 All the Group VIII metals have been reported to form... 

The main reforming reactions are listed in Table 1. Reactions 1.1 - 1.4 are catalysed by group VIII metals with nickel as the preferred metal for industrial applications. These reactions may be accompanied by thermal cracking (pyrolysis) of the hydrocarbons (1.5) at temperatures above 600-650 C. 

Rate oscillations, spatiotemporal patterns and chaos, e.g. dissipative structures were also observed in heterogeneous catalytic reactions. If compared with pattern formation in homogeneous systems, the surface studies introduced new aspects, like anisotropic diffusion, and the possibility of global synchronization via the gas phase. Application of field electron and field ion microscopy to the study of oscillatory surface reactions provided the capability of obtaining images with near-atomic resolution. The most extensively studied reaction is CO oxidation, which is catalyzed by group VIII noble metals. 

As it is well known, metals of group VIII of Mendeleev s periodic system have found a widespread application as catalysts in a variety of chemical reactions. 

Nevertheless only scare data is available in the recent literature on the application of Group VIII noble metal (M) or rhenium-based mono- and Re-M bimetallic catalysts, in the hydrogenolysis of esters or hydrogenation of acids to alcohols. Recently a few publications, - and patents. have been reported on the transformation of different carbonyl compounds (saturated and unsaturated esters, acids and carboxamides) over rhenium-containing catalysts. In the bimetallic catalysts used for the hydrogenation of carbonyl compounds the rhenium was combined with Pd, or Rh. In the case of catalysts used for the hydrogenation of unsaturated carbonyl compounds the rhenium is usually modified with tin. ... 

Homogeneous Metathesis Polymerization by Well-Defined Group VI and Group VIII Transition-Metal Alkylidenes Fundamentals and Applications in... 

The two insertion modes are designated a and b, to make the scheme applicable to various kinds of substituted ethylenes. For the case of propylene (X = CH3), a is the anti-Markownikoff mode, and we have seen that, for electronic reasons, this mode is generally favored in the case of group VIII catalysts, in particular in the presence of donor ligands (Table 6). Actually, if no particularly bulky ligands are present in catalytic Ni species, the aa route is by far predominant, and 4-methylpentene-l, and positional isomers therefrom, are the main products of dimerization -66)... 

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