Graphite intercalates catalysis

Fischer-Hepp rearrangement, 22 151 Fischer-Tropsch catalysis, by graphite intercalation compounds, 23 318 Fish, arsenic in, 44 150, 167, 168, 170, 180 Fission... 

The reaction of various carbonaceous materials with steam to yield CO, CO2, and H2 has been intensively studied. Of special interest has been the catalysis of this reaction by various alkali metal containing compounds, most notably potassium carbonate (32-37). Various mechanisms have been proposed, some including alkali metal atoms (37) or even graphite intercalation compounds (38) as intermediates. 

Aside from new metals, novel technical and practical developments have widened the scope of the one-step procedure. Examples of these are the introduction of highly reactive metals (either through their fine particle size or through their graphite intercallation compounds) or the use of sonochemical catalysis. 

M. A.H.Boersma, Catalytic properties of graphite Intercalation compounds, in J.J.Burton and R.L,Garten, Advanced Materials in Catalysis, Academic Press, New York, San Francisco, London 1977, pp. 67-99. 

Amorphous carbons, carbon black, soot, charcoals, and so on, are forms of graphite or fullerenes. The physical properties depend on the nature and magnitude of the surface area. They show electrical conductivity, have high chemical reactivity due to oxygenated groups on the surface, and readily intercalate other molecules (see later). Graphite and amorphous carbons as supports for Pd, Pt, and other metals are widely used in catalysis and for the preparation of diamond films.18... 

Transition metal carbonyl clusters intercalated with lamellar materials such as graphite or smectites have been prepared and have been shown to be useful in catalysis 68). For instance, sodium montmorillonite was impregnated with [Ru(NH3)5]Cl3 in water under reflux. After flltration and drying, the resulting complex was dissolved in methanol and reduced with carbon monoxide at 80°C, 100 bar, for 16 hours. Infrared analysis has shown the formation of a sodium montmorillonite-intercalated [Ru3(CO),2] complex. This system was claimed to be active for the hydro-formylation of propene either with CO/Hj or CO/HjO in the presence of a basic promoter. 

Considering adsorption as the first step in catalysis, both physical and chemical adsorption has been observed with intercalates. Watanabe et a/. have shown that selective adsorption based on molecular size occurs with potassium-, rubidium-, and caesium-graphite. The molecular sieve properties are not as distinctive as in zeolites, as a result of the comparatively easy expandability of the layers. Once the gas enters the layers, both chemisorption and chemical reaction is possible. Therefore, for example, adsorption... 

Graphite is certainly a layered material for which there is a large body of NMR literature, although the connection with catalysis is a bit more tenuous. In general, carbon supports (which may contain graphitic phases) for catalysts are rarely used at this point. There is, however, some interest in metal intercalated... 

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