Graphite, intercalation compounds chlorides

Issi, J. -P., Transport properties of metal chloride acceptor graphite intercalation compounds. In Graphite Intercalation Compounds,... 

A quite different sort of graphite intercalation compound is formed by the halides of many elements, particularly those halides which themselves have layer structures or weak intermolecular binding. The first such compound (1932) was with FeCl3 chlorides, in general, have been the most studied, but fluoride and bromide intercalates are also known. Halides which have been reported to intercalate include the following ... 

Layer misfit was first recognised in the structures of two metal chloride-graphite intercalation compounds. Intercalates of graphite with many other metal halides, including fluorides and bromides, have since been reported, but they seem to be of the CC type and are not discussed here. 

Graphite intercalate compounds have also been used to catalyse Fischer-Tropsch reactions. Although alkah-metal intercalates are active,the yield of hydrocarbons can be markedly improved by replacing the alkali metal with a transition-metal chloride complex or an alkali-metal/transition-metal chloride intercalate. 

Kang F, Leng Y, Zhang T (1998), Electrochemical synthesis and characterization of ferric chloride-graphite intercalation compounds in aqueous solution , Garbon, 36(4), 383-390. 

Iwashita N, Izumi I, Hamada Y (1998), Photosensitization of graphite intercalation compounds with metal chlorides , Garbon, 36(11), 1700-1703. 

The graphite-metal halides constitute the most populous group of intercalation compounds. Most of the investigative efforts have been directed towards the metal chlorides, particularly FeCls, whereas considerably less is known about the metal bromides S21). Compounds... 

The first compound of this sort was ferric chloride graphite 21, 84)-Riidorff and Schulz (65) obtained from graphite and ferric chloride at 200-300° a stage 1 compound with 60-70% of ferric chloride. In this compound separate layers of ferric chloride, as they occur in the lattice of the pure FeCls, were intercalated between the carbon planes, which were unchanged, though the distance between them was increased to 9.4 A. 

In attempts to separate ferric chloride and aluminum chloride by intercalation in graphite, Croft (10) found that aluminum chloride could be intercalated either alone or together with ferric chloride. Further work (11, 11a) led to the surprising result that numerous metal chlorides are able to react with graphite. The compounds studied are set out in Table VI, which is taken from Croft s work. It includes thirty... 

These intercalation compounds were obtained by prolonged heating of graphite with the lower chlorides CoCls or PdCh in a stream of chlorine. 

The similarity of the two structures led Croft (15) to attempt the preparation of boron nitride intercalation compounds. He used the metal halides SbCls, SbCU, AsCU, CuCl, CuCh, FeCU, Aids, and also BF3, BCls, Br2, ICl, liquid ammonia, and N2H4. The same procedure was used as in the preparation of metal chloride-graphite compounds. 

Imides, lattice energies of, 196 Indenyl compounds, eighth-group elements and, 73,75 Intercalation, metal chlorides, graphite and, 254-259 metal oxides, graphite and, 260-262 metal sulfides, graphite and, 260-262 Intercalation compounds, graphite, comparative survey of, 263-264... 

Metal chloride intercalate compounds such as graphite-FeQa, ZnCl2, BeCl2, ZrCU, NbCls, and TaCls are all Friedel-Crafts catalysts, and their action has been well described. The mechanism of formation of graphite acceptor compounds of this type is of interest in that electrons are removed from graphite to form negative ions the neutral molecules formed at the same time diffuse into the lattice. 

Capacitance measurements of carbon electrodes have also been made in molten halides, particularly chlorides [30-32], molten nitrates [33, 34], and in cryolite—alumina melts (graphite and glassy carbons). In cryolite—alumina melts, the double-layer capacitance of the basal plane of graphite, in the range 0.7—1.0 V (vs aluminum reference electrode) is about 20[xF/cm at 0.9 V, i.e., in a potential range where no appreciable flow of current has been observed. Data indicate that the capacitance is influenced by adsorbed species from the melt, possibly yielding intercalation compounds, and uncertainty in the true area of the electrode [34]. 

Biintercalation, an interleaving of different inserted species, has been studied in the case of inserted halide species " . Halogen-containing solvents, with metal chlorides, can also lead to ternary phases, such as graphite-FeCl3-C2H4Cl2 . A different approach to inserted halides is the intercalation compound with trimethyltin chloride . Finally, the intercalation of halides into carbon fibers is an area of increasing interest . ... 

The electrical conductivity of carbon fibers is improved by intercalating donors (e.g., alkali metals) or acceptors (e.g., Br2, CI2, F2, chlorides or fluorides) between the carbon layers [1] [62]. These intercalation compounds are more easily formed in fibers which exhibit a highly ordered graphitic structure, i.e., the mesopitch based UHM carbon fibers. Some intercalation... 

There is relevance of these considerations to the processes of activation of carbons (discussed in Chapters 5 and 6). A series of compounds, known as intercalation compounds, exists in which ions and molecules are located between the graphene layers of carbon materials, principally graphitic structures, but not necessarily so. These reactions, leading to the formation of intercalation compounds, involve electron transfer processes. For example, electron transfer from the graphene layer forms a bromine anion (Br ), or electron transfer to the graphene layer forms a potassium cation (K ). Ferric chloride also forms an intercalation compound. 

Detailed structure determinations are rather rare (FeCl3 [96, 100], Br2 [91], M0CI5 [104, 105]). In contrast to the alkali-metal compounds and the CF3COOH compounds, the relative orientation ABAB of the graphite layers is not altered by the intercalation of most of these metal chlorides, HF and bromine. For the graphite bisulfate compound apparently both types of stacking exist for the first-stage compound. 

Preparation of finely-divided iron/carbon catalysts for ammonia synthesis by the controlled reduction of graphite/ferric chloride intercalation compounds. K. Kalucki, W. Morawski, and W. Arabczyk (Politechnika Szczecinska). PL 141907 (1988). 

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