The demand for graphites with specific properties and for an improvement in the economics of graphite production in recent years has led to an increased interest in catalytic graphitisation. At the present time, however, there is no review available of published studies and this paper attempts to make good this deficiency. Mechanisms whereby inorganic additives can catalyse graphitisation are considered, followed by a discussion of the mechanisms by which inorganic additives promote the graphitisation process. A comprehensive survey of the relevant literature to date is presented which describes in more detail the type of carbon used, the experimental techniques employed and the improvement obtained in graphite quality.

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Gilsonite pitch and polyvinyl chloride (PVC) were carbonised at slow rates of 0 . 5 "~ min-I and the products of carbonisation examined by chromatography, mass spectrometry, nuclear magnetic resonance spectroscopy, optical microscopy, scanning electron microscopy and electron spin resonance spectroscopy. The original Gilsonite pitch contains -5 % of aromatic protons, rising to 24 % in soluble material just prior to formation of the graphitisable semi-coke at 410"~. The carbonised PVC melts ( 3 8 9 "~) to form a black isotropic liquid with 23 % aromatic protons, rising to 41 % at the onset of the coalescence of the mesophase spheres ( 4 2 0 4 4 0 "~) .The constituent molecules are considered to be hydrogenated cyclic structures possessing a great variety of saturated and unsaturated side-groups . During carbonisation, there is loss of side-groups, but it is the essentially aliphatic cyclic structures which co-cdense to form the mesophase. Further aromatisation must occur within the mesophase and semi-coke. The presence of heteroatoms within the Gilsonite pitch is considered to restrict the Rrowth of the mesophase structures and their ability to coalesce to form the much larger units of anisotropic character observed in the case of PVC. Electron spin resonance spectroscopy suggests that free radicals are not necessary to form the mesophase, the free radical character being developed afrer formation of the mesophase, probably as the aromaticity is developed.

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