Graphite coal derived

The authors wish to thank 1. C. Lewis and the UCAR Carbon Company for their assistance in the preparation and characterization of the coal-derived graphites. This work was partially funded by a grant from the U. S. Department of F.nergy DE-FG02-91NP00159. This support is gratefully acknowledged. 

Seehra, M. S., and Pavlovic, A. S., X-ray diffraction, thermal expansion, electrical conductivity, and optical microscopy studies of coal-derived graphites. Carbon, 1993, 31, 557 564. 

In recent years researchers at West Virginia University have developed coal-derived pitches on a laboratory scale in quantities sufficient to make 1 kg samples of calcined coke for fashioning graphite test specimens. The pitches were derived by uhlizmg solvent extraction with N-methyl pyrrohdone (NMP). This solvent is able to isolate coal-based pitches m high yield and with low mineral matter content [13]. It is this work that will form the basis of the discussion for the later part of this chapter. 

The coal-derived pitch precursors for WVU-1, WVU-2, and WVU-3 test graphites were de-ashed by the combined centrifugation and filtration method while all of the other pitches were de-ashed by centrifugation alone (2000 G, 90 minutes). 

Table 24. Some properties of WVU coal-derived calcined cokes and their graphites ...

It has been demonstrated that a solvent-extraction procedure with N-methyl pyrrolidone is capable of producing coal-derived extract pitches with low-ash contents. Moreover, the properties of the pitches can be varied by partial hydrogenation of the coal prior to extraction. The yield of the pitches along with the physical and chemical properties of the cokes and graphites vai in an understandable fashion. 

Preparation and Evaluation of Graphite From Coal-Derived Feedstocks... 

Petroleum- and coal-derived pitches are basic raw materials for the manufacture of carbon and graphite. It is not surprising, then, that pitch was considered as a promising material for melt spinning into fibers for later conversion into carbon fibers. Pitch contains more than 90% carbon, much more than rayon or PAM. It is a con lex mixture of aromatic hydrocarbon molecules of wide molecular weight distribution and, therefore, behaves like a glass in its ability to be drawn into a fiber. 

Coal-derived pitch coke, although it exhibits a pre-graphitic microstructure, has often a lower graphitizability than petroleum coke. Fractions of coal tar pitches (obtained by extraction or filtration) may form cokes with needle-like structures and have an improved graphitizability. The usually lower grcg>hitizability compared to petroleum coke is due to an inhibition ofmesophase growth because of chemical and physical differences of the cokes. See coal tar pitches, coke, petroleum coke... 

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